Abstract:
Systems, methods, and computer program products for displaying audio data are provided. In some implementations, a computer-implemented method is provided. The method includes receiving audio data and displaying a composite image representing the audio data. The composite image combines a first representation and a distinct second representation of the audio data. Each representation is visible in the composite image and the representations appear in the composite image as if laid one over the other.

Description:
BACKGROUND 
     This specification relates to displaying visual representations of features of audio data. 
     Different visual representations of audio data are commonly used to display different features of the audio data. For example, a frequency spectrogram shows a representation of frequencies of the audio data in the time-domain (e.g., a graphical display with time on the x-axis and frequency on the y-axis). Similarly, an amplitude display shows a representation of audio intensity in the time-domain (e.g., a graphical display with time on the x-axis and intensity on the y-axis). 
     SUMMARY 
     Systems, methods, and computer program products for displaying audio data are provided. In general, in one aspect, a computer-implemented method is provided. The method includes receiving audio data and displaying a composite image representing the audio data. The composite image combines a first representation and a distinct second representation of the audio data. Each representation is visible in the composite image and the representations appear in the composite image as if laid one over the other. 
     In general, in one aspect, a computer program product is provided. The computer program product is operable to cause data processing apparatus to perform operations. The operations include receiving audio data and displaying a composite image representing the audio data. The composite image combines a first representation and a distinct second representation of the audio data. Each representation is visible in the composite image and the representations appear in the composite image as if laid one over the other. 
     Implementations of the method and computer program product can include one or more of the following features. The first and second representations of the audio data can be displayed with respect to a shared axis. The shared axis can be a time axis. The first representation can be a frequency spectrogram. The second representation can represent an amplitude waveform. The amplitude waveform can be represented with a single pixel width line defining the outer shape of the amplitude waveform. The composite image can highlight the region composed of the first and second representations. The method and computer program product can further include editing the audio data. The editing can include receiving an input to perform an editing operation on the audio data and performing the editing operation and updating the displayed audio data to reflect the result of the editing operation. 
     In general, in one aspect, a system is provided. The system includes a user interface device and one or more computers operable to interact with the user interface device to receive audio data and display a composite image representing the audio data, the composite image combining a first representation and a distinct second representation of the audio data, each representation being visible in the composite image, the representations appearing in the composite image as if laid one over the other. 
     Implementations of the system can include one or more of the following features. The one or more computers can include a server operable to interact with the user interface device through a data communication network and the user interface device can be operable to interact with the server as a client. The user interface device can include a personal computer running a web browser or a mobile telephone running a WAP browser. The one or more computers can include one personal computer and the personal computer can include the user interface device. 
     Particular embodiments of the subject matter described in this specification can be implemented to realize one or more of the following advantages. Combining visual representations of audio data allows a user to view different features of audio data without switching between visual representations, either visually between separately positioned visual representations or by switching between displays. Display space for displaying the audio data can be maximized using a single display area instead of having multiple editors displaying distinct visual representations separately on the display. As a result it is easier for the user to identify portions of the audio data for editing including eliminating wasted display space. 
     The user can easily determine editing parameters using information from more than one visual representation of the audio data. Additionally, the user can identify the effect on a feature shown in one visual representation of the audio data of an editing operation in another visual representation. Furthermore, the combined visual representations allow for a single audio editor having benefits of multiple separate audio editors. 
     The details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an example process for displaying visual representations of audio data. 
         FIG. 2  shows an example display of a combined frequency spectrogram and an outline of an amplitude waveform. 
         FIG. 3  shows an example display of a combined frequency spectrogram and an amplitude waveform. 
         FIG. 4A  shows an example display of an amplitude waveform visual representation of audio data. 
         FIG. 4B  shows an example display of a frequency spectrogram visual representation of the audio data of  FIG. 4A . 
         FIG. 4C  shows an example display of combined frequency spectrogram and amplitude waveform of  FIGS. 4A-4B . 
         FIG. 5  is an example computing system. 
     
    
    
     Like reference numbers and designations in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
       FIG. 1  shows an example process  100  for displaying visual representations of audio data. For convenience, the process will be described with reference to a computer system that performs the process. The computer system receives audio data (step  102 ). The audio data is received, for example, as part of an audio file. The audio file can be locally stored or retrieved from a remote location. The audio data can be received, for example, in response to a user selection of a particular audio file. 
     The system displays a first visual representation of the audio data (step  104 ). For example, a particular feature of the audio data can be plotted and displayed in a window of a graphical user interface. The first visual representation can be displayed as a frequency spectrogram, an amplitude waveform, a pan position plot, or a phase display. In some implementations, the first visual representation is a frequency spectrogram. The frequency spectrogram shows various frequencies of the audio data in the time-domain (e.g., a graphical display with time on the x-axis and frequency on the y-axis). 
     The system superimposes a display of a second visual representation of the audio data over the first visual representation (i.e., a composite image of the visual representations such that the first and second visual representations appeal laid over each other by some amount) (step  106 ). As with the first visual representation, the second visual representation can be displayed as a frequency spectrogram, an amplitude waveform, a pan position plot, or a phase display. In some implementations, the second visual representation of the audio data is an amplitude waveform. An amplitude waveform shows audio intensity in the time-domain (e.g., a graphical display with time on the x-axis and intensity on the y-axis). In some implementations, the amplitude waveform is represented by an outline of the waveform only. Thus, the outline of the waveform, for example, shows the outer boundary of audio intensity with respect to time. 
       FIG. 2  shows an example display  200  of a frequency spectrogram  202  and an amplitude waveform outline  204 . The frequency spectrogram  202  shows the frequency components of the audio data in a frequency-time domain. Thus, the frequency spectrogram display  202  identifies the individual frequency components within the audio data at any particular point in time. With respect to the frequency spectrogram  200 , the y-axis of the display  200  represents frequency, for example, in hertz. The y-axis can represent frequency in linear, logarithmic or other scales. The x-axis of the display  200  represents time, e.g., in fractions of a second. 
     Additionally, the frequency spectrogram  202  shows intensity for particular frequencies according to brightness or color. For example, the frequency spectrogram  202  can include varied brightness levels to indicate the intensity of particular frequencies of the audio data at that particular point in time. The intensity can be relative intensity with respect to the audio data as a whole at that point in time (e.g., a percentage of the overall audio data) or an absolute intensity (e.g., a decibel level). For each point in time, the brighter areas indicate that a greater audio intensity of the audio data is located at that frequency while dimmer areas indict less audio intensity. In some implementations, brightness is shown in gray-scale having varying brightness levels to indicate intensity of the plotted audio data. 
     Additionally, or alternatively, the intensity of particular frequencies can be associated with a particular color. For example, colors can be assigned to represent particular intensity levels according to an absolute or relative scale. For example, using a relative scale, the color can be selected according to the percentage of the overall intensity. The number of colors used can vary depending on the number of intensity gradations as well as according to other considerations such as a determination of a particular number of visually recognizable colors. In some implementations, the colors with respect to intensity levels correspond to the ordering of colors of the visible light spectrum. 
     The amplitude waveform outline  204  shows the overall intensity of the audio data in the time-domain. In particular, the amplitude waveform outline  204  provides an outline indicating the outer boundary of the amplitude waveform over time. With respect to the amplitude waveform outline  204 , the y-axis of the display  200  represents intensity, for example, in decibels. The x-axis of the display  200  represents time. The frequency spectrogram  202  and the amplitude waveform outline  204  share a common time axis such that the visual representations of the audio data correspond in time with each other. The amplitude waveform outline  204  can be centered with respect to the y-axis or offset from the underlying frequency spectrogram  202 . In some implementations, the amplitude waveform outline  204  is provided as an overlay to the frequency spectrogram  202  while allowing a user to visually interpret both the frequency spectrogram  200  and the amplitude waveform outline  204 . 
     In some implementations of the user interface, the user can zoom in or out of either axis of the display  200  independently, which allows, for example, the user to identify particular frequencies of the frequency spectrogram  202  over a particular time range. The user can zoom in or out of each axis to modify the scale of the axis, increasing or decreasing the range of values for the displayed visual representations. The visual representations change to correspond to the selected zooming range. For example, a user can zoom in to display the audio data corresponding to a small frequency range in frequency spectrogram  202  of only a few hertz. Alternatively, the user can zoom out in order to display the entire audible frequency range. 
       FIG. 3  shows an example display  300  of a combined frequency spectrogram  302  and an amplitude waveform  304 . The frequency spectrogram  302  shows the frequency components of the audio data in a frequency-time domain. The amplitude waveform  304  shows the overall intensity of the audio data in the time-domain. In the display  300 , the full amplitude waveform  304  is shown instead of only an outline as in  FIG. 2 . However, both the amplitude waveform  304  and the frequency spectrogram  302  are visible. For example, the superimposed amplitude waveform  304  can be partially transparent such that when rendered the frequency spectrogram  302  remains visible. Alternatively, the frequency spectrogram  302  and amplitude waveform  304  can be blended together in order to present both visual representations simultaneously. Different blend tools can be used to create a desired blending effect between the two visual representations. For example, different filters used in graphics applications can be applied to increase the contrast in the superimposed region to highlight the amplitude waveform while still allowing both visual representations to be used. 
     As shown in  FIG. 1 , the system performs an editing operation on the audio data (step  108 ). In some implementations, the user interface includes one or more tools that provide access to different audio editing processes that can be performed on the audio data. The editing tools can allow a user to edit the audio data using input directly in a displayed visual representation, for example, by selecting a region within the visual representation and then performing an editing operation on audio data corresponding to the selected region. 
     In some implementations, the audio editing system includes preview functionality which allows the user to preview the edited audio results prior to modifying the audio data. Additionally, the system also can include an undo operation allowing the user undo performed audio edits, for example, which do not have the user intended results. 
     Common editing operations using frequency spectrogam and amplitude waveform visual representations include compression and equalization operations. Compression (or conversely amplification) operations modify the overall intensity of the audio data. Equalization includes performing an editing operation on one or more frequencies only. For example, a user can select a set of frequencies (e.g., as identified using a frequency spectrogram) and then modify the amplitude of the audio data corresponding to the selected set of frequencies. 
     The system updates the display of the first and second visual representations to reflect the performed editing operation (step  110 ). For example, if the user used an equalizer editing operation on a particular set of frequencies in the frequency spectrogram, the effect of the change is shown in both the frequency spectrogram and the amplitude waveform. The user can therefore determine whether a particular operation with respect to one visual representation had a detrimental effect that is visible in the other visual representation. For example, when editing particular frequencies, the user can determine if the editing operation has resulted in a clipped amplitude waveform. Clipping occurs when the overall amplitude exceeds the capacity of the audio system playing it, thus clipping may not be apparent from a visual inspection of the frequency spectrogram alone. If clipped audio data is saved, the clipping will persist even on other audio systems capable of playing at the unclipped intensity level. In some implementations, if five consecutive samples of the audio data have a maximum amplitude value, the audio data is considered clipped. 
     Additionally, the superimposed visual representations can be used to more precisely identify editing points, as will be described. 
     Particular forms of visual representations of audio data can be less precise with respect to time than other forms. For example, in a frequency spectrogram, the preciseness in the time domain is decreased when greater frequency accuracy is obtained because of the processing involved in generating a frequency spectrogram (e.g., the size of a fast Fourier transform used can increase frequency resolution while decreasing time resolution). 
       FIGS. 4A-4C  illustrate a simple example of how the superimposed visual representations can be used to more precisely identify editing points.  FIG. 4A  shows an example display  400  of an amplitude waveform  402  visual representation of audio data. In  FIG. 4A , a sine tone at 1 kHz is shown having a duration of 500 ms. Markers  404  and  406  on time axis  414  show the start of the sine tone at 1 second and ending at 1.5 seconds. The y-axis  408  indicates the intensity of the sine tone. The edges  410  and  412  of the amplitude waveform  402  are clearly defined and aligned with the markers  404  and  406 , respectively. Thus, there is no uncertainty regarding the start and end points of the sine tone. 
       FIG. 4B  shows an example display  425  of a frequency spectrogram  426  visual representation of the audio data of  FIG. 4A . In  FIG. 4B , the same 1 kHz sine tone displayed in  FIG. 4A  is shown. The display  425  shows time along the x-axis  428  and frequency along the y-axis  430 . However, as a result of the processing of the audio data to separate the audio data according to frequency, the time boundary of the signal has become blurred. Consequently, as shown in  FIG. 4B , it is unclear from the frequency spectrogram  426  exactly where the sine tone begins and ends. Thus, identifying the appropriate editing points can be more difficult. For example, a user may identify t=0.96 seconds as the starting point and t=1.54 seconds as the ending point instead of the actual start and ending points, which are clearly shown in the amplitude waveform  402  of  FIG. 4A . 
       FIG. 4C  shows an example display  445  of combined frequency spectrogram  426  and amplitude waveform  402  of  FIGS. 4A-4B . In particular, the display  445  shows an outline  446  of the amplitude waveform  402  superimposed over the frequency spectrogram  426 . The display  445  shows a common time for both visual representations on the x-axis  448 . The y-axis  450  represents frequency with respect to frequency spectrogram  426  and amplitude with respect to outline  446  of amplitude waveform  402 . The outline  446  allows the user to more clearly identify the starting and stopping points of the sine tone, which were unclear in the frequency spectrogram  426  alone. Thus, the user can identify precise editing points in the frequency spectrogram  426  using information from the superimposed outline  446 . 
     Alternatively, with audio data having multiple frequencies, the combination of frequency spectrogram and amplitude waveform can help a user more precisely define an editing region for a particular band of frequencies. For example, the frequency spectrogram allows the user to identify a very precise range of frequencies, but is less accurate with respect to time. The user can define the time range for the selected frequencies using the superimposed amplitude waveform as a guide, thereby improving editing accuracy. 
     In some implementations, different visual representations can be combined. For example, the frequency spectrogram can be combined with a pan position display or a phase display. The pan position display, for example, can allow the user to define a particular frequency and position of the audio data for editing. 
     Embodiments of the subject matter and the functional operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Embodiments of the subject matter described in this specification can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible program carrier for execution by, or to control the operation of, data processing apparatus. The tangible program carrier can be a propagated signal or a computer-readable medium. The propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus for execution by a computer. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more of them. 
     The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. 
     A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network. 
     The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). 
     Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer can be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a Global Positioning System (GPS) receiver, to name just a few. 
     Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry. 
     To provide for interaction with a user, embodiments of the subject matter described in this specification can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. 
     Embodiments of the subject matter described in this specification can be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the subject matter described is this specification, or any combination of one or more such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Internet. 
     The computing system can include clients and servers. A client  502  and server  504  are generally remote from each other and typically interact through a communication network  506  ( FIG. 5 ). The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. 
     While this specification contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 
     Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. 
     Particular embodiments of the subject matter described in this specification have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing may be advantageous.