Distributed audio capture and mixing

An apparatus for controlling a controllable position/orientation of at least one audio source within an audio scene, the audio scene including the at least one audio source; a capture device, the apparatus including a processor configured to: receive a physical position/orientation of the at least one audio source relative to a capture device capture orientation; receive an earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation; receive at least one control parameter; and control a controllable position/orientation of the at least one audio source, the controllable position being between the physical position/orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation and based on the control parameter.

CROSS REFERENCE TO RELATED APPLICATION

This patent application is a U.S. National Stage application of International Patent Application Number PCT/FI2017/050792 filed Nov. 20, 2017, which is hereby incorporated by reference in its entirety, and claims priority to GB 1620325.9 filed Nov. 30, 2016.

FIELD

The present application relates to apparatus and methods for distributed audio capture and mixing. The invention further relates to, but is not limited to, apparatus and methods for distributed audio capture and mixing for spatial processing of audio signals to enable spatial reproduction of audio signals.

BACKGROUND

Capture of audio signals from multiple sources and mixing of audio signals when these sources are moving in the spatial field requires significant effort. For example the capture and mixing of an audio signal source such as a speaker or artist within an audio environment such as a theatre or lecture hall to be presented to a listener and produce an effective audio atmosphere requires significant investment in equipment and training.

A commonly implemented system is where one or more close microphones, for example a Lavalier microphone worn by the user or an audio channel associated with an instrument is mixed with a suitable spatial (or environmental or audio field) audio signal such that the produced sound comes from an intended direction.

However as will be shown hereafter the positioning of the close microphone and other audio sources relative to the capture device may produce a poor quality output where the audio sources are not significantly distributed.

Thus, there is a need to develop solutions which enhance the spatial audio mixing and sound track creation process.

SUMMARY

There is provided according to a first aspect an apparatus for controlling a controllable position/orientation of at least one audio source within an audio scene, the audio scene comprising: the at least one audio source; a capture device comprising a microphone array for capturing audio signals of the audio scene, the capture device having a capture orientation wherein the microphone array is positioned relative to the capture orientation, the apparatus comprising a processor configured to: receive a physical position/orientation of the at least one audio source relative to the capture device capture orientation; receive an earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation; receive at least one control parameter; and control a controllable position/orientation of the at least one audio source, the controllable position being between the physical position/orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation and based on the control parameter.

The capture device may further comprise at least one camera for capturing images of the audio scene, wherein the at least one camera may be positioned relative to the capture orientation.

During a capture session the controllable position/orientation for the at least one audio source may be defined for one of the at least one audio source between the earlier physical position/orientation which may be captured on a first image of the at least one camera and the physical position/orientation which may be captured on a second image of the at least one camera.

The processor configured to control the controllable position/orientation of the at least one audio source may be configured to control the controllable position/orientation of the at least one audio source relative to the capture device capture orientation such that the controllable position/orientation may be the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation, such that a visually observed position/orientation of the at least one audio source differs from an audio experienced position/orientation of the at least one audio source.

The processor may be configured to pass the controllable position/orientation of the at least one audio source to a renderer to control a mixing or rendering of an audio signal associated with the at least one audio source based on the controllable position/orientation.

The processor configured to receive at least one control parameter may be configured to receive a weighting parameter, and the processor configured to control the controllable position/orientation may be further configured to: determine the controllable orientation based on one of the physical orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical orientation of the at least one audio source relative to the capture device capture orientation which is combined with the product of the weighting parameter applied to an orientation difference between the the physical orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation; and determine the controllable position as the intersection between a line described by the physical position of the at least one audio source relative to the capture device capture orientation and the earlier physical position of the at least one audio source relative to the capture device reference orientation and a line from the capture device at the controllable orientation.

The processor configured to receive at least one control parameter may be configured to receive a weighting parameter, and the processor configured to control the controllable position/orientation may be further configured to: determine the controllable orientation based on one of the physical orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical orientation of the at least one audio source relative to the capture device capture orientation combined with the product of the weighting parameter applied to an orientation difference between the physical orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation, and determine the controllable position based on an arc with an origin at the capture device and defined by the physical position of the at least one audio source relative to the capture device capture orientation and the earlier physical position of the at least one audio source relative to the capture device capture orientation to the capture device capture orientation and a line from the capture device at the controllable orientation.

The processor configured to receive the at least one control parameter may be configured to receive a weighting parameter, and wherein the processor configured to control the controllable position/orientation may be further configured to combine the product of unity minus the weighting parameter to the physical position of the at least one audio source relative to the capture device capture orientation and the product of the weighting function to the earlier physical position of the at least one audio source relative to the capture device capture orientation.

The processor configured to control the controllable position/orientation of the at least one audio source may be further configured to control a width of the controllable position/orientation, the width of the controllable position/orientation may be based on the distance from the physical position/orientation of at least one audio source relative to the capture device capture orientation.

The processor configured to control the width of the controllable position/orientation may be configured to set the width of the controllable position/orientation as one half a normalised distance from the physical position/orientation of the at least one audio source relative to the capture device capture orientation.

According to a second aspect there is provided a method for controlling a controllable position/orientation of at least one audio source within an audio scene, the audio scene comprising: the at least one audio source; a capture device comprising a microphone array for capturing audio signals of the audio scene, the capture device having a capture orientation wherein the microphone array is positioned relative to the capture orientation, the method comprising: receiving a physical position/orientation of the at least one audio source relative to the capture device capture orientation; receiving an earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation; receiving at least one control parameter; and controlling a controllable position/orientation of the at least one audio source, the controllable position being between the physical position/orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation and based on the control parameter.

The capture device may further comprise at least one camera for capturing images of the audio scene, wherein the at least one camera may be positioned relative to the capture orientation.

During a capture session the controllable position/orientation for the at least one audio source may be defined for one of the at least one audio source between the earlier physical position/orientation which may be captured on a first image of the at least one camera and the physical position/orientation which may be captured on a second image of the at least one camera.

Controlling the controllable position/orientation of the at least one audio source may comprise controlling the controllable position/orientation of the at least one audio source relative to the capture device capture orientation such that the controllable position/orientation is the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation, such that a visually observed position/orientation of the at least one audio source differs from an audio experienced position/orientation of the at least one audio source.

The method may further comprise passing the controllable position/orientation of the at least one audio source to a renderer to control a mixing or rendering of an audio signal associated with the at least one audio source based on the controllable position/orientation.

Receiving at least one control parameter may comprise receiving a weighting parameter, and controlling the controllable position/orientation may further comprise: determining the controllable orientation based on one of the physical orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical orientation of the at least one audio source relative to the capture device capture orientation which is combined with the product of the weighting parameter applied to an orientation difference between the the physical orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation, and determining the controllable position as the intersection between a line described by the physical position of the at least one audio source relative to the capture device capture orientation and the earlier physical position of the at least one audio source relative to the capture device reference orientation and a line from the capture device at the controllable orientation.

Receiving at least one control parameter may comprise receiving a weighting parameter, and controlling the controllable position/orientation may further comprise: determining the controllable orientation based on one of the physical orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical orientation of the at least one audio source relative to the capture device capture orientation combined with the product of the weighting parameter applied to an orientation difference between the the physical orientation of the at least one audio source relative to the capture device capture orientation and the earlier physical position/orientation of the at least one audio source relative to the capture device capture orientation, and determining the controllable position based on an arc with an origin at the capture device and defined by the physical position of the at least one audio source relative to the capture device capture orientation and the earlier physical position of the at least one audio source relative to the capture device capture orientation to the capture device capture orientation and a line from the capture device at the controllable orientation.

Receiving the at least one control parameter may comprise receiving a weighting parameter, and wherein controlling the controllable position/orientation may further comprise combining the product of unity minus the weighting parameter to the physical position of the at least one audio source relative to the capture device capture orientation and the product of the weighting function to the earlier physical position of the at least one audio source relative to the capture device capture orientation.

Controlling the controllable position/orientation of the at least one audio source may further comprise controlling a width of the controllable position/orientation, the width of the controllable position/orientation being based on the distance from the physical position/orientation of at least one audio source relative to the capture device capture orientation.

Controlling the width of the controllable position/orientation may comprise setting the width of the controllable position/orientation as one half the normalised distance from the physical position/orientation of the at least one audio source relative to the capture device capture orientation.

A computer program product stored on a medium may cause an apparatus to perform the method as described herein.

An electronic device may comprise apparatus as described herein.

A chipset may comprise apparatus as described herein.

Embodiments of the present application aim to address problems associated with the state of the art.

EMBODIMENTS OF THE APPLICATION

The following describes in further detail suitable apparatus and possible mechanisms for the provision of effective capture of audio signals from multiple sources and mixing of those audio signals when these sources are moving in the spatial field. In the following examples, audio signals and audio capture signals are described. However it would be appreciated that in some embodiments the apparatus may be part of any suitable electronic device or apparatus configured to capture an audio signal or receive the audio signals and other information signals.

A conventional approach to the capturing and mixing of audio sources with respect to an audio background or environment audio field signal would be for a professional producer to utilize a close microphone (a Lavalier microphone worn by the user, or a microphone attached to an instrument or some other microphone) to capture audio signals close to the audio source, and further utilize a ‘background’ microphone to capture a environmental audio signal. These signals or audio tracks may then be manually mixed to produce an output audio signal such that the produced sound features the audio source coming from an intended (though not necessarily the original) direction.

The concept as described herein may be considered to be enhancement to conventional Spatial Audio Capture (SPAC) technology. Spatial audio capture technology can process audio signals captured via a microphone array into a spatial audio format. In other words generating an audio signal format with a spatial perception capacity. The concept may thus be embodied in a form where audio signals may be captured such that, when rendered to a user, the user can experience the sound field as if they were present at the location of the capture device. Spatial audio capture can be implemented for microphone arrays found in mobile devices. In addition, audio processing derived from the spatial audio capture may be used employed within a presence-capturing device such as the Nokia OZO (OZO) devices.

In the examples described herein the audio signal is rendered into a suitable binaural form, where the spatial sensation may be created using rendering such as by head-related-transfer-function (HRTF) filtering a suitable audio signal.

The concept as described with respect to the embodiments herein makes it possible to capture and remix a close and environment audio signal more effectively and produce a better quality output where the sound or audio sources are more widely distributed.

The concept may for example be embodied as a capture system configured to capture both a close (speaker, instrument or other source) audio signal and a microphone array or spatial (audio field) audio signal. The capture system may furthermore be configured to determine a location of the close audio signal source relative to the spatial capture components and further determine the audio signal delay required to synchronize the close audio signal to the spatial audio signal. This information may then be stored or passed to a suitable rendering system which having received audio signals associated with the microphones and microphone array and the spatial metadata such as positional information may use this information to generate a suitable mixing and rendering of the audio signal to a user.

Furthermore in some embodiments the render system enables the user to input a suitable input to control the mixing, for example control the positioning of the close microphone mixing positions.

The concept furthermore is embodied by the ability to track locations of the close microphones generating the close audio signals using high-accuracy indoor positioning or another suitable technique. The position or location data (azimuth, elevation, distance) can then be associated with the spatial audio signal captured by the microphones. The close audio signals captured by the close microphones may in some embodiments be furthermore processed, for example time-aligned with the microphone array audio signal, and made available for rendering. For reproduction with static loudspeaker setups such as 5.1, a static downmix can be done using amplitude panning techniques. For reproduction using binaural techniques, the time-aligned close microphone audio signals can be stored or communicated together with time-varying spatial position data and the microphone array audio signals or audio track. For example, the audio signals could be encoded, stored, and transmitted in a Moving Picture Experts Group (MPEG) MPEG-H 3D audio format, specified as ISO/IEC 23008-3 (MPEG-H Part 3), where ISO stands for International Organization for Standardization and IEC stands for International Electrotechnical Commission.

It is believed that the main benefits of the invention include flexible capturing of spatial audio and separation of close microphone audio signals, which enables an enhanced rendering of the audio signals for the user or listener. An example includes increasing speech intelligibility in noisy capture situations, in reverberant environments, or in capture situations with multiple direct and ambient sources.

Although capture and render systems may be separate, it is understood that they may be implemented with the same apparatus or may be distributed over a series of physically separate but communication capable apparatus. For example, a presence-capturing device such as the OZO device could be equipped with an additional interface for receiving location data and close microphone audio signals, and could be configured to perform the capture part. The output of a capture part of the system may be the microphone audio signals (e.g. as a 5.1 channel downmix), the close microphone audio signals (which may furthermore be time-delay compensated to match the time of the microphone array audio signals), and the position information of the close microphones (such as a time-varying azimuth, elevation, distance with regard to the microphone array).

In some embodiments the raw microphone array audio signals captured by the microphone array may be transmitted to the renderer (instead of spatial audio processed into 5.1), and the renderer performs spatial processing such as described herein.

The renderer as described herein may be an audio playback device (for example a set of headphones), user input (for example motion tracker), and software capable of mixing and audio rendering. In some embodiments the user input and audio rendering parts may be implemented within a computing device with display capacity such as a mobile phone, tablet computer, virtual reality headset, augmented reality headset etc.

Furthermore it is understood that at least some elements of the following mixing and rendering may be implemented within a distributed computing system such as known as the ‘cloud’.

With respect toFIG. 1is shown a first example capture and mixing arrangement where the close microphones and the microphone array are in a first position arrangement producing a wide separation of sound sources. In this and the following examples a band performance is being recorded. However this is an example implementation only and it is understood that the apparatus may be used in any suitable recording scenario.

FIG. 1shows the performers'101,103,105(and/or the instruments that are being played) positions being tracked (by using position tags) and equipped with microphones. For example the capture apparatus101comprises a Lavalier microphone111. The close microphones may be any microphone external or separate to microphone array configured to capture the spatial audio signal. Thus the concept is applicable to any external/additional microphones be they Lavalier microphones, hand held microphones, mounted mics, or whatever. The external microphones can be worn/carried by persons or mounted as close-up microphones for instruments or a microphone in some relevant location which the designer wishes to capture accurately. The close microphone may in some embodiments be a microphone array. A Lavalier microphone typically comprises a small microphone worn around the ear or otherwise close to the mouth. For other sound sources, such as musical instruments, the audio signal may be provided either by a Lavalier microphone or by an internal microphone system of the instrument (e.g., pick-up microphones in the case of an electric guitar) or an internal audio output (e.g., a electric keyboard output). In some embodiments the close microphone may be configured to output the captured audio signals to a mixer. The close microphone may be connected to a transmitter unit (not shown), which wirelessly transmits the audio signal to a receiver unit (not shown).

Furthermore in some embodiments the close microphone comprises or is associated with a microphone position tag. The microphone position tag may be configured to transmit a radio signal such that an associated receiver may determine information identifying the position or location of the close microphone. It is important to note that microphones worn by people can be freely moved in the acoustic space and the system supporting location sensing of wearable microphone has to support continuous sensing of user or microphone location. The close microphone position tag may be configured to output this signal to a position tracker. Although the following examples show the use of the HAIP (high accuracy indoor positioning) radio frequency signal to determine the location of the close microphones it is understood that any suitable position estimation system may be used (for example satellite-based position estimation systems, inertial position estimation, beacon based position estimation etc.).

Furthermore the system is shown comprising a microphone array (shown by the Nokia OZO device)107. In some embodiments the microphone array may comprise a position estimation system such as a high accuracy in-door position (HAIP) receiver configured to determine the position of the close microphones relative to the ‘reference position and orientation’ of the microphone array. In some embodiments the estimation of the position of the close microphones relative to the microphone array is performed within a device separate from the microphone array. In such embodiments the microphone array may itself comprise a position tag or similar to enable the further device to estimate and/or determine the position of the microphone array and the close microphones and thus determine the relative position and orientation of the close microphones to the microphone array. The microphone array may be configured to output the tracked position information to a mixer (not shown inFIG. 1).

The microphone array107is an example of a spatial audio capture (SPAC) device or an ‘audio field’ capture apparatus and may in some embodiments be a directional or omnidirectional microphone array. The microphone array may be configured to output the captured audio signals or a processed form (for example a 5.1 downmix of the audio signals) to a mixer (not shown inFIG. 1).

In some embodiments the microphone array is implemented within a mobile device.

The microphone array is thus configured to capture spatial audio, which, when rendered to a listener, enables the listener to experience the sound field as if they were present in the location of the microphone array. The close microphones in such embodiments are configured to capture high quality close-up audio signals (for example from a key person's voice, or a musical instrument). When mixed to the spatial audio field, the attributes of the key source such as gain, timbre and spatial position may be adjusted in order to provide the listener with a much more realistic immersive experience. In addition, it is possible to produce more point-like auditory objects, thus increasing the engagement and intelligibility.

In this example the microphone array107is located on a camera crane109which may pivot to change the location and orientation of the microphone array107.

In the example shown inFIG. 1the keyboard101(and the associated close microphone) is shown located to the left of the scene from the perspective of the reference position, the violin105(and the associated close microphone) is shown located to the right of the scene from the perspective of the reference position, and the drums103(and the associated close microphone) located to the front or centre of the scene from the perspective of the reference position.

In this example the audio signals from the close microphones may be rendered to the viewer/listener from the direction of their position. The positions of the microphone array and the close microphones as inFIG. 1may be carefully chosen so that the resulting sound scene is pleasing to the listener. The mix provided to the viewer/listener may sound ‘good’ because the various sources from the close microphone audio signals are ‘nicely’ separated and balanced (some on the left, some on the right).

With respect toFIG. 2, the system shown inFIG. 1may change. For example between the example shown inFIG. 1andFIG. 2the microphone array may change position, by pivoting on the camera crane to produce a camera sweep and rotating to produce a camera turn. The microphone array207at its new position and orientation thus experiences the audio scene in a different way than the microphone array107at its earlier position and orientation. Furthermore the close microphone, such as the violin may move from the earlier position105to a new position205.

This may lead to a problematic mix being generated by the mixer. This is because all of the close microphone audio signals are now ‘coming’ from the same direction with respect to the microphone array. This can be shown inFIG. 3where the separation angle301between all of the close microphone positions is significantly narrower than the separation angle between the close microphone positions shown inFIG. 1. This is not optimal from the audio listening experience point of view as all of the audio would in the rendered mix appear to come from directly in front of the viewer/listener.

From a listener point of view the positions of the close microphones relative to the microphone array associated with the previous wide spaced close microphone arrangement would be preferable. However this approach is problematic. For exampleFIG. 4shows an example where the close microphones are located ‘physically’ in the second narrow spacing arrangement with the microphone array207and the close microphones101,103and205as shown inFIGS. 2 and 3.FIG. 4also shows relative to the microphone array207a mapped close microphone location101′,103′ and105′ which represent the position of the keyboard close microphone101, drum close microphone103and violin close microphone105relative to the microphone array107in the first position when mapped to the second position arrangement.

Although this mapped position arrangement would produce a ‘better’ quality wider separation mix the use of these positions may produce confusion in the viewer/listener. For example the relative positions of the violin205and the drum103seen by the viewer/listener where the violin is seen to be to the left of the drums according to the camera associated with the microphone array would not be the same as the relative positions of the mapped violin105′ and mapped drums103′ where the violin is heard as being to the right of the drums.

It would be therefore beneficial to be able to somehow control the audio source positions so that a better listening experience is achieved.

The concept which is shown in embodiments such asFIG. 5is to enable the control (either by a user to provide a manual input, or a processor to implement an automatic of semi-automatic control) of the controllable (or mix or processing) position/orientations of the close microphones relative to the microphone array between an actual position arrangement and an ‘optimal’ or determined good position arrangement.

Thus for exampleFIG. 5shows the microphone array207and a controllable position/orientation for each of the close microphones which is a controlled position between the mapped position and the tracked position of the close microphones. Thus for example there is a keyboard controllable position/orientation501which is located on the line connecting the mapped keyboard position101′ and the actual keyboard position101. Furthermore there is shown the drum controllable position/orientation503which is located on the line connecting the mapped drum position103′ and the actual drum position103. Also there is shown a violin controllable position/orientation505which is located on the line connecting the mapped violin position105′ and the actual violin position105.

In other wordsFIG. 5shows that the user (or processor) may be configured to control the sound scene such that the close microphone or sound source positions may be moved between their ‘actual’ or correct position (based on the HAIP or other positioning) and their somehow determined ‘optimal’ positions (based on listening experience). That is, the user (or processor) is given control to adjust the sound scene between the ‘correct’ positions and nice sounding positions.

With respect toFIGS. 6 to 8the effect of the control is implemented in embodiments are shown. For each close microphone/sound source the Figures show the effect of the control for a single close microphone. As described with respect toFIG. 5the control implemented affects the controllable position/orientation for the close microphone where we consider three positions:

Firstly the close microphone actual, physical or correct position shown in the Figures by the location (xi, yi), where i is the close microphone index.

A position determined to provide optimal listening experience shown in the Figures by the location, ({circumflex over (x)}i, ŷi).

A position between these positions that is controllable by the user ({tilde over (x)}i, {tilde over (y)}i). Note that these positions are with respect to the microphone array (which in this example is the OZO camera/HAIP positioning system).

FIG. 6for example shows an embodiment where the user (or processor) may control the controllable position/orientation ({tilde over (x)}i, {tilde over (y)}i)613of the close microphone/sound source between the positions (xi, yi)611and ({circumflex over (x)}i, ŷi)615. As shown inFIG. 6there are three angles α, {circumflex over (α)} and {tilde over (α)}. These angles are the angles between the microphone array (OZO device) front direction and the positions described above.

In some embodiments the user is provided a user interface control element in the form of a knob or slider, for example, to adjust a parameter w which adjusts the angle of the controllable position/orientation for the close microphone/sound source. In some embodiments the control adjustment based on the value of w is provided by:
{tilde over (α)}i=αi−w(αi−{circumflex over (α)}i),w∈[0,1],i=1 . . .N

The controllable position/orientation point ({tilde over (x)}i, {tilde over (y)}i)613is then determined to be the intersection between the line described by the two points (xi, yi)611and ({circumflex over (x)}i, ŷi)615and the line crossing the origin617at an angle {tilde over (α)}. In some embodiments where the distance between the controllable position/orientation and the microphone array is required and furthermore may be obtained from the new position of the close microphone relative to the microphone array then the mix position point may be modified to be located at the distance from the microphone array along the vector defined between the origin617and the angle {tilde over (α)}.

FIG. 7shows a further example embodiment. In the example shown inFIG. 7an alternative way to control the position of the sound source is shown. In this example a user is provided a user interface control element in the form of a knob or slider, for example, to adjust a parameter q used to control the position between the two points (xi, yi)711and ({circumflex over (x)}i, ŷi)715. In such embodiments the user (or processor) parameter q is configured to control the position of the close microphone based on:
{tilde over (x)}i=(1−q)xi+q{circumflex over (x)}i,q∈[0,1],i=1 . . .N
{tilde over (y)}i=(1−q)yi+qŷi,q∈[0,1],i=1 . . .N

In some embodiments as the user (or processor) may move the close microphone/sound source position away from its correct position, it is beneficial to add some spatial extent widening to the close microphone/sound source. This widening is configured to ‘soften’ the effect of any mismatch in audio based (or mix) position and the video based position of the close microphone.

The control of close microphone/sound source spatial extent widening is shown inFIG. 8. InFIG. 8, it is shown that the ‘width’ of the close microphone/sound source is determined to be proportional to the distance of the controllable position/orientation point ({tilde over (x)}i, {tilde over (y)}i) from the correct or physical position point (xi, yi).

In some embodiments the ‘width’ of the controllable position/orientation may be set to be equal to 0.5 times the distance from the correct or physical position point.

Thus for example as shown inFIG. 8awhere the determined or controlled controllable position/orientation point ({tilde over (x)}i, {tilde over (y)}i)813is close to the correct point (xi, yi)811and thus away from the ‘optimal’ point ({circumflex over (x)}i, ŷi)815. The spatial widening effect applied in this example results in a widening radius from the origin (microphone array801) which is narrow and is shown inFIG. 8aas a single point centred at the controllable position/orientation point.

Whereas as shown inFIG. 8bthe determined or controlled controllable position/orientation point ({tilde over (x)}i, {tilde over (y)}i)863is away from the correct point (xi, yi)861and thus close to the ‘optimal’ point ({circumflex over (x)}i, ŷi)865. The spatial widening effect871applied in this example results in a widening radius from the origin (microphone array851) which is wide and shown inFIG. 8bas a distribution along the line between the correct point (xi, yi)861and the ‘optimal’ point ({circumflex over (x)}i, ŷi)865centred at the controllable position/orientation point.

It is noted that the examples and method described herein do not change the audio rendering functionality but may be implemented as a preprocessing module for close microphone/sound object position data. This is shown for example inFIG. 9.

FIG. 9shows an example implementation wherein the close microphone and tag901transmit HAIP signals which are received by the microphone array and tag receiver903in order to determine the actual position of the close microphone901relative to the microphone array903. The actual position may be passed to a close microphone/sound source position data updater/position determiner905. Having received the close microphone901position data (the actual position the position determiner and compares these to the adjusted ideal positions.

This comparison may in some embodiments may be used to generate a suitable user interface element which is displayed to the user and enables the user to input a suitable user input909which in turn defines a position parameter value (such as the parameters q or w). In some embodiments a processor may derive parameter values based on the comparison between the actual position and ideal position and determine a parameter value for a controllable position/orientation according to the equations above. The updated controllable position/orientation (for the close microphone/object) data may then be provided for mixing/audio rendering to the renderer907, which is configured to render the audio objects in the updated positions. In other words the close microphone microphone/sound source position data is updated before it is input to the audio renderer.

The renderer907in some embodiments may be configured to use vector-base amplitude panning techniques when loudspeaker domain output is desired (e.g. 5.1 channel output) or use head-related transfer-function filtering if binaural output for headphone listening is desired.

With respect toFIG. 10an example flow diagram of the operation of the system as shown inFIG. 9is shown in further detail.

In some embodiments the position tracker, which may be implemented within the microphone array as part of a HAIP system or other suitable system, is configured to determine the actual positions of the close microphones/sound sources relative to the microphone array.

The operation of determining the microphone positions is shown inFIG. 10by step1001.

The position determiner may receive the close microphone position data (the actual positions) and furthermore determine ideal or optimised positions. These ideal or optimised positions may expert user determined, by a historical liked positioning, or determined using any other suitable ‘optimisation’ of the positions. For example in some embodiments the selected positions may be selected by the person responsible for the mixing of the sources. In such embodiments the person responsible for the mixing defines the positions by selecting the positions for each source separately. In some embodiments the person responsible for the mixing defines the positions guiding the performers and camera to a ‘default position’ and setting this as the position.FIG. 1for example may be an example of the camera and performer positions being at the ‘default position’ and the person responsible for the mixing indicates to the system that these are the chosen ‘optimal’ positions. These ideal positions may then be mapped to the current position of the microphone array to produce mapped ideal positions.

The operation of determining the ideal microphone positions/mapped ideal positions is shown inFIG. 10by step1003.

The position determiner may furthermore receive a control parameter to control the position of the microphones.

The receiving of the control parameter is shown inFIG. 10by step1007.

The position determiner may then compare the actual positions to the mapped ideal positions and based on the control parameter determine a controllable position/orientation between the two. Furthermore in some embodiments the position determiner may apply a spatial widening to the position based on the difference between the controllable position/orientation and the actual position.

The operation of determining the controllable position/orientation based on the actual position and the mapped ideal position and the control input (and optionally the spatial widening) is shown inFIG. 10by step1009.

The position determiner may then output the (spatially widened) controllable position/orientation to the renderer, which may be configured to render/process an output audio signal based on the determined controllable position/orientation.

The operation of outputting the controllable position/orientation to the renderer is shown inFIG. 10by step1011.

With respect toFIG. 11an example electronic device which may be used as the microphone array capture device and/or the position determiner is shown. The device may be any suitable electronics device or apparatus. For example in some embodiments the device1200is a mobile device, user equipment, tablet computer, computer, audio playback apparatus, etc.

The device1200may comprise a microphone array1201. The microphone array1201may comprise a plurality (for example a number N) of microphones. However it is understood that there may be any suitable configuration of microphones and any suitable number of microphones. In some embodiments the microphone array1201is separate from the apparatus and the audio signals transmitted to the apparatus by a wired or wireless coupling. The microphone array1201may in some embodiments be the microphone array as shown in the previous Figures.

The microphones may be transducers configured to convert acoustic waves into suitable electrical audio signals. In some embodiments the microphones can be solid state microphones. In other words the microphones may be capable of capturing audio signals and outputting a suitable digital format signal. In some other embodiments the microphones or microphone array1201can comprise any suitable microphone or audio capture means, for example a condenser microphone, capacitor microphone, electrostatic microphone, Electret condenser microphone, dynamic microphone, ribbon microphone, carbon microphone, piezoelectric microphone, or microelectrical-mechanical system (MEMS) microphone. The microphones can in some embodiments output the audio captured signal to an analogue-to-digital converter (ADC)1203.

The device1200may further comprise an analogue-to-digital converter1203. The analogue-to-digital converter1203may be configured to receive the audio signals from each of the microphones in the microphone array1201and convert them into a format suitable for processing. In some embodiments where the microphones are integrated microphones the analogue-to-digital converter is not required. The analogue-to-digital converter1203can be any suitable analogue-to-digital conversion or processing means. The analogue-to-digital converter1203may be configured to output the digital representations of the audio signals to a processor1207or to a memory1211.

In some embodiments the device1200comprises at least one processor or central processing unit1207. The processor1207can be configured to execute various program codes. The implemented program codes can comprise, for example, microphone position control, position determination and tracking and other code routines such as described herein.

In some embodiments the device1200comprises a memory1211. In some embodiments the at least one processor1207is coupled to the memory1211. The memory1211can be any suitable storage means. In some embodiments the memory1211comprises a program code section for storing program codes implementable upon the processor1207. Furthermore in some embodiments the memory1211can further comprise a stored data section for storing data, for example data that has been processed or to be processed in accordance with the embodiments as described herein. The implemented program code stored within the program code section and the data stored within the stored data section can be retrieved by the processor1207whenever needed via the memory-processor coupling.

In some embodiments the device1200comprises a user interface1205. The user interface1205can be coupled in some embodiments to the processor1207. In some embodiments the processor1207can control the operation of the user interface1205and receive inputs from the user interface1205. In some embodiments the user interface1205can enable a user to input commands to the device1200, for example via a keypad. In some embodiments the user interface205can enable the user to obtain information from the device1200. For example the user interface1205may comprise a display configured to display information from the device1200to the user. The user interface1205can in some embodiments comprise a touch screen or touch interface capable of both enabling information to be entered to the device1200and further displaying information to the user of the device1200. In some embodiments the user interface1205may be the user interface for communicating with the position determiner as described herein.

In some implements the device1200comprises a transceiver1209. The transceiver1209in such embodiments can be coupled to the processor1207and configured to enable a communication with other apparatus or electronic devices, for example via a wireless communications network. The transceiver1209or any suitable transceiver or transmitter and/or receiver means can in some embodiments be configured to communicate with other electronic devices or apparatus via a wire or wired coupling.

For example as shown inFIG. 11the transceiver1209may be configured to communicate with the renderer as described herein.

The transceiver1209can communicate with further apparatus by any suitable known communications protocol. For example in some embodiments the transceiver1209or transceiver means can use a suitable universal mobile telecommunications system (UMTS) protocol, a wireless local area network (WLAN) protocol such as for example IEEE 802.X, a suitable short-range radio frequency communication protocol such as Bluetooth, or infrared data communication pathway (IRDA).

In some embodiments the device1200may be employed as at least part of the renderer. As such the transceiver1209may be configured to receive the audio signals and positional information from the microphone array/close microphones/position determiner as described herein, and generate a suitable audio signal rendering by using the processor1207executing suitable code. The device1200may comprise a digital-to-analogue converter1213. The digital-to-analogue converter1213may be coupled to the processor1207and/or memory1211and be configured to convert digital representations of audio signals (such as from the processor1207following an audio rendering of the audio signals as described herein) to a suitable analogue format suitable for presentation via an audio subsystem output. The digital-to-analogue converter (DAC)1213or signal processing means can in some embodiments be any suitable DAC technology.

Furthermore the device1200can comprise in some embodiments an audio subsystem output1215. An example as shown inFIG. 11shows the audio subsystem output1215as an output socket configured to enabling a coupling with headphones121. However the audio subsystem output1215may be any suitable audio output or a connection to an audio output. For example the audio subsystem output1215may be a connection to a multichannel speaker system.

In some embodiments the digital to analogue converter1213and audio subsystem1215may be implemented within a physically separate output device. For example the DAC1213and audio subsystem1215may be implemented as cordless earphones communicating with the device1200via the transceiver1209.

Although the device1200is shown having both audio capture, audio processing and audio rendering components, it would be understood that in some embodiments the device1200can comprise just some of the elements.