Checking keyframe interval?

Question

How can I check keyframe interval of a video file?

all I can see in ffmpeg output is:

  Metadata:
    metadatacreator : Yet Another Metadata Injector         


        

Answer 1

The following command will give you the offsets of all key Frames in the Video

ffprobe -show_frames -select_streams v:0 \
        -print_format csv Video.mov 2> /dev/null |
stdbuf -oL cut -d ',' -f4 |
grep -n 1 |
stdbuf -oL cut -d ':' -f1

Note that the command might respond a little late. Have patience :-)

The ffprobe command gives you the frame level details in CSV format. Rest is a smart combination of cut and grep commands.

cut -d ',' -f4

filters the fourth column - this refers to the 'key_frame' flag.

grep -n 1

filters the key-frames only, and shows their line numbers in the CSV feed.

The

stdbuf -oL

with the cut command manipulates the buffer of the cut command.

Answer 2

You can display the timestamp for each frame with ffprobe with awk to only output key frame info. Works in Linux and macOS.

ffprobe -loglevel error -select_streams v:0 -show_entries packet=pts_time,flags -of csv=print_section=0 input.mp4 | awk -F',' '/K/ {print $1}'

Or a slower method that works on any OS and does not require awk or similar additional processing tools:

ffprobe -loglevel error -skip_frame nokey -select_streams v:0 -show_entries frame=pkt_pts_time -of csv=print_section=0 input.mp4

Results:

0.000000
2.502000
3.795000
6.131000
10.344000
12.554000
16.266000
17.559000
...

See the ffprobe documentation for more info.