Frame Editing In An AVI

[moviebuff2]

Hi everyone:

I have an AVI file that is corrupted - color dropped out. Using VirtualDubMod, I identified those few frames. I know I can use VirtualDubMod to cut off these few frames. But I want to keep and correct them. How can I do that?

Thanks

[guns1inger]

How are you going to correct them ?

What tools will you use ?

This is important because it will set the best method for extracting the frames.

[moviebuff2]

Hi guns1inger:

I have no clues!

For the sake of simplicity, I am re-downloading the file. However, I still keep the corrupted one to play with it in my spare time.

Thanks

[guns1inger]

What you need to do is split the file into three pieces. Piece one are the frames up to the problem, piece three are the frame after the problem, and piece two are the affected frames.

The problem you have is that you have downloaded the avi, so it is most likely in some form of mpeg4 encoding - divx/xvid - so it is not ideal for this type of work. You cannot do frame accurate cutting without some re-encoding. In fact, I don't know of any editor that can do smart cutting on this type of file - that is, re-emcode only the GOPs with edits in them.

So you would have to either re-encode to a lossless format (large file sizes), or re-encode the entire file and extra time using lossy compression, and therefore reduce the quality, possibly substantially.

[moviebuff2]

Hi guns1inger

You read my mind!

There are 13 corrupted frames in the AVI file. I used VirtualDubMod (VDM) to cut the original AVI into 3 parts. Part 1 is supposed to begin at the beginning and to end at the frame just before the corrupted frame. Part 2 supposedly has only the 13 corrupted frames. Part 3 supposedly contains the rest of the AVI file.

Unfortunately, VDM cannot cut precisely. Part 1 & 3 are OK, but not part 2. Part 2 has more than just 13 corrupted frames. It overlaps part 3.

I have been messing around with "save image sequence" in VDM without much success.

But as I said, I am just playing with it in my spare time. It's kind of fun! :P

[guns1inger]

What I would do is create three avisynth files to represent the three parts. Use the Trim command to get the frames right (vdub can help you find the numbers). So the three files would look something like this

#Part One
AVISource("pathtofile\filename.avi")
Trim(0,nnn) #Where nnn is the last frame of the good section

#Part Two
AVISource("pathtofile\filename.avi")
Trim(nnn+1, nnn+13) #The corrupted section

#Part Three
AVISource("pathtofile\filename.avi")
Trim(nnn+14,0)

Now these are very basic avs files. You may need to alter them to get the actual results you need, but this will give you the idea. nnn will have to be replaced by actual numbers.

You load Part Two in to virtualdub and all you should see are the corrupted frames. Save this as an image sequence, and you can work on each frame seperately.

Once you are happy, you can put everything back together again with avisynth using something like this

#reassemble
PartOne=AVISource("pathtofile\filename.avi",false) .Trim(0,nnn)
PartTwo=ImageSource("pathtoimages\image1.bmp, start=1, end=13, fps=xx) #xx=fps from original clip
PartThree=AVISource("pathtofile\filename.avi",fals e).Trim(nnn+14,0)

PartOne+PartTwo+PartThree

This will output your reassembled video using parts of the original, plus your altered stills. Note : it will not have audio at this time. Demux the audio from your original and add it back in via virtualdub when you process this script. You will have to set the compression for this as the output from avisynth is uncompressed.

[moviebuff2]

Thanks guns1linger!

I will play with this file in my spare time to gain more experience.

I once edited out 2/3 of an AVI file and appended the remainder to another AVI file. It was fun.

Cheers