[pulseaudio-discuss] Passthrough support and sink channel count

[Anssi Hannula]

Hi,

I was looking at using the PA passthrough support (and adding support
for TrueHD, DTS-HD), but it seems there is another issue that has to be
resolved first:

Pulseaudio passthrough (with ALSA) does not currently work unless a
stereo profile is in use.

If a HDMI surround profile is in use, the device seems to be permanently
in a 6 channel mode. As passthrough of e.g. 48kHz AC-3/DTS requires the
device to opened in 2 channel 48kHz mode, pa_sink_input_new() will
always fail with "Could not update sink sample spec to match passthrough
stream".

How should this be solved?


(also, TrueHD and DTS-HD MA will require a 768kHz IEC 60958 frame rate,
which in ALSA is 8 channel 192kHz)

BTW, shouldn't/couldn't the sink channel count be auto-selected from
EDID in case of HDMI instead of having to select profiles?

-- 
Anssi Hannula