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Sigurd

Member

Registered: 2010-01-14

Posts: 7

[Solved]AC3 passthrough worked last week, but not anymore

AC3 passthrough suddenly started working last week, to be precise I noticed it on staurday. On monday it didn't work anymore, my theory is that it started working on saturday due to an upgrade of either alsa, pulseaudio or a multimedia application. But why it started working and then stopped shortly after aren't my main concern, I want it to work again.  I'm using Pulseaudio and alsa, my understanding are that pulseaudio doesn't work with AC3 passthrough, would it be possible to make another session which didn't use pulseaudio, or do I have to remove Pulseaudio. Does anyone have any ideas for how to make it work?

Many Thanks Sigurd

Last edited by Sigurd (2010-02-13 21:18:38)

theDOC

Member

From: Aachen, Germany

Registered: 2009-06-18

Posts: 50

Re: [Solved]AC3 passthrough worked last week, but not anymore

my guess is, that pulseaudio grabs your spdif device as second output device. but to use passthrough, the ac3 stream has to be the only one playing on that device.
whats the output if you do: mplayer -ao alsa:device=spdif -ac hwac3 <some file with ac3 audio>

Sigurd

Member

Registered: 2010-01-14

Posts: 7

Re: [Solved]AC3 passthrough worked last week, but not anymore

Mplayer output from movie I watched with vlc and Dolby Digital one week ago

 
Forced audio codec: hwac3
Opening audio decoder: [hwac3] AC3/DTS pass-through S/PDIF
hwac3: switched to AC3, 640000 bps, 48000 Hz
AUDIO: 48000 Hz, 2 ch, ac3be, 640.0 kbit/41.67% (ratio: 80000->192000)
Selected audio codec: [hwac3] afm: hwac3 (AC3 through S/PDIF)
==========================================================================
[AO_ALSA] alsa-lib: pcm_hw.c:1291:(snd_pcm_hw_open) open /dev/snd/pcmC0D1p failed: No such file or directory
[AO_ALSA] alsa-lib: pcm_hw.c:1291:(snd_pcm_hw_open) open /dev/snd/pcmC0D1p failed: No such file or directory
[AO_ALSA] Playback open error: No such file or directory
Failed to initialize audio driver 'alsa:device=spdif'
Could not open/initialize audio device -> no sound.
Audio: no sound

theDOC

Member

From: Aachen, Germany

Registered: 2009-06-18

Posts: 50

Re: [Solved]AC3 passthrough worked last week, but not anymore

ok, what does "aplay -l" say?
does passthrough work, if you kill pulseaudio?

Sigurd

Member

Registered: 2010-01-14

Posts: 7

Re: [Solved]AC3 passthrough worked last week, but not anymore

Output from aplay -l

**** List of PLAYBACK Hardware Devices ****
card 0: HDMI [HDA ATI HDMI], device 3: ATI HDMI [ATI HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: CMI8738 [C-Media CMI8738], device 0: CMI8738-MC6 [C-Media PCI DAC/ADC]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: CMI8738 [C-Media CMI8738], device 1: CMI8738-MC6 [C-Media PCI 2nd DAC]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: CMI8738 [C-Media CMI8738], device 2: CMI8738-MC6 [C-Media PCI IEC958]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

I'm using the C-media card

My only success with passthrough today was with the xbmc live cd, I haven't had any success with killing pulseaudio either? I'v tried pasuspender which seems to temporarily disable pulseaudio however no succes. I also found this on the pulseaudio mailing list https://tango.0pointer.de/pipermail/pul … 05179.html

Any ideas?

Many thanks Sigurd

Sigurd

Member

Registered: 2010-01-14

Posts: 7

Re: [Solved]AC3 passthrough worked last week, but not anymore

I managed to get it working with xbmc by changing output device and passthrough output device, from IEC958V to <my card> IEC958V, however no succes with other programs.

As far as I'm concerned having ac3 with one program are good enough for me.

Many thanks for the help though theDoc