[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:
http://www.mjmwired.net/kernel/Documentation/sound/alsa/ALSA-Configuration.txt
David.
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