ffmpeg crapping out

[jgombos]

When I run ffmpeg using this command:

"ffmpeg.exe" -i "large.vob" -hq -vcodec mpeg4 -g 300 -b 1450 -aspect 4:3 -s 720x480 -acodec mp3 -ab 448 -ac 2 -mbd 2 -vtag xvid -qmin 2 -async 1 -y "large_1450.avi" -map 0.0:0.0 -map 0.1:0.1

I get the following failure:

ffmpeg version 0.4.9-pre1, build 4747, Copyright (c) 2000-2004 Fabrice Bellard
  configuration:  --enable-memalign-hack --enable-mingw32 --enable-mp3lame --ena
ble-gpl --enable-a52
  built on Mar 21 2005 16:41:12, gcc: 3.4.2 (mingw-special)
Input #0, mpeg, from 'larg.vob':
  Duration: 01:02:59.8, start: 0.233567, bitrate: 7586 kb/s
  Stream #0.0  Id: 1e0: Video: mpeg2video, 720x480, 29.97 fps, 7000 kb/s
  Stream #0.1  Id:  80: Audio: ac3, 48000 Hz, 5:1, 448 kb/s
Output #0, avi, to 'large_1450.avi':
  Stream #0.0  Id:   0: Video: mpeg4 (hq), 720x480, 29.97 fps, q=2-31, 1450 kb/s

  Stream #0.1  Id:   1: Audio: mp3, 48000 Hz, stereo, 448 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Error while opening codec for output stream #0.1 - maybe incorrect parameters su
ch as bit_rate, rate, width or height

This is an audio related problem, because as soon as I drop the bitrate from 448 to 128, the error goes away.

[Soopafresh]

You could use BBDEMUX or DGMpgdec to demux audio and video via the command line, convert the video portion to AVI, then mux the "untouched" .AC3 file into your new .AVI.

[jgombos]

I'm tempted to try that. But doesn't that seperation threaten the synchronization somehow?

I recall someone posting that when capturing video, it's important that the capture device handle both audio and video simultaneously, so it can match video frames to audio frames; and people who use a video-only card and a seperate sound card run into sync issues. One would think that splitting the two streams as you suggest could cause that synchronization information to get lost, resulting in a similar problem. I'm still new to all this type of technology, so please correct me if I'm off.

Isn't there some kind of pairing that could get disturbed if I perform operations on one of the streams in isolation?

BTW- I think the problem that I started this thread about might be that guiffmpeg is forcing me to use mp3, which may not be capable of 448 kbps. Stepping down to 320 kbps enables the encoder to run. So I'm speculating that it's a bug in the gui.

[Soopafresh]

Actually, I stopped using the audio portion of FFMPEG for encodes because the A/V seemed to end up out of sync ! It is kind of nice not to have to lose any audio quality on your final AVI file by muxing the original .AC3 file back in. DgMpgdec has very good audio and video demux features. The GREAT part of DgMpgDec (which you can run from the command line) is that the demuxed .AC3 file will tell you how many ms out of sync it is, so you can fix it with Ac3DelayCorrector then add it back into your final AVI.

So, it works like this:

Demux the .VOB file to .m2v and .ac3

Run FFMPEG on the .m2v file to turn it into an AVI

Check the demuxed .ac3 file for sync. It will be called something like "my_demuxed_ac3_file-500ms.ac3". That means the A/V sync is off by 500ms. Load it into Ac3DelayCorrector and the app will automatically fix the sync problem. (it's cool how it works). If the demuxed file says "0ms.ac3" at the end of it, no delay correction is necessary, so no need to load it into Ac3DelayCorrector.

Finally, mux the AVI video and the AC3 audio together and Voila !

[celtic_druid]

Could also try mencoder. Still uses the same encoders.

[jgombos]

Finally, mux the AVI video and the AC3 audio together and Voila !

What tool do you use for that? It doesn't seem dgmpegdec can take an avi as input.

[celtic_druid]

AVIMuxGUI is good.