bmp parser is more strict than the bmp decoder

[Carl Eugen Hoyos]

I will attach a bmp sample with incorrect written size, the file decodes fine with lavc, the parser breaks it.

$ cat 8bpp.bmp | ./ffmpeg -f image2pipe -vcodec bmp -i - out.png
ffmpeg version N-63596-g772d46d Copyright (c) 2000-2014 the FFmpeg developers
  built on May 30 2014 05:16:07 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl --enable-libspeex
  libavutil      52. 87.100 / 52. 87.100
  libavcodec     55. 65.100 / 55. 65.100
  libavformat    55. 42.100 / 55. 42.100
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4.  5.100 /  4.  5.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
[bmp @ 0x212a980] not enough data (785408 < 786432)
Input #0, image2pipe, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: bmp, pal8, 1024x768, 25 tbr, 25 tbn, 25 tbc
File 'out.png' already exists. Exiting.

[Michael Niedermayer]

I guess the parser would have to parse more of the header to figure out the correct size.
Simply using a 16bit header to find the next image feels a bit unreliable to me

[Carl Eugen Hoyos]

This is now simpler to reproduce:

$ cp 8bpp.bmp bmpimage

$ ffmpeg -i bmpimage out.png
ffmpeg version N-64397-g5c65aed Copyright (c) 2000-2014 the FFmpeg developers
  built on Jul  4 2014 01:47:20 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      52. 90.101 / 52. 90.101
  libavcodec     55. 68.100 / 55. 68.100
  libavformat    55. 45.100 / 55. 45.100
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4. 10.100 /  4. 10.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
[bmp @ 0x1f3ba80] not enough data (785408 < 786432)
Input #0, bmp_pipe, from 'bmpimage':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: bmp, pal8, 1024x768, 25 tbr, 25 tbn, 25 tbc
[image2 @ 0x1f3c9c0] Using AVStream.codec.time_base as a timebase hint to the muxer is deprecated. Set AVStream.time_base instead.
Output #0, image2, to 'out.png':
  Metadata:
    encoder         : Lavf55.45.100
    Stream #0:0: Video: png, pal8, 1024x768, q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
    Metadata:
      encoder         : Lavc55.68.100 png
Stream mapping:
  Stream #0:0 -> #0:0 (bmp (native) -> png (native))
Press [q] to stop, [?] for help
[bmp @ 0x1f3c520] not enough data (785408 < 786432)
Error while decoding stream #0:0: Invalid data found when processing input
bmpimage: Input/output error
frame=    0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)
Conversion failed!

[Michael Niedermayer]

Fixed in ceb2fe027fec2bf8f1847d8a9676630583031e65