Duplicate frame preview at keyframes

[dominikWin]

I have a lot of issues to go through, so in order to make it easier for me to help you, I ask that you please try these things first

• Try with the newest version from GitHub
• Read the documentation and FAQ, Known issues, Troubleshooting
• Search for your problem under Issues or Discussions
• If you have a problem only with a particular file (or file type), use this form instead
• Windows 7, 8 and 8.1 are no longer supported. This is not a question about Windows 8.1 or older.

Operating System

MacOS 13

Steps to reproduce

1. Open a file in Lossless Cut
2. Move current time a few frames before a keyframe
3. Step one frame at a time forward until you pass the keyframe

Occurs on every file I tried including ones directly output from ffmpeg in h264.

A video where frame 499 is skipped in Lossless Cut:

lossless_cut_dup_keyframe.mp4

Expected behavior

The preview window should show the frame matching the timelines timestamp.

Actual behavior

A frame at the key frame is duplicated.

Share log

No response

[mifi]

See #156 #585

tldr: with html5 video player, it's not possible to seek to a frame number, but to a time value, so losslesscut has implemented the "seek by frame" as a seek to a time (time divided by fps + 1):

lossless-cut/src/App.jsx

Line 296 in 1fe37ae

const shortStep = useCallback((direction) => {

might be something wrong there with the calculation, or maybe your file has irregular/variable fps. Hard to say without having a file that reproduces the problem. I tried with an mp4/h264 file and I don't see this behavior

[hqhbaby]

The same problem, using LosslessCut to cut and combine Youtube's webm format, also has the problem of Duplicate frame preview at keyframes

[mifi]

closing in favor of #1216