incomplete DivX Recovering method

[hypercube]

I have a divX without 10Mb from the bigning (from emule).
I wrote a recovering tool to extract Key frame from the AVI
without using VFW API. I work directly with AVI file format
(chunk 'movi' 'idx1' ...).

Now I have to found the right frame size.
then I will be able to reconstruct missing header at the begining
of the file.

Here the idea:
send the key frame to divX codec with all frame width and height
possible=> some times bitmap is black, sometimes codec crash.

Here my question:
is it possible to found the right frame size from the
raw key frame data ?
is there any public specification of divX key frame format ?

[DSPguru]

i can't answer your questions, but would suggest you to have a look at divfix source-code (delphi).

[hypercube]

divfix not seems to work on my file. meanly
because there is no AVI header !

do you know where I can found a very simple example
to use ICM ? for instance, I use drawdib and it was
slow....

[symonjfox]

Hi, I have the same problem.
I found a thread http://forum.doom9.org/showthread.php?s=&threadid=59895&highlight=missing+avi+header that indicates another program (avipreview) that is expected to work. Unfortunately it doesn't work so well with xvid files. I tried with any command line but no hope.

You are a developer, you could contact him and work together to get a real working program. I know it would be possible.
For example let's throw away avi format, it would be nice if I can put out from my file a RAW MPEG4 Video stream and the MP3 file. It would be enough for me.

[esby]

mmm
as far i am remembering

In the avi index (at the end of the file)...

we have frame flags + frame addr and frame size
(2+2+2+2 bytes if i m not wrong).

So locate the index... and get the frame size for each of the frames...

For you problem, if you are missing only the beginning of the file,
i'll try to create a dummy avi with the same number of frame & framerate,
copy the header to your avi file(or to a backup)
and adjusts the specifical information of the header to fit
the file.
If i'm not wrong, that would mean adjusting filesize (in header) and index position...

[symonjfox]

Update: i accidentally found that a program called AVICHECK can generate index file. It creates a new small file .idx

I don't know much about technical stuff. Maybe it would be useful to create a new index table from a real avi and then modify triing to check the damaged avi proprieties (resolution, codec, and so on).

[jonny]

He is missing the "header" (so general stream informations), not the "index" :)

[symonjfox]

Yeah, I was not clear.

I meant the "BEGINNING" of the file.
If the end of file is not present, is not a problem, I just open in Virtual Dub or use DivFix and it goes on!

[esby]

Afik, kazaa uses random blocks,
so how can you sure you are missing the beginning and not a weird list of random part (meaning index AND header non correct and lot of frames corrupted too...)

esby

[symonjfox]

I don't use kazaa. I use Emule, and emule let you see the the location of the part you're downloading.

It've many files without the beginning, but, if they're MP3s, just work without the beginning; if they're MPG, they work, if they're AVI ... no hope as I see