FFMPEG installed but not found

Solution 1:

pHash looks like a dead project and has not been updated since 2013.

It references avcodec_alloc_frame which for years has been deprecated for av_frame_alloc, so it is likely incompatible with the current FFmpeg API.

You'll either have to use an ancient FFmpeg version (not recommended), or update the pHash source to use the current FFmpeg libraries properly.

If you do not need support for perceptual video hashes, then configure pHash with --enable-video-hash=no and it will omit the FFmpeg dependency.

If you're looking for audio fingerprint functionality, I recommend Chromaprint instead since FFmpeg supports it.