[pulseaudio-discuss] How to use ALSA compress API in Pulseaudio with passthrough mode

[Pierre-Louis Bossart]

>>> and last you strip the header and pass the
>>> payload to your hardware decoder using the compressed API.
>>
>> Do you mean by stripping the IEC header frame with MP3 header will be
>> there and pass the same to hardware decoder?
>
> I'm not sure what Pierre meant. PulseAudio expects the alsa device to
> consume the IEC-wrapped data. I guess you could make an alsa plugin that
> shows up as a PCM device to PulseAudio, and the plugin then receives the
> wrapped data from PulseAudio, unwraps the MP3 data and finally feeds it
> to the compressed API.

Depends on what your hardware supports. The compressed API can handle 
either IEC-based payload or elementary streams (i.e. raw MP3). The 
pulseaudio sink needs to make the adjustments if needed.