[mythtv-users] Converting "mythtranscoded" files to avi...

Mike Perkins mikep at randomtraveller.org.uk
Thu Jan 3 12:46:18 UTC 2008

Steve Smith wrote:
> Folks,
> I've been doing some experimenting:
> What I'm Trying to Transcode to a Portable (i.e. non-NUV!) Format
> ================================================
> Myth:0.20-fixes
> Sources: 1) DVB-T (freeview) i.e. MPEG2-TS files
>               2) PVR-150         i.e. MPEG2-PS files
> Transcoded using Mythtranscode on MPEG4 settings to NUV files.
> O/S Ubuntu Feisty.
> What I've Tried So Far on the MPEG4 NUV files
> ==================================
> ffmpeg:
> ----------
> ffmpeg -i FILE.nuv -vcodec copy -acodec copy -r 25 OUT.avi
>        Doesn't work at all. My version of ffmpeg doesn't seem to understand
> the NUV container
> correctly. It produces completely unplayable files.
> NUVEXPORT  & nuvexport-xvid --mencoder:
> --------------------------------------
>       Bizarre!!!
>       Coversion starts OK then at some point in the conversion all goes
> haywire the left hand border of the picture moves to the centre and you get
> wierd colour washes.
> i.e.
>        ||  The IT Crowd ||           becomes      | Crowd ||||  The IT |
> This is the second time I've seen this effect with both DVB and PVR-150
> original sources. Also with mytharchive trying to create DVD from these NUV
> files.
> vlc:
> ----
>   VLC can play the nuv files on Windows with no problems, so I thought I'd
> try its transcoding abilities. It seems that there are differences between
> the Ubuntu and Windows versions.
> Suffice to say the only one with any degree of success was:
>  (Windows VLC)         NUV ---> MPEG2-PS
>  This plays perfectly on VLC but on the DVD player it looks like the bit
> rate is set way too low.
> mencoder:
> ---------------
>       mencoder INFILE.nuv -ovc copy -oac copy OUT.avi ( I forget the exact
> syntax)
> This produces ALMOST playable results. However glitches (maybe in the
> original) means that the DVD player bombs out playing them. So a 1:30 sample
> may only play for 5 secs before it "crashes".
>       Using mencoder to Re-encode (yes I said I didn't want to do this!) to
> XVID (in an AVI container).
>       HOWEVER this results in the dreaded lip-sync problems, which the
> yamada dvd-player doesn't provide adjustment for.
> So:
>    1) Has anyone else seen these nuvexport problems?
>    2) Any other suggestions for NUV (mpeg4) to "portable format"?
>    3) I'm considering replacing "mythtranscode" with something else e.g.
> ffmpeg, mencoder -> divx etc. However in the past I've had lip sync problems
> with MPEG-TS--> MPEG-PS any idea how to solve this?
> It seems the "simple" matter of archiving my recordings to a portable format
> is not really simple at all.
I really don't like mythtranscode turning all my MPEG-2 (Freeview) files into 
.nuvs which I can't do anything with. So for the time being I don't transcode at 
all. Most players I have tried seem to work OK on the original files. Problem of 
course is the amount of disk space used up.

I *really* would like to see an alternative solution to this. I seem to remember 
that someone talked about a mythtranscode MPEG2-TS to MPEG2-PS option coming in 
the near future (with the output files being .mpg not .nuv). That would be the 
way to go.

Mike Perkins

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