[mythtv-users] Problem with MPEG-4 transcoded file (no bitrate or duration)

[mythtv at kosowsky.org]

John Pilkington wrote at about 17:36:38 +0100 on Friday, May 17, 2019:
 > On 17/05/2019 15:59, mythtv at kosowsky.org wrote:
 > > John Pilkington wrote at about 08:49:48 +0100 on Tuesday, May 14, 2019:
 > >   > On 14/05/2019 01:30, mythtv at kosowsky.org wrote:
 > >   >
 > >   > > Perhaps a partial clue is that under v24, the transcoded file had an
 > >   > > 'nuv' suffix while under v29.1 the suffix is 'ts'.
 > >   > > Could it be an issue with the container?
 > >   > >
 > >   > > Note that ffprobe shows both files to be of format NuppelVideo.
 > >   > >
 > >   >
 > >   > That is the problem.  NuppelVideo is now seen as an an outdated format
 > >   > and support for it is fading away, even if it hasn't been officially
 > >   > dropped.  It might be dependent on the options used in the build of
 > >   > ffmpeg or mythffmpeg that you are using.
 > >   >
 > >   > Google found this, but I guess you have already seen it:
 > >   >
 > >   > https://www.mythtv.org/wiki/MythTV-HOWTO_-_0.27
 > > 
 > > 
 > > I think I've made some progress.
 > > It seems perhaps that myttranscode now transcodes into HTTP streaming
 > > format which could explain lack of duration.
 > > 
 > > When I use ffmpeg to copy (and concatenate) the streams, I then get a
 > > valid duration:
 > >     ffmpeg -y -i <file.ts>  -c copy  <file2.ts>
 > > 
 > > However, when I do that, for some reason the keyframes/i-frames are
 > > lost... so when I 'edit' no frames show up.
 > > 
 > > Also, 'mythcommflag --rebuild', gives the following error:
 > >        No I-frames found, rewinding...
 > > 
 > > 
 > > So, is there any way to use ffmpeg to rebuild the stream in a way
 > > that:
 > > 1. Creates a single stream with a duration
 > > 2. Preserves the frames/i-frames/keyframes
 > > 
 > > 
 > > Also, it's possible that I am way off base here...
 > > 
 > > Jeff
 > 
 > Interesting, and news to me.  I thought the problem was with ffmpeg 
 > because you reported that ffmpeg -i and ffprobe were giving different 
 > readings.  My googling for NuppelVideo also brought up a long ticket 
 > about Peter's refactoring for ffmpeg a year or so ago.  I'm currently on 
 > a laptop and can't consult that search history.
 > 
 > John P

ffmpeg -i and ffprobe give the same results on any given file.
The difference is between mp4 mythtranscode transcodings from v24 vs
v29.1. Where v24 transcodings had the .nuv suffix and showed a
well-defined duration and bitrate while v29.1 has the .ts suffix and
have a N/A bitrate and duration.

When you get a chance, would love a link to the chain you reference (if
shareable).