[mythtv-users] Intermittent playback skips and log errors

[steve]

On 11/29/2011 9:06 AM, Mark Lord wrote:
> On 11-11-29 10:36 AM, Steve wrote:
>> On Nov 28, 2011, at 7:56 AM, Mark Lord<mythtv at rtr.ca>  wrote:
> ..
>>> Easy fix:  run ffmpeg to convert the audio tracks to AC3.
>>> I wrote a shell script to do this last evening, and the results
>>> are just fine -- everything I tried it on was instantly cured.
>>>
>>> Here's the script.  Requires the "mediainfo" command.
>>> Feed it a list of video path/filenames as input.
>>> Output is to same_name.avi, or same_name-new.avi if old file was a .avi:
>>>
>>> #!/bin/bash
>>> # Fix stuttering audio:
>>>
>>> while [ "$1" != "" ]; do
>>>         f="$1"
>>>         shift
>>>         aformat=$(mediainfo --inform="Audio;%Format%" "$f")
>>>         if [ "$aformat" = "AAC" ]; then
>>>                 fname="${f%%.???}"
>>>                 out="$fname.avi"
>>>                 [ "$f" = "$out" ]&&  out="$fname-new.avi"
>>>                 ffmpeg -i "$f" -vcodec copy -acodec ac3 -ab 384k "$out"
>>>         else
>>>                 echo "$f: not AAC, skipped ($aformat)"
>>>         fi
>>> done
>>>
>> Do you run that manually or is it automatically triggered somehow?
> I use it only for downloads that have the issue.
> You probably are thinking of using it for our HD-PVR recordings,
> in which case you should first just try it manually and see if
> the resulting file works better than the original or not.
>
> If it does work better, then it could be arranged to run
> as a "user job" after each new recording completes.
>
> You'd still have to run it manually (once) to treat your existing recordings.
> But first, just try it on one, and see if the result is better or not for you.
>
> Note that the script above does NOT overwrite or delete the original file,
> so there's no real risk.  If you do end up wanting to use it on everything,
> you'll also probably want to modify that behaviour, to replace the original files.
>
> Cheers
>
OK I finally got some time to look into this.  First, I couldn't find 
the mediainfo command (or yum couldn't find it) so I verified via ffmpeg 
that the audio is AAC then ran the suggested ffmpeg command manually.  
While it was running, it put up these errors at several points:

    packet too large, ignoring buffer limits to mux it
    buffer underflow i=0 bufi=xxxxxx size=263972


where xxxxxx is a varying six digit integer.  When it got done I tried 
to play the resulting file with mplayer and got

    [root at mythtv recordings]# mplayer testfix.mpg
    MPlayer SVN-r33996-4.6.0 (C) 2000-2011 MPlayer Team
    mplayer: could not connect to socket
    mplayer: No such file or directory
    Failed to open LIRC support. You will not be able to use your remote
    control.

    Playing testfix.mpg.
    MPEG-PS file format detected.

    Too many video packets in the buffer: (4096 in 8354566 bytes).
    Maybe you are playing a non-interleaved stream/file or the codec failed?
    For AVI files, try to force non-interleaved mode with the -ni option.
    MPEG: No audio stream found -> no sound.
    MPEG: FATAL: EOF while searching for sequence header.
    Video: Cannot read properties.
    No stream found.


    Exiting... (End of file)


So clearly something did not go well with the rewrite.

BTW when I try to play the original file with mplayer it throws 
multiples of the errors I originally wrote about, i.e.

    2011-11-22 06:42:11.701 [h264 @ 0x35326f4f20]non-existing PPS 0
    referenced
    2011-11-22 06:42:11.701 [h264 @ 0x35326f4f20]decode_slice_header error
    2011-11-22 06:42:11.701 [h264 @ 0x35326f4f20]no frame!
    2011-11-22 06:42:11.753 [h264 @ 0x35326f4f20]mmco: unref short failure


Then says

    Too many audio packets in the buffer (4096 in 1426713 bytes)
    Maybe you are playing a non-interlaced stream/file or the codec failed?


Then it plays the file with the same audio stutters. Playing with the 
non-interlaced option doesn't help.

The odd thing about all this is that I was playing things fine with the 
exact same hardware before a system rebuild, except that I had to get a 
new HDPVR (the reason I had to rebuild).

What to do?

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