[pulseaudio-discuss] Dolby Digital / DTS s/pdif pass-through

Colin Guthrie gmane at colin.guthr.ie
Tue Dec 28 05:44:31 PST 2010

'Twas brillig, and Michał Sawicz at 28/12/10 12:35 did gyre and gimble:
> Dnia 2010-12-28, wto o godzinie 12:46 +0100, Vincent Tschanz pisze:
> Can someone explain to me in broad terms how things should work through 
>> Pulseaudio and Alsa?  And what I should do to get ac3/DTS decoded by
>> my amp?
> Pulseaudio can't currently pass AC3 or DTS through to your SPDIF output.
> There are pending patches [1] for AC3 but AFAIK they're not ready yet.
> You can use ALSA to pass through AC3 and DTS in mplayer by providing a
> 'alsa:spdif' as a default audio output (mplayer option 'ao') and
> 'hwac3,hwdts,' as audio codec (mplayer option 'ac', note the comma!).
> With the above, mplayer will pass through AC3 and DTS through SPDIF and
> also feed stereo streams as PCM. You could use Pulse for stereo streams
> over SPDIF, but mplayer has no facilities to switch audio outputs
> easily, you'd have to provide a '-ao pulse' option on the command line
> when there's a stereo stream played.
> In VLC you will also need to use ALSA:spdif output and enable pass
> through.
> [1]
> https://tango.0pointer.de/pipermail/pulseaudio-discuss/2010-October/thread.html

In addition, while it's often not as good as pass through on various
levels, a solution I use quite happily is documented here:



Colin Guthrie

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