Patent Publication Number: US-8977962-B2

Title: Reference waveforms

Description:
BACKGROUND 
     Currently, many media editing applications for creating media presentations exist that composite several pieces of media content such as video, audio, animation, still image, etc. Such applications give graphical designers, media artists, and other users the ability to edit, combine, transition, overlay, and piece together different media content in a variety of manners to create a resulting composite presentation. Examples of media editing applications include Final Cut Pro® and iMovie®, both sold by Apple® Inc. 
     The media editing applications include a graphical user interface (“GUI”) that provides different tools for creating and manipulating media content. These tools include different controls for changing the volume of audio for different media contents. One way of changing the audio volume is to display a waveform that plots the audio levels as a function of time and provide a control to change the relative level of the audio. Some GUIs display a volume bar on the audio waveform and allow the user to change the volume by dragging the volume bar up or down by a relative value. For instance, by moving the volume bar from −7 decibels (dB) to −5 dB the volume of the audio is increased by 2 dB. 
     This method of changing the volume has several shortcomings. For instance, even after the maximum allowed adjustment, the volume of a quiet clip might not become loud enough. On the other hand, a clip with a loud peak might be clipped off if the volume is raised by a relative value that makes the peak go beyond the maximum allowed level. In addition, in a non-linear volume scale, changes to the volume bar and the resulting changes to the corresponding waveform do not move in locked step. 
     Additionally, when portions of an audio clip have different loudness, using a single volume bar to adjust the volume of the audio clip does not allow fine tuning of the volume in different portions of the clip. Similarly, when an audio clip or a portion of an audio clip is displayed with low volume, visually identifying different points such as maximum points and minimum points (or the peaks and valleys) of the clip and aligning them to each other or to a specific time on a displayed timeline is difficult. 
     BRIEF SUMMARY 
     Some embodiments provide a method for adjusting the sound volume of media clips. In some of these embodiments, volume adjuster graphs are provided to adjust the media clips volumes. Each volume adjuster graph includes one or more segments. The segments are either straight (e.g., horizontal, vertical, or diagonal lines) or curved (e.g., curved lines). The volume adjuster graphs are individually set for each clip based on the intrinsic (or absolute) volume values of the clip. In some embodiments, the volume adjuster graphs are set for each clip based on the peak value, RMS value, or loudness value of the clip. A user can drag a segment of a volume adjuster graph and move the segment to set the absolute sound level of a clip. The volume adjuster graphs can be hidden in some embodiments. In these embodiments, dragging on any portion of a clip is treated as dragging on the corresponding segment of the volume adjuster graph. 
     Using the absolute values to adjust the volume has several advantages. For instance, a quiet clip can be adjusted to the maximum allowed level by dragging the volume adjuster graph to set the peak of the clip to the maximum allowed level. Also, a loud clip can be adjusted without clipping a portion of the clip by setting the volume adjuster graph to automatically stop at the maximum allowed absolute value. Accordingly, maximum advantage is taken from the available adjustment range based on the loudness of each clip. 
     Furthermore, using the absolute values to adjust the volume makes the volume adjuster graph and the audio waveform to move in locked steps. Another advantage of using the absolute values is each clip can have its own volume adjuster as opposed to using a relative volume adjuster that is generally the same for all clips even when the clips have different loudness values. Also, using an absolute level adjuster allows the user to match the loudness of two clips simply by setting their values to the same amount. 
     Some embodiments provide a deformable volume adjuster graph with multiple segments for each clip. In these embodiments, a single audio clip can have different volume adjuster segments for different portions of the clip. When one or more portions of the clip are selected, the selected and non-selected portions of the clip are analyzed and different volume adjuster segments are provided for each portion of the clip. For instance, in an embodiment where volume adjuster graphs are set based on the peak value of the clip, each particular portion of the clip is assigned a separate volume adjuster segment based on the peak volume value for the particular portion. The deformable volume adjuster graphs allow for better adjustment of volume, especially when different portions of the clip have different volume levels. 
     Some embodiments display reference waveforms to facilitate visual identification of different points such as maximum points and minimum points (or peaks and valleys) of an audio clip. The reference waveform includes points that correspond to points on the original audio waveform, except that some or all points on the reference waveform are accentuated to easily identify the positions of the corresponding points on the audio waveform. The reference waveform in some embodiments is superimposed over a corresponding audio waveform. In other embodiments, the reference waveform is displayed in another position (e.g., above or below the audio waveform) or is displayed in lieu of the audio waveform. 
     The reference waveforms are especially useful when an audio waveform (or at least a portion of the clip) has low volume which makes the visual identification of the maximums and minimums of the waveform difficult. Displaying the reference waveform which accentuates the peaks and valleys of the original waveform facilitates the identification of these maximums and minimums. In addition, the reference waveform makes it easier to align a point on the audio waveform to a certain time instance or to align them with other waveforms or other media clips. For instance, the user identifies the desired point on the reference waveform and drags the identified point along with the corresponding point on the original clip to a target time value. 
     The preceding Summary is intended to serve as a brief introduction to some embodiments of the invention. It is not meant to be an introduction or overview of all inventive subject matter disclosed in this document. The Detailed Description that follows and the Drawings that are referred to in the Detailed Description will further describe the embodiments described in the Summary as well as other embodiments. Accordingly, to understand all the embodiments described by this document, a full review of the Summary, Detailed Description and the Drawings is needed. Moreover, the claimed subject matters are not to be limited by the illustrative details in the Summary, Detailed Description and the Drawings, but rather are to be defined by the appended claims, because the claimed subject matters can be embodied in other specific forms without departing from the spirit of the subject matters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the invention are set forth in the appended claims. However, for purpose of explanation, several embodiments of the invention are set forth in the following figures. 
         FIGS. 1A and 1B  conceptually illustrate a graphical user interface (“GUI”) of a media editing application that utilizes a prior art relative volume adjustment scale. 
         FIG. 2  conceptually illustrates three prior art examples of the effects of changing the volume level by a relative amount for a quiet waveform. 
         FIG. 3  conceptually illustrates three prior art examples of the effects of changing the volume level by a relative value for a waveform with a loud peak. 
         FIG. 4  illustrates changing the volume of an audio clips by using a relative volume adjustment according to prior art. 
         FIG. 5  conceptually illustrates a graphical user interface for changing audio volumes in a media editing application of some embodiments of the invention. 
         FIG. 6  conceptually illustrates a graphical user interface of a media editing application for providing deformable volume adjuster lines in some embodiments of the invention. 
         FIG. 7  conceptually illustrates a graphical user interface for displaying reference waveforms in a media editing application of some embodiments of the invention. 
         FIG. 8  conceptually illustrates a process for changing the audio volume of one or more multimedia clips in some embodiments. 
         FIG. 9  conceptually illustrates three audio waveforms displayed in the waveform display area of a GUI in some embodiments. 
         FIG. 10  conceptually illustrates changing the volume of a quiet clip in some embodiments. 
         FIG. 11  conceptually illustrates changing the volume of a loud clip in some embodiments. 
         FIG. 12  conceptually illustrates a process  0  for changing the audio volume of one or more multimedia clips in some embodiments. 
         FIG. 13  conceptually illustrates several possible positions for setting the volume adjuster lines in some embodiments. 
         FIG. 14  conceptually illustrates a volume adjuster line which is placed at the RMS level (or any other level below the peak) of a waveform in some embodiments. 
         FIG. 15  conceptually illustrates a volume adjuster line which is placed at the RMS level (or any other level below the peak) of a waveform in some embodiments. 
         FIG. 16  conceptually illustrates a process for changing the audio volume of a multimedia clip in some embodiments. 
         FIG. 17  conceptually illustrates different operations for pre-normalization in some embodiments. 
         FIG. 18  conceptually illustrates three waveforms in two stages in some embodiments. 
         FIG. 19  conceptually illustrates a process for adjusting the volume adjuster line after trimming a portion of the clip in some embodiments. 
         FIG. 20  conceptually illustrates a waveform with the volume adjuster line set at the peak volume in some embodiments. 
         FIG. 21  conceptually illustrates a process for setting and displaying deformable volume adjuster lines in some embodiments of the invention. 
         FIG. 22  illustrates a single audio clip with a deformable volume adjustment adjuster line in some embodiments. 
         FIG. 23  conceptually illustrates a single audio clip with a deformable volume adjustment adjuster line in some embodiments. 
         FIG. 24  conceptually illustrates the audio clip of  FIG. 22  where two portions of the clip are selected. 
         FIG. 25  conceptually illustrates adjusting the transitional portion between two volume adjuster lines in some embodiments. 
         FIG. 26  conceptually illustrates a deformable volume adjuster line where adjusting a portion of the deformable adjuster line does not affect the other portions of the deformable volume adjuster line. 
         FIG. 27  conceptually illustrates a deformable volume adjuster line where adjusting a portion of the deformable adjuster line affect the other portions of the deformable volume adjuster line. 
         FIG. 28  conceptually illustrates displaying a reference graph that identifies the original volume adjuster graph in some embodiments of the invention after the original volume adjuster graph is modified. 
         FIG. 29  conceptually illustrates three audio clips with the corresponding volume adjuster lines in some embodiments. 
         FIG. 30  conceptually illustrates an audio waveform and its corresponding reference waveform in some embodiments. 
         FIG. 31  conceptually illustrates a clip and its associated reference waveform in two stages in some embodiments. 
         FIG. 32  conceptually illustrates a process for displaying reference waveforms in some embodiments. 
         FIG. 33  conceptually illustrates determining the values of different points for reference waveforms in some embodiments of the invention. 
         FIG. 34  conceptually illustrates a process for aligning an audio in with a desired point on a display area of some embodiments of the invention. 
         FIGS. 35 and 36  conceptually illustrate aligning of an audio clip to a particular point on a timeline in some embodiments. 
         FIG. 37  conceptually illustrates a process for aligning several audio clips in some embodiments of the invention. 
         FIGS. 38 and 39  conceptually illustrate aligning of several audio clips in some embodiments of the invention. 
         FIG. 40  conceptually illustrates the software architecture for adjusting media clip volumes in a media editing application in some embodiments. 
         FIG. 41  conceptually illustrates a graphical user interface of a media-editing application of some embodiments. 
         FIG. 42  conceptually illustrates an electronic system with which some embodiments of the invention are implemented. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description of the invention, numerous details, examples, and embodiments of the invention are set forth and described. However, it will be clear and apparent to one skilled in the art that the invention is not limited to the embodiments set forth and that the invention may be practiced without some of the specific details and examples discussed. 
     Some embodiments provide a method for adjusting the sound volume of media clips. In some of these embodiments, volume adjuster graphs are provided to adjust the media clips volumes. Each volume adjuster graph includes one or more segments. The segments are either straight (e.g., horizontal, vertical, or diagonal lines) or curved (e.g., curved lines). The volume adjuster graphs are individually set for each clip based on the intrinsic (or absolute) volume values of the clip. In some embodiments, the volume adjuster graphs are set for each clip based on the peak value, RMS value, or loudness value of the clip. A user can drag a segment of a volume adjuster graph and move the segment to set the absolute sound level of a clip. The volume adjuster graphs can be hidden in some embodiments. In these embodiments, dragging on any portion of a clip is treated as dragging on the corresponding segment of the volume adjuster graph. 
     Using the absolute values to adjust the volume has several advantages. For instance, a quiet clip can be adjusted to the maximum allowed level by dragging the volume adjuster graph to set the peak of the clip to the maximum allowed level. Also, a loud clip can be adjusted without clipping a portion of the clip by setting the volume adjuster graph to automatically stop at the maximum allowed absolute value. Accordingly, maximum advantage is taken from the available adjustment range based on the loudness of each clip. 
     Furthermore, using the absolute values to adjust the volume makes the volume adjuster graph and the audio waveform to move in locked steps. Another advantage of using the absolute values is each clip can have its own volume adjuster as opposed to using a relative volume adjuster that is generally the same for all clips even when the clips have different loudness values. Also, using an absolute level adjuster allows the user to match the loudness of two clips simply by setting their values to the same amount. 
     Some embodiments provide a deformable volume adjuster graph with multiple segments for each clip. In these embodiments, a single audio clip can have different volume adjuster segments for different portions of the clip. When one or more portions of the clip are selected, the selected and non-selected portions of the clip are analyzed and different volume adjuster segments are provided for each portion of the clip. For instance, in an embodiment where volume adjuster graphs are set based on the peak value of the clip, each particular portion of the clip is assigned a separate volume adjuster segment based on the peak volume value for the particular portion. The deformable volume adjuster graphs allow for better adjustment of volume, especially when different portions of the clip have different volume levels. 
     Some embodiments display reference waveforms to facilitate visual identification of different points such as maximum points and minimum points (or peaks and valleys) of an audio clip. The reference waveform includes points that correspond to points on the original audio waveform, except that some or all points on the reference waveform are accentuated to easily identify the positions of the corresponding points on the audio waveform. The reference waveform in some embodiments is superimposed over a corresponding audio waveform. In other embodiments, the reference waveform is displayed in another position (e.g., above or below the audio waveform) or is displayed in lieu of the audio waveform. 
     The reference waveforms are especially useful when an audio waveform (or at least a portion of the clip) has low volume which makes the visual identification of the maximums and minimums of the waveform difficult. Displaying the reference waveform which accentuates the peaks and valleys of the original waveform facilitates the identification of these maximums and minimums. In addition, the reference waveform makes it easier to align a point on the audio waveform to a certain time instance or to align them with other waveforms or other media clips. For instance, the user identifies the desired point on the reference waveform and drags the identified point along with the corresponding point on the original clip to a target time value. 
     Several more detailed embodiments of the invention are described in sections below. Section I provides an overview of the invention. Next, Section II describes providing optimized volume adjustments in some embodiments. Section III describes displaying reference waveforms to facilitate visual identification of different points of audio clips in some embodiments. Next, Section IV describes the software architecture of some embodiments. Section V describes a graphical user interface (GUI) of some embodiments. Finally, a description of an electronic system with which some embodiments of the invention are implemented is provided in Section VI. 
     I. Overview 
     A. Issues with a Relative Volume Adjustment Scale for Changing Volume 
       FIGS. 1A and 1B  illustrate a graphical user interface (“GUI”)  100  of a media editing application that utilizes a prior art relative volume adjustment scale. The relative volume adjustment scale is used to increase or decrease volume by amounts set with the volume adjuster or adjustment bar. For instance, setting the relative volume bar to −10 dB decreases the clip&#39;s arbitrary volume level by 10 dB rather than setting the average volume of the clip to −10 dB. The GUI  100  is shown at four stages  101 - 104 . The GUI  100  includes a track display area  105 , a video preview area  110 , and a clip selection area  115 . The track display area  105  includes a set of tracks  120  for displaying one or more video clips (e.g., Clips  1 - 6 ) and one or more audio clips (e.g., Clips  7 - 14 ). Each clip is provided with a volume bar. For instance, as shown in the expanded view  165 , volume bars  112 ,  113 , and  114  are provided for Clips  9 ,  10 , and  11  respectively. 
     In the first stage  101 , the track display area  105  includes original waveforms  115 ,  116 , and  117  for Clips  9 - 12 . In the first stage  101 , the gain for each of the clips is set at zero decibels (dB). Therefore, the original volume of each of the clips has not been adjusted. In the second stage  102 , the track display area  105  includes adjusted waveform  125 . In the third stage  103 , the track display area  105  includes adjusted waveform  126 . In the fourth stage  104 , the track display area  105  includes adjusted waveform  127 . There are several shortcomings in adjusting the volume by using a relative adjustment scale. For instance, even after the maximum allowed adjustment, the volume of a quiet clip (such as clip  115 ) might not become loud enough while a clip with a loud peak (such as clip  116 ) might be clipped off if the volume is raised beyond a certain level. In addition, changes to the volume bar and the resulting changes to the corresponding waveforms are not aligned. Specially, in a non-linear volume scale, the changes to the volume bar and the resulting changes to the corresponding waveform are not in locked step. 
     Details of these shortcomings are described by reference to  FIGS. 2-4  below. In these figures, it is assumed that the intrinsic sound level cannot exceed 0 dB. Also, the maximum gain adjustment is assumed to be 12 dB.  FIG. 2  conceptually illustrates three prior art examples of the effects of setting the volume level to a relative amount for waveform  115  when the peak of the original waveform  115  is at −30 dB. Each example shows the selected gain (shown as the volume bar  210 ) and the resulting waveforms  115 ,  222 , and  224 . The peak of each waveform is shown with a dashed line. Waveform  115  represents a clip with a low original volume of −30 dB. 
     In this example it is assumed that the volume of a clip cannot exceed 0 dB. However, since changes to the volume bar are relative, the maximum value for the relative increase for the volume bar is shown to be 12 dB. Since the changes are relative, setting the volume bar at 8 dB, does not set any particular point on the clip to 8 dB. Instead, the volume for every point on the clip is increased by 8 dB. 
     As shown, when the gain level is at 0 dB (as indicated by the volume bar  210 ), the peak of the resulting waveform  115  is at −30 dB. When the relative gain level is increased to 10 dB, the peak of the resulting waveform  222  is increased by 10 dB and is set at −20 dB. Also, when the relative gain level is increased to 12 dB, the peak of the resulting waveform  224  is increased by 12 dB and is set at −18 dB. 
     Since GUI  100  uses a relative volume scale, adjusting the volume bar  210  up or down applies a positive or negative gain to the original volume level of the clip (and therefore increases or decreases the height of the associated waveform). As a result, for waveform  115  that has a very low original volume, setting the gain to the maximum possible 12 dB level still results in a peak volume level of only −18 dB. Accordingly, a prior art system with an arbitrary maximum volume adjustment does not raise a quiet clip loud enough, even when the volume adjustment is maximized. 
       FIG. 3  conceptually illustrates three prior art examples of the effects of setting the volume level to a relative amount for waveform  116  when the peak of the original waveform  116  is at −7 dB. Each example shows the selected gain (shown as the volume bar  310 ) and the resulting waveforms  116 ,  322 , and  324 . Waveform  116  represents a clip with a relatively high original volume where the difference between the original peak volume (i.e., −7 dB) and the maximum possible peak volume (i.e., 0 dB) is less that the maximum possible gain adjustment of 12 dB. As shown, when the gain level is set at −7 dB, the resulting waveform peak volume  116  is also at −7 dB. When the gain level is set at 7 dB, the peak of the resulting waveform  322  is at maximum possible level of 0 dB. However, when the gain level is set at 12 dB, the resulting waveform  324  that would have been at 5 dB is clipped at 0 dB. 
     Since GUI  100  uses a relative volume scale, changing the gain for waveform  116  from 0 dB to 12 dB results in the unwanted clipping of the resulting waveform  324  at maximum 0 dB. Accordingly, a prior art system with an arbitrary maximum volume adjustment might clip a waveform when the gain level is raised beyond a level that brings the maximum volume level to 0 dB. 
     Another problem with relative volume adjustment is that the changes to the volume bar and the resulting changes to the corresponding waveform are not aligned.  FIG. 4  illustrates changing the volumes of an audio clips by using a relative volume adjustment according to prior art. The waveforms are shown in two stages  430  and  435 . As shown, in the first stage  430 , the original peak volume of audio clip  115  is at −30 dB and the volume bar  113  is originally at 0 dB level. The difference between the peak value and the volume bar is 30 dB. 
     In the second stage  435 , when the volume bar  113  is moved to 7 dB, the volume of the resulting waveform  405  is increased by 7 dB and the peak of the waveform is set at −23 dB. The distance between the peak value and the volume bar is still 3 dB. However, the displayed visual distance between the volume bar and the peak is more in the second stage  435  than in the first stage  430  due to the non-liner scale used to display the waveform. Accordingly, the volume bar and the waveform are not visually moving in locked steps. 
     B. Absolute Volume Adjustment Scale for Changing Volume 
       FIG. 5  conceptually illustrates a graphical user interface (“GUI”)  500  of a media editing application in some embodiments of the invention. As shown, GUI  500  includes a waveform display area  505 , a video preview area  510 , and a clip selection area  515 . Waveform display area  505  displays waveforms that represent the audio portions of media clips. Although, several overlapping and non-overlapping waveforms can be displayed in the waveform display area  505 , overlapping waveforms are not shown for simplicity. A more detailed description of the GUI of some embodiments is described in Section IV, below. The waveforms represent the sound levels of the clip as a function of time. In some embodiments, one or more of the represented media clips has a video portion as well. In other embodiments, none of the media clips represented have a video portion. 
     GUI  500  is shown at four stages  501 - 504 . Stage  501  represents the state of GUI  500  when three clips have been loaded and the volume of the clips has not been adjusted. Stages  502 - 504  represent the state of the GUI when the volumes of various clips have been adjusted. The video preview area  510  displays previews of the video portions of media clips (for those media clips that have a video portion). The clip selection area  515  displays icons representing clips that can be selected for display of the sound portion of the clips in the waveform display area. Volume adjuster graphs  562 ,  563 , and  564  provide adjustable gain levels for the waveforms  565 ,  566 , and  567 , respectively. The volume adjuster graphs in  FIG. 5  are shown as horizontal lines for simplicity. However, as described in more detail in Section II below, the volume adjuster graphs in some embodiments include one or more segments and each segment can have a different geometric shape such as a straight line or a curved line. 
     In the first stage  501 , the waveform display area  505  includes original waveforms  565 ,  566 , and  567 . In the second stage  502 , the waveform display area  505  includes adjusted waveform  575 . In the third stage  503 , the waveform display area  505  includes adjusted waveform  576 . In the fourth stage  504 , the waveform display area  505  includes adjusted waveform  577 . 
     As described in more detail in Section II below, the volume adjuster graphs adjust the absolute value of the volumes. In other words, setting the volume adjuster graph at a specific target volume value sets a corresponding point (e.g., the peak) of the waveform at the specified target volume value. As opposed to volume adjusters in  FIGS. 1A and 1B  which add a certain gain to volume levels, the volume adjusters  562 - 564  in  FIG. 5  set the intrinsic (or absolute) values of the volumes to a selected volume level. Volume adjuster graphs  562 - 564  provide the advantage of making a quiet clip volume to be as loud as the maximum volume level, avoiding clipping of a loud clip, and maintaining the alignment of the clips after changing their volumes. 
     C. Deformable Volume Graphs 
       FIG. 6  conceptually illustrates a graphical user interface  600  of a media editing application for providing deformable volume adjuster graphs in some embodiments of the invention. GUI  600  is shown in two stages  601  and  602 . As shown in the first stage  601 , the three audio clips each has a volume graph  562 - 564 , respectively. In this example, the volume graphs are set at the maximum peak of each audio waveform  565 - 567 . 
     As shown in the second stage  602 , a user has selected two portions of waveform  566 . The selected portions are showed by dashed rectangles  630  and  635 . As shown, after selecting different portions of waveform  566 , each particular portion is displayed with a different volume graph set at the local peak of the particular portion that controls the volume of the portion. The deformable volume graphs provide the advantage of allowing better adjustment of volume without breaking a clip into separate clips. Deformable volume graphs are especially useful when different portions of the clip have different volume levels. As described further below, in some embodiments, deformable volume graphs are automatically generated over a clip (e.g., as a running average). 
     D. Reference Waveforms 
       FIG. 7  conceptually illustrates a graphical user interface  700  of a media editing application for displaying reference waveforms in some embodiments of the invention. As shown, GUI  700  includes a waveform display area  705 , a video preview area  710 , and a clip selection area  715 . An audio waveform  720  is displayed (shown in dark highlight) in the waveform display area  705 . The waveform includes a maximum peak volume and several local maximums or minimums (or peaks and valleys). The maximums and minimums are points on the displayed waveform with a zero slope. Since the local maximums and minimums are less than the maximum peak, the local peaks are more difficult to identify on the displayed waveform  720 . In addition, for a low volume clip, it is difficult to align a point of the audio clip to a certain time instance or to align them with other waveforms (not shown) on the waveform display area  705 . 
     GUI  700  is shown in three stages  701 - 703 . As shown in the first stage  701 , a reference waveform  725  (shown in gray highlight) is superimposed over the audio waveform  720  (shown in dark highlight) in the waveform display area  705 . The reference waveform  725  includes points such as maximum points that correspond to maximum points in the waveform  720 , except that some or all of the local maximum points and minimum points in the reference waveform are accentuated to identify the positions of local maximum points and local minimums points of the audio waveform  720 . 
     In the second stage  702 , a directional input (such as dragging) is received from the user which results the reference waveform  725  along with the waveform  720  to move in the waveform display area. As described in more detail in Section III below, displaying the reference waveform also facilitates aligning points of the audio waveform to a specific time or with other waveforms or other media clips. Also, as shown in the third stage  703 , changing the volume of the audio clip results in the reference waveform keeping its general contour in some embodiments. 
     II. Optimized Volume Adjustment 
     A. Setting Volume Adjuster Graphs Based on Intrinsic Audio Volume Values 
     Some embodiments provide volume adjuster graphs to adjust the media clips volumes. Each volume adjuster graph includes one or more segments (or sections) and each segment can have a different geometric shape such as a straight line (e.g., horizontal, vertical, or diagonal lines) or a curved line. The terms volume adjuster, volume adjuster graph, volume adjuster curve, volume graph, and volume curve are used interchangeably in this specification and refer to geometric shapes used to adjust volume of audio clips. 
       FIG. 8  conceptually illustrates a process  800  for changing the audio volume of one or more multimedia clips in some embodiments of the invention. Different operations of process  800  are shown by reference to  FIGS. 9-11 . Process  800  is used in some embodiments to set volume adjuster graphs  562 - 564  in GUI  500  shown in  FIG. 5 . As shown in  FIG. 8 , process  800  displays each audio waveform by plotting volumes of the original audio clips as a function of time on absolute scale.  FIG. 9  conceptually illustrates three audio waveforms  905 - 915  displayed in waveform display area  505  of GUI  500  in some embodiments of the invention. Each of the audio waveforms  905 - 915  is shown as a set of intrinsic (or absolute) volume levels (e.g., in decibels) plotted a function of time. 
     Next, process  800  identifies (at  810 ) the peak value (e.g., in decibels) of each waveform.  FIG. 9  illustrates the peaks  920 - 930  of waveforms  905 - 915  respectively. As described further below by reference to  FIG. 12 , other embodiments set the level for the volume adjuster at locations other than the peak of the waveform (e.g., at the RMS level of the waveform). 
     Process  800  then sets (at  815 ) a separate volume adjuster for each clip at the identified peaks of the audio waveform. In some embodiments, the volume adjuster graph is superimposed over the corresponding audio waveform.  FIG. 9  illustrates volume adjuster graphs  935 - 945  for waveforms  905 - 915  respectively. As shown, each volume adjuster graph is set at the peak (or maximum) of the corresponding waveform and individually controls the particular waveform. As shown, each volume adjuster graph is superimposed over the corresponding waveform. 
     Process  800  then receives (at  820 ) adjustments to the volume adjuster graph of a particular clip (e.g., in the form of a directional input to move the volume adjuster graph). The process changes (at  825 ) the volume of the clip based on the received adjustments. While changing the volume of the clip, the process maintains the position of the volume adjuster graph at the peak of the waveform. In other words, the peak of the waveform and the volume adjuster graph move together. 
       FIG. 10  conceptually illustrates changing the volume of a quiet clip in some embodiments of the invention. The figure shows the three waveforms of  FIG. 9  in two stages  1005  and  1010 . The first stage  1005  shows the original waveforms  905 - 915  and their corresponding volume adjuster graphs  935 - 945 . As shown, the peak value of waveform  905  is at −30 dB which is similar to the peak of waveform  115  shown in  FIG. 2 . 
     In the second stage  1010 , a user drags up the volume adjuster graph  935  to set the absolute value of the peak of the waveform  905  to the maximum possible 0 dB. As shown, the resulting waveform  1015  has a peak value  1020  of 0 dB. In contrast to waveform  224  in  FIG. 2  which was resulted from setting the volume control  214  to maximum, the quiet clip  905  is adjusted to have a peak  1020  at the maximum possible of 0 dB level. Accordingly, setting the volume adjustment scale to absolute values solves the issue of a quiet waveform still being quiet after the maximum possible adjustment in a relative adjustment scale. 
       FIG. 11  conceptually illustrates changing the volume of a loud clip in some embodiments of the invention. The figure shows the three waveforms of  FIG. 9  in two stages  1105  and  1110 . As shown in the first stage  1105 , the peak value of waveform  910  is at −7 dB which is similar to the peak of waveform  116  shown in  FIG. 3 . 
     In the second stage  1110 , a user drags up the volume adjuster graph  940  to set the maximum peak of the waveform  910  to the maximum possible 0 dB. As shown, the resulting waveform  1115  has a peak value  1120  of 0 dB. In contrast to waveform  324  in  FIG. 3  which was clipped as a result of setting the volume control  314  to maximum, the loud clip  910  in  FIG. 11  is adjusted to have a peak  1120  at the maximum possible of 0 dB level without being clipped. Accordingly, setting the volume adjustment scale to absolute values solves the issue of a loud waveform being clipped after the volume adjuster is set to maximum in a relative adjustment scale. 
     In addition, as shown in  FIGS. 10 and 11 , the volume adjuster graphs and the corresponding waveforms are aligned and the distance between the volume adjuster graph and the corresponding waveform (e.g., the distance between the peak of the waveforms and the volume adjuster graph) remain the same. In other words, the volume adjuster graph and the corresponding waveform move in locked steps. This is in contrast with the volume bars and corresponding waveforms in  FIGS. 2-4  that would change alignment between the waveform and the volume bar after each change to the volume bar. 
     Also, as shown in  FIGS. 10 and 11 , some embodiments display an additional reference graph  1030  and  1130  to show the original unmodified volume adjuster graph. In these embodiments, the reference graphs are displayed with different line pattering (e.g., solid, dashed, dotted, or stippled patterning), different line thickness, or different color as the volume adjuster graphs. 
     One of ordinary skill in the art will recognize that process  800  is a conceptual representation of the operations used for adjusting audio volume. The specific operations of process  800  may not be performed in the exact order shown and described. For instance, displaying of the original clip in some embodiments is done after operations  810  and  815 . Also, operations  820  and  825  can be repeated many times to change the volume adjuster graphs in response to different user inputs. In these embodiments, after performing operation  825 , process  800  proceeds to  820  and awaits the next user command. Furthermore, the specific operations of process  800  may not be performed in one continuous series of operations and different specific operations may be performed in different embodiments. Also, the process could be implemented using several sub-processes, or as part of a larger macro process. 
     B. Setting the Volume Adjuster Graph at a Level Different than the Waveform Peak 
     Some embodiments set the volume adjuster graphs at positions other than the peak of each waveform.  FIG. 12  conceptually illustrates a process  1200  for changing the audio volume of one or more multimedia clips in some embodiments of the invention. Different operations of process  1200  are shown by reference to  FIGS. 13-15 . As shown in  FIG. 12 , process  1200  displays each audio waveform by plotting volumes of the original audio clips as a function of time on absolute scale. 
     Next, process  1200  analyzes each clip and identifies (at  1210 ) a volume level for setting the location of the volume adjuster graph for the clip. For instance, in some embodiments, process  1200  determines the mean square root (RMS) of each waveform. In some other embodiments, the process determines average loudness of each waveform. Different embodiments use different techniques to determine (or calculate) loudness equivalent of a clip. For instance, in some embodiments, the process determines a level for volume adjuster graph after subjecting the waveform to a loudness filter to determine the loudness of the clip. Yet in other embodiments, the loudness equivalent is calculated using a mathematical formula. Process  1200  then sets (at  1215 ) a separate volume adjuster graph for each clip at the identified levels of the clip. In some embodiments, the volume adjuster graph is superimposed over the corresponding audio waveform of the clip. 
       FIG. 13  conceptually illustrates several possible positions for setting the volume adjuster graphs in some embodiments of the invention. Volume adjuster graph  1305  is set at a position determined based on the RMS of the waveform  1310 . As shown, the peak of the waveform  1310  is at −7 dB. In this example, the RMS is calculated to be −15 dB. The volume adjuster graph  1305  is set at the RMS level. In contrast, volume adjuster graph  1315  is placed at the peak of the waveform  1310  which is similar to the embodiments described by reference to  FIGS. 9 and 10 , above. As shown in  FIG. 13 , the peak of the waveform is at −7 dB and the volume adjuster graph  1315  is placed at the peak.  FIG. 13  also illustrates Volume adjuster graph  1325 . This volume adjuster graph is set at a position based on the loudness of the clip. In some embodiments, loudness is determined by using a loudness filter. 
     Referring back to  FIG. 12 , process  1200  then receives (at  1220 ) adjustments to the volume adjuster of a particular clip. The process changes (at  1225 ) the volume of the clip based on the received adjustments. The process then exits. While changing the volume of the clip, as long as the peak of the waveform has not reached the maximum, process  1200  maintains the position of the volume adjuster graph on the waveform (e.g., at the RMS position). In other words, the RMS of the waveform and the volume adjuster graph move together. When the peak of the waveform reaches the maximum, some embodiments prevent the volume adjuster graph to increase any further while other embodiments clip a portion of the waveform. 
       FIG. 14  conceptually illustrates a volume adjuster graph  1405  which is placed at the RMS level (or any other level below the peak) of a waveform  1410  in some embodiments of the invention. Volume adjustment is shown in two stages  1420  and  1425 . As shown in the first stage  1420 , as long as the peak  1415  of the waveform  1410  has not reached the maximum value of 0 dB, the volume adjuster graph (and the waveform) can move up. However, as shown in stage two  1425 , when the peak  1415  of the waveform  1410  reaches the maximum allowed volume at 0 dB, the volume adjuster graph is automatically prevented from moving up any further. 
       FIG. 15  conceptually illustrates a volume adjuster graph  1505  which is placed at the RMS level (or any other level below the peak) of a waveform  1510  in some embodiments. Volume adjustment is shown in three stages  1520 - 1530 . As shown in the first stage  1520 , as long as the peak  1515  of the waveform  1510  has not reached the maximum value of 0 dB, the volume adjuster graph and the waveform move up without the waveform being clipped. However, as shown in stage two  1525 , when the peak of the waveform  1510  reaches the maximum allowed volume at 0 dB, the volume adjuster graph can continue moving up and the portions of the clip that reach 0 dB are clipped away. As shown in stage three  1530 , the volume adjuster graph stops when it reaches the maximum limit and the portion of the clip with higher volumes than the level of the volume adjuster graph are clipped away. 
     One of ordinary skill in the art will recognize that process  1200  is a conceptual representation of the operations used for adjusting audio volume. The specific operations of process  1200  may not be performed in the exact order shown and described. For instance, displaying of the original clip in some embodiments is done after operations  1210  and  1215 . Also, operations  1220  and  1225  can be repeated many times to change the volume adjuster graphs in response to different user inputs. In these embodiments, after performing operation  1225 , process  1200  proceeds to  1220  and awaits the next user command. Furthermore, the specific operations of process  1200  may not be performed in one continuous series of operations and different specific operations may be performed in different embodiments. Also, the process could be implemented using several sub-processes, or as part of a larger macro process. 
     C. Shape of Volume Adjuster Graph 
     In  FIGS. 5-6 ,  9 - 11 ,  13 - 15  as well some other figures described below, the volume adjuster graph or its segments are shown as straight lines for simplicity. However, in some embodiments, the volume adjuster graph or any of the segments of the graph can be straight lines (e.g., horizontal, vertical, diagonal line) or curved lines. In these embodiments, a section of the audio waveform is examined to determine the particular intrinsic volume level (e.g., peak, RMS, average volume, calculated loudness equivalent, etc.) at which the volume adjuster graph is to be set. The volume adjuster graph segment corresponding to each section of the audio waveform is then set based on the determined value for that section of the audio waveform. 
     For instance, if the intrinsic value at which the volume adjuster graph is set is the peak volume, then the peak for each section of the audio waveform is determined and each volume adjuster graph segment is set to the peak value of the corresponding section of the audio waveform. Accordingly, when the examined section of the audio waveform is the whole audio waveform, the peak of the examined section is the peak of the audio waveform and the volume adjuster graph is a straight line set at the peak of the audio waveform. On the other hand, when the section of the audio is a single sample of the audio waveform, the volume adjuster graph is the same curve as the audio waveform itself. When the examined section of the audio waveform is anywhere between an individual sample and the whole audio waveform, the volume adjuster graph is a running average of the intrinsic value (in this example, the peak) of different sections of the audio waveform. The volume adjuster graph is, therefore, a curve comprised of curved and/or straight lines that is fit according to the values determined for the particular intrinsic value for each section of the audio waveform. 
     D Pre-Normalization 
     Some embodiments perform a pre-normalization on a waveform in order to determine a level to set the volume adjuster graph for a clip.  FIG. 16  conceptually illustrates a process  1600  for changing the audio volume of a multimedia clip in some embodiments of the invention. Process  1600  is described by reference to  FIG. 17  which conceptually shows different operations for pre-normalization in some embodiments. As shown in  FIG. 16 , process  1600  identifies (at  1605 ) the value of a desired level (such as the peak or RMS) of the original sound clip for placing the volume adjuster graph. In the example of  FIG. 17 , the peak level  1710  of the waveform  1705  is determined to be at −25 dB. 
     Next, the process increases (i.e., pre-normalizes) (at  1610 ) sound levels of the clip by the difference between the identified level and the maximum allowed sound level (e.g., 0 dB). As shown in  FIG. 17 , the difference between the peak value (i.e., −25 dB) of waveform  1705  and the maximum allowed volume value (i.e., 0 dB) is 25 dB. The normalized waveform  1715  has volume levels that are 25 dB louder than waveform  1705 . 
     Next, process  1600  compensates for pre-normalization by setting (at  1615 ) the volume adjuster for the clip below the maximum allowed value by an amount equal to the difference value. As shown in  FIG. 17 , the volume adjuster graph  1720  is set at −25 dB below the maximum allowed value of 0 dB. Next, process  1600  displays (at  1620 ) the visual representation of the clip with the adjusted volume by plotting volumes values as a function of time on absolute scale. As shown in  FIG. 17 , the resulting waveform  1725  is displayed at the adjusted volume with the volume adjuster graph placed at the peak  1730  of the waveform  1725 . 
     One of ordinary skill in the art will recognize that process  1600  is a conceptual representation of the operations used for doing pre-normalization for setting the volume level adjuster. The specific operations of process  1600  may not be performed in the exact order shown and described. Furthermore, the specific operations of process  1600  may not be performed in one continuous series of operations and different specific operations may be performed in different embodiments. Also, the process could be implemented using several sub-processes, or as part of a larger macro process. 
     E. Changing Absolute Volume Levels without Using Volume Adjuster Graphs 
     Some embodiments change audio clip levels without the use of volume adjuster graphs. In some of these embodiments, the volume adjuster is set at a desired position such as the peak or RMS level without being displayed. When a user drags on any portion of a clip, the clip volume is adjusted as if the user has dragged the volume adjuster graph. Some embodiments provide a selection tool (e.g., a radio button) on GUI  500  to turn the display of the volume adjuster graph on or off. Other embodiments always display or always hide the volume adjuster graphs. 
       FIG. 18  illustrates three waveforms  1805 - 1815  in two stages  1820  and  1825  in some embodiments. The first stage  1820  illustrates the original volumes of the clips.  FIG. 18  also conceptually shows that a GUI selection tool  1830  is set to hide the volume adjuster graphs. In stage two  1825 , a user drags down on a point  1830  of the waveform. The volume of the resulting waveform  1835  is adjusted as if a volume adjuster graph was displayed and the user has dragged on the volume adjuster graph. For instance, if the volume adjuster graph is set at the peak and is hidden, dragging down point  1830  on the clip by a particular dB amount results in a waveform as if the user has dragged a volume adjuster graph placed at the peak by the particular dB amount. As a result, the peak of the waveform is set at the absolute value indicated by the hidden volume adjuster graph. 
     F. Resetting Volume Adjuster Graphs when an Audio Clip is Cropped 
     In some embodiments, when a volume adjuster graph is set and subsequently a portion of the clip is trimmed, the volume adjuster graph for the clip is adjusted accordingly.  FIG. 19  conceptually illustrates a process  1900  for adjusting the volume adjuster graph after trimming a portion of the clip in some embodiments of the invention. Process  1900  is described by reference to  FIG. 20  which conceptually shows different operations for resetting volume adjuster graphs in some embodiments. 
     As shown in  FIG. 19 , process  1900  displays (at  1905 ) sound levels of an audio clip as a function of time and sets the volume adjuster graph at a particular level (e.g., at the peak or at the RMS level). In the example of  FIG. 20 , the volume adjuster graph  2010  is set at the peak of the corresponding waveform  2005 . 
     Next, process  1900  receives (at  1910 ) a command to crop the audio clip. For instance, some embodiments provide different cropping tools to crop and trip media clips.  FIG. 20  shows that a portion  2015  of the waveform  2005  is identified to be cropped. Process  1900  then crops (at  1915 ) the clip.  FIG. 20  shows the cropped portion  2020  of the waveform. 
     Process  1900  then identifies (at  1920 ) the new desired sound level value (e.g., new peak or new RMS) of the cropped clip to set the volume adjuster graph. In the example of  FIG. 20 , the new peak of the cropped waveform  2020  is at −25 dB. Process  1900  then pre-normalizes (at  1925 ) the cropped clip to the loudest possible level by increasing the sound levels of the cropped clip by the difference between the maximum allowed volume level and the identified desired level for the volume adjuster graph.  FIG. 20  shows the resulting pre-normalized waveform  2025 . 
     Process  1900  then sets the volume adjuster to a new value to compensate for the difference between the maximum allowed volume level and the identified desired level for the volume adjuster graph. The process then displays (at  1935 ) the clip and the adjusted volume adjuster graph.  FIG. 20  shows the resulting waveform  2030  and the new volume adjuster graph  2035 . As shown, the volume adjuster graph is changed from −7 dB to −25 dB after the audio clip is cropped. 
     One of ordinary skill in the art will recognize that process  1900  is a conceptual representation of the operations used for resetting the volume adjuster graph. The specific operations of process  1900  may not be performed in the exact order shown and described. For instance, in some embodiments pre-normalization is not done. Instead, when the new desired sound level value for the volume adjuster graph (e.g., the new peak or new RMS) is determined, the volume adjuster graph is set at the identified level. In these embodiments, process  1900  skips operations  1925  and  1930  and instead sets the volume adjuster graph at the new identified sound level. Furthermore, the specific operations of process  1900  may not be performed in one continuous series of operations and different specific operations may be performed in different embodiments. Also, the process could be implemented using several sub-processes, or as part of a larger macro process. 
     G. Deformable Volume Adjuster Graphs 
     Some embodiments allow volume adjuster graphs to be split for an audio clip based on one or more selected time ranges. In some of these embodiments, when a portion of an audio clip is selected, a new multi-segment volume adjuster graph (or volume adjuster curve) based on the properties of the selected portion (i.e., peak, RMS, etc.) is displayed. In other embodiments, a multi-segment volume adjuster graph is automatically displayed for an audio clip. Each segment of the volume adjuster graph can have a different geometric shape such as a straight line (e.g., horizontal, vertical, or diagonal lines) or a curved line. In some embodiments, the volume adjuster graph is a continuous graph that includes different curved and/or straight line segments. 
       FIG. 21  conceptually illustrates a process  2100  for setting and displaying deformable volume adjuster graphs in some embodiments of the invention. Different operations of process  2100  are described by reference to  FIGS. 22-29 . As shown in  FIG. 21 , process  2100  displays (at  2105 ) an audio clip by plotting the volume of the audio clip as a function of time and sets the volume adjuster graph at a particular level (e.g., the peak or RMS) of the clip. Some embodiments, utilize an absolute volume adjustment scale. In these embodiments, each audio waveform is displayed by plotting volumes of the original audio clips as a function of time on absolute scale and the deformable volume adjuster graphs are set based on the intrinsic or absolute volume values of the clip. Other embodiments use a relative volume adjustment scale for displaying deformable volume adjuster graphs. In these embodiments, each audio waveform is displayed by plotting volumes of the original audio clips as a function of time on a relative scale and the deformable volume adjuster graphs are set based on the relative volume values of the clip. 
       FIG. 22  conceptually illustrates a single audio clip  2205  with a single volume adjustment adjuster graph segment  2210  in some embodiments. In this example, the volume adjuster graph is set at the peak of the audio clip. However, the following discussion also applies to other volume adjuster graphs such as volume adjuster graphs set at RMS or loudness levels. The audio clip is shown in three stages  2215 - 2225 . As shown in the first stage  2215 , the volume adjuster graph is set at −7 dB. 
     Next, process  2100  receives (at  2110 ) a selection of one or more portions of the audio clip. As shown in  FIG. 20 , in the second stage  2220 , a particular range  2230  of the audio clip is selected. This is shown by the dashed rectangle  2235 . 
     Process  2100  then analyzes (at  2115 ) the selected portion(s) as well as the portions that are not selected and determines the new desired sound level value (e.g., new peak or new RMS) of the each portion to set an individual volume adjuster graph segment for each portion. For instance, in the example of  FIG. 22 , the volume adjuster graph is placed at the peak of the original audio clip. After a portion of the audio clip is selected, the new peak of each portion is determined. In some embodiments, setting and displaying of deformable volume adjuster graphs is done automatically without requiring receiving of a selection of one or more portions of the audio clip. In these embodiments, operation  2110  is bypassed and operation  2115  is done automatically (e.g., as a part of operation  2105  when a volume adjuster graph is being displayed on an audio clip or after receiving a command to generate a deformable volume adjuster graph). In these embodiments, different portions of the audio clip are automatically identified based on criteria such as average volume level, maximum volume level, loudness, maximum or minimum length of different portions, etc. 
     Process  2100  then sets (at  2120 ) individual volume adjuster graph segments for each portion of the audio clip based on the identified level for the portion. In some embodiments, the individual volume adjuster graph segments are automatically set after one or more portions of an audio clip are selected. In other embodiments, process  2100  receives a command through the GUI to deform the volume adjuster graph. Yet in other embodiments, a deformable volume adjuster graph is automatically generated for each audio clip. 
     As shown in the third stage  2225  in  FIG. 22 , the volume adjuster graph is divided into two segments  2240  and  2245 . Segment  2240  is set at the peak of the portion that was not selected (which in this example is the same as the peak of original clip  2205 ) and segment  2245  is set at the peak value of the selected portion  2230 . In some embodiments, the splitting of the volume adjuster graph is performed by defining two keyframes. A first keyframe  2250  at the peak level of the first portion of the clip and a second keyframe  2255  at the peak level of the second portion of the clip. Using the keyframes allows smooth transition between the volume adjuster graph segments as described below by reference to  FIG. 25 . In some embodiments, when a portion of an audio graph is selected, the handles  2280  are automatically displayed to allow adjustment and smoothing of the volume adjuster graph segments. In other embodiments, the handles are displayed only after the user adjusts (e.g., by applying a directional input) a selected portion (such as  2235  and  2310  shown in  FIGS. 22 and 23 ) of an audio waveform. Yet in other embodiments, when a user double clicks on any point on the volume adjuster graph, a single handle is displayed on that point. 
     The same volume adjuster graph segments would have been generated if the first portion of the audio (instead of the second portion) was selected.  FIG. 23  conceptually illustrates a single audio clip  2205  with a single volume adjuster graph  2210  in some embodiments of the invention. In this figure, the first portion  2305  of the audio clip is selected as shown by the dashed rectangle  2310 . As a result, two volume adjuster graph segments  2315  and  2320  are generated. Since the peaks of the two portions are the same as the peaks of the two portions shown in  FIG. 22 , the volume adjuster graph segments  2315  and  2320  are generated at the same positions as volume adjuster graph segments  2240  and  2245  shown in  FIG. 22 . 
     Process  2100  is also used to generate more than two volume adjuster graph segments when multiple portions of a clip are selected.  FIG. 24  conceptually illustrates the audio clip  2250  of  FIG. 22  where two portions of the clip (as shown by dashed rectangles  2405  and  2410 ) are selected. In some embodiments, these portions can be selected simultaneously and individual volume adjuster graph segments are set for all selected portions simultaneously. In other embodiments, the portions have to be selected one at a time with each selection resulting in one additional individual volume adjuster graph segments to be added. 
     As shown in  FIG. 24 , four volume adjuster graph segments  2415 - 2430  are generated for the clip. In some embodiments, the volume adjuster graph segments are generated by adding four keyframes  2435 - 2450  at peak levels of different selected portions and remaining portions of the clip. As shown, one of the volume adjuster graph segment  2420  which corresponds to the portion of the clip with the highest peak is at the same level as the volume adjuster graph segment  2210  of the original clip. 
     Next, process  2100  optionally smoothes (at  2125 ) the transition between the individual volume adjuster graph segments. In some embodiments, the segments are smoothed automatically. Other embodiments provide tools to a user to smooth the segments.  FIG. 25  conceptually illustrates adjusting the transition portion in two stages  2550  and  2555  in some embodiments of the invention. As shown in  FIG. 25 , audio clip  2505  has two volume adjuster graph segments  2510  and  2515 . The volume adjuster graph segments are generated by adding two keyframes  2520  and  2525 . The handles  2530  and  2535  are selectable and can be moved to left or right in order to create a smooth transitional segment  2560  between the two volume adjuster graph segments  2510  and  2515 . 
     As shown in the first stage  2550 , handle  2530  is selected and is moved to the left. Stage two  2555  shows that the transitional segment  2560  between the two volume adjuster graph segments is expanded. Each one of the handles  2530  and  2535  can be selected and moved to left or right in order to increase or decrease the transitional segment  2560  between the two volume adjuster graph segments. In some embodiments, instead of or in addition to the keyframes, a separate control is provided that allows the transitional segment  2540  between the volume adjuster graph segments to be adjusted. 
     Some embodiments treat the transitional segments such as  2560  as any other segments of the volume adjuster graph. Accordingly, when the segment is moved up or down, the corresponding section of the audio waveform is adjusted the same way as when other segments (e.g.,  2510  or  2515 ) are moved up or down. In other embodiments, when a transitional segment such as segment  2560  is moved, the transitional segment shape stays the same and instead the two points on the two segments  2520  and  2525  that are adjacent to the transitional segment  2560  (i.e., points on the volume adjuster graph corresponding to handles  2530  and  2535 ) move. 
     Process  2100  then receives (at  2130 ) adjustment to individual volume adjuster graph segment corresponding to a particular portion of the audio clip. The process then changes (at  2135 ) the volume of the audio clip in accord with the received adjustment. When a segment of a deformable volume adjuster graph is changed, different embodiments change the other segments of the deformable volume adjuster graph differently.  FIG. 26  conceptually illustrates a deformable volume adjuster graph where adjusting a segment of the deformable adjuster graph does not affect the other segments of the deformable volume adjuster graph. 
     Specifically,  FIG. 26  shows the deformable volume adjuster graph of  FIG. 24 , where the segment  2430  is moved down after receiving a directional input (such as dragging). As a result, only the segment  2430  of the deformable volume adjuster graph and only the portion  2610  of the audio waveform  2205  is moved down. The other segments  2315 - 2325  of the deformable volume adjuster graph as well as the rest of the waveform  2205  are not affected by the movement of the segment  2430 . 
       FIG. 27  conceptually illustrates a deformable volume adjuster graph where adjusting a segment (or a portion) of the deformable volume adjuster graph affects the other segments of the deformable volume adjuster graph. Specifically,  FIG. 27  shows the deformable volume adjuster graph of  FIG. 25  where the segment  2515  is moved up after receiving a directional input (such as dragging). As shown in  FIG. 27 , moving segment  2515  results in other segment  2510  of the deformable volume adjuster graph to also move up. However, after segment  2510  reaches a point that the audio waveform  2505  has to be clipped, segment  2510  does not move anymore to prevent the clipping. Any further adjustments to move segment  2515  up result only in segment  2515  (and not  2510 ) to move up. As a result, the distance between the two segments  2510  and  2515  is reduced and the slope # 2705  between the two segments starts to flatten. 
     In the embodiment shown in  FIG. 27  where adjusting one portion of the audio waveform adjusts the other portions, the volume adjuster graph might flatten as the user drags one section that has headroom but where another section approaches a point that causes clipping the audio waveform. In other embodiments, when the first portion of the waveform reaches 0 dB, the volume of no other section of the waveform can raised (similar to what was described by reference to  FIG. 14 , above). Yet in other embodiments, the volume of the waveform is raised by clipping the waveform at 0 dB until the lowest section of the deformable volume adjuster graph (e.g.,  2430 ) reaches 0 dB (similar to what was described by reference to  FIG. 15 , above). 
     In some embodiments, process  2100  displays a reference graph (or reference curve) to show the original unmodified volume adjuster graph.  FIG. 28  conceptually illustrates displaying a reference graph that identifies the original volume adjuster graph in some embodiments of the invention after the original volume adjuster graph is modified.  FIG. 28  shows adjusting an audio waveform in two stages  2850  and  2855 . As shown in the first stage  2850 , an audio waveform  2805  and a deformable volume adjuster graph with three segments  2820 - 2830  are displayed. 
     As shown in the second stage  2855 , the volume adjuster graph is adjusted by moving segments  2825  and  2830  down. The resulting volume adjuster graph has a different shape than the original volume adjuster graph. However, as shown in the second stage  2855 , when the original volume adjuster graph is modified, a reference graph  2810  is displayed which identifies the original unmodified volume adjuster graph. In some embodiments, the reference graph  2810  that identifies the original volume adjuster graph, is displayed with different line pattering (e.g., solid, dashed, dotted, or stippled patterning), different line thickness, or different color as the current (i.e., the modified) volume adjuster graph. 
     One of ordinary skill in the art will recognize that process  2100  is a conceptual representation of the operations used for providing a deformable volume adjuster graph for an audio clip. The specific operations of process  2100  may not be performed in the exact order shown and described. For instance, operations  2130  and  2135  can be repeated many times to change the volume adjuster graph segments in response to different user inputs. In these embodiments, after performing operation  2135 , process  2100  proceeds to  2130  and awaits the next user command. Furthermore, operations  2125  and  2130  can be used to adjust the volume adjuster graph segments for individual portions of a clip as well volume adjuster graphs of different audio clips. 
     Furthermore, the specific operations of process  2100  may not be performed in one continuous series of operations and different specific operations may be performed in different embodiments. Also, the process could be implemented using several sub-processes, or as part of a larger macro process. 
     Some embodiments provide a similar smooth transition (as shown in  FIG. 25 ) between separate audio clips.  FIG. 29  illustrates three audio clips  2905 - 2915  with the corresponding volume adjuster graphs  2920 - 2930  in some embodiments. Using a similar technique for adding keyframes and handles as described by reference to  FIG. 25  above, the transitional segments  2935  and  2940  are made smooth. Specifically, handles  2945 - 2960  are individually selectable. By moving the handles to right or left, the transitions between the volume adjuster graphs  2920 - 2930  are made smooth. 
     III. Reference Waveforms 
     A. Improved Visual Identification of Points on Audio Clips 
     Some embodiments provide for easy identification of different points such as maximum points and minimum points (or peaks and valleys) of audio clips by displaying reference waveforms with accentuated points that correspond to the points on the audio clip.  FIG. 30  conceptually illustrates an audio waveform and its corresponding reference waveform in some embodiments of the invention. As shown, the audio waveform  3005  has a maximum peak  3010  and several local maximum points and minimum points  3014  and  3015 . It is often hard to identify the individual maximum points and minimum points of a clip, especially in a portion of the clip that has a lower volume. Each maximum or minimum point on the displayed audio clip corresponds to a point on the audio clip that is displayed with a zero slope. 
     As shown, a reference waveform  3020  is superimposed over the original waveform  3005  in some embodiments. The reference waveform in some embodiments has the same number of points as the original waveform, except that some of the points on the reference waveform (e.g., some or all or the maximum points and minimum points) are accentuated (i.e., displayed with a higher height or at a higher volume level) compared to the corresponding points on the audio waveform. For instance, in some embodiments the highest peak of the original waveform  3005  in a given period of time (e.g., in a 20 seconds interval) corresponds to a maximum peak on the reference waveform  3020 . As shown in  FIG. 30 , local peak  3014  of the original waveform  3005  is the highest peak in a given interval  3030 . The reference waveform  3020  has a maximum peak  3035  which corresponds to the local peak  3014 . Some or all other local minimums and maximums of the reference waveform are also accentuated to values more than the corresponding local minimums and maximums of the original waveform but less than the maximum allowable volume level. 
     Furthermore, in some embodiments, the audio waveform and the corresponding reference waveform are displayed with different highlights to facilitate visual distinction between the two waveforms. For instance, the audio clip in  FIG. 30  is highlighted in black and the reference waveform is highlighted in gray. In other embodiments, the waveforms for the audio clip and the reference waveform are displayed in different colors. Yet in other embodiments, the waveforms for the audio clip and the reference waveform are displayed with different line pattering (e.g., solid, dashed, dotted, or stippled patterning) or different line thickness. Although in the following examples the reference waveforms are displayed as being superposed on the original audio waveforms, some embodiments do not superimpose the reference waveform and the corresponding audio waveform. For instance, in some embodiment embodiments, the reference waveform is displayed in lieu of the original waveform or is displayed above or below the original audio waveform. 
     Displaying the reference waveform is particularly useful for portions of the clips that have lower volumes as well as when the whole audio clip has a low volume which makes visually identifying the maximum and minimum points of the waveform difficult.  FIG. 31  conceptually illustrates a clip and its associated reference waveform in two stages in some embodiments of the invention. In the first stage  3105 , the audio waveform  3115  has a high volume with a maximum peak  3120  of −3 dB. Since the waveform has a high volume, it is easy to identify its maximum and minimum points. 
     In stage two  3110 , the volume of the clip is reduced to set the peak at −50 dB. As shown, although the resulting waveform  3125  has the same contour or outline as the original waveform  3115 , it is hard to identify the local maximum and minimum points of the waveform  3125 . Superimposing the reference waveform  3130  on the waveforms  3125  provides an easy way of identifying the maximum and minimum points of the waveform  3125 . As shown, the reference waveform  3130  is identical for both waveform  3115  and the corresponding low volume waveform  3125  as the waveforms  3115  and  3125  have the same contour. 
       FIG. 32  conceptually illustrates a process  3200  for displaying reference waveforms in some embodiments of the invention. As shown, process  3200  selects (at  3205 ) a point on the audio waveform to determine the value of the corresponding point on the reference waveform. 
     The process then selects (at  3210 ) a pre-determined pixel range or a time interval around the selected point to examine the volume of the audio waveform. For instance, in  FIG. 30  a 20 pixel range  3030  of the clip is selected. 
     The process then examines (at  3215 ) the values of the points on the audio waveform in the selected range (or interval) around the current point to identify a value for the corresponding point on the reference waveform. In some embodiments, determination of the values of the points in each interval is done based on the displayed original waveform. In some of these embodiments, the pixel coordinates of the displayed waveform are used to determine the values of the points of the waveform. In some embodiments, the value of the point on the reference waveform is determined based on mathematic formulas that take the maximum and minimum values of the audio waveform in the examined range as well as the value of the current point of the audio waveform being examined. Example formulas for determining the value of the points on the reference waveform are described by reference to  FIG. 33 , below. 
     In some embodiments, displaying the reference waveform includes identifying the maximum and minimum points of the audio clip, accentuating these points, and smoothly connecting the points together to display the reference waveform with a similar contour as the audio clip. In other embodiments, additional points on the audio clip (other than the maximum and minimum points) are identified and accentuated to generate their corresponding points on the reference waveform. Yet in other embodiments, not all maximum and minimum points on the audio clip are used to generate the reference waveform. This is especially useful when the audio clip has many local maximum and minimum points and it makes easier to show the reference waveform with fewer maximum and minimum points than the audio clip. 
     Some embodiments determine the values of different points for reference waveforms by examining pre-determined intervals around each point on the audio waveform.  FIG. 33  conceptually illustrates determining the values of different points for reference waveforms in some embodiments of the invention. As shown, an audio waveform  3305  is displayed on the display area  3310 . An example for determining the value for displaying a point on the reference waveform that corresponds to the point  3315  of the audio waveform  3305  is described below. 
     The volume levels of the audio waveform  3305  for a pre-determined interval  3320  around the point  3315  are examined. In some embodiments, the interval is pixel range with a certain number of pixels (in this example 20 pixels) on each direction before and after the point  3315 . In other embodiments, the interval is a time interval on each direction around the point  3315 . In either embodiments (whether the interval is a pixel interval or time interval) different points (i.e., pixels or timeslices) corresponding to the audio waveform  3305  are examined to determine the value of their correspond point on the reference waveform. 
     For every pixel or timeslice, a pre-determined number of the surrounding pixels (20 pixels in the example of  FIG. 33 ) or timeslices are examined and the loudest and quietest volume values in that pixel range or time interval are determined. The current value of the point on the audio waveform is then fitted into that range and the reference level (or the value of the corresponding point on the reference waveform) is determined. Once the value of the corresponding point on the reference waveform is found, the next pixel or timeslice on the audio waveform is examined. This slides the window  3320  to the right by one pixel or one timeslice (i.e. 39 of the values are the same, one falls off the left, and one gets added to the right). The cycle repeats until all points or timeslices are examined and the values of the corresponding points on the reference waveform are determined. 
     In some embodiments, the following formula is used to determine the volume of the current point on the audio clip with respect to the loudest and quietest points in the range being examined.
 
 Cur - Pt  volume ratio=(Value−Min)/(Max−Min)
 
where “Cur-pt volume ratio” is the ratio (or percentage) of the volume level of the current point with respect to the volume levels of the quietest and loudest points in the range; “Value” is the volume level of the current point on the audio waveform being examined; “Min” is the volume of the quietest point in the range, and “Max” is the volume of the loudest point in the range.
 
     The value of the point on the reference waveform that corresponds to the current point is then determined by the following formula.
 
Ref-level=((1−Value)* Cur - Pt  volume ratio)+Value
 
where “Ref-level” is the value at which the corresponding point on the reference waveform is displayed; “Cur-pt volume ratio” is the ratio (or percentage) of the volume level of the current point calculated above, and “Value” is the volume level of the current point being examined on the audio waveform.
 
     As shown in  FIG. 33 , the audio waveform is assumed to be displayed between values of 0% to 100% of the maximum allowed value. In the example of  FIG. 33 , the loudest point  3330  in the range  3320  is at 50% (or 0.5) of the volume range, the quietest point  3335  in the range  3320  is at 10% (or 0.1) of the volume range and the current point  3315  is at 30% (or 0.3) of the volume range. Accordingly, “Cur-pt volume ratio” is calculated as follows (using decimal values for percentages):
 
 Cur - pt volume ratio=( 0.3−0.1)/(0.5−0.1)=0.2/0.4=0.5
 
     Using this value, the “Ref-level” is calculated as follows:
 
Ref-level=((1−0.3)*0.5)+0.3=0.65
 
     Accordingly, the point  3350  (identified by an X mark in  FIG. 33 ) on the reference waveform that corresponds to the current point  3315  on the audio waveform is displayed at 0.65 (or 65%) of the volume range. Using the above formulas for Ref-level, if a point is the lowest in its surrounding range, the level of the reference waveform at that point will be equal to the actual waveform value at that point. In this example, if the point  3315  was the lowest (i.e., the quietest) point in the range  3320 , “Value” would have been 0.1, “Cur-pt volume ratio” would have been 0.0, and “Ref-level” would have been 0.1. Accordingly, the point on the reference waveform would have been displayed at the actual level  3360  of the current point  3315 . Similarly, if a point is the highest in its surrounding range, the level of the reference waveform at that point will be equal to the full scale 1.0 (or 100%) at that point. In this example, if the point  3315  was the loudest point in the range  3320 , “Value” would have been 0.5, “Cur-pt percentage” would have been 1.0, and “Ref-level” would have been 1.0. Accordingly, the point on the reference waveform would have been displayed at the maximum allowed value (or 100%)  3370 . 
     Referring back to  FIG. 32 , process  3200  then determines (at  3220 ) whether all points on the displayed audio waveform are examined. When all points are not examined, the process selects (at  3225 ) the next point on the audio waveform in order to determine the value of the corresponding point on the reference waveform. The process then proceeds to  3210  which was described above. 
     Otherwise, when all point are examined, the process displays (at  3230 ) the reference waveform with a corresponding number of points as the identified points of the audio clip using the values identified for the points on the reference waveform. In some embodiments the highest peak of the reference waveform in the interval is displayed at the maximum allowed volume level. For instance, in  FIG. 30 , peaks  3010  and  3014  are the highest peaks in their corresponding intervals. As shown in  FIG. 30 , the corresponding peaks  3050  and  3035  of these peaks on the reference waveform  3020  are set to maximum allowed volume of 0 dB. Process  3200  also accentuates some or all of the other maximum and minimum points of the selected portion. 
     One of ordinary skill in the art will recognize that process  3200  is a conceptual representation of the operations used for displaying reference waveforms. The specific operations of process  3200  may not be performed in the exact order shown and described. For instance, instead of displaying (at  3205 ) the reference waveform for a portion of the original waveform and then performing operations  3225  and  3210  for the next portion of the original waveform, some embodiments save the portion of the reference waveform in a temporary storage until all portions of the reference waveform for the audio clip that is displayed on the GUI are determined. The process then displays all portions of the reference waveform at once. Furthermore, the specific operations of process  3200  may not be performed in one continuous series of operations and different specific operations may be performed in different embodiments. Also, the process could be implemented using several sub-processes, or as part of a larger macro process. 
     B. Aligning an Audio Clip to a Point on a Timeline 
     Using the reference waveforms facilitates aligning a particular point such as a maximum or minimum point of a waveform to a particular time shown on a display area.  FIG. 34  conceptually illustrates a process  3400  for aligning a point on an audio clip in with a desired point on a display area of some embodiments of the invention. This process is described by reference to  FIGS. 35 and 36  which conceptually illustrate aligning of a waveform to a particular time in some embodiments of the invention. 
     As shown in  FIG. 34 , process  3400  displays (at  3405 ) an audio clip with a corresponding superimposed reference waveform.  FIG. 35  illustrates an audio clip and a corresponding reference waveform. The audio clip in the example of  FIG. 35  is a low volume clip and is displayed on the waveform display area  3550  of  FIG. 35  as waveform  3505 . As shown, it is difficult to visually identify individual maximum and minimum points of the waveform  3505 . The corresponding reference waveform  3510 , on the other hand, accentuates the maximum and minimum points of the original waveform  3505  and makes it easier to identify these peaks and valleys. 
     Process  3400  next identifies (at  3410 ) a point on the audio clip to align with a point on a displayed timeline. For instance, a desired point such as peak  3525  of the waveform  3505  is identified by selecting the corresponding peak  3515  on the reference waveform  3510 . 
     Next, process  3400  receives a directional input to align a point on the reference waveform, which corresponds to the identified point on the audio clip, with the point on the timeline. Process  3420  next drags (at  3420 ) the reference waveform corresponding to the audio clip along with the audio clip to align the point on the reference waveform (along with the point on the audio clip) with the point on the timeline. 
     As shown in  FIG. 36 , the selected peak  3515  of the reference waveform is dragged (e.g., by receiving a directional input from the user) to align the point with a desired displayed time  3530 . As shown, the original waveform  3505  is also dragged with the superimposed reference waveform  3510  to the desired position. In some embodiments, any point on the waveform  3510  or any point on or inside the geometric shape (in this example, the rectangle  3520 ) that represents the audio clip  3505  can be dragged in order to align an identified point on the reference waveform  3510  (and the corresponding point on the audio clip  3505 ) with a point on the timeline. 
     One of ordinary skill in the art will recognize that process  3400  is a conceptual representation of the operations used for aligning an audio clip to a point in a display area. The specific operations of process  3400  may not be performed in the exact order shown and described. For instance, instead of identifying a point on the audio clip (at  3410 ) may be done while any of the operations  3415  and  3420  are being performed. Also, instead of dragging a reference waveform and the associated audio clip on a display area, some embodiments update the display only when the directional input operation is completed (e.g., when a user drags and then releases a cursor or a touch point on the screen). Furthermore, the specific operations of process  3400  may not be performed in one continuous series of operations and different specific operations may be performed in different embodiments. Also, the process could be implemented using several sub-processes, or as part of a larger macro process. 
     C. Aligning Different Clips with an Audio Clip 
     Often the users of a media-editing application look for an audio event to line different items up. A user might be looking for the sound of an event to put a video clip at that event. For instance, a user might be looking for an interesting word mentioned in an interview in order to make a cutaway shot to a location on a video clip where the word is mentioned. Using the reference waveforms facilitates aligning different clips with an audio clip or vice versa. For instance, a user might want to align two audio clips by moving one of them, align a video clip and an audio clip by moving one of them, etc. 
       FIG. 37  conceptually illustrates a process  3400  for aligning several audio clips in some embodiments of the invention. This process is described by reference to  FIGS. 38 and 39  that conceptually illustrate aligning of several waveforms in some embodiments of the invention. As shown in  FIG. 37 , process  3700  displays (at  3705 ) a first audio clip with a corresponding superimposed first reference waveform and a second audio clip with a corresponding superimposed second reference waveform. Although the process and the examples are described for aligning several audio clips, a similar process is used in some embodiments to align other displayed items (e.g., a video clip) with an audio clip. 
       FIG. 38  illustrates a waveform display area  3805  that includes a primary lane (also referred to as spine, primary compositing lane, central compositing lane)  3810  and several secondary lanes (also referred to as anchor lanes)  3855 - 3860 . In the example of  FIG. 38 , the primary lane  3810  includes a primary sequence of media and the two secondary lanes  3855  and  3860  each includes an audio clip with an audio waveform  3825  and  3830  respectively. In some embodiments, the secondary lanes are anchored (as shown by anchors  3835  and  3840 ) to the primary lane. However, the teachings of the invention apply to embodiments where several lanes run in parallels to each other and are not anchored to each other. 
     Next, process  3700  identifies (at  3710 ) a point on the first audio waveform to align with a point on the second audio clip. In the example of  FIGS. 38 and 39 , a user wants to align the highest peak  3865  of audio waveform  3825  to the second highest peak  3870  of audio waveform  3830 . As shown, the audio waveform  3825 - 3830  do not cover the full range of −∞ to 0 dB and it is hard to visually identify the maximum and minimum points or any particular points on these clips. On the other hand, the reference waveforms  3845  and  3850  that have the same number of maximum and minimum points as audio waveform  3825  and  3830  respectively include accentuated maximum and minimum points which are easier to visually identify. For instance, the peak  3875  on reference waveform  3845  that corresponds to the highest peak  3865  of audio waveform  3825  is shown at 0 dB an is easy to visually identify. Similarly, the peak  3880  on reference waveform  3850  that corresponds to the second highest peak  3870  of audio waveform  3830  is accentuated and is shown at a much higher volume level and is easier to visually identify than the peak  3870 . 
     Process  3700  then receives a directional input to align a first point on the first reference waveform that corresponds to the point on the first waveform with a second point on the second reference point that corresponds to the point on the second audio waveform. Next, process  3700  drags the reference waveform corresponding to the first audio waveform along with the first audio waveform to align the first point on the first reference waveform and the point on the first audio waveform with the second point on the second reference waveform and the point on the second audio waveform. 
     As shown in  FIG. 39 , a user can apply a directional input anywhere on or inside the geometric shape (in this example the rectangle  3905 ) that represents audio clip (e.g., by selecting and dragging the peak  3875 ) to move the reference waveform  3845  along with audio waveform  3825  until the highest peak  3875  on the reference waveform  3845  is aligned with the second highest peak  3880  on the reference waveform  3850 . Since reference waveforms  3845  and  3850  have corresponding peaks and valleys with audio waveform  3825  and  3830  respectively, aligning the peaks  3875  and  3880  results in aligning the peaks  3865  and  3870  on the audio waveform. 
     Using this technique, any point on a reference waveform can be aligned with any point on another reference waveform which results in the similar points on the corresponding audio waveform to also be aligned. Similarly, any audio waveform (such as audio clips  3825  and  3830 ) can be aligned at any point on the primary lane  3810  by dragging the corresponding reference waveform of the audio waveform (which provides better visual identification of maximum and minimum points) to a desired point. 
     One of ordinary skill in the art will recognize that process  3700  is a conceptual representation of the operations used for aligning several audio clips in a display area. The specific operations of process  3700  may not be performed in the exact order shown and described. For instance, instead of identifying a point on the first audio clip (at  3710 ) may be done while any of the operations  3715  and  3720  are being performed. Also, instead of dragging a reference waveform and the associated audio clip on a display area, some embodiments update the display only when the directional input operation is completed (e.g., when a user drags and then releases a cursor or a touch point on the screen). Furthermore, the specific operations of process  3700  may not be performed in one continuous series of operations and different specific operations may be performed in different embodiments. Also, the process could be implemented using several sub-processes, or as part of a larger macro process. 
     IV. Software Architecture 
       FIG. 40  conceptually illustrates the software architecture  4000  for adjusting media clip volumes and displaying reference waveforms in a media editing application in some embodiments of the invention. As shown, the application includes a user interface module  4005  which interacts with a user through the input device driver(s)  4010  and the audio/video display/play module(s)  4015 . The user interface module receives user inputs (e.g., through the GUI  500 ). The user interface module passes the user inputs to other modules and sends display information to audio/video display/play modules  4015 . 
       FIG. 40  also illustrates an operating system  4018 . As shown, in some embodiments the device drivers  4010  and audio/video display/play modules  4015  are part of the operating system  4018  even when the media editing application is an application separate from the operating system. The input device drivers  4010  may include drivers for translating signals from a keyboard, mouse, touchpad, drawing tablet, touchscreen, etc. A user interacts with one or more of these input devices, which send signals to their corresponding device driver. The device driver then translates the signals into user input data that is provided to the user interface module  4005 . 
     The present application describes a graphical user interface that provides users with numerous ways to perform different sets of operations and functionalities. In some embodiments, these operations and functionalities are performed based on different commands that are received from users through different input devices (e.g., keyboard, trackpad, touchpad, mouse, etc.). For example, in some embodiments, the present application uses a cursor in the graphical user interface to control (e.g., select, move) objects in the graphical user interface. However, in some embodiments, objects in the graphical user interface can also be controlled or manipulated through other controls, such as touch control. In some embodiments, touch control is implemented through an input device that can detect the presence and location of touch on a display of the input device. An example of a device with such functionality is a touch screen device (e.g., as incorporated into a smart phone, a tablet computer, etc.). In some embodiments with touch control, a user directly manipulates objects by interacting with the graphical user interface that is displayed on the display of the touch screen device. For instance, a user can select a particular object in the graphical user interface by simply touching that particular object on the display of the touch screen device. As such, when touch control is utilized, a cursor may not even be provided for enabling selection of an object of a graphical user interface in some embodiments. However, when a cursor is provided in a graphical user interface, touch control can be used to control the cursor in some embodiments. 
     As shown in  FIG. 40 , the software architecture also includes a module  4030  to receive audio clips, a module  4035  to analyze audio clips, a normalize audio module  4040 , a volume adjuster setting module  4045 , a deformable volume adjuster graph generation module  4050 , and a reference waveform display module  4055 . These modules perform one or more of the operations discussed for the process and methods described in different embodiments above. 
     As shown, different modules of the software architecture utilize different storage  4090  to store project information. The storage includes intermediate audio data storage  4080 , finalized audio data storage  4085 , as well as other storage  4087 . 
     V. Graphical User Interface 
       FIG. 41  illustrates a graphical user interface (“GUI”)  4100  of a media-editing application of some embodiments. One of ordinary skill will recognize that the graphical user interface  4100  is only one of many possible GUIs for such a media-editing application. In fact, the GUI  4100  includes several display areas which may be adjusted in size, opened or closed, replaced with other display areas, etc. The GUI  4100  includes a clip library  4105 , a clip browser  4110 , a composite display area (also referred to in this specification as the waveform display area)  4115 , a preview display area  4120 , an inspector display area  4125 , an additional media display area  4130 , and a toolbar  4135 . 
     The clip library  4105  includes a set of folders through which a user accesses media clips (i.e. video clips, audio clips, etc.) that have been imported into the media-editing application. Some embodiments organize the media clips according to the device (e.g., physical storage device such as an internal or external hard drive, virtual storage device such as a hard drive partition, etc.) on which the media represented by the clips are stored. Some embodiments also enable the user to organize the media clips based on the date the media represented by the clips was created (e.g., recorded by a camera). 
     Within a storage device and/or date, users may group the media clips into “events”, or organized folders of media clips. For instance, a user might give the events descriptive names that indicate what media is stored in the event (e.g., the “New Event 2-8-09” event shown in clip library  4105  might be renamed “European Vacation” as a descriptor of the content). In some embodiments, the media files corresponding to these clips are stored in a file storage structure that mirrors the folders shown in the clip library. 
     Within the clip library, some embodiments enable a user to perform various clip management actions. These clip management actions may include moving clips between events, creating new events, merging two events together, duplicating events (which, in some embodiments, creates a duplicate copy of the media to which the clips in the event correspond), deleting events, etc. In addition, some embodiments allow a user to create sub-folders of an event. These sub-folders may include media clips filtered based on tags (e.g., keyword tags). For instance, in the “New Event 2-8-09” event, all media clips showing children might be tagged by the user with a “kids” keyword, and then these particular media clips could be displayed in a sub-folder of the event that filters clips in this event to only display media clips tagged with the “kids” keyword. 
     The clip browser  4110  allows the user to view clips from a selected folder (e.g., an event, a sub-folder, etc.) of the clip library  4105 . As shown in this example, the highlighted folder “New Event 2-8-09”  4190  is selected in the clip library  4105 , and the clips belonging to that folder are displayed in the clip browser  4110 . Some embodiments display the clips as thumbnail filmstrips, as shown in this example. By moving a cursor (or a finger on a touchscreen) over one of the thumbnails (e.g., with a mouse, a touchpad, a touchscreen, etc.), the user can skim through the clip. That is, when the user places the cursor at a particular horizontal location within the thumbnail filmstrip, the media-editing application associates that horizontal location with a time in the associated media file, and displays the image from the media file for that time. In addition, the user can command the application to play back the media file in the thumbnail filmstrip. 
     In addition, the thumbnails for the clips in the browser display an audio waveform underneath the clip that represents the audio of the media file. In some embodiments, as a user skims through or plays back the thumbnail filmstrip, the audio plays as well. 
     Many of the features of the clip browser are user-modifiable. For instance, in some embodiments, the user can modify one or more of the thumbnail size, the percentage of the thumbnail occupied by the audio waveform, whether audio plays back when the user skims through the media files, etc. In addition, some embodiments enable the user to view the clips in the clip browser in a list view. In this view, the clips are presented as a list (e.g., with clip name, duration, etc.). Some embodiments also display a selected clip from the list in a filmstrip view at the top of the browser so that the user can skim through or playback the selected clip. 
     The composite display area  4115  provides a visual representation of a composite presentation (or project) being created by the user of the media-editing application. Specifically, it displays one or more geometric shapes that represent one or more media clips that are part of the composite presentation. The composite display area  4115  of some embodiments includes a primary lane (also called a “spine”, “primary compositing lane”, or “central compositing lane”)  4160  as well as one or more secondary lanes (also called “anchor lanes”)  4165 . The spine represents a primary sequence of media which, in some embodiments, does not have any gaps. The clips in the anchor lanes are anchored (as shown by anchor  4185 ) to a particular position along the spine (or along a different anchor lane). Anchor lanes may be used for compositing (e.g., removing portions of one video and showing a different video in those portions), B-roll cuts (i.e., cutting away from the primary video to a different video whose clip is in the anchor lane), audio clips, or other composite presentation techniques. In some embodiments, the audio clips displayed in the composite display area  4115  include superimposed reference waveforms as described by reference to  FIGS. 30-39 , above. In some embodiments, the composite display area  4115  spans a displayed timeline  4180  which displays time (e.g., the elapsed time of clips displayed on the composite display area). 
     The user can add media clips from the clip browser  4110  into the timeline  4115  in order to add the clip to a presentation represented in the timeline. Within the timeline, the user can perform further edits to the media clips (e.g., move the clips around, split the clips, trim the clips, apply effects to the clips, etc.). The length (i.e., horizontal expanse) of a clip in the timeline is a function of the length of media represented by the clip. As the timeline is broken into increments of time, a media clip occupies a particular length of time in the timeline. As shown, in some embodiments the clips within the timeline are shown as a series of images. The number of images displayed for a clip varies depending on the length of the clip in the timeline, as well as the size of the clips (as the aspect ratio of each image will stay constant). 
     As with the clips in the clip browser, the user can skim through the timeline or play back the timeline (either a portion of the timeline or the entire timeline). In some embodiments, the playback (or skimming) is not shown in the timeline clips, but rather in the preview display area  4120 . 
     In some embodiments, the preview display area  4120  (also referred to as a “viewer”) displays images from video clips that the user is skimming through, playing back, or editing. These images may be from a composite presentation in the timeline  4115  or from a media clip in the clip browser  4110 . In this example, the user has been skimming through the beginning of video clip  4140 , and therefore an image from the start of this media file is displayed in the preview display area  4120 . As shown, some embodiments will display the images as large as possible within the display area while maintaining the aspect ratio of the image. 
     The inspector display area  4125  displays detailed properties about a selected item and allows a user to modify some or all of these properties. The additional media display area  4130  displays various types of additional media, such as video effects, transitions, still images, titles, audio effects, standard audio clips, etc. In some embodiments, the set of effects is represented by a set of selectable UI items, each selectable UI item representing a particular effect. In some embodiments, each selectable UI item also includes a thumbnail image with the particular effect applied. The display area  4130  is currently displaying a set of effects for the user to apply to a clip. In this example, several video effects are shown in the display area  4130 . 
     The toolbar  4135  includes various selectable items for editing, modifying, changing what is displayed in one or more display areas, etc. The right side of the toolbar includes various selectable items for modifying what type of media is displayed in the additional media display area  4130 . The illustrated toolbar  4135  includes items for video effects, visual transitions between media clips, photos, titles, generators and backgrounds, etc. In addition, the toolbar  4135  includes an inspector selectable item that causes the display of the inspector display area  4125  as well as the display of items for applying a retiming operation to a portion of the timeline, adjusting color, and other functions. 
     The left side of the toolbar  4135  includes selectable items for media management and editing. Selectable items are provided for adding clips from the clip browser  4110  to the timeline  4115 . In some embodiments, different selectable items may be used to add a clip to the end of the spine, add a clip at a selected point in the spine (e.g., at the location of a playhead), add an anchored clip at the selected point, perform various trim operations on the media clips in the timeline, etc. The media management tools of some embodiments allow a user to mark selected clips as favorites, among other options. 
     In some embodiments, the toolbar includes a selection tool (e.g., a selection or radio button) to show or hide volume adjuster graphs as described by reference to  FIGS. 17 and 18 , above. In some embodiments, the toolbar includes tools for cropping an audio clip as described by reference to  FIGS. 19 and 20 , above. The toolbar, in some embodiments, also includes tools for selecting portions of an audio clip as described by reference to  FIGS. 21-29 , above. In some of these embodiments, the toolbar also includes a selection tool (e.g., a selection button or a radio button) to generate a deformable volume adjuster graph after different portions of an audio clip are selected. In other embodiments, the deformable volume adjuster graph is automatically generated when one or more portions of an audio clip are selected. In some of these embodiments, the toolbar also includes a selection tool (e.g., a selection button or a radio button) to generate reference waveforms as described by reference to  FIGS. 30-32 , above 
     One or ordinary skill will also recognize that the set of display areas shown in the GUI  4100  is one of many possible configurations for the GUI of some embodiments. For instance, in some embodiments, the presence or absence of many of the display areas can be toggled through the GUI (e.g., the inspector display area  4125 , additional media display area  4130 , and clip library  4105 ). In addition, some embodiments allow the user to modify the size of the various display areas within the UI. For instance, when the display area  4130  is removed, the timeline  4115  can increase in size to include that area. Similarly, the preview display area  4120  increases in size when the inspector display area  4125  is removed. 
     VI. Electronic System 
     Many of the above-described features and applications are implemented as software processes that are specified as a set of instructions recorded on a computer readable storage medium (also referred to as computer readable medium, machine readable medium, machine readable storage). When these instructions are executed by one or more computational or processing unit(s) (e.g., one or more processors, cores of processors, or other processing units), they cause the processing unit(s) to perform the actions indicated in the instructions. Examples of computer readable media include, but are not limited to, CD-ROMs, flash drives, random access memory (RAM) chips, hard drives, erasable programmable read only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), etc. The computer readable media does not include carrier waves and electronic signals passing wirelessly or over wired connections. 
     In this specification, the term “software” is meant to include firmware residing in read-only memory or applications stored in magnetic storage which can be read into memory for processing by a processor. Also, in some embodiments, multiple software inventions can be implemented as sub-parts of a larger program while remaining distinct software inventions. In some embodiments, multiple software inventions can also be implemented as separate programs. Finally, any combination of separate programs that together implement a software invention described here is within the scope of the invention. In some embodiments, the software programs, when installed to operate on one or more electronic systems, define one or more specific machine implementations that execute and perform the operations of the software programs. 
       FIG. 42  conceptually illustrates an electronic system  4200  with which some embodiments of the invention are implemented. The electronic system  4200  may be a computer (e.g., a desktop computer, personal computer, tablet computer, etc.), phone, PDA, or any other sort of electronic or computing device. Such an electronic system includes various types of computer readable media and interfaces for various other types of computer readable media. Electronic system  4200  includes a bus  4205 , processing unit(s)  4210 , a graphics processing unit (GPU)  4215 , a system memory  4220 , a network  4225 , a read-only memory  4230 , a permanent storage device  4235 , input devices  4240 , and output devices  4245 . 
     The bus  4205  collectively represents all system, peripheral, and chipset buses that communicatively connect the numerous internal devices of the electronic system  4200 . For instance, the bus  4205  communicatively connects the processing unit(s)  4210  with the read-only memory  4230 , the GPU  4215 , the system memory  4220 , and the permanent storage device  4235 . 
     From these various memory units, the processing unit(s)  4210  retrieves instructions to execute and data to process in order to execute the processes of the invention. The processing unit(s) may be a single processor or a multi-core processor in different embodiments. Some instructions are passed to and executed by the GPU  4215 . The GPU  4215  can offload various computations or complement the image processing provided by the processing unit(s)  4210 . In some embodiments, such functionality can be provided using CoreImage&#39;s kernel shading language. 
     The read-only-memory (ROM)  4230  stores static data and instructions that are needed by the processing unit(s)  4210  and other modules of the electronic system. The permanent storage device  4235 , on the other hand, is a read-and-write memory device. This device is a non-volatile memory unit that stores instructions and data even when the electronic system  4200  is off. Some embodiments of the invention use a mass-storage device (such as a magnetic or optical disk and its corresponding disk drive) as the permanent storage device  4235 . 
     Other embodiments use a removable storage device (such as a floppy disk, flash memory device, etc., and its corresponding disk drive) as the permanent storage device. Like the permanent storage device  4235 , the system memory  4220  is a read-and-write memory device. However, unlike storage device  4235 , the system memory  4220  is a volatile read-and-write memory, such a random access memory. The system memory  4220  stores some of the instructions and data that the processor needs at runtime. In some embodiments, the invention&#39;s processes are stored in the system memory  4220 , the permanent storage device  4235 , and/or the read-only memory  4230 . For example, the various memory units include instructions for processing multimedia clips in accordance with some embodiments. From these various memory units, the processing unit(s)  4210  retrieves instructions to execute and data to process in order to execute the processes of some embodiments. 
     The bus  4205  also connects to the input and output devices  4240  and  4245 . The input devices  4240  enable the user to communicate information and select commands to the electronic system. The input devices  4240  include alphanumeric keyboards and pointing devices (also called “cursor control devices”), cameras (e.g., webcams), microphones or similar devices for receiving voice commands, etc. The output devices  4245  display images generated by the electronic system or otherwise output data. The output devices  4245  include printers and display devices, such as cathode ray tubes (CRT) or liquid crystal displays (LCD), as well as speakers or similar audio output devices. Some embodiments include devices such as a touchscreen that function as both input and output devices. 
     Finally, as shown in  FIG. 42 , bus  4205  also couples electronic system  4200  to a network  4225  through a network adapter (not shown). In this manner, the computer can be a part of a network of computers (such as a local area network (“LAN”), a wide area network (“WAN”), or an Intranet, or a network of networks, such as the Internet. Any or all components of electronic system  4200  may be used in conjunction with the invention. 
     Some embodiments include electronic components, such as microprocessors, storage and memory that store computer program instructions in a machine-readable or computer-readable medium (alternatively referred to as computer-readable storage media, machine-readable media, or machine-readable storage media). Some examples of such computer-readable media include RAM, ROM, read-only compact discs (CD-ROM), recordable compact discs (CD-R), rewritable compact discs (CD-RW), read-only digital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a variety of recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.), flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magnetic and/or solid state hard drives, read-only and recordable Blu-Ray® discs, ultra density optical discs, any other optical or magnetic media, and floppy disks. The computer-readable media may store a computer program that is executable by at least one processing unit and includes sets of instructions for performing various operations. Examples of computer programs or computer code include machine code, such as is produced by a compiler, and files including higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter. 
     While the above discussion primarily refers to microprocessor or multi-core processors that execute software, some embodiments are performed by one or more integrated circuits, such as application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). 
     In some embodiments, such integrated circuits execute instructions that are stored on the circuit itself. In addition, some embodiments execute software stored in programmable logic devices (PLDs), ROM, or RAM devices. 
     As used in this specification and any claims of this application, the terms “computer”, “server”, “processor”, and “memory” all refer to electronic or other technological devices. These terms exclude people or groups of people. For the purposes of the specification, the terms display or displaying means displaying on an electronic device. As used in this specification and any claims of this application, the terms “computer readable medium,” “computer readable media,” and “machine readable medium” are entirely restricted to tangible, physical objects that store information in a form that is readable by a computer. These terms exclude any wireless signals, wired download signals, and any other ephemeral signals. 
     While the invention has been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. In addition, a number of the figures (including  FIGS. 8 ,  12 ,  16 ,  19 ,  21 ,  32 ,  34 , and  37 ) conceptually illustrate processes. The specific operations of these processes may not be performed in the exact order shown and described. The specific operations may not be performed in one continuous series of operations, and different specific operations may be performed in different embodiments. Furthermore, the process could be implemented using several sub-processes, or as part of a larger macro process. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims. 
     While the invention has been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.