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

[John Pilkington]

On 17/05/2019 19:49, mythtv at kosowsky.org wrote:
> 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  NuppelVideo is now seen as an an outdated format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).

The exact ticket that I found earlier isn't coming up, but this is a 
thread from the dev list at much the same time that shows how things 
were moving...

https://lists.gt.net/mythtv/dev/613834#613834