[pulseaudio-discuss] Buffering attributes with variable format

[Rémi Denis-Courmont]

Le lundi 10 octobre 2011 18:35:02 Pierre-Louis Bossart, vous avez écrit :
> > 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.

Yeah? I never said there were formats with variable bit rate. I said I don't 
know the format, hence the bit rate, until after the buffer attributes have 
already been transmitted.

>  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.

This is only an option if there are no latency constraints.

-- 
Rémi Denis-Courmont
http://www.remlab.net/
http://fi.linkedin.com/in/remidenis