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• How to cut video, add audio and burn subtitle while cropping video all in one command - ffmpeg

  15 mars 2023, par constantlyFlagged

  Currently I have the following code,

  


  which cuts the video, adds audio and burns subtitle into the video.

  


  -ss 00:00:30 -t -i video.mp4 -i audio.wav -vcodec copy  -acodec copy -map 0:0 -map 1:0 -vf subtitles=subtitle.srt


  


  but I need to crop the video before the subtitle is added. I know it is possible to crop video using the command :

  


  -vf crop=405:720


  


  or using

  


  -filter:v crop=405:720


  


  but I am unable to use it in conjunction with the above statement. What would be the best approch to get the desribed outcome ?

  


• Cutting sections with -ss and -t is not frame accurate

  16 avril 2024, par Théo Champion

  I'm using ffmpeg 6.0 to extract small sections from longer videos. According to the doc i can use the -ss option to specify the start time and the -t option to specify the duration and this should result in frame accurate cuts (since FFmpeg 2.1).

  


  However, in my testing i found that the cuts are not frame accurate. I'm using the following command :

  


  ffmpeg -ss 10 -i ffmpeg -ss 10 -i https://storage.googleapis.com/klap-assets/Frame%20Counter%20%5B4K%2C%2060%20FPS%5D%20%E2%80%93%200100.mp4   -t 10 -y -vcodec libx264 -acodec aac -movflags +faststart out2.mp4   -t 10 -y -vcodec libx264 -acodec aac -movflags +faststart out.mp4


  


  This result in a video that start at 9:57 (-2 frames) and ends at 19:57 (-2 frames) instead of 10:00 and 20:00.

  


  Also weird is that ffprobe on the resulting video show its duration being exactly 10 seconds.

  


  FFprobe of the resulting video :

  


  ffprobe version 6.0 Copyright (c) 2007-2023 the FFmpeg developers
  built with Apple clang version 14.0.0 (clang-1400.0.29.202)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.0 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-neon
  libavutil      58.  2.100 / 58.  2.100
  libavcodec     60.  3.100 / 60.  3.100
  libavformat    60.  3.100 / 60.  3.100
  libavdevice    60.  1.100 / 60.  1.100
  libavfilter     9.  3.100 /  9.  3.100
  libswscale      7.  1.100 /  7.  1.100
  libswresample   4. 10.100 /  4. 10.100
  libpostproc    57.  1.100 / 57.  1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'out2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf60.3.100
  Duration: 00:00:10.00, start: 0.000000, bitrate: 303 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, smpte170m/bt470bg/bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 287 kb/s, 60 fps, 60 tbr, 15360 tbn (default)
    Metadata:
      handler_name    : ISO Media file produced by Google Inc.
      vendor_id       : [0][0][0][0]
      encoder         : Lavc60.3.100 libx264
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 2 kb/s (default)
    Metadata:
      handler_name    : ISO Media file produced by Google Inc.
      vendor_id       : [0][0][0][0]


  


  I've done some testing with other videos and results are never totally frame accurate.

  


  What am i missing here ? How can i get frame accurate cuts with FFmpeg ?

  


• Does H.264 standard allow separate luma and chroma QP control in Baseline Profile ?

  28 août 2013, par Bhaskar Dey

  Although the wikipedia article states that separate luma and chroma QP (quantization parameter) is only supported in High profiles, I didn't find any supporting reference. At least, Rec. ITU-T H.264 (04/2013) section A.2.1 does not mention any such limitation for the Baseline Profile.

  Any comment in this regard would be of great help.