[bug] Wrong video levels when converting AVC-Intra to H.264

[ischeriad]

For a while and at the moment (Shutter Encoder 16.8), I get the wrong video levels resulting in a low contrast picture when converting from MXF OP1a / AVC-Intra 100 to MP4 / H.264. (Tested on macOS and Windows.)

As a workaround, I can use "Colorimetry / Covert levels: 16-235 > 0-255" to force the correct levels, but it used to work automatically.

I could narrow down the issue to the version change from 16.0 to 16.1 (16.0 still produces the desired result). It seems like with this version change, a different build of the ffmpeg suite has been introduced (version details below).

When I drop the ffmpeg files and associated dylib from 16.0 into the 16.8 application bundle on macOS (/Applications/Shutter Encoder.app/Contents/Resources/Library), I get the desired result again. So I suspect the specific ffmpeg version.

ffmpeg in version 16.0:

ffmpeg version N-105691-gc439c6b191 Copyright (c) 2000-2022 the FFmpeg developers
built with Apple clang version 13.0.0 (clang-1300.0.29.30)

libavutil      57. 21.100 / 57. 21.100
libavcodec     59. 21.100 / 59. 21.100
libavformat    59. 17.102 / 59. 17.102
libavdevice    59.  5.100 / 59.  5.100
libavfilter     8. 27.100 /  8. 27.100
libswscale      6.  5.100 /  6.  5.100
libswresample   4.  4.100 /  4.  4.100
libpostproc    56.  4.100 / 56.  4.100

ffmpeg in versions 16.1 and up:

ffmpeg version N-109649-gab8cde6efa Copyright (c) 2000-2023 the FFmpeg developers
built with Apple LLVM version 10.0.0 (clang-1000.10.44.2)

libavutil      57. 44.100 / 57. 44.100
libavcodec     59. 56.100 / 59. 56.100
libavformat    59. 35.100 / 59. 35.100
libavdevice    59.  8.101 / 59.  8.101
libavfilter     8. 54.100 /  8. 54.100
libswscale      6.  8.112 /  6.  8.112
libswresample   4.  9.100 /  4.  9.100
libpostproc    56.  7.100 / 56.  7.100

[ischeriad]

This issue is still present with the new ffmpeg version shipped with 17.0.