[pulseaudio-discuss] Buffering attributes with variable format

[Pierre-Louis Bossart]

> Whether passing multiple format infos to negotiate digital passthrough,
> or
> setting one of the PA_STREAM_FIX_* flags on a record stream, I'm a bit
> puzzled
> how the buffering attributes are supposed to work.
> 
> Most of the values are expressed in bytes. How should the application
> negotiate certain timings then? The mapping of bytes to microseconds
> depends
> on the bitrate, which is not known to the application until after
> PulseAudio
> chooses the exact stream format and returns it.

 Actually there's no variable format. With the IEC61937 format, the compressed frames are padded with zeroes to reach the same bitrate as 2ch, 16-bit PCM. In short if you have AC3 at 48kHz, PulseAudio will handle 1,536 Mbits/s. You can set the buffering as if it was a PCM stream. I would recommend you set -1 to all the fields and let PulseAudio select the best buffering for low-power.
-Pierre