How to use FFmpeg for video editing, merging, and screenshots? What are some practical tips?

FFmpeg provides powerful video editing and processing capabilities, allowing precise control over video time ranges, segment extraction, and merging.

Video Editing

Clip by Time Range

bash
# Start from 10 seconds, clip 30 seconds
ffmpeg -i input.mp4 -ss 00:00:10 -t 00:00:30 -c copy output.mp4

# Start from 1 minute 30 seconds, clip to 3 minutes
ffmpeg -i input.mp4 -ss 00:01:30 -to 00:03:00 -c copy output.mp4

Precise Clipping Techniques

When using the -ss parameter, placing it before -i enables fast seeking but may not be precise; placing it after -i is more precise but slower.

bash
# Fast seeking (may not be precise)
ffmpeg -ss 00:00:10 -i input.mp4 -t 00:00:30 -c copy output.mp4

# Precise seeking (slower)
ffmpeg -i input.mp4 -ss 00:00:10 -t 00:00:30 -c copy output.mp4

Video Merging

Using concat protocol

bash
# Create file list filelist.txt
file 'part1.mp4'
file 'part2.mp4'
file 'part3.mp4'

# Merge videos
ffmpeg -f concat -safe 0 -i filelist.txt -c copy output.mp4

Using concat filter

bash
ffmpeg -i part1.mp4 -i part2.mp4 -i part3.mp4 \
  -filter_complex "[0:v][0:a][1:v][1:a][2:v][2:a]concat=n=3:v=1:a=1[outv][outa]" \
  -map "[outv]" -map "[outa]" output.mp4

Video Screenshots

Single Frame Screenshot

bash
# Capture one frame at 5 seconds
ffmpeg -i input.mp4 -ss 00:00:05 -vframes 1 screenshot.jpg

# Capture first frame
ffmpeg -i input.mp4 -vframes 1 first_frame.png

Batch Screenshots

bash
# Capture one frame per second
ffmpeg -i input.mp4 -vf fps=1 screenshot_%04d.jpg

# Capture one frame every 5 seconds
ffmpeg -i input.mp4 -vf fps=1/5 screenshot_%04d.jpg

Video Processing

Adjust Resolution

bash
# Scale to 1280x720
ffmpeg -i input.mp4 -vf scale=1280:720 output.mp4

# Scale while maintaining aspect ratio
ffmpeg -i input.mp4 -vf scale=1280:-1 output.mp4

Rotate Video

bash
# Rotate 90 degrees clockwise
ffmpeg -i input.mp4 -vf "transpose=1" output.mp4

# Rotate 90 degrees counter-clockwise
ffmpeg -i input.mp4 -vf "transpose=2" output.mp4

Add Watermark

bash
# Add image watermark
ffmpeg -i input.mp4 -i watermark.png -filter_complex "overlay=10:10" output.mp4

# Add text watermark
ffmpeg -i input.mp4 -vf "drawtext=text='Watermark':fontcolor=white:fontsize=24:x=10:y=10" output.mp4

Audio/Video Separation and Merging

Extract Audio

bash
# Extract audio stream
ffmpeg -i video.mp4 -vn -acodec copy audio.aac

# Convert audio format
ffmpeg -i video.mp4 -vn -acodec libmp3lame -ab 192k audio.mp3

Extract Video

bash
# Extract video stream (no audio)
ffmpeg -i video.mp4 -an -c:v copy video.mp4

Merge Audio and Video

bash
# Merge audio and video
ffmpeg -i video.mp4 -i audio.mp3 -c:v copy -c:a aac -strict experimental output.mp4

When editing and processing videos, using -c copy avoids re-encoding, improving processing speed while maintaining original quality.