Packet based delivery of multi-channel audio over wireless links
The present disclosure is directed to systems, apparatuses, and methods for wirelessly delivering multi-channel audio over a packet based network with tight synchronization, high fidelity, and/or low delay as described above. The systems can include a source device that provides multi-channel audio to a distributor device, which wirelessly distributes the multi-channel audio over the packet based network to audio rendering devices, referred to as “sink” devices. The distributor device and the sink devices each include a playback clock that is used to read audio samples of the multi-channel audio from a local memory and drive a digital-to-analog converter (DAC) coupled to a speaker to render the audio samples.
1. An audio sink device comprising:
a playback clock generator configured to provide a playback timer based on a playback clock; and
an application level processor configured to:
receive an audio packet including non-temporally contiguous audio samples that are associated with a same audio channel;
de-shuffle the non-temporally contiguous audio samples to generate audio samples that are temporally contiguous; and
store the temporally contiguous audio samples in a buffer for rendering using the playback timer.
2. The audio sink device of claim 1 , wherein the non-temporally contiguous audio samples were previously shuffled by a distributor device prior to transmission to the audio sink device.
3. The audio sink device of claim 2 , further comprising a network clock generator configured to provide a network timer based on a network clock that is associated with the distributor device.
4. The audio sink device of claim 3 , further comprising a playback clock tuner configured to:
determine an offset between the playback timer and a second playback timer of the distributor device; and
adjust the playback clock generator to reduce the offset between the playback timer and the second playback timer.
5. The audio sink device of claim 4 , wherein the playback clock tuner is configured to:
determine a first difference between the playback timer and the network timer;
determine a second difference between the second playback timer and a second network timer of the distributor device; and
compare the first difference to the second difference to determine the offset between the playback timer and the second playback timer of the distributor device.
6. The audio sink device of claim 2 , further comprising a distribution transceiver configured to receive the non-temporally contiguous audio samples from the distributor device, wherein the distribution transceiver is a wireless transceiver operating accordingly to one or more wireless standards.
7. The audio sink device of claim 6 , wherein the distribution transceiver is further configured to send an acknowledgement receipt to the distributor device based on successful receipt of the non-temporally contiguous audio samples from the distributor device.
8. The audio sink device of claim 1 , further comprising:
a speaker; and
a digital-to-analog converter, coupled to the buffer and the speaker, configured to convert the temporally contiguous audio samples from digital to analog to generate analog audio samples and drive the speaker with the analog audio samples.
9. A method of playing audio at an audio sink device, comprising:
providing a playback timer based on a playback clock;
receiving an audio packet including non-temporally contiguous audio samples that are associated with a same audio channel;
de-shuffling the non-temporally contiguous audio samples to generate audio samples that are temporally contiguous;
storing the temporally contiguous audio samples in a buffer; and
rendering the temporally contiguous audio samples using the playback timer and a speaker.
10. The method of claim 9 , wherein the non-temporally contiguous audio samples were previously shuffled by a distributor device prior to wireless transmission to the audio sink device.
11. The method of claim 10 , further comprising providing a network timer based on a network clock that is associated with the distributor device.
12. The method of claim 11 , further comprising:
determining an offset between the playback timer and a second playback timer of the distributor device; and
adjusting the playback timer to reduce the difference between the playback timer and the second playback timer to reduce the offset.
13. The method of claim 12 , further comprising:
determining a first difference between the playback timer and the network timer;
determining a second difference between the second playback timer and a second network timer of the distributor device; and
comparing the first difference to the second difference to determine the offset between the playback timer and the second playback timer.
14. The method of claim 10 , further comprising receiving the non-temporally contiguous audio samples from the distributor device accordingly to one or more wireless standards.
15. The method of claim 14 , further comprising sending an acknowledgement receipt to the distributor device based on successfully receiving the non-temporally contiguous audio samples from the distributor device.
16. An audio system, comprising:
a distributor device, including:
a first playback clock generator configured to provide a first playback timer based on a first playback clock used to playback a first portion of audio samples at the distributor device;
a first application level processor configured to place a sample of the first playback timer and a second portion of the audio samples into a packet for transmission to a plurality of sink devices, wherein the second portion of the audio samples placed into the packet for transmission to the plurality of sink devices does not include temporally contiguous audio samples that belong to a same audio channel; and
a distribution transceiver configured to transmit the packet to the plurality of sink devices; and
an audio sink device from among the plurality of audio sink devices, including:
a second playback clock generator configured to provide a second playback timer based on a second playback clock;
a second application level processor configured to:
receive the packet including the second portion of audio samples;
de-shuffle the second portion of audio samples to generate audio samples that are temporally contiguous; and
store the temporally contiguous audio samples in a buffer for rendering using the second playback timer.
17. The audio system of claim 16 , wherein the distributor device further comprises a source transceiver configured to receive the audio samples from a source device, wherein the source transceiver is a Bluetooth transceiver or a High Definition Multimedia Interface (HDMI) transceiver.
18. The audio system of claim 16 , wherein the audio sink device includes a second distribution transceiver configured to receive the non-temporally contiguous audio samples from the distributor device.
19. The audio system of claim 16 , wherein the audio sink device further comprises:
a speaker; and
a digital-to-analog converter, coupled to the buffer and the speaker, configured to convert the temporally contiguous audio samples from digital to analog to generate analog audio samples and drive the speaker with the analog audio samples.
20. The audio system of claim 16 , wherein the audio sink device further includes a playback clock tuner configured to:
determine an offset between the first playback timer and the second playback timer; and
adjust the second playback clock generator to reduce the offset between the playback timer and the second playback timer.