[mythtv-users] New spdif setup suggestions

Joel Means means.joel at gmail.com
Wed Feb 11 16:25:29 UTC 2009


On Wed, Feb 11, 2009 at 9:06 AM, James Crow <james at ultratans.com> wrote:
> On Wed, 2009-02-11 at 08:23 -0700, Joel Means wrote:
>> On Wed, Feb 11, 2009 at 5:59 AM, James Crow <james at ultratans.com> wrote:
>> > On Tue, 2009-02-10 at 19:05 -0800, Allen Edwards wrote:
>> >
>> > <snip>
>> >>
>> >> Can someone who has gotten HDMI audio to work help out here with the
>> >> version numbers required as a minimum on alsa and nvidia drivers to
>> >> get HDMI audio working?
>> > <snip>
>> >>
>> >> Allen
>> >>
>> >
>> > Allen,
>> >
>> >  I recently built a machine with Ubuntu Intrepid. The MB was an Asus
>> > M2N68 with HDMI onboard. The integrated GPU is a 7050. I had to update
>> > the included ALSA (1.0.17) to get HDMI to show in the list of available
>> > audio outputs. I used the script that was references on this list from
>> > ubuntuforums.org. It pulled the latest version from alsa-project.org
>> > which was 1.0.19. The script is here:
>> > http://www.ubuntuforums.org/showthread.php?p=6589810
>> >
>> >  The nvidia driver was the default that came with Intrepid. I think it
>> > is 177.xx.
>> >
>> >  This was not built as a Myth system, but I was able to test mpeg2 ATSC
>> > video through mplayer and audio was playing over the HDMI connection.
>> >
>> > Cheers,
>> > James
>> >
>> >
>> > _______________________________________________
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>> >
>>
>> Just out of curiosity, was the audio ac3 using passthrough, or was it
>> downmixed?  Or was it not ac3 at all (I think it usually is with ATSC,
>> but I don't really know).  I have the same GPU on an Abit board and
>> can't get passthrough to work on the HDMI port, but regular audio
>> does.
>> Thanks,
>>
>> Joel
>
> I had a 1080i file from the presidential inauguration recorded by clear
> QAM from my local NBC affiliate. The audio is ac3. This is the line I
> used to play the file:
>
> mplayer -ao alsa:device=hw=0.3 -vf pp=fd 4032_20090120114500.mpg
>
> I did no other configuration except to check that the iec958 device was
> not muted. The xorg.conf file is stock Ubuntu 8.10 with the distro
> supplied 177.xx nvidia binary. The '-vf pp=fd' part of the command is a
> deinterlacer. The first time I played the 1080i video on the attached
> 37" 1080p LCD display it looked terrible.
>
> I am not very familiar with mplayer options, but I would guess that it
> decoded the ac3 audio before sending it out the HDMI port.
>
> I no longer have the HDMI device and this PC is about to leave for its
> final home as part of a digital billboard so I do doubt further testing
> will be possible.
>
> Cheers,
> James
>
>
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>

Well, just for future reference (since you can't test it now), if you
use the "-ac hwac3" switch, it will send the bitstream out.  Without
that, it does decode it, as you assumed.  Thanks for the info.

Joel


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