ffmpeg log missing "dup" and "drop" key-value pairs For some reason, my ffmpeg output log does not show dup and drop key-value pairs.

expect:

...
frame=563 fps=138 q=23.0 size=13056kB time=00:00:09.42 bitrate=11346.8kbits/s dup=0 drop=0 speed= 2.3x
...


running the following:

~/bin/ffmpeg -i INPUT.mkv \
    -t 00:00:10.000 \
    -c:v libx264 -crf 15 -preset veryfast \
    OUTPUT.mkv 2&gt;&amp;1|tee ffmpeg.log


results in this output instead:

...
frame=  563 fps=138 q=23.0 size=   13056kB time=00:00:09.42 bitrate=11346.8kbits/s speed= 2.3x
frame=  600 fps=134 q=-1.0 Lsize=   16199kB time=00:00:09.98 bitrate=13294.4kbits/s speed=2.23x
video:16095kB audio:92kB subtitle:0kB other streams:0kB global headers:4kB muxing overhead: 0.077694%
[libx264 @ 0x55d5711efac0] frame I:3     Avg QP:15.71  size:227164
...


or running:

~/bin/ffmpeg -f v4l2 \
    -framerate 60 -video_size 1920x1080 \
    -input_format mjpeg -i /dev/video0 \
    -c:v libx264 -crf 15 -preset veryfast \
    -tune film -profile:v high -pix_fmt yuv420p \
    -color_primaries 1 -color_trc 1 -colorspace 1 \
    -dst_range 1 -color_range 2 \
    OUTPUT.mkv 2&gt;&amp;1|tee ffmpeg.log


gives:

...
frame=  880 fps= 60 q=23.0 size=   64512kB time=00:00:14.31 bitrate=36910.3kbits/s speed=0.977x
frame=  911 fps= 60 q=23.0 size=   64512kB time=00:00:14.83 bitrate=35626.4kbits/s speed=0.978x


system info


OS: Linux Debian 10 (buster) x86_64
tested with two versions of ffmpeg:


1) Debian package

$ ffmpeg -version
ffmpeg version 4.1.4-1~deb10u1 built with gcc 8 (Debian 8.3.0-6)


2) compiled for myself

$ ~/bin/ffmpeg -version
ffmpeg version N-97910-g88567a2 built with gcc 8 (Debian 8.3.0-6)


using -loglevel debug and ffv1

~/bin/ffmpeg -i INPUT.mkv \
    -t 00:00:10.000     \
    -acodec  copy       \
    -vcodec  ffv1       \
    -level 1 -coder 1 -context 1 -g 1 \
    -loglevel debug     \
    OUTPUT.mkv 2&gt;&amp;1|tee ffmpeg.log


result: unable to find a single occurrence of the word "drop" in log.txt file

How to output the missing "dup" and "drop" in my log?
If no frames are dupped or dropped, then those fields are not printed.

If you need a definitive statement, add -progress filename to print progress report to a file and search for dup_frames and drop_frames.