Support 12bit colour jpeg

[Carl Eugen Hoyos]

I will attach two 12bit colour jpeg samples, made with libjpegv6b, see also ticket #2812.

$ ffmpeg -i lena.jpg
ffmpeg version N-56060-gbcd1c20 Copyright (c) 2000-2013 the FFmpeg developers
  built on Sep  6 2013 09:47:17 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl --disable-indev=jack
  libavutil      52. 43.100 / 52. 43.100
  libavcodec     55. 31.101 / 55. 31.101
  libavformat    55. 16.101 / 55. 16.101
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 83.104 /  3. 83.104
  libswscale      2.  5.100 /  2.  5.100
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
[mjpeg @ 0x1b72020] lossy that is not <= 8 bits/component or 16-bit gray is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
[image2 @ 0x1b71080] decoding for stream 0 failed
[image2 @ 0x1b71080] Could not find codec parameters for stream 0 (Video: mjpeg): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
lena.jpg: could not find codec parameters

[Carl Eugen Hoyos]

Fixed by Michael in 64b6279.

[ami_stuff]

Replying to cehoyos:

Fixed by Michael in 64b6279.

Could you test if progressive images decodes as well?

for example generated with:

cjpeg /*-grayscale*/ -quality 20 -progressive -restart 25

?

I have compiled jpegv6b with 12bit support, but for some reason it decodes/encodes trash here :(
(even when I use gif as an output format)

[Carl Eugen Hoyos]

Both appear to work to fine (you attached a gray sample to ticket #2812).