[mythtv-users] Exasperated: DD/DTS SPDIF works with everything *except* MythTV

Gordon McLellan gordonthree at gmail.com
Sun Dec 7 00:11:48 UTC 2008


In Myth's playback setup, for movies at least, even with DD/DTS
passthrough enabled, I never was able to get it to work that way.  My
solution was to abandon myth's internal player in favor of mplayer.  I
use the "-ac hwdts,hwac3, " option.  Note the extra comma - this is
important, as it tells mplayer to try other encoding methods if dts or
dd is not found.

If you're talking about tv recordings, no idea to help you there - I
didn't even realize there were options other than plain stereo.


On Sat, Dec 6, 2008 at 12:26 PM, Kingsley Turner <krt at krt.com.au> wrote:
> Hi,
> Upgraded my motherboard to a Gigabyte E7AUM-DS2H today; but that's
> beside the point, I think I had this problem before the upgrade, and
> stupidly hoped it would help.
> Anything with a DD or DTS digital audio stream (HDTV channels and DVD
> playback) is in a world of FAIL.
> I've spent all day (since 6am this morning) trawling though doco, mail
> posts from 2005, etc. etc.  I just can't seem to work out what's wrong.
> I'm pulling my hair out, and the kids wont come near me for fear of
> being snapped at.
> Basically the problem is that any sort of dolby digital (or DTS) signal
> goes out over SPDIF incorrectly or goes out without volume (no iec958
> isn't muted).  The display on the amp shows a DD (or DTS) stream is
> happening, but there's no sound.  However VLC can play DVDs with DD5.1
> and DTS perfectly, mplayer can do the same.  It's only myth that's
> exhibiting the problem.
> After playing with lots of /etc/asound.conf configurations, now I have
> none (which seems to work best), and is recommended by the alsa wiki,
> and in a few other places.
> I have configured Myth to use
>    "alsa:default" for audio,
> and "ALSA:iec958:{AES0 0x02}" as the SPDIF output device.
> Obviously the two checkboxes for sending AC3 and DTS sound out via SPDIF
> are checked.
> Mplayer works fine with: -ao alsa:device=iec958 hwac3
> VLC works fine with: --spdif    (oh, *so* easy!)
> Since the first thing asked for is "aplay -L" here it is:
> kingsley at mediabox:~$ aplay -L
> default:CARD=NVidia
>    HDA NVidia, ALC885 Analog
>    Default Audio Device
> front:CARD=NVidia,DEV=0
>    HDA NVidia, ALC885 Analog
>    Front speakers
> surround40:CARD=NVidia,DEV=0
>    HDA NVidia, ALC885 Analog
>    4.0 Surround output to Front and Rear speakers
> surround41:CARD=NVidia,DEV=0
>    HDA NVidia, ALC885 Analog
>    4.1 Surround output to Front, Rear and Subwoofer speakers
> surround50:CARD=NVidia,DEV=0
>    HDA NVidia, ALC885 Analog
>    5.0 Surround output to Front, Center and Rear speakers
> surround51:CARD=NVidia,DEV=0
>    HDA NVidia, ALC885 Analog
>    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
> surround71:CARD=NVidia,DEV=0
>    HDA NVidia, ALC885 Analog
>    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
> iec958:CARD=NVidia,DEV=0
>    HDA NVidia, ALC885 Digital
>    IEC958 (S/PDIF) Digital Audio Output
> hdmi:CARD=NVidia,DEV=0
>    HDA NVidia
>    HDMI Audio Output
> The log isn't showing anything too untoward, it logs where it opens the
> audio device without any hint of errors.
> 2008-12-06 18:19:41.116 AFD: codec AC3 has 0 channels
> 2008-12-06 18:19:41.117 AFD: Opened codec 0xa8eb7930, id(AC3) type(Audio)
> 2008-12-06 18:19:41.119 Opening audio device 'default'. ch 2(2) sr 48000
> 2008-12-06 18:19:41.119 Opening ALSA audio device 'iec958:{ AES0 0x02 }'.
> 2008-12-06 18:19:41.134 NVP: Enabling Audio
> 2008-12-06 18:19:41.136 Opening audio device 'default'. ch 2(2) sr 48000
> 2008-12-06 18:19:41.136 Opening ALSA audio device 'iec958:{ AES0 0x02 }'.
> All audio goes out through SPDIF to an amplifier.  As I've already said,
> Myth plays tv with mpeg audio fine, mplayer/vlc play anything with
> DD/DTS/mpeg audio fine.  But MythTV wont play DD/DTS audio.
> *Please*   Any sage advice?
> thanks,
> -Kingsley
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