[mythtv-users] Trunk problems with SPDIF 5.1 / iecset data still audio

Lee Koloszyc pantslessape at gmail.com
Sat Jul 31 15:16:59 UTC 2010

I have been working the last two days on trying to fix a problem with
not getting 5.1 through SPDIF with trunk 25510M and AD1988
(snd_hda_intel) sound card, kernel 2.6.34r2
I think I have found the problem but I have not been able to figure
out a solution.
Basically if I set the speakers to 2 channels everything works, when
setting to 5.1 I get the ratatat sound when a program switches to AC3
Through research it seems this has to do with iec not being set to
non-audio and I have confirmed with iecset the Data item is still
audio when mythtv is trying to play AC3 sound.  I used a test ac3 file
with mplayer and it does switch to non-audio and everything works
fine.  If I try to set audio to false with mythtv playing I get:
snd_ctl_elem_write: Operation not permitted which I would assume is
because the card is in use.
In the verbose log from mythfrontend I see (2010-07-31 11:08:17.412
ALSA: Setting IEC958 status: non-audio) so it looks like it is trying
to change.  I have tried various alsa configuration and settings and
have been unable to get this to work.  Anyone have any ideas? Let me
know if you need more info.


Frontend Log:

2010-07-31 11:08:17.368 AFD: Audio format changed
                        from id( AC3)  48000Hz  2ch 16bps     to id(
AC3)  48000Hz  6ch 16bps  pt
2010-07-31 11:08:17.368 AO: SetEffDsp: 4800000
2010-07-31 11:08:17.368 AO: Killing AudioOutputDSP
2010-07-31 11:08:17.412 AO: OutputAudioLoop: Stop Event
2010-07-31 11:08:17.412 AO: kickoffOutputAudioLoop exiting
2010-07-31 11:08:17.412 AO: Original codec was AC3, signed 16 bit, 48
kHz, 6 channels
2010-07-31 11:08:17.412 AO: Opening audio device 'spdif' ch 2(6) sr
48000 sf signed 16 bit reenc 0
2010-07-31 11:08:17.412 ALSA: Setting IEC958 status: non-audio
2010-07-31 11:08:17.414 Opening ALSA audio device 'spdif'.
2010-07-31 11:08:17.416 ALSA: SetParameters(format=2, channels=2,
rate=48000, buffer_time=100000, period_time=50000)
2010-07-31 11:08:17.416 ALSA: Buffer time = 100000 us
2010-07-31 11:08:17.416 ALSA: Period time = 50000 us
2010-07-31 11:08:17.417 ALSA: Buffer size = 4800 | Period size = 2400
2010-07-31 11:08:17.419 AO: Audio fragment size: 4800
2010-07-31 11:08:17.419 AO: Audio Stretch Factor: 1
2010-07-31 11:08:17.420 AO: Ending Reconfigure()
2010-07-31 11:08:17.420 AO: kickoffOutputAudioLoop: pid = 4719

# aplay -L
    HDA ATI SB, AD198x Analog
    Default Audio Device
    HDA ATI SB, AD198x Analog
    Front speakers
    HDA ATI SB, AD198x Analog
    4.0 Surround output to Front and Rear speakers
    HDA ATI SB, AD198x Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
    HDA ATI SB, AD198x Analog
    5.0 Surround output to Front, Center and Rear speakers
    HDA ATI SB, AD198x Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
    HDA ATI SB, AD198x Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
    HDA ATI SB, AD198x Digital
    IEC958 (S/PDIF) Digital Audio Output
    Discard all samples (playback) or generate zero samples (capture)

# lspci  | grep -i audio

00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA)

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