#213 Apparently good file crashing Dr DivX

open
nobody
drffmpeg (3)
5
2007-07-08
2007-07-08
Gingko
No

This is a very reproductible (at least on my computer) bug that I got when encoding a specific MPEG2 movie to DivX using Dr DivX, that, after some researchs, I think it could occurs into the Dr DivX MPEG2 decoder.

The movie to encode (actually a French TV capture of the movie "Abyss [long version]" edited using VideoRedo) is about 3.3Gb long. When encoding, it always crashes near 63% of the file, obviously always at the same point.
The crash actually consists in a big freeze in the encoding, during which my computer's memory becomes nearly full and the program takes almost all my computer's resources, making it sometimes difficult to abort because even the task manager can become tremendeously slow.
The only resource that I have - If ever I can, otherwise I should reboot the computer - is to abort the encoding, because it looks like obvious that it will never end by itself.

If I look at the logs recorded by Dr DivX, I can see, starting at the time the codec crashes, a huge list of errors like these ones :
-------------------------------------------------------
07-07-2007 19:12:47 Error [mpeg2video] ac-tex damaged at 28 21
07-07-2007 19:12:47 Error [mpeg2video] Warning MVs not available
07-07-2007 19:12:47 Info [mpeg2video] concealing 44 DC, 44 AC, 44 MV errors
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 0
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 1
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 2
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 3
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 4
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 5
07-07-2007 19:12:50 Error [mpeg2video] ac-tex damaged at 1 6
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 3 7
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 8
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 3 9
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 10
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 11
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 12
07-07-2007 19:12:50 Error [mpeg2video] invalid mb type in I Frame at 2 13
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 14
07-07-2007 19:12:50 Error [mpeg2video] invalid mb type in I Frame at 3 15
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 16
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 3 17
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 18
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 19
07-07-2007 19:12:50 Error [mpeg2video] invalid mb type in I Frame at 3 20
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 21
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 22
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 23
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 24
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 25
07-07-2007 19:12:50 Error [mpeg2video] invalid mb type in I Frame at 2 26
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 27
07-07-2007 19:12:50 Error [mpeg2video] invalid mb type in I Frame at 2 28
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 2 29
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 30
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 31
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 32
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 33
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 34
07-07-2007 19:12:50 Error [mpeg2video] skipped MB in I frame at 1 35
07-07-2007 19:12:50 Error [mpeg2video] Warning MVs not available
07-07-2007 19:12:50 Info [mpeg2video] concealing 1584 DC, 1584 AC, 1584 MV errors
...
...
-------------------------------------------------------
... and this repeats continuously without never recovering (or this would need one day or two, I never tried).

Of course I supposed there is a problem with my movie but ... I have been unable to find any fault inside it when watching around the crash point, the video seen using Media Player Classic or VLC looks perfectly good (but DivX player & Windows Meda Player had problems ; see below) ! - So it was very difficult to find the exact point where the encoding uses to crash.

Proceeding by tries and errors, I then made successive trimmed copies of the movie around the crash point, trying to get an excerpt as short as possible which still produces the crash. I ended with a 13 seconds sequence which still freezes at 75% of its length when encoding to DivX. Trying various encoding options, including single or multiple passes doesn't change anything.

This 13 seconds sequence still contains 3 shots, and the crash problem occurs probably at the transition between the 2nd and the last one. The 2nd sequence shows the screen of an analogic TV monitor, which is rather flickering.

I uploaded the excerpt on my web server, so you can get it here :
http://gingko.homeip.net/misc/excerpt_crashing_divx_encoding.mpg
if ever you need it for testing. The file is a little more than 4Mb in size. I cannot upload this here.

If ever it matters, I have an AMD Athlon XP 2400 computer (2 GHz), 1Gb ram with Windows XP Pro SP2. I encode using Dr DivX 2.0 OSS (stable version, not beta !), and the DivX encoder codecs 6.6.1 pro.

Other issues :
When I first try to watch the video using Windows Media Player or DivX player, these programs crashed at the very same point where the video freezes Dr DivX. The error dialog in both programs identifies the crash as originating from "mcmpgdec.dll" which is an MPEG Stream decoder made by MainConcept GmbH, version 1.1.1.11. I tried to rename this file so it cannot accessed. This didn't make WMP and DivX player unable to read the video : they use instead "MpegVideo.dll" from DScaler Team version 0.0.6.0 that I also have on my computer, and with this decoder WMP and DivX player both read my video without any visible problem.
Apparently, Media Player Classic and VLC have their own decoder. This seems to be true also with Dr DivX (in "drffmpeg.dll").

I got this problem inside Dr DivX 2.0 stable release. I cannot test it with 2.0.1 b4 because of another problem that I already reported there :
http://sourceforge.net/tracker/index.php?func=detail&aid=1740617&group_id=145411&atid=761876

Gingko

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