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| rambot |
| Posted: Aug 26 2002, 06:57 PM |
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I just got the Real Magic XCard (highly recommended) but I have to upgrade all my old divX collection from DivX3.11 to at least DivX 4. I am actually using the codec from SigmaDesigns. Anyway, to my question. When I open a lot of my video files, I get the meassage about audio being encoded with bad VBR headers and that I will get Audio Skew.
I tried what the message said to do, I saved the audio to a WAV file (but today I realized it was the compressed WAV as it was a small file). Anyway, I then take the original file and mix it with the wav file, but I still get the skew. I adjusted the skew parameter under the interleave section and that did not help. The audio on this file in particular changes over the length of the clip.
My question is how do re-encode this file without messing up the audio? My next guess is to do two passes where I first do a direct stream copy of the video and for the audio select PCM (or wav). and then with that file encode the video in DivX 4 and Audio in MP3. IS this the right track? Any ideas? I have seen other posts related to this, but nothing that seems to answer it directly. |
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| valja |
| Posted: Aug 26 2002, 07:21 PM |
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Advanced Member
Group: Members
Posts: 179
Member No.: 66
Joined: 1-August 02
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Simplest way - worked here 100% so far in just the same cases - leave VD audio interlieve default settings untouched (preload 500ms of audio..., interleave audio every 1 frames, audio skew correction 0ms). As result you will have an avi file with some 0.12 - 0.14 s preload skew.
That's all. No problems with video-audio sync.
Regards,
Valja
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| rambot |
| Posted: Aug 26 2002, 07:36 PM |
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Well, I originally left the auto interleave options untouched, but in the new avi file I got the audio skew. THats when I started trying to experiment and play with those settings (which did not help).
The skew I am talking about here is like 8 seconds originally but it does change over the movie. At some points the audio is first, at others the video is first. |
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| ProfDrMorph |
| Posted: Aug 26 2002, 08:37 PM |
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Set Audio to Direct Stream Copy and save the Audio to a .wav file.
Reencode your video stream.
Open the new .avi file in Nandub ( you can find it at www.doom9.org ), set both Video and Audio to Direct Stream Copy, select Wav Source for Audio -> the file you saved previously.
Choose File | Save As in Nandub.
Should work. |
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| valja |
| Posted: Aug 27 2002, 10:14 AM |
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Advanced Member
Group: Members
Posts: 179
Member No.: 66
Joined: 1-August 02
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I suspect, this way will not work.
Looks like sound has been encoded with variable bitrate (some frames "borrow" space from another frames). So if you save wav in "direct mode", you will still have the same encoded stream with variable bitrate and later reencoding will not help - you will have just the same problems you had.
IMHO only way is to save wav in "Full porocessing mode" WITHOUT compression - in this case you will have sequence of normal frames. Borrowing of the space is AFAIK a feature of MPEG3 (reason of current troubles) and without compression you will get rid of it.
I know, that tihs uncompressed wav will be big - some 15 times bigger than compressed audio traclk. But if I uderstand this issue correctly, it's only way to solve the problem. And as a side effect - no need for nandub. You can use VD: after saving the wav you can recode video and set audio to "Wav audio..." choosing this big wav as a source.
Regards,
Valja
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