STREAM CACHING FOR AUDIO MIXERS

• US 20150201274A1
• Filed: 02/28/2013
• Published: 07/16/2015
• Est. Priority Date: 02/28/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: ELLNER, Lars Henrik, SHABESTARY, Turaj Zakizadeh, ENBOM, Niklas
• Granted Patent: US 9,602,918 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10
• CPC Class Codes: H04M 1/60 including speech amplifiers
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones

Abstract

Methods and systems are provided for reusing audio streams in an audio mixing environment such that processing resources (e.g., CPU cycles) are not wasted on encoding the same audio streams multiple times (e.g., more than once). Instead, processing resources are conserved without comprising audio quality. The methods described herein are particularly useful when a participant transitions from using a shared encoder to using the participant'"'"'s own encoder, and when the participant transitions from using the participant'"'"'s own encoder to using a shared encoder.

Claims

1. A method for sharing encoded audio, the method comprising:

encoding, by an audio mixing apparatus, audio signals to send to a first client using a first encoder and audio signals to send to a second client using a second encoder;

determining that the first encoder is in a similar state as the second encoder; and

in response to determining that the first encoder is in a similar state as the second encoder, the audio mixing apparatus sending the audio signals encoded using the second encoder to the first client and the second client.

2. The method of claim 1, further comprising:

receiving, at the audio mixing apparatus, audio signals from a plurality of clients in communication with the audio mixing apparatus;

performing a mixing algorithm on the received audio signals to generate a plurality of mixed audio signals; and

sending each of the plurality of mixed audio signals to one or more of the plurality of clients.

3. The method of claim 2, wherein the mixing algorithm is performed based on voice activity detected in the received audio signals.

4. The method of claim 1, wherein the determination that the first encoder is in a similar state as the second encoder is based on an absence of audible distortions when encoding and decoding a segment of audio.

5. The method of claim 1, wherein the first and second clients are participants in an audio conference.

6. The method of claim 1, further comprising storing a number of audio frames to bring the first encoder to a similar state as the second encoder.

7. The method of claim 1, wherein the first encoder and the second encoder are synchronized with respect to buffered audio.

8. A method comprising:

encoding, by an audio mixing apparatus, audio signals to send to a first client and a second client using a first encoder;

copying an encoder state of the first encoder;

updating a second encoder with the copied encoder state of the first encoder; and

encoding audio signals to send to the second client using the updated second encoder.

9. The method of claim 8, wherein copying the encoder state of the first encoder includes copying buffered audio for the first encoder to the second encoder.

10. The method of claim 8, wherein the first encoder and the second encoder are synchronized with respect to buffered audio.

11. A method comprising:

performing, by an audio mixing apparatus, a mixing algorithm on audio signals received from a plurality of channels to generate mixed audio signals;

identifying, from the plurality of channels, a unique channel set and one or more non-unique channel sets, wherein the unique channel set includes channels that each receive a unique one of the mixed audio signals, and wherein the one or more non-unique channel sets each includes channels that receive a non-unique one of the mixed audio signals;

determining that in the previous mix cycle a channel in the unique channel set was re-using audio frames encoded by a channel in a non-unique channel set; and

copying a codec state of the channel in the non-unique channel set to the channel in the unique channel set that was re-using the audio frames encoded by the channel in the non-unique channel set.

12. The method of claim 11, further comprising encoding, for each of the channels in the unique channel set, the unique one of the mixed audio signals corresponding to that channel using an encoder for that channel.

13. The method of claim 11, further comprising:

identifying, for each of the one or more non-unique channel sets, an encoder used by a channel in the non-unique channel set that was encoding the same non-unique one of the mixed audio signals in the previous mix cycle; and

encoding, for each of the one or more non-unique channel sets, a corresponding one of the non-unique mixed audio signals using the identified encoder.

14. The method of claim 13, wherein each of the one or more non-unique channel sets receives a different one of the non-unique mixed audio signals.

15. The method of claim 11, wherein the channel in the non-unique channel set and the channel in the unique channel set are synchronized with respect to buffered audio.