[mythtv-users] 0.24 no sound with Alsa multi pcm - channels setup problem

[David Knight]

On Wed, November 17, 2010 10:28 pm, Matt Taylor wrote:
> Thanks for your help, I've tried the first solution you suggested:
> #define FILTER_FLAGS ~(SND_PCM_NO_AUTO_FORMAT|SND_PCM_NO_AUTO_CHANNELS)
>
> this works with no problems I can see.
>
> I had a brief try with the second suggestion but didn't get it to work
> (same error as before when starting to watch something). I was doing it
> against the fixes branch, should I be trying against trunk? I can have
> another go with this tomorrow and see if I can get a bit more time to do
> it properly.
>
> Cheers,
> Matt
>
> On Wed, 2010-11-17 at 22:52 +1100, Jean-Yves Avenard wrote:
>> On 17 November 2010 08:45, Matt Taylor <mwtaylor at gmail.com> wrote:
>> > Hi,
>> >
>> > I use a custom asound.conf to give me output over optical (for my
>> > receiver) and analogue simultaneously so that I can have sound in
>> > another room at the same time, this uses the alsa multi pcm. This
>> setup
>> > worked fine with 0.23 (and is fine in mplayer, mpd etc.) but with 0.24
>> > release and 0.24-fixes svn I cannot produce sound using this output. I
>> > get an error like this one when trying to use ALSA:default:
>> >
>> > 2010-11-16 21:12:30.186 Opening ALSA audio device 'default'.
>> > 2010-11-16 21:12:30.233 ALSA, Error: Channels count 2 not available:
>> > Invalid argument
>> > 2010-11-16 21:12:30.233 ALSA, Error: Unable to set ALSA parameters:
>> > Invalid argument
>> > 2010-11-16 21:12:30.265 AudioOutput Error: Aborting reconfigure
>> > 2010-11-16 21:12:30.265 AudioPlayer: Disabling Audio, reason is:
>> > Aborting reconfigure
>> >
>> > If I disable the channel configuring stuff by changing
>> > mythtv/libs/libmyth/audiooutputalsa.cpp
>>
>> Actually, use this patch would work too.
>> Index: libs/libmyth/audiooutputalsa.cpp
>> ===================================================================
>> --- libs/libmyth/audiooutputalsa.cpp	(revision 27227)
>> +++ libs/libmyth/audiooutputalsa.cpp	(working copy)
>> @@ -335,7 +335,7 @@
>>
>>      QByteArray dev_ba = real_device.toAscii();
>>      if ((err = snd_pcm_open(&pcm_handle, dev_ba.constData(),
>> -                            SND_PCM_STREAM_PLAYBACK,
>> OPEN_FLAGS&FILTER_FLAGS)) < 0)
>> +                            SND_PCM_STREAM_PLAYBACK, 0)) < 0)
>>      {
>>          AERROR(QString("snd_pcm_open(%1)").arg(real_device));
>>          if (pcm_handle)
>>
>> I think this is a good solution, we have retrieve all the info we need
>> by the time we get to that point, so we can let alsa do whatever is
>> required to open the audio device, including downmixing.
>>
>> JY
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>
>
>
>

Ah I missed this thread will have a look on gossamer threads.

JY - I'm guessing the solutions here will also help me with the problem I
emailed about a few days ago. Where I used to get audio via analogue and
digital spdif in 0.23 using ALSA:default ?

Dave