On Tue, Aug 6, 2024 at 8:41 AM Rob Hallam <ffm...@roberthallam.com> wrote:
> Hi, > > I'd like to programmatically detect the 'busiest' parts of a video- ie > the most visually active areas. I am leaving audio aside for the > purposes of considering this. > > I figured it might be possible by looking at one / more of: > > - the bitrate for VBR videos -- a higher bitrate for a given segment > will tend to be associated with more activity (other things being > equal) > - frame differences -- count pixels/blocks which differ, average over > a time segment > - optical flow? (higher flow values = more activity) I'm not too > familiar with this > > I'm not sure if there are better approaches, or if here is even the > right place to ask but figured the expertise of folks on the list > would be a good place to start. > > Are there ways of doing this efficiently with ffmpeg or libav? I would > trade precision for speed! > > Thanks for your time, > Rob > _______________________________________________ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". > The first thing that came to mind when I read your question was your first suggestion - observing the bitrate over time of the VBR-encoded video. That seemed to me to be the simplest way that would be pretty accurate. (I know nothing about this field of programming, though.) The second thing I thought of was your second suggestion, but I figured it's inadequate because "superficial" changes can cause every pixel or large proportions of pixels to be different over time. For example, the camera moves by a tenth of a degree, or an object moves a half an inch, and all those pixels will be totally different. I wouldn't try this way. I just looked up "optical flow," and it seems to be more or less a description of why the second approach wouldn't work, the reasons I just mentioned. It seems to be more or less the very thing you'd want to remove from the equation when determining how busy a part of a video is, the effect that you'd eliminate when applying the first method mentioned, observing encoded bitrate... _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
