[mythtv-users] Transcoded recordings playback fails: audio failure, video stutters (was Last MythTV Gentoo ebuild... buffer issues)

[Yianni Vidalis]

> Date: Sat, 17 Dec 2011 19:47:55 -0800
> From: jk90090 at gmail.com
> To: mythtv-users at mythtv.org
> Subject: [mythtv-users] Transcoded recordings playback fails: audio failure, video stutters (was Last MythTV Gentoo ebuild... buffer issues)
> 
> On 12/9/11 12:41 PM, jk90090 wrote:
> > On 12/8/11 9:57 PM, Raymond Wagner wrote:
> >> On 12/8/2011 23:11, jk90090 wrote:
> >>> I've narrowed down my playback issues now to Transcoded recordings.  
> >>> Any
> >>> recording that isn't transcoded is playing back perfectly (720p, 1080i
> >>> both smooth as silk), and it's pretty much for all transcoded content,
> >>> so simply newly transcoded recordings.  Anyone have any ideas?
> >> How are you transcoding these?
> >> ________________________________
> > Ticking the 'transcode' option for the recording schedule, either with 
> > Medium Quality or Low Quality
> >
> > The settings I use are:  (Advanced -> TV Settings -> Recording 
> > Profiles -> Transcoders -> ..)
> >     Media Quality - Resize video while transcoding, 1280x720, MPEG4, 
> > 2200 Bitrate, Max Qual 2, Min Qual 15, Max qual diff between frames 3, 
> > Scale bitrate for frame size, Enable High-quality encoding, Enable 4MV 
> > encoding; MP3 audio, 32000 sampling rate, qual 7, volume 90%
> >     Low Quality - Resize video while transcoding, 960x540, MPEG4, 2200 
> > Bitrate, Max Qual 2, Min Qual 15, Max qual diff between frames 3, 
> > Scale bitrate for frame size, Enable High-quality encoding, Enable 4MV 
> > encoding; MP3 audio, 32000 sampling rate, qual 5, volume 90%
> >
> > As a side likely unrelated note, in the past I usually used High 
> > Quality (RTjpeg, qual 170; MP3 audio, qual 7), and it worked for years 
> > until an update in the past 6 months completely broke it, and 
> > required, oddly, for me to go back into the settings and just hit next 
> > and finish (effectively re-saving the setting for HQ).  It still never 
> > worked like it had in the past however, and I had started using Medium 
> > and Low Qual Transcode more often anyways so I didn't look into it 
> > further.
> >
> > No difference in playback between the Medium and Low Qual transcoded 
> > recordings, still stuttering video with audio cutout generally, 720p 
> > or 1080i.  Eventually (seconds) the playback gives up and exits. It 
> > looks like I had one recent recording that was transcoded with High 
> > Quality, and it is playing back fine.
> >
> > I am using a Frontend with VPDAU high quality playback (and I have 
> > tried without using VPDAU with no different results), and CPU usage 
> > for the system is single digits generally when doing playback.  Dual 
> > Core i5 I think, 6 GB memory.
> >
> >
> So I never could figure out how to rollback to the earlier build, and 
> frankly it would probably be more of a pain than to just have someone 
> figure out what is now broken in Myth.  I went ahead and built the 
> latest ebuild from github ( using scripts/mythtv-buildebuild.py ):
> 
> [ebuild   R   ~] media-tv/mythtv-0.25_pre20111217  USE="alsa autostart 
> dvb dvd ieee1394 lame lcd lirc vdpau x264 xvid (-altivec) -bluray 
> -crystalhd -debug -jack -perl -pulseaudio -python -vaapi" 
> INPUT_DEVICES="-joystick" VIDEO_CARDS="nvidia" 0 kB [1]
> 
> No change to my woes.  Next I tried using mythcommflag to rebuild the 
> seek tables, just to rule it out.  No change.
> I have yet to find a single transcoded recording that plays back anymore.
> 
> I switched audio to NULL and no change, so I can't quite see it as a AV 
> sync issue.  Ideas anyone?  This is driving me crazy.
> 
> -J
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> mythtv-users at mythtv.org
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I think I am facing the same problem. I am using HEAD and the mythnuv2mkv.sh script to transcode recordings. Things started breaking about 2 months ago, but I didn't realize it on time because I wasn't watching the recordings.

The symptom is like missing frames, and it occurs in both .nuv and .mpg recordings. I intend to find some time and experiment more with the transcoding settings (not of mythnuv2mkv.sh, of mythtranscode) because I seem to remember that trying one of the default-high-low quality setting didn't corrupt the file. Unfortunately, I didn't keep the original. So I must be more thorough in my search. Don't worry, you're not alone.

Regards, 

Yianni
 		 	   		  
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