On 04 Jul 2016, at 00:45, Henk D. Schoneveld <[email protected]> wrote:
> > On 03 Jul 2016, at 23:28, Rae, Philip John <[email protected]> wrote: > >> I am new to ffmpeg and I have a question about ‘decimating’ movies to remove >> unwanted frames. I have a high speed movie with too many frames (too little >> motion between frames) that I want to remove 4 in 5 frames (for instance) >> and resave the shorter one (fewer frames and a shorter duration movie). >> >> I thought the following would work after some research >> >> ffmpeg -y -i Test_too_slow.avi -filter:v "select='not(mod(n\,5))'” out.avi >> >> but it keeps the duration of the movie the same as the input rather than a >> fifth as long and it appears to do this by repeating frames. This is >> obviously not what I want. The original had 700 frames and played at 12 fps. >> 700/5 is 140. Indeed looking at the output below, the number of processed >> frames is 141, however, the duration is still 58 seconds rather than 11.6. >> >> I have tried playing with the -r and -framerate options, but this appeared >> to do nothing useful in this case. >> >> I also tried post processing the output >> >> ffmpeg -i out.avi -filter:v "setpts=0.2*PTS" out2.avi >> >> but that worked poorly since the movie became very jumpy as if the >> extraction did not rip out evenly spaced extra dummy frames installed by the >> previous operation but a variable frame each few cycles. >> >> >> I am sure there is a simple fix, but it escapes me at the moment. > What works: ffmpeg -r 5timesoriginalspeed -i source.ext -c:v lbx264 -c:a copy > -r originalspeed resultwith20%oforiginalframes.ext > Sample: > frame= 7942 fps= 69 q=-1.0 Lsize= 92340kB time=00:26:27.16 bitrate= > 476.6kbits/s dup=0 drop=31758 > Resulting 7942 frames and dropped 31758. It obviously plays at 5 times the > speed of the original. Sound isn’t synced that’s another hurdle to be solved though. Audio is unsynced and undecimated. >> >> >> Many thanks >> >> Philip >> >> ffmpeg -y -i Test_too_slow.avi -filter:v "select='not(mod(n\,5))'" out.avi >> ffmpeg version 3.1.1-tessus Copyright (c) 2000-2016 the FFmpeg developers >> built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn) >> configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --as=yasm >> --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl >> --enable-libass --enable-libbluray --enable-libfreetype --enable-libgsm >> --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb >> --enable-libopencore-amrwb --enable-libopus --enable-libschroedinger >> --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora >> --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis >> --enable-libvpx --enable-libwavpack --enable-libx264 --enable-libx265 >> --enable-libxavs --enable-libxvid --enable-libzmq --enable-version3 >> --disable-ffplay --disable-indev=qtkit --disable-indev=x11grab_xcb >> libavutil 55. 28.100 / 55. 28.100 >> libavcodec 57. 48.101 / 57. 48.101 >> libavformat 57. 41.100 / 57. 41.100 >> libavdevice 57. 0.101 / 57. 0.101 >> libavfilter 6. 47.100 / 6. 47.100 >> libswscale 4. 1.100 / 4. 1.100 >> libswresample 2. 1.100 / 2. 1.100 >> libpostproc 54. 0.100 / 54. 0.100 >> Input #0, avi, from 'Test_too_slow.avi': >> Duration: 00:00:58.27, start: 0.000000, bitrate: 138830 kb/s >> Stream #0:0: Video: rawvideo, bgr24, 800x600, 138993 kb/s, 12.05 fps, >> 12.05 tbr, 12.05 tbn, 12.05 tbc >> [avi @ 0x7fc38a00fc00] Using AVStream.codec to pass codec parameters to >> muxers is deprecated, use AVStream.codecpar instead. >> Output #0, avi, to 'out.avi': >> Metadata: >> ISFT : Lavf57.41.100 >> Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 800x600, q=2-31, >> 200 kb/s, 12.05 fps, 12.05 tbn, 12.05 tbc >> Metadata: >> encoder : Lavc57.48.101 mpeg4 >> Side data: >> cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1 >> Stream mapping: >> Stream #0:0 -> #0:0 (rawvideo (native) -> mpeg4 (native)) >> Press [q] to stop, [?] for help >> frame= 141 fps=0.0 q=4.5 Lsize= 956kB time=00:00:58.18 bitrate= >> 134.5kbits/s speed= 134x >> video:934kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB >> muxing overhead: 2.362345% >> >> >> >> >> >> >> >> >> >> "You are entitled to your own opinion, but you are not entitled to your own >> facts.", Daniel Patrick Moynihan (1927-2003) >> >> ************************************ >> Philip Rae >> PO Box 1663, MS-J564 >> Los Alamos >> NM 87545 >> Tel:- 505 667 4436 >> Fax:- 505 667 9809 >> e-mail:- [email protected]<mailto:[email protected]> >> ************************************ >> >> >> >> >> >> >> _______________________________________________ >> ffmpeg-user mailing list >> [email protected] >> http://ffmpeg.org/mailman/listinfo/ffmpeg-user >> >> To unsubscribe, visit link above, or email >> [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
