ffmpeg

  Video conversion tool.
  More information: <https://ffmpeg.org>.

  Extract the sound from a video and save it as MP3:

      ffmpeg -i path/to/video.mp4 -vn path/to/sound.mp3

  Transcode a FLAC file to Red Book CD format (44100kHz, 16bit):

      ffmpeg -i path/to/input_audio.flac -ar 44100 -sample_fmt s16 path/to/output_audio.wav

  Save a video as GIF, scaling the height to 1000px and setting framerate to 15:

      ffmpeg -i path/to/video.mp4 [-vf|-filter:v] 'scale=-1:1000' -r 15 path/to/output.gif

  Combine numbered images (`frame_1.jpg`, `frame_2.jpg`, etc) into a video or GIF:

      ffmpeg -i path/to/frame_%d.jpg -f image2 video.mpg|video.gif

  Trim a video from a given start time mm:ss to an end time mm2:ss2 (omit the -to flag to trim till the end):

      ffmpeg -i path/to/input_video.mp4 -ss mm:ss -to mm2:ss2 [-c|-codec] copy path/to/output_video.mp4

  Convert AVI video to MP4. AAC Audio @ 128kbit, h264 Video @ CRF 23:

      ffmpeg -i path/to/input_video.avi [-c|-codec]:a aac -b:a 128k [-c|-codec]:v libx264 -crf 23 path/to/output_video.mp4

  Remux MKV video to MP4 without re-encoding audio or video streams:

      ffmpeg -i path/to/input_video.mkv [-c|-codec] copy path/to/output_video.mp4

  Convert MP4 video to VP9 codec. For the best quality, use a CRF value (recommended range 15-35) and -b:v MUST be 0:

      ffmpeg -i path/to/input_video.mp4 [-c|-codec]:v libvpx-vp9 -crf 30 -b:v 0 [-c|-codec]:a libopus -vbr on -threads number_of_threads path/to/output_video.webm