Processing: Editing and Audio/Video Operations

General FFmpeg Usage

Start at one minute and output 30 seconds:

ffmpeg \
  -ss 00:01:00 \
  -i input.mp4 \
  -t 30 \
  -c copy \
  clip.mp4

With -c copy, copying can only begin at a nearby keyframe, so the start point may not be exact. Re-encode when frame-accurate trimming is required:

ffmpeg \
  -ss 00:01:00 \
  -i input.mp4 \
  -t 30 \
  -c:v libx264 \
  -crf 23 \
  -c:a aac \
  clip-accurate.mp4

Scale proportionally to 720p:

ffmpeg -i input.mp4 -vf 'scale=-2:720' -c:v libx264 -crf 23 -c:a copy output-720p.mp4

Crop the center to 1280x720:

ffmpeg \
  -i input.mp4 \
  -vf "crop=1280:720:(iw-ow)/2:(ih-oh)/2" \
  -c:v libx264 \
  -crf 23 \
  -c:a copy \
  output-crop.mp4

Rotate clockwise by 90 degrees:

ffmpeg -i input.mp4 -vf 'transpose=clock' -c:v libx264 -crf 23 -c:a copy output-rotate.mp4

Extract one frame at 10 seconds:

ffmpeg -ss 10 -i input.mp4 -frames:v 1 screenshot.png

Output one image every five seconds:

ffmpeg -i input.mp4 -vf 'fps=1/5' 'frame-%05d.jpg'

Extract an AAC audio stream without re-encoding:

ffmpeg -i input.mp4 -vn -c:a copy output.m4a

Convert to 48 kHz stereo AAC:

ffmpeg \
  -i input.mp4 \
  -vn \
  -ar 48000 \
  -ac 2 \
  -c:a aac \
  -b:a 192k \
  output.m4a

Adjust the volume:

ffmpeg -i input.wav -af 'volume=1.5' output.wav