iff: fix aspect ratio

[ami_stuff]

ignoring aspect ration in iff demuxer seems to fix ffplay's displayed aspect ratio

C:\>ffmpeg -i CELTIC2.LBM
ffmpeg version N-43803-g2c0b164 Copyright (c) 2000-2012 the FFmpeg developers
  built on Aug 22 2012 02:22:47 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      51. 70.100 / 51. 70.100
  libavcodec     54. 54.100 / 54. 54.100
  libavformat    54. 25.104 / 54. 25.104
  libavdevice    54.  2.100 / 54.  2.100
  libavfilter     3. 13.100 /  3. 13.100
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
[iff @ 0x1eace00] Estimating duration from bitrate, this may be inaccurate
Input #0, iff, from 'CELTIC2.LBM':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: iff_byterun1 (PBM  / 0x204D4250), pal8, 320x200, SAR 5:6
 DAR 4:3, 90k tbr, 90k tbn, 90k tbc
At least one output file must be specified

[cehoyos]

Don't you agree that the aspect is correct for A4000T_HAM6.IFF without your patch (and wrong with the change)?

(Unrelated: Isn't there a bug visible decoding A4000T_HAM6.IFF? The table is not completely blue here.)

[ami_stuff]

Replying to cehoyos:

Don't you agree that the aspect is correct for A4000T_HAM6.IFF without your patch (and wrong with the change)?

This one may be correct, but I'm unsure if I like correct aspect ratio or maybe not resized image without black borders. Most (all?) image viewers seems to ignore ar for iff.

(Unrelated: Isn't there a bug visible decoding A4000T_HAM6.IFF? The table is not completely blue here.)

Yes, I have created ticket #1701 for this.

[pross]

FFmpeg is decoding the aspect ratio information according to the specification, and it works well for some files. Its just the files attached to this ticket contain "bad" aspect ratio information.

Not sure what can be done here!

[ami_stuff]

Here is some more info about aspect ratio:

 http://amigadev.elowar.com/read/ADCD_2.1/AmigaMail_Vol2_guide/node00CB.html

[ami_stuff]

If as is totally incorrect then maybe we could ignore it?

[richardpl]

what creates this files

It is bad idea to ignore aspect ratio for correct files.

[cehoyos]

What about a demuxer option that allows to ignore the written aspect ratio (assuming it is impossible to detect the faulty encoders)?

[richardpl]

Good idea, patch welcome!