[mythtv-users] Playing back transcoded files (transcoded to Mpeg-4)

Michael T. Dean mtdean at thirdcontact.com
Wed Apr 5 23:12:27 UTC 2006


On 04/05/2006 03:39 AM, ffrr wrote:

>My mythtv install is Knoppmyth R5B7, so that's 0.19 with fixes. My TV 
>card is DVB-T so recordings are Mpeg2-TS.
>
>Last night I thought I'd experiment with transcoding to mpeg4 so I could 
>fit more shows on my 250GB disk. I set up the profile for autodetect 
>from MEG2, and all I did was to change the main setting from rtjpeg to 
>mpeg4.  I left everything at the default setttings.  Then I selected a 
>one hour show, using the front end, and told it to transcode.
>
>The result - a one hour show (with extra before/after) went from 3.5GB 
>to 1.6GB.  That's good.  Now I am trying to play back the file 
>remotely.  I normally do this using NFS mapped drives, and the 'pretty' 
>symlinks to launch gxine to play them - although Kaffeine and others 
>work as well.
>
>Now, all I get is distorted scratchy sounds and no picture.  I went to 
>the actual file to try it directly, and discovered it was now an .nuv 
>file (started out as an mpg file).  Shouldn't MPEG4 files use mp4 or mpg 
>extensions?
>

File extensions don't mean anything.  We're not on Windows. ;)

Anyway, MPEG-4 from Myth is video encoded with an MPEG-4 CODEC and 
contained in a NuppelVideo container (so it is a NuppelVideo file).  You 
can use the MPEG-2 lossless transcoding to remove commercials and save 
around 3% of the space used by the original.

>  Anyway, it still wouldn't play in gxine, so I tried playing 
>it with VLC.  This works (although it was stretched tall until I 
>manually switched VLC to 16:9 - but that may be a quirk of VLC itself)
>
>So, what do I need to be able to play these files in gxine?  I thought I 
>had all the usual codecs (installed from a pack downloaded from mplayer 
>HQ about 6 months ago).  Is myth using some special codec to transcode 
>to 'mpeg4'?
>

NuppelVideo...  (But, IIRC it's not straight NuppelVideo, it has some 
Myth mods to it.)  Search the archives for MPlayer and NuppelVideo--it's 
possible to get MPlayer to play it, so may also be for other media players.

Although, for an easier solution, you could always install Myth to play 
it.  Even if you have the "version difference" problems someone 
mentioned (run a version of Myth on one distro for your main Myth system 
that's not available on the distro for your desktop distro), just 
install Myth on the desktop and don't use mythfrontend...  Instead, 
start playback with:

mythtv /path/to/filename.nuv

Mike


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