CODEWITHSUNDEEP
ffmpegimage-compressionopenh264
Navid Ahmadi
Navid Ahmadi

Reputation: 13

Generating a P frame based on an I frame

Say I have 5 images that are quite similar. I'd like to compress images 2, 3, 4 and 5 based on the first image, somewhat similar to the way P frames are generated from an I frame.

Edit: Although similar, I am not looking for simply generating a diff between the two images. My goal is to somehow use the information in the first image to make the consecutive images much smaller. If I simply do a diff, the diff itself is about the same size (about 10% reduced) which is not as much as I expect. If I generate a mp4 video including these 5 frames, the video size is much less than putting 5 frames in a file, which probably has to with frame predications based on the I frames. Is there a way to generate those predicted frames one by one and store them individually?

Upvotes: 0

Views: 1449

Answers (1)

Gyan
Gyan

Reputation: 92928

Here's the basic syntax:

Let's say I.png is your base frame and P1.png is the frame which you wish to reduce to its difference from I.png

Then

ffmpeg -i P1.png -i I.png -lavfi blend=all_expr='A-B' D1.png

produces the difference frame D1.png.

To reconstruct P1 from I and D1, run

ffmpeg -i D1.png -i I.png -lavfi blend=all_expr='A+B' P1-r.png

PI-r.png will be identical to P1.png.

Upvotes: 1

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