[mythtv] [mythtv-commits] Ticket #5749: Internal player stutters on 720p content

David Asher asherml at gmail.com
Wed Oct 1 19:07:04 UTC 2008

On Tue, Sep 30, 2008 at 1:57 AM, MythTV <mythtv at cvs.mythtv.org> wrote:
> #5749: Internal player stutters on 720p content
>  It appears the the problem occurs when AvFormatDecoder::GetFrame() is
>  processing a large number of sequential video packets without any
>  intervening audio packets, and the audio output buffers drain.  I don't
>  know if the problem is that the loop that calls vFormatDecoder::GetFrame()
>  is taking too long, or if it is being blocked by a shortage of video
>  buffer space.  In the log file excerpt that I will attach, the last "audio
>  timecode" is processed at 18:52:51.807, the internal audio buffer is empty
>  by 18:52:52.047, and the sound card buffer is empty by 18:52:52.385.  The
>  next "audio timecode" does not occur until 18:52:52.776.

I had this exact problem on my system, though it was both 1080i and
720p -- intermittent audio dropouts.  I spent weeks debugging Myth's
audio handling and came to the same conclusions that the audio buffers
were running out.  I could never figure out WHY they were running out.
 My best guess what that it seemed like a blocked/lost interrupt
causing the audio servicing to stop for an extended period of time.

After poking around the alsa forums/documentation I saw that there are
different "models" for the snd-hda-intel driver.  What finally fixed
it for me was adding:

options snd-hda-intel model=targa-dig

to my /etc/modprobe.d/alsa-base file.  I'm using a MSI Media Live as
my frontend (Nvidia MCP51 providing ALC883 audio, I think).  Obviously
this specific model won't help you if you're not running an MSI board,
but if you are using the snd-hda-intel driver you might want to look
at the available "models" in:



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