Smart Cut - set has_b_frames correctly

[nneonneo]

Hello! I used LosslessCut to remove some segments out of a video. I needed frame-level accuracy, so I tried Smart Cut.

However, the resulting video appears corrupt across the short "encoded" segments - I get just a green video (audio is fine).

I looked into it more deeply. Using ffprobe -show_streams, I determined that the encoded and copy files differ in the has_b_frames: the copies have has_b_frames=1, and the encoded ones have has_b_frames=2. I am using the ffmpeg built into LosslessCut 3.67.2 (macOS x64).

I manually reran the commands to generate the encoded segments with -bf 1 to set the has_b_frames parameter for the encoder, then concatenated them using -i concat:... (I am using mpegts intermediaries for simplicity). Surprisingly, this works great!

So, I would suggest that in addition to the bit rate and codec, that the has_b_frames/bf encoder parameter be copied from the original input. It seems like many videos in the wild use has_b_frames=1, but the built-in encoder with LosslessCut seems to default to 2.

Thank you for the nice project! I successfully completed my editing task using this tool and the small manual fix, so I hope this idea is useful to others.

P.S.: I would sincerely wish for the app.log to produce copy-paste-able commands. In particular, -f concat -i- is a bit unfortunate because I have to guess what the input is. Even something like echo ... >> concat.tmp then -f concat -i concat.tmp would be helpful. That way I can manually rerun the entire sequence of commands if some manual fix is required.