[pulseaudio-discuss] Decode SPDIF compressed formats

[Denis Shulyaka]

12 июля 2017 г. 7:42 PM пользователь "Tanu Kaskinen" <tanuk at iki.fi> написал:

On Tue, 2017-07-11 at 23:21 +0300, Denis Shulyaka wrote:
> Hi list,
>
> I am making a small project, a home sound server. It will have a 5.1
analog
> output and S/PDIF optical input, besides others. The server has to mix all
> inputs and send them to the output.
> My initial proof-of-concept with a loopback module failed when I realized
> that S/PDIF interface can receive compressed formats that sounded like a
> loud white noice to me instead of music.
>
> Can pulseaudio handle compressed audio streams apart from passthrough? You
> cannot passthrough to an analog output without decode.
>
> I've found some different info here:
> https://www.freedesktop.org/wiki/Software/PulseAudio/
Documentation/Developer/Passthrough/
> And here:
> https://lists.freedesktop.org/archives/pulseaudio-discuss/
2015-March/023322.html
>
> But could not understand its current status.

No, pulseaudio can't decode compressed formats


Well, that was more or less expected. Is such support planned?
It means I need to write my own decoding application. But that leads me to
another question:
When I open the stream, how do I know its format? And how can I detect when
it changes?
I've came up with an idea to try different codecs and sample rates until I
get something without decoder errors and not looking like a white noise,
but well... you know... there must be a less ugly solution for that! (And I
will have a really hard time detecting the format if my source _is_ a white
noise for some reason).

Best regards,
Denis Shulyaka
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