[pulseaudio-discuss] HDMI passthrough request for help

pl bossart bossart.nospam at gmail.com
Fri Feb 18 06:41:04 PST 2011

> First of all I patched pulseaudio git with some updates to treat
> hdmi-passthrough as it does iec958-passthrough.  That seems to work.  I can
> use paplay to pass a dts-wav file through to the receiver and the receiver
> triggers into dts mode and plays it.  A native dts file stripped from and
> mkv movie file on the other hand doesn't play.
> I made some minor changes to the Xbmc pulseaudio driver so that it does not
> ignore passthrough requests.  Xbmc's pulseaudio driver assumes (without
> patching) that passthrough is not available for pulseaudio.  Now I can
> select the pulseaudio passthrough device.  Xbmc has code in it to manipulate
> dts streams.
> The problem is that I can start a movie, Xbmc will select the dts track and
> play, but the receiver doesn't go into dts mode, but instead just buzzes the
> speakers.

Did you actually add the PASSTHROUGH flag when you create the pa_stream?
When the receiver doesn't lock it's typically when the data was
modified by the volume control.
Another possibility is mismatch between frequencies. Make sure the
sink and the stream sampling frequencies match.

Note that we are completely reworking this part, you may want to wait
1-2 months before the feature becomes more stable.

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