ffmpegh.264libavcodeclibx265

Extract motion vectors from x265 (HEVC) encoded video with ffmpeg/libavcodec?

I know that one can extract the motion vectors from an h264 encoded via by first setting the flag

av_dict_set(&opts, "flags2", "+export_mvs", 0);

then you can query the side-data for the motion vectors by doing this

sd = av_frame_get_side_data(frame, AV_FRAME_DATA_MOTION_VECTORS);

When I looked online to see if you can do something similar with HEVC encoded videos, I wasn't able to find any information. All I found was this by the definition of "AV_FRAME_DATA_MOTION_VECTORS"

Motion vectors exported by some codecs (on demand through the export_mvs flag set in the libavcodec AVCodecContext flags2 option).

The data is the AVMotionVector struct defined in libavutil/motion_vector.h.

but there was no information on exactly which codecs export this motion vector information. How would I go about finding this out?

Solution

  • If I'm not mistaken h264 is the only codec to print Motion Estimation Vectors.

    I would suggest trying out the video filter mestimate.

    Also, if you want to have a better ideia what's going on in ffmpeg, check the function ff_print_debug_info2 in libavcodec/mpegvideo.c