[mythtv] Why nuppelvideo mpeg4?

Lincoln Dale ltd at interlink.com.au
Mon Aug 8 17:25:58 EDT 2005


Reza,

firstly, thanks for compiling up a mplayer.dll with the diff to 
mplayer's .nuv support i posted.  i have been using an xbox as a 
frontend for playing back recordings with 100% stability, including 
content transcoded into mpeg4.
(note that i only say previous recordings here - even with CVS 
xbmcmythtv it has issues with "live tv", "status" & various other things 
- basically i've created a xbmc front-menu which only calls 
'mythtvrecordedshows.py'.

i'll contribute a Wiki on how to set it all up as xbmc makes a pretty 
awesome frontend for folks that want a quick way of playing back 
content.  i used to use linux-on-xbox to do it - with the ~2 minutes 
boot-time - but with xbmc as my dashboard its more like 15 seconds from 
poweron to viewing a listing of recordings.


regarding "why not use .avi":

.avi has numerous problems.  for one, the indexes are at the tail of the 
file and are only written at the last moment.  therefore 
partially-recorded files or files-currently-being-recorded have no index.

likewise its not a very nice 'streaming' protocol if one has to seek to 
the end to read the index at the beginning of playing back a stream.

.nuv as a container is just fine - and mplayer's previous inability to 
play it back is not Myth's fault - but rather mplayer.
patches have been around for years but never accepted by mplayer folks.
perhaps we can jointly work on improving those to the point where 
mplayer folks _will_ accept them?

i have found that a patched mplayer can play back .nuv files just fine - 
while you cannot use jump-forward/jump-back (left-arrow / right-arrow) 
to seek, you can use RW/FF (left-trigger / right-trigger) to RW/FF at 
1x/2x/4x/8x/16x/32x.  sure - the picture breaks up until it sees a 
keyframe - but that isn't so bad - and if we did want to fix something, 
that'd be one of the things to address.

it may make sense to extend Myth to add specific containers relating to 
the information that also goes into a SQL table - jump tables, 
commercial-detection etc - and i don't think the Myth team would resist 
having that as an option - but in reality, its up to mplayer to do much 
of the heavy lifting, not Myth.


cheers,

lincoln.

Reza Naima wrote:
> I was wondering why we are using the nuppelvideo container for mpeg4? It
> can't be hard to convert to a different format - nuv2avi works great.
> Why is it that we're not using avi's (for example) rather than nuv's to
> store the files?  mplayer (used by xbmc) has a lot of issues with the
> .nuv files, and unless you have the special codecs installed on windows
> .nuv mpeg4 files will not play.  
> 
> How hard would it be (and are there any reasons no to) modify the code
> such that it will generate more friendly mpeg4 files?
> 
> Thnx
> Reza
> 
> p.s. what is all the seek information in the DB for?  why isn't that
> in the video file itself?


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