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Amazing for many reasons, but what I really find impressive is that messing with video encoding requires like a PHD in everything because of how complex things

Amazing for many reasons, but what I really find impressive is that messing with video encoding requires like a PHD in everything because of how complex things like H.264 are. At least that's my perspective after trying to grok the H.264 spec. There are all kinds of optimizations and algorithms for network latency and video sizes, etc. I don't consider myself a layman but I certainly do not have the knowledge and skill to do anything at all with video. Do you know what a Inverse sub-macroblock partition scanning process is? I don't, not even after reading the part about it in the spec.

justinsb 14y ago
No need to mess with the encoding format - just use an existing utility (or library) to grab the raw frame data. e.g. ffmpeg
ZenPsycho 14y ago
a macroblock is a chunk of an image which is identified to have some constancy between frames. a sub-macroblock would be some subdivision of this for finer motion details. sub-Macroblock partitian scanning would be applying an algorithm to identify the sub-macroblocks in a set of images. Add the word "Inverse" though and now I have no idea what the hell that means.
taliesinb 14y ago
This really doesn't have much to do with what makes computer vision difficult (or rather, interesting). I doubt very many computer vision researchers are conversent with the H.264 spec. Typically toolkits like OpenCV take care of codecs for you (which make them quite annoyingly difficult to compile on different platforms). (I speak as someone who had done commercial computer vision algorithm development.)
- joeconway 14y ago
  Unfortunately when they do (My dissertation is on motion analysis using H.264 compression artifacts) things get pretty complicated very quickly
  - taliesinb 14y ago
    What precisely is your dissertation about? Inferring motion from compression artifacts? Exploiting the fact that many codecs have already done motion estimation so that you don't have to do image flow again?
    - joeconway 14y ago
      Yes, exactly that. Then filtering them because they don't actually show optical flow, they just show a lot of noise

justinsb 14y ago

No need to mess with the encoding format - just use an existing utility (or library) to grab the raw frame data. e.g. ffmpeg

ZenPsycho 14y ago

a macroblock is a chunk of an image which is identified to have some constancy between frames. a sub-macroblock would be some subdivision of this for finer motion details. sub-Macroblock partitian scanning would be applying an algorithm to identify the sub-macroblocks in a set of images. Add the word "Inverse" though and now I have no idea what the hell that means.

taliesinb 14y ago

This really doesn't have much to do with what makes computer vision difficult (or rather, interesting). I doubt very many computer vision researchers are conversent with the H.264 spec. Typically toolkits like OpenCV take care of codecs for you (which make them quite annoyingly difficult to compile on different platforms). (I speak as someone who had done commercial computer vision algorithm development.)

joeconway 14y ago
Unfortunately when they do (My dissertation is on motion analysis using H.264 compression artifacts) things get pretty complicated very quickly
- taliesinb 14y ago
  What precisely is your dissertation about? Inferring motion from compression artifacts? Exploiting the fact that many codecs have already done motion estimation so that you don't have to do image flow again?
  - joeconway 14y ago
    Yes, exactly that. Then filtering them because they don't actually show optical flow, they just show a lot of noise