Shoutcut crashes after opening more than one M4V (h.264) file.
Shotcut version 19.12.31
It is a repeatable crash
The case:
I had some 4K files, I made proxys with Handbrake “Production Proxy 540p” preset modified to use h.264 QSV for encoding.
If I open more than one file at once first, after opening tose files Shotcut exits without any warning.
Originals do not cause problem, only the mentioned proxy files.
Proxy file info:
MPEG-4 AVC (part 10)
960x540, 29,7 fps
Audio AAC (mp4a)
How to repeat:
Starting Shotcut -> open files -> I select 3 files, files open, 3 files appear on Playlist, automatically starts to play the first item, then I pause it and Shotcut exits without warning.
If I do not pause, then it plays a few seconds then exits without warning.
The workaround is opening one file first, then I can add any, without crash:
Starting Shotcut -> open files -> select one file, file opens, no problem
I can seek, put it on timeline, etc. Repeat, open 3 files, I can seek, add to timeline, no problem now.
I had trouble trying to reproduce this. I picked a source to make 3 proxy test files with Handbrake using the same preset you mentioned but for some reason the 540p proxy files came back with variable frame rates. That means that every time I tried to open them in Shotcut I would get the message telling me I should make intermediate files because of the variable frame rates. So this did not crash on me. Plus, I don’t have QSV. I have NVEnc so I don’t know if the type of hardware acceleration makes a difference. I tried both the regular H.264 and the NVEnc and both gave me the same variable frame rate result.
I’m on Windows. I don’t know if that’s the same OS you are using and if that would also make a difference.
However, if you are looking to use proxies, have you seen @KKnBB’s great proxy tool? If you haven’t, check out his thread here and try it out. See if that serves you any better.
That would be best. You can send it in a private message to @shotcut as he is the lead developer. Hopefully he can reproduce your issue on his end and take care of it.
constant bitrate is not the same as constant frame rate.
There is a known issue when dropping multiple files and any of them are variable frame rate or not seekable such that they preset a dialog. I will try to fix it for the next version.
I took a look, and this Handbrake preset produces variable frame rate (VFR) if the source is VFR, which is wrong to do for a “production” transcode, but I think it chooses not to pick a framerate for you. Also, it encodes using constant quality rather than constant bitrate, which is fine, and you should leave it that way. I was not able to reproduce the crash using a mix of VFR and constant files.
Are you using Automatic Video Mode in Settings? If so, try changing that and see if the problem goes away. Feel free to share your files on a cloud drive if you are able.
Yes, I was using automatic settings.
You are right, not all files caused this. I had 44 files, and the crash happened always when the first 3 opened, not others. Another day I tried again, before sharing the files, but it opened without crash, so I am not sure what caused it. I will try it again today.
