[MEncoder-users] Sound problem when transcoding and joining 2 mpg-files

[Jan Ehrhardt]

Jan Ehrhardt in gmane.comp.video.mencoder.user (Thu, 20 Sep 2012
17:36:27 +0200):
>3. Transcode the files separately and knit them together with
>   ASFbin.exe.
[snip]
>Moreover: ASFbin works for knitting WMV-files, FLVbind for knitting
>FLV-files and MP4box for knitting MP4-files. But MP4box is terribly slow
>when working on SD cards (it takes much longer than a transcode) and our
>project requires that the sensitive videos do not use HD-space (not even
>for temporary files). We want to switch to MP4 (x264/aac), which will
>break solution 3. I will file an issue concerning MP4Box at the GPac
>developers, but for the moment only sticking with the old MEncoder is
>left open after we switch to MP4-files.

Not quite. Sometimes you overlook solutions:

5. Transcode the files separately and knit them together with:
   - asfbin for wmv
   - flvbind for flv
   - mencoder (!) for mp4, followed by mp4creator -optimize

I am now timing the 'knitting' on a SD card for a 1:21h video file,
consisting of 5 parts:

The mencoder part is:
mencoder -of lavf -ovc copy -oac lavc
	-lavcopts acodec=aac:abitrate=96:aglobal=1:threads=8
	-af volnorm -o mp4concat-by-mencoder.mp4
	0.mp4 1.mp4 2.mp4 3.mp4 4.mp4 5.mp4
mp4creator.exe -optimize mp4concat-by-mencoder.mp4

Timing up until now:
21/09/12 17:42:05,41 start mencoder 
21/09/12 17:44:19,78 start mp4creator 
21/09/12 17:44:52,62 optimized mp4concat-by-mencoder.mp4 ready 
21/09/12 17:44:52,64 start mp4box 

And mp4box is after 3/4 of an hour still busy with appending 4.mp4. This
will take 2 hours or something like that. mencoder+mp4creator did that
in less than 3 minutes...

Jan