MPEG-7 Motion Descriptors. Reference. ISO/IEC JTC1/SC29/WG11 N4031 ISO/IEC JTC1/SC29/WG11 N4062 MPEG-7 Visual Motion Descriptors (IEEE Transactions on Circuits and Systems for Video Technology) Video Indexing using Descriptors of Spatial Distribution of Motion Activity
(IEEE Transactions on Circuits and Systems for Video Technology)
(submitted to IEEE Transactions on Circuits and Systems for Video Technology)
1 vector magnitudes, appropriately normalized by the frame resolution.– very low activity2 – low activity3 – medium activity4 – high activity5 – very high activity
if(std_dev<t1) intensity = 1;else if(std_dev<t2) intensity = 2;else if(std_dev<t3) intensity = 3;else if(std_dev<t4) intensity = 4;else intensity = 5;
t1 = 0.257*l/F
t2 = 0.706*l/F
t3 = 1.280*l/F
t4 = 2.111*l/F
diagonal length l = sqrt(w*w + h*h)
F is the frame rate in frames/second.
The dark area consists of macroblocks that get non-zero values after thresholding.
The remaining area consists of macroblocks that get “zero out” after thresholding.
With smaller,widely spaced objects note that there are more long-run lengths and medium run-lengths
The motion-activity intensity descriptor enables selection of the video segments of a program based on intensity of motion activity.
We can use motion activity to separate the high and low motion parts of the video sequence and or as a first stage content filter.