frwu: change fields order mode

[ami_stuff]

the first horizontal line from top is moved to bottom of the video frame when file is encoded with "change filelds order" option enabled

C:\>ffmpeg -i frwu_change_field_order.avi out.avi
ffmpeg version N-37208-g01fcbdf Copyright (c) 2000-2012 the FFmpeg developers
  built on Jan 27 2012 18:34:52 with gcc 4.6.2
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-ru
ntime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-libope
ncore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --en
able-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-libschroedinger -
-enable-libspeex --enable-libtheora --enable-libvo-aacenc --enable-libvo-amrwben
c --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-
libxvid --enable-zlib
  libavutil      51. 34.101 / 51. 34.101
  libavcodec     53. 60.100 / 53. 60.100
  libavformat    53. 31.100 / 53. 31.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 60.100 /  2. 60.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0.  6.100 /  0.  6.100
  libpostproc    52.  0.100 / 52.  0.100
Input #0, avi, from 'frwu_change_field_order.avi':
  Duration: 00:00:01.37, start: 0.000000, bitrate: 9493 kb/s
    Stream #0:0: Video: frwu (FRWU / 0x55575246), uyvy422, 192x128, 24 tbr, 24 t
bn, 24 tbc
Incompatible pixel format 'uyvy422' for codec 'mpeg4', auto-selecting format 'yu
v420p'
[buffer @ 02151B20] w:192 h:128 pixfmt:uyvy422 tb:1/1000000 sar:0/1 sws_param:
[buffersink @ 02151DA0] auto-inserting filter 'auto-inserted scale 0' between th
e filter 'src' and the filter 'out'
[scale @ 02151320] w:192 h:128 fmt:uyvy422 -> w:192 h:128 fmt:yuv420p flags:0x4
Output #0, avi, to 'out.avi':
  Metadata:
    ISFT            : Lavf53.31.100
    Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 192x128, q=2-31, 200
 kb/s, 24 tbn, 24 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (frwu -> mpeg4)
Press [q] to stop, [?] for help
frame=   33 fps=  0 q=2.6 Lsize=      64kB time=00:00:01.37 bitrate= 378.5kbits/
s
video:57kB audio:0kB global headers:0kB muxing overhead 11.094793%

[Elon Musk]

Does file still plays correctly with native decoder if you remux it with ffmpeg into another container?

[ami_stuff]

If you mean

ffmpeg -i frwu.avi -vcodec copy frwu.mov
ffmpeg -i frwu.mov -vcodec copy frwu2.avi

then yes, frwu2.avi plays fine with binary codec.

[Elon Musk]

Could you create two samples one without this option and one with it but make sure that data is all zeroes in both cases - everything is black - that is only way to found where is such option hidden in bitstream.

[ami_stuff]

The output files are identical, so it looks like there is no way to identify fields order without user interaction.

[Elon Musk]

Than how reference decoder could handle it, if it handles it at all?

Closing as there is no way to fix it, it just looks like broken software.

[ami_stuff]

Replying to richardpl:

Than how reference decoder could handle it, if it handles it at all?

There is an option in the codec to select which field order should be used for decoding and encoding (I thought it is only for encoding, but looks like this is to select decoding field order as well). Similar option is available for mpeg and dv codecs from this company.

[Carl Eugen Hoyos]

Does attached patch improve the situation?
(Can you test real interlaced content?)

[ami_stuff]

Replying to cehoyos:

Does attached patch improve the situation?
(Can you test real interlaced content?)

How do I activate this priv option?

This doesn't work for me:

$ ffmpeg -i frwu_change_field_order.avi -change_field_order out.avi
ffmpeg version 1.0.git-da8242e Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov 20 2012 13:54:35 with gcc 4.6.1 (GCC)
  configuration: --disable-sse --disable-ffprobe --enable-gpl
  libavutil      52.  8.100 / 52.  8.100
  libavcodec     54. 73.100 / 54. 73.100
  libavformat    54. 37.100 / 54. 37.100
  libavdevice    54.  3.100 / 54.  3.100
  libavfilter     3. 23.101 /  3. 23.101
  libswscale      2.  1.102 /  2.  1.102
  libswresample   0. 17.100 /  0. 17.100
  libpostproc    52.  2.100 / 52.  2.100
Input #0, avi, from 'frwu_change_field_order.avi':
  Duration: 00:00:01.38, start: 0.000000, bitrate: 9493 kb/s
    Stream #0:0: Video: frwu (FRWU / 0x55575246), uyvy422, 192x128, 24 tbr, 24 t
bn, 24 tbc
At least one output file must be specified

[Carl Eugen Hoyos]

$ ffmpeg -change_field_order 1 -i frwu_change_field_order.avi out.avi

[ami_stuff]

Replying to cehoyos:

$ ffmpeg -change_field_order 1 -i frwu_change_field_order.avi out.avi

Ok, this finally works. Could you point me to interlaced avi raw file which I could reencode with VirtualDub into frwu?

[Carl Eugen Hoyos]

​http://samples.ffmpeg.org/MPEG-VOB/interlaced contains some samples, V.VOB is the typical sample that actually needs change of field order (at least with some decoders) to allow de-interlacing.

[ami_stuff]

I reencoded vob to rawvideo:

ffmpeg -i v.vob -vcodec rawvideo -pix_fmt yuv420p out.avi

and loaded the output into VD + reencoded part of it to frwu:

​http://www.datafilehost.com/download-3b1ad60b.html

[Carl Eugen Hoyos]

The question is:
Does the FFmpeg frwu decoder behave differently than the binary decoder without my patch (I believe so, you already provided a sample)? And does it behave identically with my patch assuming you set change_field_order identically for both decoders?

[ami_stuff]

Replying to cehoyos:

The question is:
Does the FFmpeg frwu decoder behave differently than the binary decoder without my patch (I believe so, you already provided a sample)?

yes

And does it behave identically with my patch assuming you set change_field_order identically for both decoders?

yes

[ami_stuff]

131 static const AVClass frwu_class = {
132 "srwu Decoder",

please fix typo in the final patch s/srwu/frwu

[Carl Eugen Hoyos]

Replying to ami_stuff:

131 static const AVClass frwu_class = {
132 "srwu Decoder",

please fix typo in the final patch s/srwu/frwu

Done, thank you for spotting!

[Carl Eugen Hoyos]

Patch applied.