[FFmpeg-user] Extract Motion vectors result in empty log and json files

[Sengupta, Aileen]

Dear Dev Team,

I may be new to the FFMpeg world, but I am trying to extract motion vectors into a json file to be used by my code later. I have used all possible combnation as below:


ffmpeg -flags2 +export_mvs -i input.mp4 -vf codecview=mv=pf+bf+bb -c:v libx264 -preset fast -crf 18 -an output_with_motion_vectors.mp4


First of all this command runs perfectly fine and delivers me all the motion vector inside the video.


ffmpeg -flags2 +export_mvs -i input.mp4 -vf select=gte(n\,0) -vsync vfr -f null - 2> motion_vectors.log


This is where I have a problem where I do not get any coordinates of the motion vector files. Am I doing something wrong? I have to parse the log file myself and have the code for that but I wanted to attach that as well. The video is having motion but it is somewhat not able to extract it. In case we need ssma


Take Care,

Thanks and regards,
Aileen Sengupta,
Ph.D. Final Year, EE Dept, UTA
VEL Lab NH 142
Lead GTA EE 3330, EE 4330, EE 2320/2440, EE 5309/5331
Graduate Student Advisor Fall 2024 || IEEE HKN Epsilon Mu
Chair 2025 || Graduate Student Subcommittee IEEE HKN

[cid:ac904a3b-e759-4577-8a63-518a3239be07]

-------------- next part --------------
A non-text attachment was scrubbed...
Name: Outlook-ebj0bwpy.png
Type: image/png
Size: 13653 bytes
Desc: Outlook-ebj0bwpy.png
URL: <https://ffmpeg.org/pipermail/ffmpeg-user/attachments/20241204/3e2052c2/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: motion_vectors.log
Type: application/octet-stream
Size: 8222 bytes
Desc: motion_vectors.log
URL: <https://ffmpeg.org/pipermail/ffmpeg-user/attachments/20241204/3e2052c2/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: motion_vectors.json
Type: application/json
Size: 2 bytes
Desc: motion_vectors.json
URL: <https://ffmpeg.org/pipermail/ffmpeg-user/attachments/20241204/3e2052c2/attachment.json>