1st@all: I know it's a still known problem due to limitations of ffmpeg ...

but I think, it would be helpful to post my problem too ...

My System: Athlon X2 5200 / 2GB RAM / 500 GB Samsung HD / Win7prof. x32
My Mezzmo: 2.1.11.0 (downloaded 2010-10-20)

There's a folder containing about 50 small avi-files, ripped from DVD in the same format with the same software
only three of these files don't have a thumbnail ...
but all of these files have the same ffmpeg information than the other ones ...
so I can't find a difference betwenn the "good" and "bad" files ...

here an ffmpeg-info from a "bad" file:
Code:
FFmpeg version SVN-r25446, Copyright (c) 2000-2010 the FFmpeg developers
  built on Oct 12 2010 10:38:21 with gcc 4.4.2
  configuration: --enable-memalign-hack --arch=x86 --target-os=mingw32 --cross-prefix=i686-mingw32- --enable-static --disable-shared --enable-zlib --disable-ffprobe --disable-ffplay --prefix=/media/windows-share/ffmpeg --extra-cflags=-U__STRICT_ANSI__ --enable-libmp3lame --enable-libx264 --enable-gpl --extra-libs='-lx264 -lpthread' --enable-runtime-cpudetect
  libavutil     50.32. 3 / 50.32. 3
  libavcore      0. 9. 1 /  0. 9. 1
  libavcodec    52.92. 0 / 52.92. 0
  libavformat   52.81. 0 / 52.81. 0
  libavdevice   52. 2. 2 / 52. 2. 2
  libavfilter    1.50. 1 /  1.50. 1
  libswscale     0.12. 0 /  0.12. 0
[mpeg4 @ 03241fc0] Invalid and inefficient vfw-avi packed B frames detected

Seems stream 0 codec frame rate differs from container frame rate: 30000.00 (30000/1) -> 25.00 (25/1)
Input #0, avi, from 'D:\video\avi\1989.avi':
  Duration: 00:14:09.00, start: 0.000000, bitrate: 1438 kb/s
    Stream #0.0: Video: mpeg4, yuv420p, 676x384 [PAR 1:1 DAR 169:96], 25 fps, 25 tbr, 25 tbn, 30k tbc
    Metadata:
      strn            : Video 
    Stream #0.1: Audio: mp3, 48000 Hz, 2 channels, s16, 128 kb/s
    Metadata:
      strn            : Audio 
At least one output file must be specified


---> DB Level Info: -99
by excluding these three files the thumbnail creation works well ...
by including these files, I get an error message from ffmpeg.exe ...

tried out last pre-compiled win32 ffmpeg.exe from 2010-10-21 ... no changes ...

Tested once more on another machine with same mezzmo-version:
2nd TestSystem: Intel Core2Duo 8600 / 8GB RAM / 120GB SSD / 1TB HD / Win7prof. x64
same result ...

any ideas !?