Keep original VOB video, convert audio to mpeg 2 or 3?

[kenmaston]

I have QuickTime Pro with the MPEG2 plug-in and would like to use it to convert a VOB into nice MPEG4 file. The problem of course is that that QT doens't understand the AC3 audio track. So, what I'm trying to do is use FFMPEG to pass the original MPEG2 video through, untouched, and convert the audio track to MPEG2. Does this make sense? And does it seem like it should work? And does anyone have any tips?

[major]

It should work by using the preset "mp2".

It should work by using the preset "mp2".

You'd think that would work, but it doesn't. The preset doesn't encode the video so I just end up with an MP2 audio file. If I change ffmpeg to "passthrough" the video and click encode, then it tries to do the video but both it and the audio are broken.

Another option is to encode the video as MPG2, which seems redundant? That uses the MPEG2ENC, which makes the following complaint:

++ WARN: [mpeg2enc] Generating dummy SVCD scan-data offsets to be filled in by "vcdimager"
++ WARN: [mpeg2enc] If you're not using vcdimager you may wish to turn this off using -d

So I go to options and change the Profile to DVD. That creates three files, a video, an audio, and a muxed mpeg2. The mpeg2 playes great, but when I try to export it to something else (like mpeg4) it doesn't see the audio track.

Suggestions?

[major]

The preset doesn't encode the video so I just end up with an MP2 audio file.?

That's correct. Your problem was, not being able to export the AC3 audio with Quicktime. So what you really need, is this MP2 audio file. Now you can export the video only with Quicktime, and then paste the mp2 audio on the result (or whatever other audio format you can now convert to).

[rack]

I have an demuxed VOB file. The audio is ac3. I'd like to convert this to mp2 then mux so Quicktime can deal with it.

When I try to use the "mp2" preset in ffmpegX to convert the ac3 file, I get the following error:

Encoding started on Wed Jun 11 10:00:20 PDT 2003
Input #0, ac3, from '/Users/admin/Desktop/movie/audio.ac3':
Stream #0.0: Audio: ac3, 48000 Hz, 5:1, 448 kb/s
sh: line 1: 3630 Bus error /Applications/ffmpegX.app//Contents/Resources/ffmpeg -i /Users/admin/Desktop/movie/audio.ac3 -y -vn -f mp2 -acodec mp2 -ab 224 -ar 48000 -ac 2 -map 0.1:0.0 -benchmark /Users/admin/Desktop/movie/audio.m2a

Do you have any idea what's up?

[major]

When encoding from an audio-only file, you should check the "Invert mapping" option.

[rack]

And a person would know that, how?

Perhaps I'm better suited to Forty-Two.

Frustrated...

[major]

And a person would know that, how?

By reading the manual page.

[rack]

I've read the following:

Invert mapping
"Enable this checkbox to handle input files having inverted streams ie audio first and video second. Supported by ffmpeg engine only."

It would be helpful if you could add the following:

"When encoding from an audio-only file, you must check this box."

[major]

I've read the following:
Invert mapping
"Enable this checkbox to handle input files having inverted streams ie audio first and video second. Supported by ffmpeg engine only."

I also say:
"MP3- This popular format is normally used... By also selecting "invert mapping" you can convert a WAV, AC3 or MP2 file to an MP3 file."

It would be helpful if you could add the following:
"When encoding from an audio-only file, you must check this box."

I agree, I'll add that.