[vlc-devel] S/PDIF passthrough with ALSA (Ticket #894)

[Mikko Korkalo]

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Hi!

I have an issue with optical S/PDIF output using VLC 0.8.6c.

I found this thread:
http://forum.videolan.org/viewtopic.php?f=13&t=34083

I would have posted this message there, but the board seems to be having
some difficulties:
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Anyway, I tried the patch (alsafix1.diff 08/01/07 13:50:31) suggested here:
http://trac.videolan.org/vlc/ticket/894

I applied the patch "by hand", and VLC (ubuntu package) compiles cleanly.

I can clearly see an improvement over the repeating snapping sound I had
before, but:
- - The sound is very choppy
- - I got one segmentation fault when I fast forwarded a media file from
beginning to 50%. I can maybe reproduce this if necessary.
- - I hear _one_ snap when I start A/52 playback (without the patch, I
only hear the same kind of snap repeating, and nothing else)
- - Changing the output to stereo immediately fixes the problem, but of
course, I'm not getting 5.1 sound then (2 channels over S/PDIF is ok)
- - I get some errors in console during playback (the error appears about
2 times per sec):
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[00000893] alsa audio output error: write failed (Broken pipe)
[00000893] alsa audio output error: write failed (Broken pipe)
[00000893] alsa audio output error: write failed (Broken pipe)
[00000893] alsa audio output error: write failed (Broken pipe)
[00000893] alsa audio output error: write failed (Broken pipe)
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Here is some information about my system:
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keitsi at keitsi:~$ lspci|grep audio
00:04.0 Multimedia audio controller: nVidia Corporation CK804 AC'97
Audio Controller (rev a2)
keitsi at keitsi:~$ uname -a
Linux keitsi 2.6.22-14-generic #1 SMP Sun Oct 14 21:45:15 GMT 2007
x86_64 GNU/Linux
keitsi at keitsi:~$ aplay -L
default:CARD=CK804
    NVidia CK804, NVidia CK804
    Default Audio Device
front:CARD=CK804,DEV=0
    NVidia CK804, NVidia CK804
    Front speakers
surround40:CARD=CK804,DEV=0
    NVidia CK804, NVidia CK804
    4.0 Surround output to Front and Rear speakers
surround41:CARD=CK804,DEV=0
    NVidia CK804, NVidia CK804
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=CK804,DEV=0
    NVidia CK804, NVidia CK804
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=CK804,DEV=0
    NVidia CK804, NVidia CK804
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
null
    Discard all samples (playback) or generate zero samples (capture)
default:CARD=UART
    MPU-401 UART
    Default Audio Device
keitsi at keitsi:~$ dpkg -l|grep asound
ii  lib32asound2                               1.0.14-1ubuntu8
                 ALSA library (32bit)
ii  libasound2                                 1.0.14-1ubuntu8
                 ALSA library
ii  libasound2-dev                             1.0.14-1ubuntu8
                 ALSA library development files
ii  libasound2-plugins                         1.0.14-1ubuntu3
                 ALSA library additional plugins
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- - (k)ubuntu 7.10 gutsy x64_64
- - Asus A8N-SLI Premium with integrated Realtek ALC850
- - AMD Athlon64 X2 3800+

If anyone needs any help debugging the problem, I will be glad to help.

Best regards,
Mikko Korkalo
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