[FFmpeg-user] Cutting out part of a video does not work

[Cecil Westerhof]

I want to publish a speech I gave during a Zoom meeting. But cutting
it out does not work.

When I use:
    ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 -acodec copy -vcodec copy -async 1 speech.mp4

The video starts just a bit to late. But when I use:
    ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 -acodec copy -vcodec copy -async 1 speech.mp4

which is five seconds earlier. I get the same output.

Am I doing something wrong?


Output:
ffmpeg version 4.1.6-1~deb10u1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 8 (Debian 8.3.0-6)
  configuration: --prefix=/usr --extra-version='1~deb10u1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '2021-03-25ToastmastersClubAvond.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2021-03-25T19:02:11.000000Z
  Duration: 01:34:26.16, start: 0.000000, bitrate: 2198 kb/s
    Chapter #0:0: start 0.000000, end 4016.120000
    Metadata:
      title           : Recording Started
    Chapter #0:1: start 4016.120000, end 4048.200000
    Metadata:
      title           : Sharing Started
    Chapter #0:2: start 4048.200000, end 5666.160000
    Metadata:
      title           : Sharing Stopped
    Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 126 kb/s (default)
    Metadata:
      creation_time   : 2021-03-25T19:02:11.000000Z
      handler_name    : AAC audio
    Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 2070 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 2021-03-25T19:02:11.000000Z
      handler_name    : H.264/AVC video
      encoder         : AVC Coding
    Stream #0:2(und): Data: bin_data (text / 0x74786574)
    Metadata:
      creation_time   : 2021-03-25T19:02:11.000000Z
      handler_name    : Text
Output #0, mp4, to 'speech.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    encoder         : Lavf58.20.100
    Chapter #0:0: start 0.000000, end 446.000000
    Metadata:
      title           : Recording Started
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, q=2-31, 2070 kb/s, 25 fps, 25 tbr, 30k tbn, 30k tbc (default)
    Metadata:
      creation_time   : 2021-03-25T19:02:11.000000Z
      handler_name    : H.264/AVC video
      encoder         : AVC Coding
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 126 kb/s (default)
    Metadata:
      creation_time   : 2021-03-25T19:02:11.000000Z
      handler_name    : AAC audio
Stream mapping:
  Stream #0:1 -> #0:0 (copy)
  Stream #0:0 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame=    0 fps=0.0 q=-1.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x    .frame= 2057 fps=2057 q=-1.0 size=   39168kB time=00:01:27.80 bitrate=3654.5kbits/s speed=87.8x    .frame= 7885 fps=5256 q=-1.0 size=  154112kB time=00:05:21.27 bitrate=3929.6kbits/s speed= 214x    .frame=11017 fps=5760 q=-1.0 Lsize=  232009kB time=00:07:25.97 bitrate=4261.7kbits/s speed= 233x    
video:224885kB audio:6873kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.107917%

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof