Repairing AVI in Vdub

[robomonkey]

Hi,

I'm trying to repair an AVI using Vdub, I've read the how to which consists of 3 lines, but am confused.

I apologise in advance for being thick

I've loaded the file and full processing on audio and video, then done scan for bad frames I get:-
21216 frames masked
380 frames bad
20836 frames good but undecodable

What does this mean?

Is this file worth fixing as if it's at 29.976fps I assume I have:-
12 minutes of masked frames whatever that means
13 seconds of bad frames
12 minutes of undecodable frames

from an hour long file half of it is knackered, does repairing the file actually repair it or does it delete the dodgy frames?

And then how do I fix it, when I click 'save avi as' I get a warning saying that I'm saving an uncompressed file that will be HUGE, I assume that I need to pick a video and audio compression but don't know what to choose?

Lastly once I've fixed the file do I need to reindex it?

Thanks for your help and for reading

[bugster]

Hi,


And then how do I fix it, when I click 'save avi as' I get a warning saying that I'm saving an uncompressed file that will be HUGE, I assume that I need to pick a video and audio compression but don't know what to choose?

Lastly once I've fixed the file do I need to reindex it?

Thanks for your help and for reading

Set video and audio to direct stream copy and the save as avi. vdub will remove the bad frames during the save, no need to select a compression method.

re-index should not be required.

If you intend to convert this to a mpeg, I would play through it 1st as a lot of bad frames can cause audio sync problems.

[robomonkey]

Thanks for help,

So VDub will delete the bad frames only???, so will the audio for those frames get deleted as well?, or will the film be 11 seconds behind at the end.

Also what will the movie look like?, will it jump at the missing frames?

Sorry for asking silly questions, escepially if they have already been asked

[musher70]

question:how many bad frames in avi is comsidered
a lot? over a few hundred?

[robomonkey]

Hey thats quick!!!

I get from VDub:
21216 frames masked
380 frames bad
20836 frames good but undecodable

I have no idea what masked or undecodable mean either

[robomonkey]

Also what causes these masked, bad and undecodable frames?

[musher70]

robo, what are you gonna do with avi?

[ZippyP.]

Also what causes these masked, bad and undecodable frames?

Masked frames = bad frames + undecodable frames
When you check for bad frames, Vdub "masks" them so that when you save the AVI all the masked frames are deleted, both audio and video.

Bad frames are created in videos due to various hardware and software problems, they are a quality issue. They also can be caused when files are distributed over the internet, resulting in some of the information getting garbled or missed. Bad frames can cause all kinds problems when the AVI is being converted to mpeg, everything from bad audio/video sync to causing freezing or crashes.
Clips with bad frames usually can still be viewed on a PC without too much problem. For conversion to VCD they need to be removed (if there's not too many). I never had much success, but some people recommend using Divfix to repair and recover bad frames.

[marcusmv3]

I just tried converting an XviD I have to MPEG-2 (with TMPGEnc). At one point in the movie it just goes blank, the whole video, after the mpeg-2 is encoded. Now when I watch the XviD, the video freezes on that frame but the audio keeps on going. Now if I skip over this frame before the player comes up to it, the video will go on to play the frames after it that are not corrupt.

So by opening the video in VDub and saving it, this error will be corrected?

[ZippyP.]

So by opening the video in VDub and saving it, this error will be corrected?

No. First you have to "scan video stream for errors" under the video tab in Vdub. Vdub masks (and reports) any bad and undecodable frames. Then, set both audio and video to Direct Stream Copy and then Save AVI (better give it a new name). This will create a file without the bad frames (which hopefully will not be too much).

[marcusmv3]

So by opening the video in VDub and saving it, this error will be corrected?

No. First you have to "scan video stream for errors" under the video tab in Vdub. Vdub masks (and reports) any bad and undecodable frames. Then, set both audio and video to Direct Stream Copy and then Save AVI (better give it a new name). This will create a file without the bad frames (which hopefully will not be too much).

I have already extracted the audio (which was AC3), repaired the AC3 stream and converted it to PCM (what MyDVD uses to burn to DVD). So would it be OK if I just selected "no audio"?

[ZippyP.]

I have already extracted the audio (which was AC3), repaired the AC3 stream and converted it to PCM (what MyDVD uses to burn to DVD). So would it be OK if I just selected "no audio"?

No. If you did that then the audio and video will be out of sync after the point where you lose some frames. You need to do the repairs with the audio included but I don't think that the standard Vdub will handle AC3. PCM is an uncompressed WAV so you can use it along with your original AVI. Here's how:
Open the original AVI in Vdub
Under audio>select wav audio and then your PCM wav
Under video>select scan video stream for errors
Under both audio and video>select direct stream copy
Save avi
Reload your repaired avi and select Save wav.
You should now have a repaired AVI and matching Wav file.

[marcusmv3]

I have already extracted the audio (which was AC3), repaired the AC3 stream and converted it to PCM (what MyDVD uses to burn to DVD). So would it be OK if I just selected "no audio"?

No. If you did that then the audio and video will be out of sync after the point where you lose some frames. You need to do the repairs with the audio included but I don't think that the standard Vdub will handle AC3. PCM is an uncompressed WAV so you can use it along with your original AVI. Here's how:
Open the original AVI in Vdub
Under audio>select wav audio and then your PCM wav
Under video>select scan video stream for errors
Under both audio and video>select direct stream copy
Save avi
Reload your repaired avi and select Save wav.
You should now have a repaired AVI and matching Wav file.

I did this and when I play the avi, after the point where the frames are removed the audio is fast by about 1 second. I have checked to see if the audio that was saved separately skips where the video does. It does not, instead, it appears to be a copy of the audio from the avi that doesn't have those frames removed. What should I do?

[ZippyP.]

Now we have an A/V sync problem, which is getting a little off topic but here goes...
I have had a similar problem, here's what I did. With VDub seperate the file in two parts, in sync and out. Strip the wav out of the second, use Goldwave (or similar) to adjust the audio, in your case trim 1 sec. or so from the start. Put the audio back in, then recombine the 2 files.
Bad frames are a Bitch.

[marcusmv3]

Now we have an A/V sync problem, which is getting a little off topic but here goes...
I have had a similar problem, here's what I did. With VDub seperate the file in two parts, in sync and out. Strip the wav out of the second, use Goldwave (or similar) to adjust the audio, in your case trim 1 sec. or so from the start. Put the audio back in, then recombine the 2 files.
Bad frames are a Bitch.

I'll try that tomorrow, but damn, there's a lot of ways everything could get botched up doing it that way.

[ZippyP.]

Believe me, you're right. I've wasted all kinds of time repairing AVI's. Now I'm less patient and I'll usually try to find a better source.

[robomonkey]

What does undecodable mean?, if I install a different Codec will that solve the problem?

And lastly before I give up, will frame serving the unrepaired AVI file make any difference?