[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]
>Solution 3 is what I am using now. In a followup I will tell you this
>also fails in some cases with recent MEncoders.

OK, then for this one. The Sony breaks files into separate parts when
filesizes increase beyond 2GB. FFProbe of the first and second file of a
one hour recording:

FFprobe SD00004.MPG
Input #0, mpeg, from 'SD00004.MPG':
  Duration: 00:30:18.68, start: 0.226767, bitrate: 9309 kb/s
    Stream #0:0[0x80]: Audio: ac3, 48000 Hz, stereo, s16, 256 kb/s
    Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x576
    [SAR 64:45 DAR 16:9], 9100 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc

FFprobe SD00005.MPG
Input #0, mpeg, from 'SD00005.MPG':
  Duration: 00:29:42.42, start: 1818.722767, bitrate: 9327 kb/s
    Stream #0:0[0x80]: Audio: ac3, 48000 Hz, stereo, s16, 256 kb/s
    Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x576
    [SAR 64:45 DAR 16:9], 9100 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc

The 'start: 1818.722767' is not handled correctly by recent MEncoders.

mencoder -endpos 00:00:20 -mc 1 -demuxer lavf
	-vf scale=448:256 -aspect 16:9 -sws 2 -lavdopts fast:threads=8
	-of lavf -lavfopts format=asf -ovc lavc
	-lavcopts vcodec=wmv2:vbitrate=336:keyint=90
	-oac lavc -lavcopts acodec=wmav2:abitrate=64
	-srate 22050 -af volnorm -o SD00005_part.wmv SD00005.MPG

The result as reported by FFprobe:
Input #0, asf, from 'SD00005_part.wmv':
  Metadata:
    encoder         : Lavf54.27.101
  Duration: 01:00:58.12, start: 0.000000, bitrate: 2 kb/s
    Stream #0:0: Video: wmv2 (WMV2 / 0x32564D57), yuv420p, 448x256,
        25 tbr, 1k tbn, 1k tbc
    Stream #0:1: Audio: wmav2 (a[1][0][0] / 0x0161), 22050 Hz,
        2 channels, s16, 64 kb/s

Duration: 01:00:58.12 !? Filesize: 1280 KB
http://x32.elijst.nl/SD00005_part.wmv

The Windows Media Player reports it as a 00:30:39 file. If you play it:
the 20 seconds sound is at the beginning, the 20 seconds video at the
very end of the file.

The same commandline using old MEncoders is doing fine:
http://x32.elijst.nl/SD00005_part-old-mencoder.wmv

It probably is more or less the same bug as in my previous message, I
guess.

Jan