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submitted 4 months ago by Fisch@discuss.tchncs.de to c/ffmpeg@lemmy.world

cross-posted from: https://discuss.tchncs.de/post/18870157

I'm trying to extract the frames of a video as individual images but it's really slow, except when I'm using jpeg. The obvious issue with jpegs is the data loss from the compression, I want the images to be lossless. Extracting them as jpegs manages about 50-70 fps but as pngs it's only 4 fps and it seems to continue getting slower, after 1 minute of the 11 minute video it's only 3.5 fps.

I suspect it's because I'm doing this on an external 5tb hard drive, connected over USB 3.0 and the write speed can't keep up. So my idea was to use a different image format. I tried lossless jpeg xl and lossless webp but both of them are even slower, only managing to extract at about 0.5 fps or something. I have no idea why that's so slow, the files are a lot smaller than png, so it can't be because of the write speed.

I would appreciate it if anyone could help me with this.

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[-] MelastSB@sh.itjust.works 1 points 4 months ago

I guess you could check the size of the lossless and lossy frames it outputs, to convert the fps to Mbps. If both values are similar then it's probably the drive

[-] Fisch@discuss.tchncs.de 2 points 4 months ago

I just did a rough calculation where I did estimated size of png / estimated size of jpg * fps of png and the value was roughly in the ballpark of what the fps for jpg were, so I'm very sure it's the drive

this post was submitted on 14 Jul 2024
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