Binaural rendering for headphones using metadata processing

1. A method for rendering audio for playback through headphones comprising:

receiving digital audio content comprising a plurality of audio objects;

receiving binaural rendering metadata generated by an authoring tool processing the received digital audio content, wherein the binaural rendering metadata controls a plurality of channel and object characteristics including content dependent settings and at least one of: position; size; gain adjustment; elevation emphasis; stereo/full toggling; 3D scaling factors; or spatial and timbre properties, and wherein the content dependent settings comprise, for each of the plurality of audio objects, a bypass flag indicating, for the object, stereo instead of binaural rendering;

receiving playback metadata generated by a playback device; and

rendering the digital audio content in response to a combination of the binaural rendering metadata and playback metadata.

2. The method of claim 1 wherein the digital audio content comprises channel-based audio and object-based audio including spatial cues for reproducing an intended location of a corresponding sound source in three-dimensional space relative to a listener.

3. The method of claim 1 further comprising separating the digital audio content into one or more components based on content type, and wherein the content type is selected from the group consisting of: dialog, music, audio effects, transient signals, and ambient signals.

4. The method of claim 1 wherein the content dependent settings further comprise at least one of: cross-over points for low frequency management; or direct/reverb room modeling.

5. The method of claim 1 wherein the playback metadata controls a plurality of listener specific characteristics selected from the group consisting of: head position, head orientation, head size, listening room noise levels, and listening room properties.

6. The method of claim 1 further comprising one or more user input commands modifying the binaural rendering metadata, the user input commands controlling one or more characteristics selected from the group consisting of: elevation emphasis, preferred sound radius, and binaural mode enablement.

7. The method of claim 1 wherein the headphones are coupled to the playback device over a wired or wireless link, the playback device sourcing the digital audio content, and including one or more sensors providing audio location cues.

8. The method of claim 2 further comprising unmixing at least one of the channel-based and object-based audio into constituent direct content and diffuse content, wherein the diffuse content comprises reverberated or reflected sound elements.

9. The method of claim 8 further comprising performing binaural rendering on the direct content separately from binaural rendering on the diffuse content.

10. The method of claim 9 further comprising performing at least one of dynamic timbre equalization or headphone equalization on the binaural rendered direct or diffuse content.

11. A system comprising:

an authoring tool generating content dependent metadata dictating rendering of an audio signal comprising a plurality of audio objects through headphones used by a listener, wherein the content dependent metadata controls a plurality of channel and object characteristics including content dependent settings and at least one of: position; size; gain adjustment; elevation emphasis; stereo/full toggling; 3D scaling factors; or spatial and timbre properties, and wherein the content dependent settings comprise, for each of the plurality of audio objects, a bypass flag indicating, for the object, stereo instead of binaural rendering;

a rendering component functionally coupled to the authoring tool to perform binaural rendering of the source audio signal for playback through the headphones; and

a feedback interface transmitting sensor data to the rendering component for modification of the content dependent metadata, wherein the sensor data encodes one or more characteristics associated with the listener or a listening environment containing the listener.

12. The system of claim 11 wherein the audio is transmitted for playback through the headphones by a portable audio source device.

13. The system of claim 11 wherein the audio comprises channel-based audio having surround sound encoded audio and object-based audio having objects featuring spatial parameters.

14. The system of claim 11 further comprising a formatting component formatting the sensor data into a metadata format compatible with the content dependent metadata to produce playback metadata.

15. The system of claim 14 wherein the playback metadata controls a plurality of listener specific characteristics selected from the group consisting of: head position, head orientation, head size, listening room noise levels, and listening room properties.

16. The system of claim 11 wherein the sensor data is obtained from a plurality of sensors selected from the group consisting of: a range sensor, a head size sensor, a gyroscopic sensor, an internal microphone, and an external microphone.

17. The system of claim 16 wherein at least one or more sensors of the plurality of sensors is located in a portion of the headphones, and wherein the headphones are coupled to the playback device over one of a wireless link and a wired link.

18. The system of claim 11 wherein the rendering component comprises a post-processing stage configured to perform functions comprising at least one of: downmixing from a plurality of surround sound channels to one of a binaural mix or a stereo mix, level management, equalization, timbre correction, and noise cancellation.

19. The system of claim 11 wherein the content dependent settings further comprise at least one of: cross-over points for low frequency management; or direct/reverb room modeling.

20. A system for rendering audio for playback through headphones, the system comprising one or more processors that:

receive digital audio content comprising a plurality of audio objects;

receive binaural rendering metadata generated by an authoring tool processing the received digital audio content, wherein the binaural rendering metadata controls a plurality of channel and object characteristics including content dependent settings and at least one of: position; size; gain adjustment; elevation emphasis; stereo/full toggling; 3D scaling factors; or spatial and timbre properties, and wherein the content dependent settings comprise, for each of the plurality of audio objects, a bypass flag indicating, for the object, stereo instead of binaural rendering;

receive playback metadata generated by a playback device; and

render the digital audio content in response to a combination of the binaural rendering metadata and playback metadata.