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* vf_fingerprint: use aligned_alloc instead of posix_memalignwm42019-09-191-2/+2
| | | | | | | | | | | I was assuming posix_memalign was the most portable function to use, but MinGW does not provide it for some reason. Switch to C11 aligned_alloc() which someone suggested was provided by MinGW (but actually isn't, someone probably confused it with the incompatible _aligned_malloc), and add a configure check. Even though it turned out that MinGW doesn't provide it, the function is slightly more elegant than posix_memalign(), so stay with it.
* video: add vf_fingerprint and a skip-logo scriptwm42019-09-191-0/+293
skip-logo.lua is just what I wanted to have. Explanations are on the top of that file. As usual, all documentation threatens to remove this stuff all the time, since this stuff is just for me, and unlike a normal user I can afford the luxuary of hacking the shit directly into the player. vf_fingerprint is needed to support this script. It needs to scale down video frames as part of its operation. For that, it uses zimg. zimg is much faster than libswscale and generates more correct output. (The filter includes a runtime fallback, but it doesn't even work because libswscale fucks up and can't do YUV->Gray with range adjustment.) Note on the algorithm: seems almost too simple, but was suggested to me. It seems to be pretty effective, although long time experience with false positives is missing. At first I wanted to use dHash [1][2], which is also pretty simple and effective, but might actually be worse than the implemented mechanism. dHash has the advantage that the fingerprint is smaller. But exact matching is too unreliable, and you'd still need to determine the number of different bits for fuzzier comparison. So there wasn't really a reason to use it. [1] https://pypi.org/project/dhash/ [2] http://www.hackerfactor.com/blog/index.php?/archives/529-Kind-of-Like-That.html