Motion Vector extraction from encoded video file

Question

I am trying to extract motion vector data from an encoded mp4 file. In a previous post I found an answer http://www.princeton.edu/~jiasic/cos435/motion_vector.c . But I am not able to run the code without errors . What are the other files that have to be included in the file ? I am a newbie here . So any help would be appreciated .

Toxoplasmosis

What errors do you get when you try to compile it? – Semicircle

You can take a look at MV-Tractus. – Sp

Answer 1

I had modified the source code of mplayer (ffmpeg) to extract motion vectors for any compressed video, I have uploaded the modified mplayer code which can be used for extracting motion vectors here http://www.cs.umd.edu/~bharat/modmplayer.zip

You need to do the following to extract motion vectors if you use the modified version of mplayer

./mplayer -nosound -fps 200 -vo null -lavdopts vismv=1 path_of_video_file 2> path_of_output_file.txt

Pre-compiled executable and some useful files are available in the outputs folder

Kramlich

I am trying some non-video related algorithm and this saved my day – Gemmule

Can you offer the changes in the form of a patch file? That way we could apply it to pretty much any version of mplayer. (mplayer is not ffmpeg, btw. It just uses ffmpeg.) – Teddi

yes, its a change in the ffmpeg folder. If I remember correctly, I had added 5 tprintf statements each in ffmpeg/libavcodec/h264_cabac.c and ffmpeg/libavcodec/h264_cavlc.c which print the motion vectors. Hopefully, the structure of this file would be the same in newer versions of ffmpeg, so that these edits can be made. – Kramlich