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I am tring to cut a video in linux OS

$ ffmpeg -i dhol.mkv 
ffmpeg version n4.1.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 8.2.1 (GCC) 20181127
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3
  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
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Input #0, matroska,webm, from 'dhol.mkv':
  Metadata:
    ENCODER         : Lavf58.20.100
  Duration: 00:03:56.18, start: -0.007000, bitrate: 2688 kb/s
    Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv, bt709/unknown/unknown), 1920x1080, SAR 1:1 DAR 16:9, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      DURATION        : 00:03:56.167000000
    Stream #0:1(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
    Metadata:
      DURATION        : 00:03:56.181000000

I was trying to precisely cut the video file:

But using ffmpeg I was not successfull. It cuts from the nearest key frames to the given start time

ffmpeg -y -i dhol.mkv -ss $shift   -t $duration -c:v copy -an output.mkv

ONE OF THE REASONS HERE IS H.264 Video format (YUV420p vs YUV420sp). I am using -c:v copy so it has to use the same format YUV420p, so it has to start from nearest keyframe

Now the only reliable software that i can fully depend if avidemux.

Even in that i have to select

video-codec: MJPEG
audio-codec: vorbis

But the cut video size will be large.

I tried in avidemux 

video-codec: copy
audio-codec: copy

It will cut from nearest keyframe than precisely.

One conclusion: So irrespective of ffmpeg or avidemux, the output video format yuv420p will not allow precise formatting

Only option currently possible:

Using avidemux and with

video-codec: MJPEG
audio-codec: vorbis

Cons: 

1) bigger video size.
2) no proper command line examples available for avidemux to do the same as gui does

I tried command line in avidemux:

avidemux3_cli --video-codec MJPEG --audio-codec AAC --output-format AVI --load dhol.mkv --begin 137.633 --end 141.334 --save dhol2.mkv

It tries to convert the whole file rather than from the start to end time

My requirement: I want to do it command line.

I didnt try with ffmpeg (with video codec: MJPEG and audio: vorbis). I never saw any example

How to precisely cut a video (even the output format can be different (like MJPEG instead of yuv420p, and also bigger sizes, its ok) using command line

Santhosh
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  • have you tried adding keyframes where you need them `ffmpeg -i input.mp4 -force_key_frames 00:00:10,00:00:24 output.mp4` though that does require a recode. also check https://stackoverflow.com/questions/21420296/how-to-extract-time-accurate-video-segments-with-ffmpeg – Offbeatmammal Oct 19 '19 at 09:39
  • Use a more efficient codec that MJPEG, and set a bit rate. Also, the pixel format (yuv420) is unrelated to your question. – szatmary Oct 19 '19 at 15:21
  • `getting black frames at the end of the trimmed video`. https://stackoverflow.com/questions/21420296/how-to-extract-time-accurate-video-segments-with-ffmpeg#comment32354905_21422776. How to avoid black frames – Santhosh Nov 07 '19 at 04:21
  • I am facing a similar issue. So far the only thing that worked for me is converting video to images in a folder and assemble them back based on timing. I used ffmpeg. – Axeon Thra Nov 26 '21 at 04:48

0 Answers0