On Tue, Mar 09, 2021 at 04:27:14PM +0100, Peter White wrote: > Hi all, > > as a follow-up to this discussion: > https://ffmpeg.org/pipermail/ffmpeg-user/2021-March/052358.html > > I would like to ask, if frame counting with ffprobe can be made faster. > The way it done now is obviously by decoding every single frame and > afterwards incrementing the counter. See how slow this example runs: > > time ffprobe -count_frames -select_streams v:0 -show_entries > stream=nb_read_frames -of default=nokey=1:noprint_wrappers=1 input.mkv > [...] > title : English > BPS-eng : 72 > DURATION-eng : 00:21:36.169000000 > NUMBER_OF_FRAMES-eng: 370 > NUMBER_OF_BYTES-eng: 11676 > _STATISTICS_WRITING_APP-eng: mkvmerge v45.0.0 ('Heaven in Pennies') > 64-bit > _STATISTICS_WRITING_DATE_UTC-eng: 2021-02-16 19:59:37 > _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES > 31186 > ffprobe -count_frames -select_streams v:0 -show_entries stream=nb_read_frames > 55,01s user 0,10s system 99% cpu 55,182 total > > And apparently ffprobe only uses one CPU core by default as opposed to > ffmpeg; see the 99% load. This machine has 8 threads, hence is capable > of 800%, theoretically. But that is just an aside.
FWIW, this last bit seems to be due to different defaults for ffprobe. -threads 0 does show a load of 250% but the speedup is marginal, less than 5 seconds. Peter _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
