[mythtv-users] HDMI audio issues on Intel NUC

Matt W mwood23 at gmail.com
Fri Jul 10 01:27:07 UTC 2015


thanks for the tips, Tim, I'll give all that a whirl.

fwiw: so far I have tried changing to ffmpeg high quality for watching
and setting the sound card buffer to 4096 at bootup. the messages re:
buffer size have gone and the ffmpeg decoding doesn't experience as
many audio buffer underruns as VAAPI does, but does from time to time.

another thing I might try: going with a USB SPDIF adapter and grabbing
audio from there, hopefully without any sync issues.

On Thu, Jul 9, 2015 at 12:23 PM, Tim Draper <veehexx at zoho.com> wrote:
>
>
> ---- On Wed, 08 Jul 2015 08:24:39 +0100 Matt W  wrote ----
>>Hi -- I'm running a frontend on an Intel NUC D34010WYK. The backend is
>>another box, running the same version of Debian and MythTV, connected
>>over gigabit wired network. I am using the current release version:
>>
>>mythtv at myth-nuc:~/frontend.logs$ mythfrontend --version
>>
>>Please attach all output as a file in bug reports.
>>MythTV Version : e4f65c8
>>MythTV Branch : tag: v0.27.4
>>Network Protocol : 77
>>Library API : 0.27.20140719-1
>>QT Version : 4.8.6
>>
>>Options compiled in:
>> linux profile use_hidesyms using_alsa using_oss using_backend
>>using_bindings_php using_dvb using_frontend using_hdhomerun
>>using_ceton using_hdpvr using_ivtv using_joystick_menu using_libxml2
>>using_lirc using_mheg using_opengl using_opengl_video using_qtwebkit
>>using_qtscript using_qtdbus using_taglib using_v4l2 using_x11
>>using_xrandr using_profiletype using_mythlogserver using_bindings_php
>>using_mythtranscode using_opengl using_vaapi using_ffmpeg_threads
>>using_mheg using_libxml2
>>
>>OS is Debian Jessie/8: 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1
>>
>>using the VAAPI normal profile (needed SNA acceleration set), the
>>video looks good and does 1080 content well.
>>
>>Audio is another matter. It will work for some content but gets
>>intermittent on LiveTV playback and some recorded shows. I get "ALSA:
>>WriteAudio: buffer underrun" and plenty of "ALSA: Try to manually
>>increase audio buffer with: echo 576 | sudo tee
>>/proc/asound/card0/pcm3p/sub0/prealloc" (no matter what number I push
>>into the prealloc).
>>
>>Upmixing is turned off, but sometimes it seems to help in playback
>>when changed manually in the playback 'auto detect' button. But then
>>not long after, the audio will go out and the log will show buffer
>>underruns.
>>
>>Can someone recommend some troubleshooting methods here? My usual net
>>search skills have yielded nothing concrete. Any help is appreciated!
>>thanks
>>-Matt
>
> this is my general build notes, but have you tried configuring as follows:
> install pavucontrol via repos and then run 'pavucontrol' in gui > configure to 'Digital Surround 5.1 (HDMI) output' (this output name may change, but correct for my Celeron NUC). Next, goto MythTV frontend > setup > audio > set to Alsa:pulse and 5.1 output
>
> see if that helps - i doubt it as the problem is intermittent but might help to get you moved over to pulse. I cant remember the reason for 'Alsa:Pulse' model, but my system works best with this.
>
> I also have to toggle HDMI audio output via xrandr on resume - 5.1 audio channels gets screwed up until you re-initialize the link. the script was take from the kodi project for the Celeron NUC specifically for messed up audio.
>
> The XAUTHORITY path looks like it's for the logged in user - in my case a dedicated mythbuntu FE which uses 'myth' as the auto-login user.
>
> touch /etc/pm/sleep.d/98-audio.sh
> chmod +x /etc/pm/sleep.d/98-audio.sh
> nano /etc/pm/sleep.d/98-audio.sh
>         #!/bin/bash
>         export XAUTHORITY=/home/myth/.Xauthority
>         export DISPLAY=:0.0
>         case "$1" in
>            hibernate|suspend)
>              xrandr --output HDMI1 --off --set "audio" "off";
>                  ;;
>            thaw|resume)
>              xrandr --output HDMI1 --auto --set "audio" "on";
>              ;;
>         esac
>
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