[mythtv] nuv formats for mpeg4? mythtranscode?

Subbyz subbyz at kinison.puremagic.com
Tue Mar 20 00:45:49 UTC 2007

I've been doing a lot of looking for something to allow conversion of 
already transcoded (from mpeg2 to mpeg4 format) recordings into a plain-jane 
avi container for playing on other platforms, without having to reencode and 
incur another level of quality loss.

Unfortunately, the only thing I've found that looks like it fills this need 
is nuvtools nuv2avi, which has some problems that I won't go into here since 
they are unrelated to mythtv.  I'm surprised more people aren't concerned 
with having to go through another full transcode and associated generational 
loss to get the recordings out of .nuv format.

I've read on the wiki that the NUV container is used internally to Myth to 
solve sync issues between the audio and video.  I understand why that might 
be necessary for RTJPEG recordings, but am not clear on why that is 
necessary for mpeg4 recordings, wether they are transcoded or not.

So, here's my questions:  Is NUV format still necessary for mpeg4 original 
or transcoded recordings?  Could the .nuv container be replaced internally 
to make the recordings more compatible with other systems without 
functionality loss within mythtv?  Is the nuv container for mpeg4 just an 
artifact of that being the way it was originally done for RTJPEG, and an 
attempt to keep the container format consistent with the older format, or 
are there still technical reasons for keeping mpeg4 in the non-standard nuv 

As a semi-related question, I see that mythtranscode has the --mpeg2 option 
for what I'm assuming is a non-lossy transcode (except for the GOP's after 
cutpoints).  Is there anyone working towards doing the same thing for mpeg4? 
Has there been interest in such a feature?



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