On Sun, Jan 05, 2003 at 06:53:21PM -0800, Richard Ellis wrote: > > It's a weird issue with movtar. The sound is almost as if when recording > to movtar, every other sample is dropped, and the remaining set is > duplicated to fill in the gaps.
That could certainly be what I am hearing.
> Since both avi and qt work correctly,
> there is a workaround for the problem.
Right, but neither are readable before the file is complete and
closed.
> At least with the qt4linux distributed with mjpegtools 1.6.0, it was
> impossible to access the qt file for any mjpeg purpose until after lavrec
> had finished recording and closed out the file.
Same is true for mplayer/mencoder.
> Yes, Linux could read the
> file from disk, but any attempt to access the qt file as a video file
> would fail.
Correct. This is what I am seeing here.
> Additionally, any problem with recording ("ring
> buffer overflow", machine crash, etc.) during the session will almost
> always result in a inaccessable qt file sitting on disk taking up space.
:-( But then again, for television recording (what I am doing) if it
don't complete, I am probably not interested in it anyway.
> With avi's they still are not playable while being recorded to, but as a
> new one is created every 2G (by default) all the previous closed avi's are
> completely usable as video files.
Right. But there is still a problem... Being as mpeg2enc is far too
intensive for my needs, I am using mencoder to transcode from MJPEG
to mpeg4. Mencoder cannot transcode multiple avi files into one and
it does not check for new files when it reaches the end of a list of
files. Ideally, you could do the following with mencoder:
$ mencoder ... -o foo.avi foo%2d.avi
and it would look for the files foo01.avi, foo02.avi, foo03.avi, etc.
and encode them sequentially into foo.avi, but additionally, after
every file it encoded, it would go back to the disk and see if the
next segment has appeared and continue on with it. This would
continue until it found no more segments. This assumes that mencoder
is slower than real-time however. Some other "no more files"
mechanism would need to be developed for the alternate case.
Alternatively, if mecoder had a "-slave" switch like mplayer where you
could send commands to mencoder while it was running, like:
"append <file>"
to have it add a file to the end of the list of files it is
transcoding. Also:
"end input"
could close the output file.
> I'd suggest that Brian avoid qt's due to the risk of losing everything due
> to a tiny little glitch at the last moment, and instead just use avi's.
Dealing with multiple files because they have a 2G limit is just too
much of a pain. mencoder cannot deal with more than one avi file at a
time.
> If you give lavrec a filename with a %d (e.g., %02d for two digits zero
> filled) expansion in it, lavrec will make multiple 2G files for you as it
> goes along, all automatically.
I know, but then what do I do with them to get mencoder to "cat" them
all together and transcode them to (say) mpeg4?
Thanx for all of your insight Rich. Much appreciated.
b.
--
Brian J. Murrell
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