Professional video editing is usually done in Adobe Premiere or Final Cut Pro. However, for simple video editing tasks, such as cutting one segment out of a long video, or cropping the frame to a smaller size, etc., it is not necessary to use these bulky software, let alone they are quite expensive. Fortunately, ffmpeg is a free but powerful tool to solve these video editing tasks.

This article serves as a cookbook for frequently used video editing tasks using ffmpeg. It will be updated as new recipes emerges.

Video Size Modification

Cropping frame

ffmpeg -i input.mp4 -filter:v "crop=width:height:left:top" output.mp4

The above command crops the input video from the (left, top) point using a rectangle with width and height.

Resize Video

ffmpeg \
    -i input.mp4 \
    -vf scale=1280:720 \
    -fps_mode passthrough \
    -c:v libx264 \
    -b:v 1M \
    -c:a copy \
    output.mp4

With an NVIDIA GPU, you can significantely expedite the process

ffmpeg \
    -hwaccel cuvid \
    -hwaccel_output_format cuda \
    -c:v h264_cuvid \
    -resize 1280x720 \
    -i input.mp4 \
    -fps_mode passthrough \
    -c:v h264_nvenc \
    -c:a copy \
    -b:v 1M \
    output.mp4

Note that the code above requires the input to be encoded using H.264.

File Operations

Concatenating a series of files

ffmpeg -f concat -i files.txt output.mp4

where files.txt contains the list of files to concatenate¹. The format is

file '/path/to/file1'
file '/path/to/file2'

Time Related Operations

Cut Video By Time

ffmpeg \
    -i input.mp4 \
    -t 00:05:00 \
    -c copy part1.mp4 \
    -ss 00:05:00 \
    -c copy part2.mp4

Option -t specifies the time length of the output video and option -ss specifies the start timestamp. Combining these two options can be used to split or cut video by time.

References