in_tile_headers not reset in jpeg2000_read_main_headers()

[Pierre-Anthony Lemieux]

in_tile_headers is a context variable that is preserved across calls to jpeg2000_read_main_headers(), and thus across frames in a multi-frame file. Once set to 1 it remains equal to 1 forever, even though we might not be in a tile header.

This is an issue since some processing in jpeg2000_read_main_headers() depends on the value of in_tile_headers. In particular, checking whether COD markers are present tile part headers, which is prohibited for homogeneous HT codestreams.

To make a long story short, processing an MXF file that contains HT codestreams will fail on the second frame.

./ffmpeg -i mer_shrt_23976_vdm_sdr_rec709_g24_3840x2160_20170913_12bit_DCDM.4bpp.mxf out.mp4

throws

[jpeg2000 @ 0x55fac474ee00] COD marker found in a tile header but the codestream belongs to the HOMOGENEOUS set
[vist#0:0/jpeg2000 @ 0x55fac47400c0] [dec:jpeg2000 @ 0x55fac474e380] Error submitting packet to decoder: Invalid data found when processing input

NOTE: It is not clear why in_tile_headers is a context variable since it looks like it is only used in jpeg2000_read_main_headers().

Sample file at:

​https://www.sandflow.com/public/mer_shrt_23976_vdm_sdr_rec709_g24_3840x2160_20170913_12bit_DCDM.4bpp.mxf

[Pierre-Anthony Lemieux]

​https://patchwork.ffmpeg.org/project/ffmpeg/patch/20241025002317.25786-1-pal@sandflow.com/

[Pierre-Anthony Lemieux]

Fixed at ​https://github.com/FFmpeg/FFmpeg/commit/839f6d38a0ff32d8fb89fc1f1b281ed874ae3543