How to use FFmpeg for screen recording and camera capture?

FFmpeg can not only process existing video files but also capture video and audio from various devices, enabling recording functionality.

Screen Recording

macOS Screen Recording

bash
# Record entire screen
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset ultrafast -crf 23 output.mp4

# Record specific area
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset ultrafast -crf 23 -vf "crop=1280:720:0:0" output.mp4

# Record screen and audio
ffmpeg -f avfoundation -i "1:0" -r 30 -c:v libx264 -preset ultrafast -crf 23 -c:a aac -b:a 128k output.mp4

Linux Screen Recording

bash
# Record using x11grab
ffmpeg -f x11grab -video_size 1920x1080 -framerate 30 -i :0.0 -c:v libx264 -preset ultrafast -crf 23 output.mp4

# Record specific window
ffmpeg -f x11grab -video_size 800x600 -framerate 30 -i :0.0+100,100 -c:v libx264 -preset ultrafast -crf 23 output.mp4

Windows Screen Recording

bash
# Record entire screen using gdigrab
ffmpeg -f gdigrab -framerate 30 -i desktop -c:v libx264 -preset ultrafast -crf 23 output.mp4

# Record specific window
ffmpeg -f gdigrab -framerate 30 -i title="Window Title" -c:v libx264 -preset ultrafast -crf 23 output.mp4

Camera Recording

macOS Camera Recording

bash
# List available devices
ffmpeg -f avfoundation -list_devices true -i ""

# Record camera
ffmpeg -f avfoundation -i "0" -r 30 -c:v libx264 -preset ultrafast -crf 23 output.mp4

# Record camera and microphone
ffmpeg -f avfoundation -i "0:0" -r 30 -c:v libx264 -preset ultrafast -crf 23 -c:a aac -b:a 128k output.mp4

Linux Camera Recording

bash
# Record using v4l2
ffmpeg -f v4l2 -video_size 640x480 -framerate 30 -i /dev/video0 -c:v libx264 -preset ultrafast -crf 23 output.mp4

# Record camera and audio
ffmpeg -f v4l2 -video_size 640x480 -framerate 30 -i /dev/video0 -f alsa -i hw:0 -c:v libx264 -preset ultrafast -crf 23 -c:a aac -b:a 128k output.mp4

Windows Camera Recording

bash
# Record using dshow
ffmpeg -f dshow -video_size 640x480 -framerate 30 -i video="Camera Name" -c:v libx264 -preset ultrafast -crf 23 output.mp4

# Record camera and microphone
ffmpeg -f dshow -video_size 640x480 -framerate 30 -i video="Camera Name" -f dshow -i audio="Microphone Name" -c:v libx264 -preset ultrafast -crf 23 -c:a aac -b:a 128k output.mp4

Audio Recording

macOS Audio Recording

bash
# Record system audio
ffmpeg -f avfoundation -i ":0" -c:a aac -b:a 128k output.aac

# Record microphone
ffmpeg -f avfoundation -i "0:0" -c:a aac -b:a 128k output.aac

Linux Audio Recording

bash
# Record using alsa
ffmpeg -f alsa -i hw:0 -c:a aac -b:a 128k output.aac

# Record using pulseaudio
ffmpeg -f pulse -i default -c:a aac -b:a 128k output.aac

Windows Audio Recording

bash
# Record audio using dshow
ffmpeg -f dshow -i audio="Microphone Name" -c:a aac -b:a 128k output.aac

Real-time Streaming Recording

Stream to RTMP Server

bash
# Screen recording and streaming
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset ultrafast -b:v 2000k -f flv rtmp://server/live/stream_key

# Camera recording and streaming
ffmpeg -f avfoundation -i "0:0" -r 30 -c:v libx264 -preset ultrafast -b:v 2000k -c:a aac -b:a 128k -f flv rtmp://server/live/stream_key

Stream to RTSP Server

bash
# Stream to RTSP
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset ultrafast -f rtsp rtsp://server/live/stream

Recording Parameter Optimization

Reduce Latency

bash
# Use ultrafast preset
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset ultrafast -tune zerolatency -crf 23 output.mp4

# Use hardware acceleration
ffmpeg -f avfoundation -i "1" -r 30 -c:v h264_videotoolbox -b:v 2000k output.mp4

Improve Quality

bash
# Use higher quality encoding parameters
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset medium -crf 18 output.mp4

# Use higher bitrate
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset medium -b:v 5000k output.mp4

Reduce File Size

bash
# Use higher CRF value
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset medium -crf 28 output.mp4

# Lower resolution
ffmpeg -f avfoundation -i "1" -r 30 -vf scale=1280:720 -c:v libx264 -preset medium -crf 23 output.mp4

Advanced Recording Features

Timed Recording

bash
# Record for 60 seconds
ffmpeg -f avfoundation -i "1" -r 30 -t 60 -c:v libx264 -preset ultrafast -crf 23 output.mp4

# Record until specified time
ffmpeg -f avfoundation -i "1" -r 30 -to 00:01:00 -c:v libx264 -preset ultrafast -crf 23 output.mp4

Segmented Recording

bash
# Generate new file every 60 seconds
ffmpeg -f avfoundation -i "1" -r 30 -c:v libx264 -preset ultrafast -crf 23 -f segment -segment_time 60 output_%03d.mp4

Add Watermark

bash
# Add watermark while recording
ffmpeg -f avfoundation -i "1" -i watermark.png -filter_complex "overlay=10:10" -r 30 -c:v libx264 -preset ultrafast -crf 23 output.mp4

Device List Query

Query Available Devices

bash
# macOS
ffmpeg -f avfoundation -list_devices true -i ""

# Linux
v4l2-ctl --list-devices
ffmpeg -f v4l2 -list_formats all -i /dev/video0

# Windows
ffmpeg -f dshow -list_devices true -i dummy

Recording Best Practices

1. Choose appropriate preset: Use ultrafast or veryfast for real-time recording
2. Use hardware acceleration: Use hardware encoding when supported
3. Set reasonable resolution: Choose based on network bandwidth and storage space
4. Monitor resource usage: Pay attention to CPU and memory usage
5. Test recording effect: Test before formal recording

When recording, you need to choose appropriate parameter combinations based on specific application scenarios (such as live streaming, recording, monitoring, etc.).