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Extracting frames from a video with ffmpeg very slow if not using jpeg
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this post was submitted on 14 Jul 2024
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A) Export using a lower effort, with libjxl effort 2 or something will be fine.
B) Export to a faster image format like QOI or TIFF or PPM/PNM etc.
PNG, JXL, WEBP, all have fairly high encode times by default with ffmpeg. lower the effort or use a faster format
If you think that it really could be write speed limitations, encode to a ramdisk first then transfer if you have the spare ram, but using a different and faster format will probably help as PNG is still very slow to encode. (writing to /tmp is fine for this)
A) I actually didn't know about this before, do you know what option I need to use in ffmpeg to set the effort?
B) I tried those but it's the same issue as with png, that the hard drive's write speed is too slow (or it's the USB 3 connection but the result is the same)
Edit: Just found out how to set the effort. Setting it to 1 is quite a bit faster but still slow at only 3.8 fps.
what are your system specs? at a low effort you should be getting a lot more FPS, what cli command are you using? but I guess it would be best for you to export to /tmp given enough ram and then go from there
EDIT: for context, when encoding libjxl I would do
-distance 0 -effort 2for lossless outputI have a Ryzen 5 3600. My command was
ffmpeg -i video.mp4 -threads 12 -distance 0 -effort 1 extract/%06d.jxl.