very strange divx file with mystery fourcc

[cooldude859]

Video Track #1:
FOURCC: "DX50" (DivX® Video)
512x1482049860


Hi all

I downloaded a divx movie that seemed to play fine the day i got it. Well, today I went to play it and none of the players would open it. But virtual dub appeared to open it. I checked it with fourcc changer and it showed description codec as DIVX, but the used codec was just a couple of weird symbols. Well, I changed the weird symbols to DIVX and now I can open the file in DIVX player, but the video vertical size is so enormous that it runs out of memory and crashes the player!

Virtual Dub now reports "Out of memory" when opening the file. I tried Gspot and it shows DX50. So does DIVX player. I can see the video in that player as well, just not properly.

Any solution to this problem? Is there some way to straighten this video out? I know its a good file because I played it early on.

[Ai Haibara]

Post a screenshot of the GSpot window with the video loaded. I suspect the video's corrupt. GSpot should probably be able to tell, as well (it may mention it in one of the top left panes).

[cooldude859]

Here's a screenshot. I didn't use the render function at the bottom because it crashes Gspot. 512x808802378 is the reported size in Media Player Classic and will open the file. But it will not play because of the ridiculous vertical size. But if I look at the properties of the file using Explorer, I see 512x384 which is correct.

I had wondered if the fourccc was wrong so I tried different ones, but DX50 seems to be the correct one and Gspot will report this no matter what I change the fourcc to.

If something has gotten corrupted, any ideas on how to fix it? Already tried DivFix and such.

Thanks.

[jagabo]

DX50 is the usual fourcc for Divx 5.x, 6.x, and 7.x (the decoding of Divx has not changed since 5.0 so the fourcc remains the same).

It does sound like your file is corrupt. Can you open it with VirtualDub?

[cooldude859]

It seems like VirtualDub tries to open the file. But, it shows an "Out of memory" error and I am guessing it is because Vdub cannot display a video with a reported vertical size of a million.

Heres another screenshot after opening the video using DivxPlayer. Its the only player that will run the file with no problems, except the stupid vertical size runs a mile long. Is there a way to change header info in a avi file?

[jman98]

I know its a good file because I played it early on.

Actually, all you know is that it was a good file in the past. While I have no way to know if this is your problem or not, I can't rule it out either. Windows file systems can get corrupted and they can damage what's inside them. If your hard disk is going bad and/or corrupted, it could have damaged the file. You admit to downloading it (probably shouldn't admit to such here, but we'll just assume it's content you are legally allowed to get for free) so it's not like you're out any money on it in the worst case.

[jagabo]

You can patch the header with a hex editor. If only the vertical size is wrong that is easily fixed -- if you know what the right vertical size is.

[cooldude859]

I have tinkered with hex editors but dont know much practically. I just used aviedit to look at the headers and it says the correct video size. But it also shows the wrong size as well. Strange.

[cooldude859]

Here's a shot using Aviedit to show what I mean.

screen.bmp

[jagabo]

Here's an AVI file opened with a hex editor. The 4 byte value in the red box is the frame height:



The four bytes are in reverse order. You see 20 01 00 00 but that reprents the hex value 00000120 -- 288 decimal. Guessing that your file may be 512x384 try changing the four bytes you see there to 80 01 00 00 (384 decimal).

Windows' calculator can translate decimal to hex. So if you have a similar file from the same source you might be able to get the correct frame height from that.

Even with the wrong value you may be able to open the file and get a hint about what the right size is. For example, I changed my 288 line file to 384 and opened it with VirtualDub. This is what I saw:



The black bar at the top is 96 lines. 384 - 96 = 288, which we know is the correct size.

Oh wait. 7 lines above the marked frame height is another frame height. The first one (the one closer to the top) is the height indicated in the AVI header, the second is the height indicated within the codec. You may have to change both, or only one. After a little testing, all the programs I tried playing and editing the file with, ignored the frame height indicated in the AVI header.

In case the strf chunk is in a slightly different place, just look for the four bytes below the strf chunk label.

VirtualDub has a hex editor under the Tools menu.

[cooldude859]

That was an excellent reply!

I will get on this now and see what happens.

[cooldude859]

Okay, I used Vdub's Hex Editor on a copy of the file. You were right on the money about using 80 01 00 00 because 7 lines up already had those numbers. But 7 lines down had a different number. I noticed that vdub referred to the second line as a bitmap and the top line as the height frame size. So again you were right.

Nowfor the bad news...

It still opens with an enormous height in deed. The difference is that vlc and vdub both attempt to repair the file. After doing so, I still get "Out of memory" error. Whatever is causing the problem is stilol there.

[cooldude859]

GOT IT FIXED!!

Using vdub's editor, i notice when you click around in different fields, it will tell you what part of that file is getting changed. As it turns out the first field you spoke about was "size of bitmap structure". But the 4 fields to the right are width, and the last four are for height. When I changed the last four to the 80 01 00 00 it fixed the file. So you helped me tremendously. You were slightly off, but if it had not been for your help, I probably would have never gotten it fixed.

THANKS A MILLION.

[poisondeathray]

try opening with avidemux; the junk data in the header indicates that avidemux was used on that file at one point in time

try re-wrapping it with avi-mux gui (i.e swap the avi container) , or putting it into .mkv container or use mkvmergegui

EDIT: ^too late I see you got it fixed I wonder why the value was changed in the first place?