What does "deep buffer" mean in the audio system/driver?

[尹豪雲]

Hello Experts,

I am studying the Audio Framework recently.

And I found the "deep buffer" playback which is used when playing MUSIC stream. Right?

I wonder to know what is the difference by comparing with other playback.

1. Deep Buffer

2. Codec Offload

3. Normal Tracks

I think I know what are Codec Offload & Normal Tracks for.

But I don't understand "deep buffer"

1. How does "deep buffer" work?

2. Why music stream plays as "deep buffer" way?

3. What is the benefit of the "deep buffer"

5. Where can I find any reference data about "deep buffer"

Thanks & Best Regards.

[Glenn Kasten]

normal tracks - PCM, typical buffer size is ~20 ms, higher latency

fast tracks - PCM, typical buffer size is 5 ms or less, lower latency

deep buffer - PCM, typical buffer size is >= 100 ms, very high latency, intended to save power

codec offload - MP3/AAC/etc., very high latency, intended to save even more power than deep buffer

grep -r DEEP_BUFFER in frameworks/av/* is a starting point for details

[Neil Agarwal]

Thanks a lot!