Don’t stop at 50, allow arbitrary speed in clips’ settings.
There is a technical reason that will likely not be addressed soon. You can workaround it by exporting the clip and adjusting the speed of the export result. You can do one clip in your project by opening it in the Source player and choosing Export > From > Source. You can minimize quality loss of export by using an intermediate or lossless export preset (warning, these create large files).
Already requested and discussed multiple times:
https://forum.shotcut.org/search?q=speed%2050
Upon reviewing this issue, I think it can be increased if the clip does not have audio or if it is disabled in Properties > Audio > Track. Does your clip have audio? If it did, do you think it is OK if Shotcut automatically disables the audio when > 50?
I don’t think anyone has any expectation of >50x audio to sound even remotely useful (even at 50x it’s moslty some abstract windy-like gibberish).
For any speed increases over 10x, the sound is already just high pitched garbage. So I think we could add a rule to mute audio outside of certain speed tolerances.
The other problem, that Dan did not mention is that the preview performance gets destroyed for high speed increases. Think of it this way, in order to perform a speed increase of 100x, Shotcut has to skip over 100 frames for each frame that it displays. But for many files, “skipping” is not easy or fast. Most of those intermediate frames will have to be decoded at least partially. On my computer, when I speed up a clip at 50x, the preview is a useless herkey-jerkey mess.
For (what I would call) extreme speed changes, maybe we should add an offline processing option. It could be an option in the Convert To Edit Friendly dialog. This would be similar to how we put the motion compensation in there because it is not realistic to do in real time preview.
Hmm, I think the manual workaround is fairly viable and obvious (already similar to using Convert) that we do not need to put the workaround into the UI and make both it and the code more complicated.
This heavily depends on video, 4k HEVC video is already laggy at 2x, gopro proxy is still buttery smooth at 50x.
I personally vote against the convert option for this one, the “on the fly method” allows changing the value later and also doesn’t create another copy of my files that I have to manually cleanup.
A few months ago I manually edited the .mlt project to make a video 500x (it was a ~2 month long camera footage that I wanted to timelapse as a fun project) and I remember it was ok to seek through it and add filters, I don’t exactly remember how bad the playback was but I think because of the very low bitrate (1-2mbps) the entire experience was really acceptable.
This is not a problem at all, my performance will be affected even at normal speed. Proxy files do not always help and I just export to YouTube presets to see what happens. What am I getting at? You can turn off the preview window at high speeds and hang up a “not fate” sign if people really really want it. I myself do not intend to use such speeds, so I am satisfied with the current option.