I am generating 12bit gray12le lossless HEVC files with FFMPEG and can open these no problem with MPC-BE. But when I open them in AVI Demux, I just see a black video and nothing more. Is there a way I can change the decoder to something that supports it?
Avidemux doesn't support this colorspace (yet). Support for yuv420p12le has been just added (https://github.com/mean00/avidemux2/commit/9d96568ec8f50924ac015e8a93b6f01a0e536693), so this should not be a big deal to implement.
However, the internal picture format in Avidemux is YV12 (yuv420p 8-bit with U and V planes swapped), so the original bit depth is always lost when the video is re-encoded, even when using 12-bit HEVC for output.
I see. Thanks. I guess I will have to find another tool.
Just to avoid misunderstandings: when cutting in copy mode, the original bit depth and quality is fully preserved.