support decoding of forward dvcpro codec

[ami_stuff]

ntsc mode decodes correctly with

ffmpeg -vcodec dvvideo -i ntsc.avi out.bmp

but there is a problem with pal mode (incorrect output)

C:\>ffmpeg -i pal.avi
ffmpeg version N-40622-g1caf614 Copyright (c) 2000-2012 the FFmpeg developers
  built on May 13 2012 02:22:21 with gcc 4.5.0 20100414 (Fedora MinGW 4.5.0-1.fc
14)
  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' --extra-cflags='--static -I/var/www/users/research/ffmpeg/snapshots/buil
d/include' --extra-ldflags='-static -L/var/www/users/research/ffmpeg/snapshots/b
uild/lib' --enable-bzlib --enable-zlib --enable-gpl --enable-version3 --enable-n
onfree --enable-libx264 --enable-libspeex --enable-libtheora --enable-libvorbis
--enable-libfaac --enable-libxvid --enable-libopencore-amrnb --enable-libopencor
e-amrwb --enable-libmp3lame --enable-libvpx --disable-decoder=libvpx
  libavutil      51. 50.100 / 51. 50.100
  libavcodec     54. 21.101 / 54. 21.101
  libavformat    54.  4.100 / 54.  4.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 72.105 /  2. 72.105
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 11.100 /  0. 11.100
  libpostproc    52.  0.100 / 52.  0.100
[avi @ 0x1ddc5c0] Could not find codec parameters (Video: none (SL25 / 0x35324C5
3), 720x576)
pal.avi: could not find codec parameters

[Carl Eugen Hoyos]

Output looks wrong.

$ ffmpeg -i pal.avi out.bmp
ffmpeg version N-40694-ge013abe Copyright (c) 2000-2012 the FFmpeg developers
  built on May 15 2012 07:49:10 with gcc 4.3.2
  configuration: --cc=/usr/local/gcc-4.3.2/bin/gcc --enable-gpl --enable-libopenjpeg --enable-libvorbis --enable-libspeex --enable-libmp3lame --enable-libtheora --extra-ldflags=-lm
  libavutil      51. 51.100 / 51. 51.100
  libavcodec     54. 21.101 / 54. 21.101
  libavformat    54.  5.100 / 54.  5.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 73.100 /  2. 73.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 11.100 /  0. 11.100
  libpostproc    52.  0.100 / 52.  0.100
Input #0, avi, from 'pal.avi':
  Duration: 00:00:00.10, start: 0.000000, bitrate: 12178 kb/s
    Stream #0:0: Video: dvvideo (SL25 / 0x35324C53), yuv420p, 720x576 [SAR 16:15 DAR 4:3], 10 tbr, 10 tbn, 25 tbc
[buffer @ 0x8f113e0] w:720 h:576 pixfmt:yuv420p tb:1/1000000 sar:16/15 sws_param:flags=2
[buffersink @ 0x8f11760] No opaque field provided
[format @ 0x8f06fc0] auto-inserting filter 'auto-inserted scale 0' between the filter 'src' and the filter 'format'
[scale @ 0x8f06dc0] w:720 h:576 fmt:yuv420p sar:16/15 -> w:720 h:576 fmt:bgr24 sar:16/15 flags:0x4
Output #0, image2, to 'out.bmp':
  Metadata:
    encoder         : Lavf54.5.100
    Stream #0:0: Video: bmp, bgr24, 720x576 [SAR 16:15 DAR 4:3], q=2-31, 200 kb/s, 90k tbn, 10 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (dvvideo -> bmp)
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=0.0 Lsize=       0kB time=00:00:00.10 bitrate=   0.0kbits/s
video:1215kB audio:0kB global headers:0kB muxing overhead -100.000000%

[Carl Eugen Hoyos]

Fixed by you.