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Notes on a particularly perplexing ffmpeg problem.

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yrriban 2025-05-30 02:10:06 -04:00
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try to create an image with a custom buffer, format rbga
image is 278x57
got 63384 bytes, need 63840 bytes
63384=278*57*4, checks out. why 63840?
factor 63384=2*2*2*3*19*139
factor 63840=2*2*2*2*2*3*5*7*19
factor 278=2*139
factor 57=3*19
factor 4=2*2
63840 doesn't have 139 as a factor... if we divide by the other two we get 2*2*2*5*7=280
is it padding an extra pixel on each side? no, reducing video frame width to 276 still demands 63840 bytes.
does stretching image to 280 work? yes! so it has to be a multiple of 5... or 10, or 20. and larger than the requested dimension.
after some further fiddling, it's 8.