[mythtv-users] Recordedmarkup corrupt - consequences ?

[cmisip]

I am currently using mencoder to convert the raw video to divx and
oggenc to encode the raw audio to .ogg. I use ogmmerge to multiplex
audio and video streams. Have you had a chance to compare the
performance of mencoder with avidemux, and other such programs?

The only problem I have is that there are more than occasional audio
video desynch issues during playback on the zaurus.



On Fri, 2004-02-20 at 12:49, Andrew Dodd wrote:
> Quoting cmisip <cmisip at insightbb.com>:
> 
> > Thanks for replying.  What is a GOP and why do I need it?
> Group of Pictures.  It's an MPEG-2 term.  MPEG-2 is pretty strictly structured,
> with a fixed GOP length within any given file (15 frames for NTSC and 12 for PAL
> IIRC, or is it the other way around?), and within a GOP, the order of I/P/B
> frames is fixed.  Most importantly, GOPs ALWAYS start with an I-frame, and since
> in compressed video that uses difference encoding you can only seek to a
> keyframe (i.e. an I-frame in MPEG-2), a table of the beginning of each GOP and
> its position in the file makes seeking much easier.  Without the GOP table,
> seeking is slow, and with VBR files Myth's estimate of remaining time will jump
> around.
> 
> 
> > How does one strip commercials with avidemux?
> Load the video, edit out the commercials, save raw audio/video streams,
> remultiplex them with mplex from mjpegtools.  AVIDemux now has support for
> outputtting DVD program streams, but it didn't work well last time I tried it. 
> mplex is much more consistent and reliable.
> 
> > I am also trying to convert the recordings into a format playable in a
> > zaurus 5600.  By rebuilding the recorded markup with mythcommflag, does
> > this automatically mark the beginning and end of commercials so
> > nuvexport can use this information? I expect running mythcommflag on a
> > system with about 420 gigs of storage (90 % full) will take a long time.
> > I wonder if it is worth it.  I need to compress videos so they will fit
> > on a compactflash.  So far I have been able to compress 1 gig to 100 mb
> > with good quality.  Removing commercials automatically will further
> > reduce the file size but I dont want to sit and manually mark the
> > commercials.  
> > 
> > What is the state of commercial detection in mythtv? 
> Depends on your signal source.
> 
> Pure blank frame detection works EXTREMELY well if blank frames can be detected
> reliably (i.e. channel is not noisy, brightness is set properly.).  Scene change
> detection is close to useless.  Too many false positives/negatives.
> 
> 420 gigs of storage - it's going to take you a long time to export that no
> matter what.  mythcommflag is going to be a drop in the bucket compared to the
> need to transcode everything.
> 
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