[mythtv-users] MythTV 0.24 HDMI audio problem

[Jean-Yves Avenard]

Hi

On Saturday, November 20, 2010, Steven Adeff <adeffs.mythtv at gmail.com> wrote:
> On Fri, Nov 19, 2010 at 2:47 AM, Jean-Yves Avenard <jyavenard at gmail.com> wrote:
>> On 19 November 2010 15:01, Steven Adeff <adeffs.mythtv at gmail.com> wrote:
>>> ssh in, use mplayer with "-ao alsa:device=hw=1.3", I can replace 3
>>> with 7, 8 or 9 and all will playback stereo from mp3, AC3 and DTS from
>>> movies, and my 96KHz 24bit FLAC from HDTracks.
>>>
>>> here's what it shows in the frontend log,
>>> 2010-11-18 22:32:38.650 AO: Opening audio device 'hw:1,7' ch 2(6) sr
>>> 48000 sf signed 16 bit reenc 0
>>
>> What about if you used hw=1,7
>
> hw= with anything does not work at all.
>
>> Okay..
>>
>> I see a bug there...
>>
>> I the mean time, uncheck DTS and AC3 and you will get sound until the
>> fix is pushed through.
>
> yes, that is what I'm doing. Not ideal, but in theory there should be
> no difference since it is passing multichannel LPCM over HDMI.
>
>>> So, it looks to be with how Myth is trying to open the device and pass
>>> AC3/DTS through. I also don't quite understand why in mplayer I can
>>> use 3,7,8, or 9 but Myth seems to only work with 7?
>>
>> If you check the XBMC page I linked to earlier, you will find that
>> those devices aren't all equal.
>>
>> Some can do stereo only and won't work with AC3 or DTS passthrough.
>>
>> Did you use passthrough in mplayer ?
>
> I understand, but in mplayer it works for all four devices no matter
> what, which could just be a smart parsing on mplayer's part, or?  yes,
> I run mplayer with "-ac hwac3,hwdts,". Actually, I have it in my
> ~/.mplayer/config

Yeah, I used to configure the audio device for passthrough in a
similar fashion than mplayer, but was told that it wasn't the proper
way of doing it and it actually failed for some people (personally
never had a problem with it and that's the way it was done in 0.23).

which version of mplayer a you using? (svn revision that is)

>
> what's more annoying is that I can't get AC3/DTS passthrough for any
> of the devices.
>

I had a talked about this.
And depending on the version of ALSA you are using, the device
information you should enter in myth is either;

1)With a recent kernel (not sure which version it started from) and a
version of ALSA-lib containing this change:
http://git.alsa-project.org/?p=alsa-lib.git;a=commitdiff;h=e6d5dcf1f625984605d362338d71162de45a6c60

ALSA:hdmi:CARD=YourCardName,DEV=id

YourCardName being what's returned by a play -L like: NVidia
id: being one of the number device used by the hdmi port

Or:
2)Define an alias in ALSA
like mythtv_hdmi:CARD=foo,DEV=x that link to
intel hda, allowing the use of the extra DEVs when the system alsa-lib
doesn't have the above patch..
and use ALSA:mythtv_hdmi in the myth audio configuration.

Uncheck the advanced audio bit and force of passthrough.

I'll get myself a GT220 and see how it goes. Hopefully will find a way
to make all of this a bit easier to configure.

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