Patent Description:
This application claims priority to <CIT> and <CIT>.

This disclosure relates to authoring and rendering of audio reproduction data. In particular, this disclosure relates to authoring and rendering audio reproduction data for reproduction environments such as cinema sound reproduction systems.

Since the introduction of sound with film in <NUM>, there has been a steady evolution of technology used to capture the artistic intent of the motion picture sound track and to replay it in a cinema environment. In the <NUM>, synchronized sound on disc gave way to variable area sound on film, which was further improved in the <NUM> with theatrical acoustic considerations and improved loudspeaker design, along with early introduction of multi-track recording and steerable replay (using control tones to move sounds). In the <NUM> and <NUM>, magnetic striping of film allowed multi-channel playback in theatre, introducing surround channels and up to five screen channels in premium theatres.

In the <NUM> Dolby introduced noise reduction, both in post-production and on film, along with a cost-effective means of encoding and distributing mixes with <NUM> screen channels and a mono surround channel. The quality of cinema sound was further improved in the <NUM> with Dolby Spectral Recording (SR) noise reduction and certification programs such as THX. Dolby brought digital sound to the cinema during the <NUM> with a <NUM> channel format that provides discrete left, center and right screen channels, left and right surround arrays and a subwoofer channel for low-frequency effects. Dolby Surround <NUM>, introduced in <NUM>, increased the number of surround channels by splitting the existing left and right surround channels into four "zones.

As the number of channels increases and the loudspeaker layout transitions from a planar two-dimensional (2D) array to a three-dimensional (3D) array including elevation, the task of positioning and rendering sounds becomes increasingly difficult. Improved audio authoring and rendering methods would be desirable.

<CIT> discloses a system and method for recording and reproducing three-dimensional sound events using a discretized, integrated macro-micro sound volume for reproducing a 3D acoustical matrix that reproduces sound including natural propagation and reverberation. The system and method may include sound modeling and synthesis that may enable sound to be reproduced as a volumetric matrix. The volumetric matrix may be captured, transferred, reproduced, or otherwise processed, as a spatial spectra of discretely reproduced sound events with controllable macro-micro relationships.

<CIT> discloses a system and method for forming and rendering 3D MIDI messages.

<CIT> discloses an acoustic signal conversion device <NUM> comprises reproduction channel determination means <NUM> for determining a reproduction speaker which includes the direction of the original speaker in a direction region identified by directions of three reproduction speakers; weighting coefficient calculation means <NUM> for calculating as a weighting coefficient the distribution ratio of the original acoustic signal for each reproduction speaker where the acoustic physical quantity at a received point of the original acoustic signal and the acoustic physical quantity at a received point of a reproduction acoustic signal corresponding to each determined reproduction speaker agree, the calculation being performed based on positions of original speakers and the position of each determined reproduction speaker; and acoustic signal distribution means <NUM> for distributing the original acoustic signal based on a weighting coefficient, thereby generating reproduction acoustic signals for the number of channels matching the reproduction speakers.

<CIT> discloses a system for mixing five channel sound which surrounds an audio plane.

"Report ITU-R BS. <NUM>-<NUM>, Multichannel sound technology in home and broadcasting applications, BS Series Broadcasting service (sound)", <NUM> January <NUM>, BS. <NUM>-<NUM> discloses A <NUM> multichannel sound system which has nine channels at the top layer, ten channels at the middle layer, three channels at the bottom layer and two low frequency effects (LFE) channels. This system is suited to wide screens such as <NUM> inch (<NUM>) FPD display, because it can localize two-dimensionally a sound image over the entire screen by using three bottom channels, five middle channels and three top channels around the screen.

<CIT> discloses audio perception in local proximity to visual cues.

<CIT> discloses a three-dimensional space divider <NUM> outputs plane information and channel mapping information, based on positions of a plurality of speakers arranged stereoscopically in three-dimensional space for outputting audio signals of a plurality of channels, and based on a dividing direction for dividing the three dimensional space into a plurality of planes. Plane encoders <NUM> to <NUM> generate encoding elements as a result of encoding as a group of programs for each two-dimensional plane based on the plane information and the channel mapping information, and further generates and outputs plane positional information. A stream integrating section <NUM> integrates all the encoding elements and the plane positional information to generate and output one encoding stream.

<CIT> discloses an apparatus for controlling a wave field synthesis renderer with audio objects includes a provider for providing a scene description.

Some aspects of the subject matter described in this disclosure can be implemented in tools for authoring and rendering audio reproduction data. Some such authoring tools allow audio reproduction data to be generalized for a wide variety of reproduction environments. According to some such implementations, audio reproduction data may be authored by creating metadata for audio objects. The metadata may be created with reference to speaker zones. During the rendering process, the audio reproduction data may be reproduced according to the reproduction speaker layout of a particular reproduction environment.

According to the invention, there is provided an apparatus as defined by claim <NUM>, a method as defined by claim <NUM>, and a non-transitory medium having software stored thereon as defined by claim <NUM>.

The following description is directed to certain implementations for the purposes of describing some innovative aspects of this disclosure, as well as examples of contexts in which these innovative aspects may be implemented. However, the teachings herein can be applied in various different ways. For example, while various implementations have been described in terms of particular reproduction environments, the teachings herein are widely applicable to other known reproduction environments, as well as reproduction environments that may be introduced in the future. Similarly, whereas examples of graphical user interfaces (GUIs) are presented herein, some of which provide examples of speaker locations, speaker zones, etc., other implementations are contemplated by the inventors. Moreover, the described implementations may be implemented in various authoring and/or rendering tools, which may be implemented in a variety of hardware, software, firmware, etc. Accordingly, the teachings of this disclosure are not intended to be limited to the implementations shown in the figures and/or described herein, but instead have wide applicability. The following description is useful to illustrate the invention which is defined in the appended claims.

<FIG> shows an example of a reproduction environment having a Dolby Surround <NUM> configuration. Dolby Surround <NUM> was developed in the <NUM>, but this configuration is still widely deployed in cinema sound system environments. A projector <NUM> may be configured to project video images, e.g. for a movie, on the screen <NUM>. Audio reproduction data may be synchronized with the video images and processed by the sound processor <NUM>. The power amplifiers <NUM> may provide speaker feed signals to speakers of the reproduction environment <NUM>.

The Dolby Surround <NUM> configuration includes left surround array <NUM>, right surround array <NUM>, each of which is gang-driven by a single channel. The Dolby Surround <NUM> configuration also includes separate channels for the left screen channel <NUM>, the center screen channel <NUM> and the right screen channel <NUM>. A separate channel for the subwoofer <NUM> is provided for low-frequency effects (LFE).

In <NUM>, Dolby provided enhancements to digital cinema sound by introducing Dolby Surround <NUM>. <FIG> shows an example of a reproduction environment having a Dolby Surround <NUM> configuration. A digital projector <NUM> may be configured to receive digital video data and to project video images on the screen <NUM>. Audio reproduction data may be processed by the sound processor <NUM>. The power amplifiers <NUM> may provide speaker feed signals to speakers of the reproduction environment <NUM>.

The Dolby Surround <NUM> configuration includes the left side surround array <NUM> and the right side surround array <NUM>, each of which may be driven by a single channel. Like Dolby Surround <NUM>, the Dolby Surround <NUM> configuration includes separate channels for the left screen channel <NUM>, the center screen channel <NUM>, the right screen channel <NUM> and the subwoofer <NUM>. However, Dolby Surround <NUM> increases the number of surround channels by splitting the left and right surround channels of Dolby Surround <NUM> into four zones: in addition to the left side surround array <NUM> and the right side surround array <NUM>, separate channels are included for the left rear surround speakers <NUM> and the right rear surround speakers <NUM>. Increasing the number of surround zones within the reproduction environment <NUM> can significantly improve the localization of sound.

In an effort to create a more immersive environment, some reproduction environments may be configured with increased numbers of speakers, driven by increased numbers of channels. Moreover, some reproduction environments may include speakers deployed at various elevations, some of which may be above a seating area of the reproduction environment.

<FIG> shows an example of a reproduction environment having a Hamasaki <NUM> surround sound configuration. Hamasaki <NUM> was developed at NHK Science & Technology Research Laboratories in Japan as the surround sound component of Ultra High Definition Television. Hamasaki <NUM> provides <NUM> speaker channels, which may be used to drive speakers arranged in three layers. Upper speaker layer <NUM> of reproduction environment <NUM> may be driven by <NUM> channels. Middle speaker layer <NUM> may be driven by <NUM> channels. Lower speaker layer <NUM> may be driven by <NUM> channels, two of which are for the subwoofers 345a and 345b.

Accordingly, the modern trend is to include not only more speakers and more channels, but also to include speakers at differing heights. As the number of channels increases and the speaker layout transitions from a 2D array to a 3D array, the tasks of positioning and rendering sounds becomes increasingly difficult.

This disclosure provides various tools, as well as related user interfaces, which increase functionality and/or reduce authoring complexity for a 3D audio sound system.

<FIG> shows an example of a graphical user interface (GUI) that portrays speaker zones at varying elevations in a virtual reproduction environment. GUI <NUM> may, for example, be displayed on a display device according to instructions from a logic system, according to signals received from user input devices, etc. Some such devices are described below with reference to <FIG>.

As used herein with reference to virtual reproduction environments such as the virtual reproduction environment <NUM>, the term "speaker zone" generally refers to a logical construct that may or may not have a one-to-one correspondence with a reproduction speaker of an actual reproduction environment. For example, a "speaker zone location" may or may not correspond to a particular reproduction speaker location of a cinema reproduction environment. Instead, the term "speaker zone location" may refer generally to a zone of a virtual reproduction environment. In some implementations, a speaker zone of a virtual reproduction environment may correspond to a virtual speaker, e.g., via the use of virtualizing technology such as Dolby Headphone,™ (sometimes referred to as Mobile Surround™), which creates a virtual surround sound environment in real time using a set of two-channel stereo headphones. In GUI <NUM>, there are seven speaker zones 402a at a first elevation and two speaker zones 402b at a second elevation, making a total of nine speaker zones in the virtual reproduction environment <NUM>. In this example, speaker zones <NUM>-<NUM> are in the front area <NUM> of the virtual reproduction environment <NUM>. The front area <NUM> may correspond, for example, to an area of a cinema reproduction environment in which a screen <NUM> is located, to an area of a home in which a television screen is located, etc..

Here, speaker zone <NUM> corresponds generally to speakers in the left area <NUM> and speaker zone <NUM> corresponds to speakers in the right area <NUM> of the virtual reproduction environment <NUM>. Speaker zone <NUM> corresponds to a left rear area <NUM> and speaker zone <NUM> corresponds to a right rear area <NUM> of the virtual reproduction environment <NUM>. Speaker zone <NUM> corresponds to speakers in an upper area 420a and speaker zone <NUM> corresponds to speakers in an upper area 420b, which may be a virtual ceiling area such as an area of the virtual ceiling <NUM> shown in <FIG>. Accordingly, and as described in more detail below, the locations of speaker zones <NUM>-<NUM> that are shown in <FIG> may or may not correspond to the locations of reproduction speakers of an actual reproduction environment. Moreover, other implementations may include more or fewer speaker zones and/or elevations.

In various implementations described herein, a user interface such as GUI <NUM> may be used as part of an authoring tool and/or a rendering tool. In some implementations, the authoring tool and/or rendering tool may be implemented via software stored on one or more non-transitory media. The authoring tool and/or rendering tool may be implemented (at least in part) by hardware, firmware, etc., such as the logic system and other devices described below with reference to <FIG>. In some authoring implementations, an associated authoring tool may be used to create metadata for associated audio data. The metadata may, for example, include data indicating the position and/or trajectory of an audio object in a three-dimensional space, speaker zone constraint data, etc. The metadata may be created with respect to the speaker zones <NUM> of the virtual reproduction environment <NUM>, rather than with respect to a particular speaker layout of an actual reproduction environment. A rendering tool may receive audio data and associated metadata, and may compute audio gains and speaker feed signals for a reproduction environment. Such audio gains and speaker feed signals may be computed according to an amplitude panning process, which can create a perception that a sound is coming from a position P in the reproduction environment. For example, speaker feed signals may be provided to reproduction speakers <NUM> through N of the reproduction environment according to the following equation:
<MAT>.

In Equation <NUM>, xi(t) represents the speaker feed signal to be applied to speaker i, gi represents the gain factor of the corresponding channel, x(t) represents the audio signal and t represents time. The gain factors may be determined, for example, according to the amplitude panning methods described in Section <NUM>, pages <NUM>-<NUM> of V. Pulkki, Compensating Displacement of Amplitude-Panned Virtual Sources (Audio Engineering Society (AES) International Conference on Virtual, Synthetic and Entertainment Audio). In some implementations, the gains may be frequency dependent. In some implementations, a time delay may be introduced by replacing x(t) by x(t-Δt).

In some rendering implementations, audio reproduction data created with reference to the speaker zones <NUM> may be mapped to speaker locations of a wide range of reproduction environments, which may be in a Dolby Surround <NUM> configuration, a Dolby Surround <NUM> configuration, a Hamasaki <NUM> configuration, or another configuration. For example, referring to <FIG>, a rendering tool may map audio reproduction data for speaker zones <NUM> and <NUM> to the left side surround array <NUM> and the right side surround array <NUM> of a reproduction environment having a Dolby Surround <NUM> configuration. Audio reproduction data for speaker zones <NUM>, <NUM> and <NUM> may be mapped to the left screen channel <NUM>, the right screen channel <NUM> and the center screen channel <NUM>, respectively. Audio reproduction data for speaker zones <NUM> and <NUM> may be mapped to the left rear surround speakers <NUM> and the right rear surround speakers <NUM>.

<FIG> shows an example of another reproduction environment. In some implementations, a rendering tool may map audio reproduction data for speaker zones <NUM>, <NUM> and <NUM> to corresponding screen speakers <NUM> of the reproduction environment <NUM>. A rendering tool may map audio reproduction data for speaker zones <NUM> and <NUM> to the left side surround array <NUM> and the right side surround array <NUM> and may map audio reproduction data for speaker zones <NUM> and <NUM> to left overhead speakers 470a and right overhead speakers 470b. Audio reproduction data for speaker zones <NUM> and <NUM> may be mapped to left rear surround speakers 480a and right rear surround speakers 480b.

In some authoring implementations, an authoring tool may be used to create metadata for audio objects. As used herein, the term "audio object" may refer to a stream of audio data and associated metadata. The metadata typically indicates the 3D position of the object, rendering constraints as well as content type (e.g. dialog, effects, etc.). Depending on the implementation, the metadata may include other types of data, such as width data, gain data, trajectory data, etc. Some audio objects may be static, whereas others may move. Audio object details may be authored or rendered according to the associated metadata which, among other things, may indicate the position of the audio object in a three-dimensional space at a given point in time. When audio objects are monitored or played back in a reproduction environment, the audio objects may be rendered according to the positional metadata using the reproduction speakers that are present in the reproduction environment, rather than being output to a predetermined physical channel, as is the case with traditional channel-based systems such as Dolby <NUM> and Dolby <NUM>.

Various authoring and rendering tools are described herein with reference to a GUI that is substantially the same as the GUI <NUM>. However, various other user interfaces, including but not limited to GUIs, may be used in association with these authoring and rendering tools. Some such tools can simplify the authoring process by applying various types of constraints. Some implementations will now be described with reference to <FIG> et seq.

<FIG> show examples of speaker responses corresponding to an audio object having a position that is constrained to a two-dimensional surface of a three-dimensional space, which is a hemisphere in this example. In these examples, the speaker responses have been computed by a renderer assuming a <NUM>-speaker configuration, with each speaker corresponding to one of the speaker zones <NUM>-<NUM>. However, as noted elsewhere herein, there may not generally be a one-to-one mapping between speaker zones of a virtual reproduction environment and reproduction speakers in a reproduction environment. Referring first to <FIG>, the audio object <NUM> is shown in a location in the left front portion of the virtual reproduction environment <NUM>. Accordingly, the speaker corresponding to speaker zone <NUM> indicates a substantial gain and the speakers corresponding to speaker zones <NUM> and <NUM> indicate moderate gains.

In this example, the location of the audio object <NUM> may be changed by placing a cursor <NUM> on the audio object <NUM> and "dragging" the audio object <NUM> to a desired location in the x,y plane of the virtual reproduction environment <NUM>. As the object is dragged towards the middle of the reproduction environment, it is also mapped to the surface of a hemisphere and its elevation increases. Here, increases in the elevation of the audio object <NUM> are indicated by an increase in the diameter of the circle that represents the audio object <NUM>: as shown in <FIG>, as the audio object <NUM> is dragged to the top center of the virtual reproduction environment <NUM>, the audio object <NUM> appears increasingly larger. Alternatively, or additionally, the elevation of the audio object <NUM> may be indicated by changes in color, brightness, a numerical elevation indication, etc. When the audio object <NUM> is positioned at the top center of the virtual reproduction environment <NUM>, as shown in <FIG>, the speakers corresponding to speaker zones <NUM> and <NUM> indicate substantial gains and the other speakers indicate little or no gain.

In this implementation, the position of the audio object <NUM> is constrained to a two-dimensional surface, such as a spherical surface, an elliptical surface, a conical surface, a cylindrical surface, a wedge, etc. <FIG> show examples of two-dimensional surfaces to which an audio object may be constrained. <FIG> are cross-sectional views through the virtual reproduction environment <NUM>, with the front area <NUM> shown on the left. In <FIG>, the y values of the y-z axis increase in the direction of the front area <NUM> of the virtual reproduction environment <NUM>, to retain consistency with the orientations of the x-y axes shown in <FIG>.

In the example shown in <FIG>, the two-dimensional surface 515a is a section of an ellipsoid. In the example shown in <FIG>, the two-dimensional surface 515b is a section of a wedge. However, the shapes, orientations and positions of the two-dimensional surfaces <NUM> shown in <FIG> are merely examples. In alternative implementations, at least a portion of the two-dimensional surface <NUM> may extend outside of the virtual reproduction environment <NUM>. In some such implementations, the two-dimensional surface <NUM> may extend above the virtual ceiling <NUM>. Accordingly, the three-dimensional space within which the two-dimensional surface <NUM> extends is not necessarily co-extensive with the volume of the virtual reproduction environment <NUM>. In yet other implementations, an audio object may be constrained to one-dimensional features such as curves, straight lines, etc..

<FIG> is a flow diagram that outlines one example of a process of constraining positions of an audio object to a two-dimensional surface. As with other flow diagrams that are provided herein, the operations of the process <NUM> are not necessarily performed in the order shown. Moreover, the process <NUM> (and other processes provided herein) may include more or fewer operations than those that are indicated in the drawings and/or described. In this example, blocks <NUM> through <NUM> are performed by an authoring tool and blocks <NUM> through <NUM> are performed by a rendering tool. The authoring tool and the rendering tool may be implemented in a single apparatus or in more than one apparatus. Although <FIG> (and other flow diagrams provided herein) may create the impression that the authoring and rendering processes are performed in sequential manner, in many implementations the authoring and rendering processes are performed at substantially the same time. Authoring processes and rendering processes may be interactive. For example, the results of an authoring operation may be sent to the rendering tool, the corresponding results of the rendering tool may be evaluated by a user, who may perform further authoring based on these results, etc..

In block <NUM>, an indication is received that an audio object position should be constrained to a two-dimensional surface. The indication may, for example, be received by a logic system of an apparatus that is configured to provide authoring and/or rendering tools. As with other implementations described herein, the logic system may be operating according to instructions of software stored in a non-transitory medium, according to firmware, etc. The indication may be a signal from a user input device (such as a touch screen, a mouse, a track ball, a gesture recognition device, etc.) in response to input from a user.

In optional block <NUM>, audio data are received. Block <NUM> is optional in this example, as audio data also may go directly to a renderer from another source (e.g., a mixing console) that is time synchronized to the metadata authoring tool. In some such implementations, an implicit mechanism may exist to tie each audio stream to a corresponding incoming metadata stream to form an audio object. For example, the metadata stream may contain an identifier for the audio object it represents, e.g., a numerical value from <NUM> to N. If the rendering apparatus is configured with audio inputs that are also numbered from <NUM> to N, the rendering tool may automatically assume that an audio object is formed by the metadata stream identified with a numerical value (e.g., <NUM>) and audio data received on the first audio input. Similarly, any metadata stream identified as number <NUM> may form an object with the audio received on the second audio input channel. In some implementations, the audio and metadata may be pre-packaged by the authoring tool to form audio objects and the audio objects may be provided to the rendering tool, e.g., sent over a network as TCP/IP packets.

In alternative implementations, the authoring tool may send only the metadata on the network and the rendering tool may receive audio from another source (e.g., via a pulse-code modulation (PCM) stream, via analog audio, etc.). In such implementations, the rendering tool may be configured to group the audio data and metadata to form the audio objects. The audio data may, for example, be received by the logic system via an interface. The interface may, for example, be a network interface, an audio interface (e.g., an interface configured for communication via the AES3 standard developed by the Audio Engineering Society and the European Broadcasting Union, also known as AES/EBU, via the Multichannel Audio Digital Interface (MADI) protocol, via analog signals, etc.) or an interface between the logic system and a memory device. In this example, the data received by the renderer includes at least one audio object.

In block <NUM>, (x,y) or (x,y,z) coordinates of an audio object position are received. Block <NUM> may, for example, involve receiving an initial position of the audio object. Block <NUM> may also involve receiving an indication that a user has positioned or re-positioned the audio object, e.g. as described above with reference to <FIG>. The coordinates of the audio object are mapped to a two-dimensional surface in block <NUM>. The two-dimensional surface may be similar to one of those described above with reference to <FIG>, or it may be a different two-dimensional surface. In this example, each point of the x-y plane will be mapped to a single z value, so block <NUM> involves mapping the x and y coordinates received in block <NUM> to a value of z. In other implementations, different mapping processes and/or coordinate systems may be used. The audio object may be displayed (block <NUM>) at the (x,y,z) location that is determined in block <NUM>. The audio data and metadata, including the mapped (x,y,z) location that is determined in block <NUM>, may be stored in block <NUM>. The audio data and metadata may be sent to a rendering tool (block <NUM>). In some implementations, the metadata may be sent continuously while some authoring operations are being performed, e.g., while the audio object is being positioned, constrained, displayed in the GUI <NUM>, etc..

In block <NUM>, it is determined whether the authoring process will continue. For example, the authoring process may end (block <NUM>) upon receipt of input from a user interface indicating that a user no longer wishes to constrain audio object positions to a two-dimensional surface. Otherwise, the authoring process may continue, e.g., by reverting to block <NUM> or block <NUM>. In some implementations, rendering operations may continue whether or not the authoring process continues. In some implementations, audio objects may be recorded to disk on the authoring platform and then played back from a dedicated sound processor or cinema server connected to a sound processor, e.g., a sound processor similar the sound processor <NUM> of <FIG>, for exhibition purposes.

In some implementations, the rendering tool may be software that is running on an apparatus that is configured to provide authoring functionality. In other implementations, the rendering tool may be provided on another device. The type of communication protocol used for communication between the authoring tool and the rendering tool may vary according to whether both tools are running on the same device or whether they are communicating over a network.

In block <NUM>, the audio data and metadata (including the (x,y,z) position(s) determined in block <NUM>) are received by the rendering tool. In alternative implementations, audio data and metadata may be received separately and interpreted by the rendering tool as an audio object through an implicit mechanism. As noted above, for example, a metadata stream may contain an audio object identification code (e.g., <NUM>,<NUM>,<NUM>, etc.) and may be attached respectively with the first, second, third audio inputs (i.e., digital or analog audio connection) on the rendering system to form an audio object that can be rendered to the loudspeakers.

During the rendering operations of the process <NUM> (and other rendering operations described herein, the panning gain equations may be applied according to the reproduction speaker layout of a particular reproduction environment. Accordingly, the logic system of the rendering tool may receive reproduction environment data comprising an indication of a number of reproduction speakers in the reproduction environment and an indication of the location of each reproduction speaker within the reproduction environment. These data may be received, for example, by accessing a data structure that is stored in a memory accessible by the logic system or received via an interface system.

In this example, panning gain equations are applied for the (x,y,z) position(s) to determine gain values (block <NUM>) to apply to the audio data (block <NUM>). In some implementations, audio data that have been adjusted in level in response to the gain values may be reproduced by reproduction speakers, e.g., by speakers of headphones (or other speakers) that are configured for communication with a logic system of the rendering tool. In some implementations, the reproduction speaker locations may correspond to the locations of the speaker zones of a virtual reproduction environment, such as the virtual reproduction environment <NUM> described above. The corresponding speaker responses may be displayed on a display device, e.g., as shown in <FIG>.

In block <NUM>, it is determined whether the process will continue. For example, the process may end (block <NUM>) upon receipt of input from a user interface indicating that a user no longer wishes to continue the rendering process. Otherwise, the process may continue, e.g., by reverting to block <NUM>. If the logic system receives an indication that the user wishes to revert to the corresponding authoring process, the process <NUM> may revert to block <NUM> or block <NUM>.

Other implementations may involve imposing various other types of constraints and creating other types of constraint metadata for audio objects. <FIG> is a flow diagram that outlines one example of a process of mapping an audio object position to a single speaker location. This process also may be referred to herein as "snapping. " In block <NUM>, an indication is received that an audio object position may be snapped to a single speaker location or a single speaker zone. In this example, the indication is that the audio object position will be snapped to a single speaker location, when appropriate. The indication may, for example, be received by a logic system of an apparatus that is configured to provide authoring tools. The indication may correspond with input received from a user input device. However, the indication also may correspond with a category of the audio object (e.g., as a bullet sound, a vocalization, etc.) and/or a width of the audio object. Information regarding the category and/or width may, for example, be received as metadata for the audio object. In such implementations, block <NUM> may occur before block <NUM>.

In block <NUM>, audio data are received. Coordinates of an audio object position are received in block <NUM>. In this example, the audio object position is displayed (block <NUM>) according to the coordinates received in block <NUM>. Metadata, including the audio object coordinates and a snap flag, indicating the snapping functionality, are saved in block <NUM>. The audio data and metadata are sent by the authoring tool to a rendering tool (block <NUM>).

In block <NUM>, it is determined whether the authoring process will continue. For example, the authoring process may end (block <NUM>) upon receipt of input from a user interface indicating that a user no longer wishes to snap audio object positions to a speaker location. Otherwise, the authoring process may continue, e.g., by reverting to block <NUM>. In some implementations, rendering operations may continue whether or not the authoring process continues.

The audio data and metadata sent by the authoring tool are received by the rendering tool in block <NUM>. In block <NUM>, it is determined (e.g., by the logic system) whether to snap the audio object position to a speaker location. This determination may be based, at least in part, on the distance between the audio object position and the nearest reproduction speaker location of a reproduction environment.

In this example, if it is determined in block <NUM> to snap the audio object position to a speaker location, the audio object position will be mapped to a speaker location in block <NUM>, generally the one closest to the intended (x,y,z) position received for the audio object. In this case, the gain for audio data reproduced by this speaker location will be <NUM>, whereas the gain for audio data reproduced by other speakers will be zero. In alternative implementations, the audio object position may be mapped to a group of speaker locations in block <NUM>.

For example, referring again to <FIG>, block <NUM> may involve snapping the position of the audio object to one of the left overhead speakers 470a. Alternatively, block <NUM> may involve snapping the position of the audio object to a single speaker and neighboring speakers, e.g., <NUM> or <NUM> neighboring speakers. Accordingly, the corresponding metadata may apply to a small group of reproduction speakers and/or to an individual reproduction speaker.

However, if it is determined in block <NUM> that the audio object position will not be snapped to a speaker location, for instance if this would result in a large discrepancy in position relative to the original intended position received for the object, panning rules will be applied (block <NUM>). The panning rules may be applied according to the audio object position, as well as other characteristics of the audio object (such as width, volume, etc.).

Gain data determined in block <NUM> may be applied to audio data in block <NUM> and the result may be saved. In some implementations, the resulting audio data may be reproduced by speakers that are configured for communication with the logic system. If it is determined in block <NUM> that the process <NUM> will continue, the process <NUM> may revert to block <NUM> to continue rendering operations. Alternatively, the process <NUM> may revert to block <NUM> to resume authoring operations.

Process <NUM> may involve various types of smoothing operations. For example, the logic system may be configured to smooth transitions in the gains applied to audio data when transitioning from mapping an audio object position from a first single speaker location to a second single speaker location. Referring again to <FIG>, if the position of the audio object were initially mapped to one of the left overhead speakers 470a and later mapped to one of the right rear surround speakers 480b, the logic system may be configured to smooth the transition between speakers so that the audio object does not seem to suddenly "jump" from one speaker (or speaker zone) to another. In some implementations, the smoothing may be implemented according to a crossfade rate parameter.

In some implementations, the logic system may be configured to smooth transitions in the gains applied to audio data when transitioning between mapping an audio object position to a single speaker location and applying panning rules for the audio object position. For example, if it were subsequently determined in block <NUM> that the position of the audio object had been moved to a position that was determined to be too far from the closest speaker, panning rules for the audio object position may be applied in block <NUM>. However, when transitioning from snapping to panning (or vice versa), the logic system may be configured to smooth transitions in the gains applied to audio data. The process may end in block <NUM>, e.g., upon receipt of corresponding input from a user interface.

Some alternative implementations may involve creating logical constraints. In some instances, for example, a sound mixer may desire more explicit control over the set of speakers that is being used during a particular panning operation. Some implementations allow a user to generate one- or two-dimensional "logical mappings" between sets of speakers and a panning interface.

<FIG> is a flow diagram that outlines a process of establishing and using virtual speakers. <FIG> show examples of virtual speakers mapped to line endpoints and corresponding speaker zone responses. Referring first to process <NUM> of <FIG>, an indication is received in block <NUM> to create virtual speakers. The indication may be received, for example, by a logic system of an authoring apparatus and may correspond with input received from a user input device.

In block <NUM>, an indication of a virtual speaker location is received. For example, referring to <FIG>, a user may use a user input device to position the cursor <NUM> at the position of the virtual speaker 805a and to select that location, e.g., via a mouse click. In block <NUM>, it is determined (e.g., according to user input) that additional virtual speakers will be selected in this example. The process reverts to block <NUM> and the user selects the position of the virtual speaker 805b, shown in <FIG>, in this example.

In this instance, the user only desires to establish two virtual speaker locations. Therefore, in block <NUM>, it is determined (e.g., according to user input) that no additional virtual speakers will be selected. A polyline <NUM> may be displayed, as shown in <FIG>, connecting the positions of the virtual speaker 805a and 805b. In some implementations, the position of the audio object <NUM> will be constrained to the polyline <NUM>. In some implementations, the position of the audio object <NUM> may be constrained to a parametric curve. For example, a set of control points may be provided according to user input and a curve-fitting algorithm, such as a spline, may be used to determine the parametric curve. In block <NUM>, an indication of an audio object position along the polyline <NUM> is received. In some such implementations, the position will be indicated as a scalar value between zero and one. In block <NUM>, (x,y,z) coordinates of the audio object and the polyline defined by the virtual speakers may be displayed. Audio data and associated metadata, including the obtained scalar position and the virtual speakers' (x,y,z) coordinates, may be displayed. (Block <NUM>. ) Here, the audio data and metadata may be sent to a rendering tool via an appropriate communication protocol in block <NUM>.

In block <NUM>, it is determined whether the authoring process will continue. If not, the process <NUM> may end (block <NUM>) or may continue to rendering operations, according to user input. As noted above, however, in many implementations at least some rendering operations may be performed concurrently with authoring operations.

In block <NUM>, the audio data and metadata are received by the rendering tool. In block <NUM>, the gains to be applied to the audio data are computed for each virtual speaker position. <FIG> shows the speaker responses for the position of the virtual speaker 805a. <FIG> shows the speaker responses for the position of the virtual speaker 805b. In this example, as in many other examples described herein, the indicated speaker responses are for reproduction speakers that have locations corresponding with the locations shown for the speaker zones of the GUI <NUM>. Here, the virtual speakers 805a and 805b, and the line <NUM>, have been positioned in a plane that is not near reproduction speakers that have locations corresponding with the speaker zones <NUM> and <NUM>. Therefore, no gain for these speakers is indicated in <FIG>.

When the user moves the audio object <NUM> to other positions along the line <NUM>, the logic system will calculate cross-fading that corresponds to these positions (block <NUM>), e.g., according to the audio object scalar position parameter. In some implementations, a pair-wise panning law (e.g. an energy preserving sine or power law) may be used to blend between the gains to be applied to the audio data for the position of the virtual speaker 805a and the gains to be applied to the audio data for the position of the virtual speaker 805b.

In block <NUM>, it may be then be determined (e.g., according to user input) whether to continue the process <NUM>. A user may, for example, be presented (e.g., via a GUI) with the option of continuing with rendering operations or of reverting to authoring operations. If it is determined that the process <NUM> will not continue, the process ends. (Block <NUM>.

When panning rapidly-moving audio objects (for example, audio objects that correspond to cars, jets, etc.), it may be difficult to author a smooth trajectory if audio object positions are selected by a user one point at a time. The lack of smoothness in the audio object trajectory may influence the perceived sound image. Accordingly, some authoring implementations provided herein apply a low-pass filter to the position of an audio object in order to smooth the resulting panning gains. Alternative authoring implementations apply a low-pass filter to the gain applied to audio data.

Other authoring implementations may allow a user to simulate grabbing, pulling, throwing or similarly interacting with audio objects. Some such implementations may involve the application of simulated physical laws, such as rule sets that are used to describe velocity, acceleration, momentum, kinetic energy, the application of forces, etc..

<FIG> show examples of using a virtual tether to drag an audio object. In <FIG>, a virtual tether <NUM> has been formed between the audio object <NUM> and the cursor <NUM>. In this example, the virtual tether <NUM> has a virtual spring constant. In some such implementations, the virtual spring constant may be selectable according to user input.

<FIG> shows the audio object <NUM> and the cursor <NUM> at a subsequent time, after which the user has moved the cursor <NUM> towards speaker zone <NUM>. The user may have moved the cursor <NUM> using a mouse, a joystick, a track ball, a gesture detection apparatus, or another type of user input device. The virtual tether <NUM> has been stretched and the audio object <NUM> has been moved near speaker zone <NUM>. The audio object <NUM> is approximately the same size in <FIG>, which indicates (in this example) that the elevation of the audio object <NUM> has not substantially changed.

<FIG> shows the audio object <NUM> and the cursor <NUM> at a later time, after which the user has moved the cursor around speaker zone <NUM>. The virtual tether <NUM> has been stretched yet further. The audio object <NUM> has been moved downwards, as indicated by the decrease in size of the audio object <NUM>. The audio object <NUM> has been moved in a smooth arc. This example illustrates one potential benefit of such implementations, which is that the audio object <NUM> may be moved in a smoother trajectory than if a user is merely selecting positions for the audio object <NUM> point by point.

<FIG> is a flow diagram that outlines a process of using a virtual tether to move an audio object. Process <NUM> begins with block <NUM>, in which audio data are received. In block <NUM>, an indication is received to attach a virtual tether between an audio object and a cursor. The indication may be received by a logic system of an authoring apparatus and may correspond with input received from a user input device. Referring to <FIG>, for example, a user may position the cursor <NUM> over the audio object <NUM> and then indicate, via a user input device or a GUI, that the virtual tether <NUM> should be formed between the cursor <NUM> and the audio object <NUM>. Cursor and object position data may be received. (Block <NUM>.

In this example, cursor velocity and/or acceleration data may be computed by the logic system according to cursor position data, as the cursor <NUM> is moved. (Block <NUM>. ) Position data and/or trajectory data for the audio object <NUM> may be computed according to the virtual spring constant of the virtual tether <NUM> and the cursor position, velocity and acceleration data. Some such implementations may involve assigning a virtual mass to the audio object <NUM>. (Block <NUM>. ) For example, if the cursor <NUM> is moved at a relatively constant velocity, the virtual tether <NUM> may not stretch and the audio object <NUM> may be pulled along at the relatively constant velocity. If the cursor <NUM> accelerates, the virtual tether <NUM> may be stretched and a corresponding force may be applied to the audio object <NUM> by the virtual tether <NUM>. There may be a time lag between the acceleration of the cursor <NUM> and the force applied by the virtual tether <NUM>. In alternative implementations, the position and/or trajectory of the audio object <NUM> may be determined in a different fashion, e.g., without assigning a virtual spring constant to the virtual tether <NUM>, by applying friction and/or inertia rules to the audio object <NUM>, etc..

Discrete positions and/or the trajectory of the audio object <NUM> and the cursor <NUM> may be displayed (block <NUM>). In this example, the logic system samples audio object positions at a time interval (block <NUM>). In some such implementations, the user may determine the time interval for sampling. The audio object location and/or trajectory metadata, etc., may be saved (block <NUM>).

In block <NUM> it is determined whether this authoring mode will continue. The process may continue if the user so desires, e.g., by reverting to block <NUM> or block <NUM>. Otherwise, the process <NUM> may end (block <NUM>).

<FIG> is a flow diagram that outlines an alternative process of using a virtual tether to move an audio object. <FIG> show examples of the process outlined in <FIG>. Referring first to <FIG>, process <NUM> begins with block <NUM>, in which audio data are received. In block <NUM>, an indication is received to attach a virtual tether between an audio object and a cursor. The indication may be received by a logic system of an authoring apparatus and may correspond with input received from a user input device. Referring to <FIG>, for example, a user may position the cursor <NUM> over the audio object <NUM> and then indicate, via a user input device or a GUI, that the virtual tether <NUM> should be formed between the cursor <NUM> and the audio object <NUM>.

Cursor and audio object position data may be received in block <NUM>. In block <NUM>, the logic system may receive an indication (via a user input device or a GUI, for example), that the audio object <NUM> should be held in an indicated position, e.g., a position indicated by the cursor <NUM>. In block <NUM>, the logic device receives an indication that the cursor <NUM> has been moved to a new position, which may be displayed along with the position of the audio object <NUM> (block <NUM>). Referring to <FIG>, for example, the cursor <NUM> has been moved from the left side to the right side of the virtual reproduction environment <NUM>. However, the audio object <NUM> is still being held in the same position indicated in <FIG>. As a result, the virtual tether <NUM> has been substantially stretched.

In block <NUM>, the logic system receives an indication (via a user input device or a GUI, for example) that the audio object <NUM> is to be released. The logic system may compute the resulting audio object position and/or trajectory data, which may be displayed (block <NUM>). The resulting display may be similar to that shown in <FIG>, which shows the audio object <NUM> moving smoothly and rapidly across the virtual reproduction environment <NUM>. The logic system may save the audio object location and/or trajectory metadata in a memory system (block <NUM>).

In block <NUM>, it is determined whether the authoring process <NUM> will continue. The process may continue if the logic system receives an indication that the user desires to do so. For example, the process <NUM> may continue by reverting to block <NUM> or block <NUM>. Otherwise, the authoring tool may send the audio data and metadata to a rendering tool (block <NUM>), after which the process <NUM> may end (block <NUM>).

In order to optimize the verisimilitude of the perceived motion of an audio object, it may be desirable to let the user of an authoring tool (or a rendering tool) select a subset of the speakers in a reproduction environment and to limit the set of active speakers to the chosen subset. In some implementations, speaker zones and/or groups of speaker zones may be designated active or inactive during an authoring or a rendering operation. For example, referring to <FIG>, speaker zones of the front area <NUM>, the left area <NUM>, the right area <NUM> and/or the upper area <NUM> may be controlled as a group. Speaker zones of a back area that includes speaker zones <NUM> and <NUM> (and, in other implementations, one or more other speaker zones located between speaker zones <NUM> and <NUM>) also may be controlled as a group. A user interface may be provided to dynamically enable or disable all the speakers that correspond to a particular speaker zone or to an area that includes a plurality of speaker zones.

In some implementations, the logic system of an authoring device (or a rendering device) may be configured to create speaker zone constraint metadata according to user input received via a user input system. The speaker zone constraint metadata may include data for disabling selected speaker zones. Some such implementations will now be described with reference to <FIG> and <FIG>.

<FIG> shows an example of applying a speaker zone constraint in a virtual reproduction environment. In some such implementations, a user may be able to select speaker zones by clicking on their representations in a GUI, such as GUI <NUM>, using a user input device such as a mouse. Here, a user has disabled speaker zones <NUM> and <NUM>, on the sides of the virtual reproduction environment <NUM>. Speaker zones <NUM> and <NUM> may correspond to most (or all) of the speakers in a physical reproduction environment, such as a cinema sound system environment. In this example, the user has also constrained the positions of the audio object <NUM> to positions along the line <NUM>. With most or all of the speakers along the side walls disabled, a pan from the screen <NUM> to the back of the virtual reproduction environment <NUM> would be constrained not to use the side speakers. This may create an improved perceived motion from front to back for a wide audience area, particularly for audience members who are seated near reproduction speakers corresponding with speaker zones <NUM> and <NUM>.

In some implementations, speaker zone constraints may be carried through all re-rendering modes. For example, speaker zone constraints may be carried through in situations when fewer zones are available for rendering, e.g., when rendering for a Dolby Surround <NUM> or <NUM> configuration exposing only <NUM> or <NUM> zones. Speaker zone constraints also may be carried through when more zones are available for rendering. As such, the speaker zone constraints can also be seen as a way to guide re-rendering, providing a non-blind solution to the traditional "upmixing/downmixing" process.

<FIG> is a flow diagram that outlines some examples of applying speaker zone constraint rules. Process <NUM> begins with block <NUM>, in which one or more indications are received to apply speaker zone constraint rules. The indication(s) may be received by a logic system of an authoring or a rendering apparatus and may correspond with input received from a user input device. For example, the indications may correspond to a user's selection of one or more speaker zones to de-activate. In some implementations, block <NUM> may involve receiving an indication of what type of speaker zone constraint rules should be applied, e.g., as described below.

In block <NUM>, audio data are received by an authoring tool. Audio object position data may be received (block <NUM>), e.g., according to input from a user of the authoring tool, and displayed (block <NUM>). The position data are (x,y,z) coordinates in this example. Here, the active and inactive speaker zones for the selected speaker zone constraint rules are also displayed in block <NUM>. In block <NUM>, the audio data and associated metadata are saved. In this example, the metadata include the audio object position and speaker zone constraint metadata, which may include a speaker zone identification flag.

In some implementations, the speaker zone constraint metadata may indicate that a rendering tool should apply panning equations to compute gains in a binary fashion, e.g., by regarding all speakers of the selected (disabled) speaker zones as being "off" and all other speaker zones as being "on. " The logic system may be configured to create speaker zone constraint metadata that includes data for disabling the selected speaker zones.

In alternative implementations, the speaker zone constraint metadata may indicate that the rendering tool will apply panning equations to compute gains in a blended fashion that includes some degree of contribution from speakers of the disabled speaker zones. For example, the logic system may be configured to create speaker zone constraint metadata indicating that the rendering tool should attenuate selected speaker zones by performing the following operations: computing first gains that include contributions from the selected (disabled) speaker zones; computing second gains that do not include contributions from the selected speaker zones; and blending the first gains with the second gains. In some implementations, a bias may be applied to the first gains and/or the second gains (e.g., from a selected minimum value to a selected maximum value) in order to allow a range of potential contributions from selected speaker zones.

In this example, the authoring tool sends the audio data and metadata to a rendering tool in block <NUM>. The logic system may then determine whether the authoring process will continue (block <NUM>). The authoring process may continue if the logic system receives an indication that the user desires to do so. Otherwise, the authoring process may end (block <NUM>). In some implementations, the rendering operations may continue, according to user input.

The audio objects, including audio data and metadata created by the authoring tool, are received by the rendering tool in block <NUM>. Position data for a particular audio object are received in block <NUM> in this example. The logic system of the rendering tool may apply panning equations to compute gains for the audio object position data, according to the speaker zone constraint rules.

In block <NUM>, the computed gains are applied to the audio data. The logic system may save the gain, audio object location and speaker zone constraint metadata in a memory system. In some implementations, the audio data may be reproduced by a speaker system. Corresponding speaker responses may be shown on a display in some implementations.

In block <NUM>, it is determined whether process <NUM> will continue. The process may continue if the logic system receives an indication that the user desires to do so. For example, the rendering process may continue by reverting to block <NUM> or block <NUM>. If an indication is received that a user wishes to revert to the corresponding authoring process, the process may revert to block <NUM> or block <NUM>. Otherwise, the process <NUM> may end (block <NUM>).

The tasks of positioning and rendering audio objects in a three-dimensional virtual reproduction environment are becoming increasingly difficult. Part of the difficulty relates to challenges in representing the virtual reproduction environment in a GUI. Some authoring and rendering implementations provided herein allow a user to switch between two-dimensional screen space panning and three-dimensional room-space panning. Such functionality may help to preserve the accuracy of audio object positioning while providing a GUI that is convenient for the user.

<FIG> show an example of a GUI that can switch between a two-dimensional view and a three-dimensional view of a virtual reproduction environment. Referring first to <FIG>, the GUI <NUM> depicts an image <NUM> on the screen. In this example, the image <NUM> is that of a saber-toothed tiger. In this top view of the virtual reproduction environment <NUM>, a user can readily observe that the audio object <NUM> is near the speaker zone <NUM>. The elevation may be inferred, for example, by the size, the color, or some other attribute of the audio object <NUM>. However, the relationship of the position to that of the image <NUM> may be difficult to determine in this view.

In this example, the GUI <NUM> can appear to be dynamically rotated around an axis, such as the axis <NUM>. <FIG> shows the GUI <NUM> after the rotation process. In this view, a user can more clearly see the image <NUM> and can use information from the image <NUM> to position the audio object <NUM> more accurately. In this example, the audio object corresponds to a sound towards which the saber-toothed tiger is looking. Being able to switch between the top view and a screen view of the virtual reproduction environment <NUM> allows a user to quickly and accurately select the proper elevation for the audio object <NUM>, using information from on-screen material.

Various other convenient GUIs for authoring and/or rendering are provided herein. <FIG> show combinations of two-dimensional and three-dimensional depictions of reproduction environments. Referring first to <FIG>, a top view of the virtual reproduction environment <NUM> is depicted in a left area of the GUI <NUM>. The GUI <NUM> also includes a three-dimensional depiction <NUM> of a virtual (or actual) reproduction environment. Area <NUM> of the three-dimensional depiction <NUM> corresponds with the screen <NUM> of the GUI <NUM>. The position of the audio object <NUM>, particularly its elevation, may be clearly seen in the three-dimensional depiction <NUM>. In this example, the width of the audio object <NUM> is also shown in the three-dimensional depiction <NUM>.

The speaker layout <NUM> depicts the speaker locations <NUM> through <NUM>, each of which can indicate a gain corresponding to the position of the audio object <NUM> in the virtual reproduction environment <NUM>. In some implementations, the speaker layout <NUM> may, for example, represent reproduction speaker locations of an actual reproduction environment, such as a Dolby Surround <NUM> configuration, a Dolby Surround <NUM> configuration, a Dolby <NUM> configuration augmented with overhead speakers, etc. When a logic system receives an indication of a position of the audio object <NUM> in the virtual reproduction environment <NUM>, the logic system may be configured to map this position to gains for the speaker locations <NUM> through <NUM> of the speaker layout <NUM>, e.g., by the above-described amplitude panning process. For example, in <FIG>, the speaker locations <NUM>, <NUM> and <NUM> each have a change in color indicating gains corresponding to the position of the audio object <NUM>.

Referring now to <FIG>, the audio object has been moved to a position behind the screen <NUM>. For example, a user may have moved the audio object <NUM> by placing a cursor on the audio object <NUM> in GUI <NUM> and dragging it to a new position. This new position is also shown in the three-dimensional depiction <NUM>, which has been rotated to a new orientation. The responses of the speaker layout <NUM> may appear substantially the same in <FIG> and <FIG>. However, in an actual GUI, the speaker locations <NUM>, <NUM> and <NUM> may have a different appearance (such as a different brightness or color) to indicate corresponding gain differences cause by the new position of the audio object <NUM>.

Referring now to <FIG>, the audio object <NUM> has been moved rapidly to a position in the right rear portion of the virtual reproduction environment <NUM>. At the moment depicted in <FIG>, the speaker location <NUM> is responding to the current position of the audio object <NUM> and the speaker locations <NUM> and <NUM> are still responding to the former position of the audio object <NUM>.

<FIG> is a flow diagram that outlines a process of controlling an apparatus to present GUIs such as those shown in <FIG>. Process <NUM> begins with block <NUM>, in which one or more indications are received to display audio object locations, speaker zone locations and reproduction speaker locations for a reproduction environment. The speaker zone locations may correspond to a virtual reproduction environment and/or an actual reproduction environment, e.g., as shown in <FIG>. The indication(s) may be received by a logic system of a rendering and/or authoring apparatus and may correspond with input received from a user input device. For example, the indications may correspond to a user's selection of a reproduction environment configuration.

In block <NUM>, audio data are received. Audio object position data and width are received in block <NUM>, e.g., according to user input. In block <NUM>, the audio object, the speaker zone locations and reproduction speaker locations are displayed. The audio object position may be displayed in two-dimensional and/or three-dimensional views, e.g., as shown in <FIG>. The width data may be used not only for audio object rendering, but also may affect how the audio object is displayed (see the depiction of the audio object <NUM> in the three-dimensional depiction <NUM> of <FIG>).

The audio data and associated metadata may be recorded. (Block <NUM>). In block <NUM>, the authoring tool sends the audio data and metadata to a rendering tool. The logic system may then determine (block <NUM>) whether the authoring process will continue. The authoring process may continue (e.g., by reverting to block <NUM>) if the logic system receives an indication that the user desires to do so. Otherwise, the authoring process may end. (Block <NUM>).

The audio objects, including audio data and metadata created by the authoring tool, are received by the rendering tool in block <NUM>. Position data for a particular audio object are received in block <NUM> in this example. The logic system of the rendering tool may apply panning equations to compute gains for the audio object position data, according to the width metadata.

In some rendering implementations, the logic system may map the speaker zones to reproduction speakers of the reproduction environment. For example, the logic system may access a data structure that includes speaker zones and corresponding reproduction speaker locations. More details and examples are described below with reference to <FIG>.

In some implementations, panning equations may be applied, e.g., by a logic system, according to the audio object position, width and/or other information, such as the speaker locations of the reproduction environment (block <NUM>). In block <NUM>, the audio data are processed according to the gains that are obtained in block <NUM>. At least some of the resulting audio data may be stored, if so desired, along with the corresponding audio object position data and other metadata received from the authoring tool. The audio data may be reproduced by speakers.

The logic system may then determine (block <NUM>) whether the process <NUM> will continue. The process <NUM> may continue if, for example, the logic system receives an indication that the user desires to do so. Otherwise, the process <NUM> may end (block <NUM>).

<FIG> is a flow diagram that outlines a process of rendering audio objects for a reproduction environment. Process <NUM> begins with block <NUM>, in which one or more indications are received to render audio objects for a reproduction environment. The indication(s) may be received by a logic system of a rendering apparatus and may correspond with input received from a user input device. For example, the indications may correspond to a user's selection of a reproduction environment configuration.

In block <NUM>, audio reproduction data (including one or more audio objects and associated metadata) are received. Reproduction environment data may be received in block <NUM>. The reproduction environment data may include an indication of a number of reproduction speakers in the reproduction environment and an indication of the location of each reproduction speaker within the reproduction environment. The reproduction environment may be a cinema sound system environment, a home theater environment, etc. In some implementations, the reproduction environment data may include reproduction speaker zone layout data indicating reproduction speaker zones and reproduction speaker locations that correspond with the speaker zones.

The reproduction environment may be displayed in block <NUM>. In some implementations, the reproduction environment may be displayed in a manner similar to the speaker layout <NUM> shown in <FIG>.

In block <NUM>, audio objects may be rendered into one or more speaker feed signals for the reproduction environment. In some implementations, the metadata associated with the audio objects may have been authored in a manner such as that described above, such that the metadata may include gain data corresponding to speaker zones (for example, corresponding to speaker zones <NUM>-<NUM> of GUI <NUM>). The logic system may map the speaker zones to reproduction speakers of the reproduction environment. For example, the logic system may access a data structure, stored in a memory, that includes speaker zones and corresponding reproduction speaker locations. The rendering device may have a variety of such data structures, each of which corresponds to a different speaker configuration. In some implementations, a rendering apparatus may have such data structures for a variety of standard reproduction environment configurations, such as a Dolby Surround <NUM> configuration, a Dolby Surround <NUM> configuration\ and/or Hamasaki <NUM> surround sound configuration.

In some implementations, the metadata for the audio objects may include other information from the authoring process. For example, the metadata may include speaker constraint data. The metadata may include information for mapping an audio object position to a single reproduction speaker location or a single reproduction speaker zone. The metadata may include data constraining a position of an audio object to a one-dimensional curve or a two-dimensional surface. The metadata may include trajectory data for an audio object. The metadata may include an identifier for content type (e.g., dialog, music or effects).

Accordingly, the rendering process may involve use of the metadata, e.g., to impose speaker zone constraints. In some such implementations, the rendering apparatus may provide a user with the option of modifying constraints indicated by the metadata, e.g., of modifying speaker constraints and re-rendering accordingly. The rendering may involve creating an aggregate gain based on one or more of a desired audio object position, a distance from the desired audio object position to a reference position, a velocity of an audio object or an audio object content type. The corresponding responses of the reproduction speakers may be displayed. (Block <NUM>. ) In some implementations, the logic system may control speakers to reproduce sound corresponding to results of the rendering process.

In block <NUM>, the logic system may determine whether the process <NUM> will continue. The process <NUM> may continue if, for example, the logic system receives an indication that the user desires to do so. For example, the process <NUM> may continue by reverting to block <NUM> or block <NUM>. Otherwise, the process <NUM> may end (block <NUM>).

Spread and apparent source width control are features of some existing surround sound authoring/rendering systems. In this disclosure, the term "spread" refers to distributing the same signal over multiple speakers to blur the sound image. The term "width" refers to decorrelating the output signals to each channel for apparent width control. Width may be an additional scalar value that controls the amount of decorrelation applied to each speaker feed signal.

Some implementations described herein provide a 3D axis oriented spread control. One such implementation will now be described with reference to <FIG> shows an example of an audio object and associated audio object width in a virtual reproduction environment. Here, the GUI <NUM> indicates an ellipsoid <NUM> extending around the audio object <NUM>, indicating the audio object width. The audio object width may be indicated by audio object metadata and/or received according to user input. In this example, the x and y dimensions of the ellipsoid <NUM> are different, but in other implementations these dimensions may be the same. The z dimensions of the ellipsoid <NUM> are not shown in <FIG>.

<FIG> shows an example of a spread profile corresponding to the audio object width shown in <FIG>. Spread may be represented as a three-dimensional vector parameter. In this example, the spread profile <NUM> can be independently controlled along <NUM> dimensions, e.g., according to user input. The gains along the x and y axes are represented in <FIG> by the respective height of the curves <NUM> and <NUM>. The gain for each sample <NUM> is also indicated by the size of the corresponding circles <NUM> within the spread profile <NUM>. The responses of the speakers <NUM> are indicated by gray shading in <FIG>.

In some implementations, the spread profile <NUM> may be implemented by a separable integral for each axis. According to some implementations, a minimum spread value may be set automatically as a function of speaker placement to avoid timbral discrepancies when panning. Alternatively, or additionally, a minimum spread value may be set automatically as a function of the velocity of the panned audio object, such that as audio object velocity increases an object becomes more spread out spatially, similarly to how rapidly moving images in a motion picture appear to blur.

When using audio object-based audio rendering implementations such as those described herein, a potentially large number of audio tracks and accompanying metadata (including but not limited to metadata indicating audio object positions in three-dimensional space) may be delivered unmixed to the reproduction environment. A real-time rendering tool may use such metadata and information regarding the reproduction environment to compute the speaker feed signals for optimizing the reproduction of each audio object.

When a large number of audio objects are mixed together to the speaker outputs, overload can occur either in the digital domain (for example, the digital signal may be clipped prior to the analog conversion) or in the analog domain, when the amplified analog signal is played back by the reproduction speakers. Both cases may result in audible distortion, which is undesirable. Overload in the analog domain also could damage the reproduction speakers.

Accordingly, some implementations described herein involve dynamic object "blobbing" in response to reproduction speaker overload. When audio objects are rendered with a given spread profile, in some implementations the energy may be directed to an increased number of neighboring reproduction speakers while maintaining overall constant energy. For instance, if the energy for the audio object were uniformly spread over N reproduction speakers, it may contribute to each reproduction speaker output with a gain <NUM>/sqrt(N). This approach provides additional mixing "headroom" and can alleviate or prevent reproduction speaker distortion, such as clipping.

To use a numerical example, suppose a speaker will clip if it receives an input greater than <NUM>. Assume that two objects are indicated to be mixed into speaker A, one at level <NUM> and the other at level <NUM>. If no blobbing were used, the mixed level in speaker A would total <NUM> and clipping occurs. However, if the first object is blobbed with another speaker B, then (according to some implementations) each speaker would receive the object at <NUM>, resulting in additional "headroom" in speaker A for mixing additional objects. The second object can then be safely mixed into speaker A without clipping, as the mixed level for speaker A will be <NUM> + <NUM> = <NUM>.

In some implementations, during the authoring phase each audio object may be mixed to a subset of the speaker zones (or all the speaker zones) with a given mixing gain. A dynamic list of all objects contributing to each loudspeaker can therefore be constructed. In some implementations, this list may be sorted by decreasing energy levels, e.g. using the product of the original root mean square (RMS) level of the signal multiplied by the mixing gain. In other implementations, the list may be sorted according to other criteria, such as the relative importance assigned to the audio object.

During the rendering process, if an overload is detected for a given reproduction speaker output, the energy of audio objects may be spread across several reproduction speakers. For example, the energy of audio objects may be spread using a width or spread factor that is proportional to the amount of overload and to the relative contribution of each audio object to the given reproduction speaker. If the same audio object contributes to several overloading reproduction speakers, its width or spread factor may, in some implementations, be additively increased and applied to the next rendered frame of audio data.

Generally, a hard limiter will clip any value that exceeds a threshold to the threshold value. As in the example above, if a speaker receives a mixed object at level <NUM>, and can only allow a max level of <NUM>, the object will be ""hard limited" to <NUM>. A soft limiter will begin to apply limiting prior to reaching the absolute threshold in order to provide a smoother, more audibly pleasing result. Soft limiters may also use a "look ahead" feature to predict when future clipping may occur in order to smoothly reduce the gain prior to when clipping would occur and thus avoid clipping.

Various "blobbing" implementations provided herein may be used in conjunction with a hard or soft limiter to limit audible distortion while avoiding degradation of spatial accuracy/sharpness. As opposed to a global spread or the use of limiters alone, blobbing implementations may selectively target loud objects, or objects of a given content type. Such implementations may be controlled by the mixer. For example, if speaker zone constraint metadata for an audio object indicate that a subset of the reproduction speakers should not be used, the rendering apparatus may apply the corresponding speaker zone constraint rules in addition to implementing a blobbing method.

<FIG> is a flow diagram that that outlines a process of blobbing audio objects. Process <NUM> begins with block <NUM>, wherein one or more indications are received to activate audio object blobbing functionality. The indication(s) may be received by a logic system of a rendering apparatus and may correspond with input received from a user input device. In some implementations, the indications may include a user's selection of a reproduction environment configuration. In alternative implementations, the user may have previously selected a reproduction environment configuration.

In block <NUM>, audio reproduction data (including one or more audio objects and associated metadata) are received. In some implementations, the metadata may include speaker zone constraint metadata, e.g., as described above. In this example, audio object position, time and spread data are parsed from the audio reproduction data (or otherwise received, e.g., via input from a user interface) in block <NUM>.

Reproduction speaker responses are determined for the reproduction environment configuration by applying panning equations for the audio object data, e.g., as described above (block <NUM>). In block <NUM>, audio object position and reproduction speaker responses are displayed (block <NUM>). The reproduction speaker responses also may be reproduced via speakers that are configured for communication with the logic system.

In block <NUM>, the logic system determines whether an overload is detected for any reproduction speaker of the reproduction environment. If so, audio object blobbing rules such as those described above may be applied until no overload is detected (block <NUM>). The audio data output in block <NUM> may be saved, if so desired, and may be output to the reproduction speakers.

Some implementations provide extended panning gain equations that can be used to image an audio object position in three-dimensional space. Some examples will now be described wither reference to <FIG> show examples of an audio object positioned in a three-dimensional virtual reproduction environment. Referring first to <FIG>, the position of the audio object <NUM> may be seen within the virtual reproduction environment <NUM>. In this example, the speaker zones <NUM>-<NUM> are located in one plane and the speaker zones <NUM> and <NUM> are located in another plane, as shown in <FIG>. However, the numbers of speaker zones, planes, etc., are merely made by way of example; the concepts described herein may be extended to different numbers of speaker zones (or individual speakers) and more than two elevation planes.

In this example, an elevation parameter "z," which may range from zero to <NUM>, maps the position of an audio object to the elevation planes. In this example, the value z = <NUM> corresponds to the base plane that includes the speaker zones <NUM>-<NUM>, whereas the value z = <NUM> corresponds to the overhead plane that includes the speaker zones <NUM> and <NUM>. Values of e between zero and <NUM> correspond to a blending between a sound image generated using only the speakers in the base plane and a sound image generated using only the speakers in the overhead plane.

In the example shown in <FIG>, the elevation parameter for the audio object <NUM> has a value of <NUM>. Accordingly, in one implementation, a first sound image may be generated using panning equations for the base plane, according to the (x,y) coordinates of the audio object <NUM> in the base plane. A second sound image may be generated using panning equations for the overhead plane, according to the (x,y) coordinates of the audio object <NUM> in the overhead plane. A resulting sound image may be produced by combining the first sound image with the second sound image, according to the proximity of the audio object <NUM> to each plane. An energy- or amplitude-preserving function of the elevation z may be applied. For example, assuming that z can range from zero to one, the gain values of the first sound image may be multiplied by Cos(z*π/<NUM>) and the gain values of the second sound image may be multiplied by sin(z*π/<NUM>), so that the sum of their squares is <NUM> (energy preserving).

Other implementations described herein may involve computing gains based on two or more panning techniques and creating an aggregate gain based on one or more parameters. The parameters may include one or more of the following: desired audio object position; distance from the desired audio object position to a reference position; the speed or velocity of the audio object; or audio object content type.

Some such implementations will now be described with reference to <FIG> et seq. <FIG> shows examples of zones that correspond with different panning modes. The sizes, shapes and extent of these zones are merely made by way of example. In this example, near-field panning methods are applied for audio objects located within zone <NUM> and far-field panning methods are applied for audio objects located in zone <NUM>, outside of zone <NUM>.

<FIG> show examples of applying near-field and far-field panning techniques to audio objects at different locations. Referring first to <FIG>, the audio object is substantially outside of the virtual reproduction environment <NUM>. This location corresponds to zone <NUM> of <FIG>. Therefore, one or more far-field panning methods will be applied in this instance. In some implementations, the far-field panning methods may be based on vector-based amplitude panning (VBAP) equations that are known by those of ordinary skill in the art. For example, the far-field panning methods may be based on the VBAP equations described in Section <NUM>, page <NUM> of V. <NPL>), which is hereby incorporated by reference. In alternative implementations, other methods may be used for panning far-field and near-field audio objects, e.g., methods that involve the synthesis of corresponding acoustic planes or spherical wave.

Referring now to <FIG>, the audio object is inside of the virtual reproduction environment <NUM>. This location corresponds to zone <NUM> of <FIG>. Therefore, one or more near-field panning methods will be applied in this instance. Some such near-field panning methods will use a number of speaker zones enclosing the audio object <NUM> in the virtual reproduction environment <NUM>.

In some implementations, the near-field panning method may involve "dual-balance" panning and combining two sets of gains. In the example depicted in <FIG>, the first set of gains corresponds to a front/back balance between two sets of speaker zones enclosing positions of the audio object <NUM> along the y axis. The corresponding responses involve all speaker zones of the virtual reproduction environment <NUM>, except for speaker zones <NUM> and <NUM>.

In the example depicted in <FIG>, the second set of gains corresponds to a left/right balance between two sets of speaker zones enclosing positions of the audio object <NUM> along the x axis. The corresponding responses involve speaker zones <NUM> through <NUM>. <FIG> indicates the result of combining the responses indicated in <FIG>.

It may be desirable to blend between different panning modes as an audio object enters or leaves the virtual reproduction environment <NUM>. Accordingly, a blend of gains computed according to near-field panning methods and far-field panning methods is applied for audio objects located in zone <NUM> (see <FIG>). In some implementations, a pair-wise panning law (e.g. an energy preserving sine or power law) may be used to blend between the gains computed according to near-field panning methods and far-field panning methods. In alternative implementations, the pair-wise panning law may be amplitude preserving rather than energy preserving, such that the sum equals one instead of the sum of the squares being equal to one. It is also possible to blend the resulting processed signals, for example to process the audio signal using both panning methods independently and to cross-fade the two resulting audio signals.

It may be desirable to provide a mechanism allowing the content creator and/or the content reproducer to easily fine-tune the different re-renderings for a given authored trajectory. In the context of mixing for motion pictures, the concept of screen-to-room energy balance is considered to be important. In some instances, an automatic re-rendering of a given sound trajectory (or 'pan') will result in a different screen-to-room balance, depending on the number of reproduction speakers in the reproduction environment. According to some implementations, the screen-to-room bias may be controlled according to metadata created during an authoring process. According to alternative implementations, the screen-to-room bias may be controlled solely at the rendering side (i.e., under control of the content reproducer), and not in response to metadata.

Accordingly, some implementations described herein provide one or more forms of screen-to-room bias control. In some such implementations, screen-to-room bias may be implemented as a scaling operation. For example, the scaling operation may involve the original intended trajectory of an audio object along the front-to-back direction and/or a scaling of the speaker positions used in the renderer to determine the panning gains. In some such implementations, the screen-to-room bias control may be a variable value between zero and a maximum value (e.g., one). The variation may, for example, be controllable with a GUI, a virtual or physical slider, a knob, etc..

Alternatively, or additionally, screen-to-room bias control may be implemented using some form of speaker area constraint. <FIG> indicates speaker zones of a reproduction environment that may be used in a screen-to-room bias control process. In this example, the front speaker area <NUM> and the back speaker area <NUM> (or <NUM>) may be established. The screen-to-room bias may be adjusted as a function of the selected speaker areas. In some such implementations, a screen-to-room bias may be implemented as a scaling operation between the front speaker area <NUM> and the back speaker area <NUM> (or <NUM>). In alternative implementations, screen-to-room bias may be implemented in a binary fashion, e.g., by allowing a user to select a front-side bias, a back-side bias or no bias. The bias settings for each case may correspond with predetermined (and generally non-zero) bias levels for the front speaker area <NUM> and the back speaker area <NUM> (or <NUM>). In essence, such implementations may provide three pre-sets for the screen-to-room bias control instead of (or in addition to) a continuous-valued scaling operation.

According to some such implementations, two additional logical speaker zones may be created in an authoring GUI (e.g. <NUM>) by splitting the side walls into a front side wall and a back side wall. In some implementations, the two additional logical speaker zones correspond to the left wall/left surround sound and right wall/right surround sound areas of the renderer. Depending on a user's selection of which of these two logical speaker zones are active the rendering tool could apply preset scaling factors (e.g., as described above) when rendering to Dolby <NUM> or Dolby <NUM> configurations. The rendering tool also may apply such preset scaling factors when rendering for reproduction environments that do not support the definition of these two extra logical zones, e.g., because their physical speaker configurations have no more than one physical speaker on the side wall.

<FIG> is a block diagram that provides examples of components of an authoring and/or rendering apparatus. In this example, the device <NUM> includes an interface system <NUM>. The interface system <NUM> may include a network interface, such as a wireless network interface. Alternatively, or additionally, the interface system <NUM> may include a universal serial bus (USB) interface or another such interface.

The device <NUM> includes a logic system <NUM>. The logic system <NUM> may include a processor, such as a general purpose single- or multi-chip processor. The logic system <NUM> may include a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, or discrete hardware components, or combinations thereof. The logic system <NUM> may be configured to control the other components of the device <NUM>. Although no interfaces between the components of the device <NUM> are shown in <FIG>, the logic system <NUM> may be configured with interfaces for communication with the other components. The other components may or may not be configured for communication with one another, as appropriate.

The logic system <NUM> may be configured to perform audio authoring and/or rendering functionality, including but not limited to the types of audio authoring and/or rendering functionality described herein. In some such implementations, the logic system <NUM> may be configured to operate (at least in part) according to software stored one or more non-transitory media. The non-transitory media may include memory associated with the logic system <NUM>, such as random access memory (RAM) and/or read-only memory (ROM). The non-transitory media may include memory of the memory system <NUM>. The memory system <NUM> may include one or more suitable types of non-transitory storage media, such as flash memory, a hard drive, etc..

The display system <NUM> may include one or more suitable types of display, depending on the manifestation of the device <NUM>. For example, the display system <NUM> may include a liquid crystal display, a plasma display, a bistable display, etc..

The user input system <NUM> may include one or more devices configured to accept input from a user. In some implementations, the user input system <NUM> may include a touch screen that overlays a display of the display system <NUM>. The user input system <NUM> may include a mouse, a track ball, a gesture detection system, a joystick, one or more GUIs and/or menus presented on the display system <NUM>, buttons, a keyboard, switches, etc. In some implementations, the user input system <NUM> may include the microphone <NUM>: a user may provide voice commands for the device <NUM> via the microphone <NUM>. The logic system may be configured for speech recognition and for controlling at least some operations of the device <NUM> according to such voice commands.

The power system <NUM> may include one or more suitable energy storage devices, such as a nickel-cadmium battery or a lithium-ion battery. The power system <NUM> may be configured to receive power from an electrical outlet.

<FIG> is a block diagram that represents some components that may be used for audio content creation. The system <NUM> may, for example, be used for audio content creation in mixing studios and/or dubbing stages. In this example, the system <NUM> includes an audio and metadata authoring tool <NUM> and a rendering tool <NUM>. In this implementation, the audio and metadata authoring tool <NUM> and the rendering tool <NUM> include audio connect interfaces <NUM> and <NUM>, respectively, which may be configured for communication via AES/EBU, MADI, analog, etc. The audio and metadata authoring tool <NUM> and the rendering tool <NUM> include network interfaces <NUM> and <NUM>, respectively, which may be configured to send and receive metadata via TCP/IP or any other suitable protocol. The interface <NUM> is configured to output audio data to speakers.

The system <NUM> may, for example, include an existing authoring system, such as a Pro Tools™ system, running a metadata creation tool (i.e., a panner as described herein) as a plugin. The panner could also run on a standalone system (e.g. a PC or a mixing console) connected to the rendering tool <NUM>, or could run on the same physical device as the rendering tool <NUM>. In the latter case, the panner and renderer could use a local connection e.g., through shared memory. The panner GUI could also be remoted on a tablet device, a laptop, etc. The rendering tool <NUM> may comprise a rendering system that includes a sound processor that is configured for executing rendering software. The rendering system may include, for example, a personal computer, a laptop, etc., that includes interfaces for audio input/output and an appropriate logic system.

<FIG> is a block diagram that represents some components that may be used for audio playback in a reproduction environment (e.g., a movie theater). The system <NUM> includes a cinema server <NUM> and a rendering system <NUM> in this example. The cinema server <NUM> and the rendering system <NUM> include network interfaces <NUM> and <NUM>, respectively, which may be configured to send and receive audio objects via TCP/IP or any other suitable protocol. The interface <NUM> is configured to output audio data to speakers.

Claim 1:
An apparatus, comprising:
an interface system (<NUM>); and
a logic system (<NUM>) configured for:
receiving, via the interface system (<NUM>), audio reproduction data comprising one or more audio objects and associated metadata;
receiving, via the interface system (<NUM>), reproduction environment data comprising an indication of a number of reproduction speakers of an actual three-dimensional reproduction environment and an indication of the location of each reproduction speaker within the actual reproduction environment; and
rendering the one or more audio objects into one or more speaker feed signals based, at least in part, on the associated metadata, wherein each speaker feed signal corresponds to at least one of the reproduction speakers within the actual reproduction environment,
the apparatus being characterized in that:
the metadata associated with each audio object includes speaker zone constraint metadata indicating whether rendering the respective audio object involves imposing speaker zone constraints, and
wherein rendering the one or more audio objects includes rendering the respective audio object by imposing speaker zone constraints in response to the speaker zone constraint metadata, and
wherein rendering the one or more audio objects further includes rendering the respective audio object either by applying panning rules to map the audio object to a plurality of reproduction speakers, or by mapping the audio object to a single reproduction speaker.