[mythtv] MythTV Recording System Future

[Torbjörn Jansson]

> > Thats nice, but it doesn't truly solve the problem I have 
> which is that
> > NOTHING supports the MythTV proprietary .nuv file 
> perfectly, or without
> > having to patch and recompile the program. I also cannot use it in
> > Windows where I have to burn my DVD's. That is why I think 
> it would be
> > useful. For people who want a truly portable stream file 
> format. If you
> > are using mythtv strictly as a PVR, then the mythtv nuv 
> file is fine.
> > Having to convert the MythTV nuv file to another format and 
> only then
> > being able to work with it is a great hassle.
> 
> All it needs to be supported natively in windows is for 
> someone to write a, 
> what is it now, DMO? DirectShow filter?, for it.  I can't 
> imagine it being 
> very difficult -- this isn't a very complicated video format here.
> 

I have started to write a directshow filter, I tried to use a DMO first but
that was too limited to make it work.
I can open .nuv files with mpeg4 encoded video and mp3 or uncompressed
audio.
Rtjpeg is not implemented yet and it can't seek yet.
I haven't been able to test hardware mjpeg since I don't have that kind of
card, maybe someone have a short sample file?

The filter doesn't decompress the video or audio, that’s done by for example
the normal windows divx codec and mp3 codec.
For some reason that I haven't figured out yet directshow doesn't like to
connect the video output to the divx codec automaticaly.

I have a few questions about mythtv .nuv file format.

Sometimes the audio frames have the keyframe set to '_' what does that mean?
Is that a continuation of the previous frame?

I looked at a .nuv file with a hex editor and noticed that the audio packets
(mp3 audio) have the string "LAME3.93" followed by some 0x55 or 0xAA at the
end of each packets. It sounds fine with that extra data at the end, but why
is it there?

In directshow I need to create timestamps on all samples (IMediaSample, both
audio and video) shoud I use the rtframeheader::timecode or count frames and
use the sync frames? Video frame number woud be something like
last_videosync_timecode+current_keyframe

I don't think I got the timestampin entierly right because after a few
minutes on one of my test files the audio and video gets realy out of sync.
The audio and video is synced fine until that point in the file.