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View Full Version : Adjusting audios delay in demuxed streams


JMThomas
19th March 2013, 23:01
I have a VCR/DVR combo machine which I used to transcribe an old video tape to DVD. The ripped DVD is playable in Media Player, and the audio is synced.

The tape also has closed captions, which I've retrieved from the VOB files. Now I'm trying to mux everything back to together, and can't get the audio delay adjusted to -400 ms. At least I think that's the delay I need...

1. Copied DVD to hard disk. Note the DVD authoring is very sparse as the DVR has it's own way of doing thing.

2. Ran PgcDemux to extract audio AudioFile_80.ac3 and video VideoFile.m2v. The "Check A/V Delay" button gave a figure of -.396.

3. Used CCExtract and Subtitle Creator to generate a .sup file of subtitles.

4. Used MuxMan to put it all back together, and the audio is way off.

I tried values of -300, 0, +300 for MuxMan's audio stream "delay". My eye/ear coordination may not be too great, but none of these are close. Note that +/-300 ms is the maximum MuxMan accepts.

I didn't run a VobBlanker step to substitute the MuxMan VOBs back into the original -- everything was OK with the MuxMan output except for the audio synchronization.


Question: How can I either chop off 400 ms from the front of the audio file, or mux with a greater delay?

Bonus Question: The DVD had a single title PGC with chapters (VOB cells) nicely created every 2 minutes.

Is there a tutorial somewhere about conjuring up a PGC with a chapter for every VOB cell?

tebasuna51
20th March 2013, 03:22
Question: How can I either chop off 400 ms from the front of the audio file, or mux with a greater delay?

You can use eac3to to cut the first frames of your ac3 file.
Like ac3 frames (48 KHz) are 32ms long you can cut 384ms or 416 ms. For instance:

eac3to AudioFile_80.ac3 New_AudioFile_80.ac3 -384ms

JMThomas
22nd March 2013, 07:42
Got it done. Thank you very much!:thanks: