ffmpeg's indeo4 decoder decodes with artefacts files encoded in low quality when keyframes are repeated every 2 frames or more (bigger value - more visible artefacts
C:\>ffmpeg -i 5p_every_20.avi -vcodec msmpeg4v2 out.avi
ffmpeg version N-52725-ge756635 Copyright (c) 2000-2013 the FFmpeg developers
built on May 4 2013 02:45:38 with gcc 4.5.0 (GCC) 20100414 (Fedora MinGW 4.5.
0-1.fc14)
configuration: --prefix=/var/www/users/research/ffmpeg/snapshots/build --arch=
x86 --target-os=mingw32 --cross-prefix=i686-pc-mingw32- --cc='ccache i686-pc-min
gw32-gcc' --enable-w32threads --enable-memalign-hack --enable-runtime-cpudetect
--enable-cross-compile --enable-static --disable-shared --extra-libs='-lws2_32 -
lwinmm -lpthread' --extra-cflags='--static -I/var/www/users/research/ffmpeg/snap
shots/build/include' --extra-ldflags='-static -L/var/www/users/research/ffmpeg/s
napshots/build/lib' --enable-bzlib --enable-zlib --enable-gpl --enable-version3
--enable-nonfree --enable-libx264 --enable-libspeex --enable-libtheora --enable-
libvorbis --enable-libfaac --enable-libxvid --enable-libopencore-amrnb --enable-
libopencore-amrwb --enable-libmp3lame --enable-libvpx --disable-decoder=libvpx
libavutil 52. 28.100 / 52. 28.100
libavcodec 55. 7.100 / 55. 7.100
libavformat 55. 4.101 / 55. 4.101
libavdevice 55. 0.100 / 55. 0.100
libavfilter 3. 63.101 / 3. 63.101
libswscale 2. 2.100 / 2. 2.100
libswresample 0. 17.102 / 0. 17.102
libpostproc 52. 3.100 / 52. 3.100
Input #0, avi, from '5p_every_20.avi':
Duration: 00:00:04.67, start: 0.000000, bitrate: 177 kb/s
Stream #0:0: Video: indeo4 (IV41 / 0x31345649), yuv410p, 240x180, 15 tbr, 15
tbn, 15 tbc
Output #0, avi, to 'out.avi':
Metadata:
ISFT : Lavf55.4.101
Stream #0:0: Video: msmpeg4v2 (MP42 / 0x3234504D), yuv420p, 240x180, q=2-31,
200 kb/s, 15 tbn, 15 tbc
Stream mapping:
Stream #0:0 -> #0:0 (indeo4 -> msmpeg4v2)
Press [q] to stop, [?] for help
frame= 49 fps=0.0 q=3.7 size= 121kB time=00:00:03.26 bitrate= 303.0kbits/s
frame= 70 fps=0.0 q=4.0 Lsize= 166kB time=00:00:04.66 bitrate= 290.9kbits/
s
video:158kB audio:0kB subtitle:0 global headers:0kB muxing overhead 4.553662%
Fixed by Kostya / Duplicate of ticket #866.