FFmpeg
Probe and Inspect
# Show all stream info (codec, resolution, bitrate, duration)
ffprobe -v error -show_format -show_streams input.mp4
# One-line summary: duration, size, bitrate
ffprobe -v error -show_entries format=duration,size,bit_rate -of default=noprint_wrappers=1 input.mp4
# Show video resolution and frame rate
ffprobe -v error -select_streams v:0 -show_entries stream=width,height,r_frame_rate,codec_name -of csv=p=0 input.mp4
# List all supported codecs
ffmpeg -codecs
# List all supported formats
ffmpeg -formats
# List available encoders
ffmpeg -encoders
Convert Between Formats
# MP4 to MKV (copy streams, no re-encode -- fast)
ffmpeg -i input.mp4 -c copy output.mkv
# MKV to MP4 (re-encode if codecs are incompatible with MP4 container)
ffmpeg -i input.mkv -c:v libx264 -c:a aac output.mp4
# AVI to MP4
ffmpeg -i input.avi -c:v libx264 -c:a aac output.mp4
# MOV to MP4 (common for iPhone footage)
ffmpeg -i input.mov -c:v libx264 -c:a aac -movflags +faststart output.mp4
# MP4 to WebM (VP9 + Opus for web)
ffmpeg -i input.mp4 -c:v libvpx-vp9 -crf 30 -b:v 0 -c:a libopus output.webm
# Any format, let FFmpeg pick codecs for the target container
ffmpeg -i input.avi output.mp4
Compress Video
# CRF mode (constant quality). Lower CRF = better quality, bigger file.
# CRF 18 = visually lossless, 23 = default, 28 = smaller but visible loss.
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k output.mp4
# Faster encoding, larger file
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset fast -c:a copy output.mp4
# Slower encoding, smaller file (use for archival)
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset slow -c:a aac output.mp4
# H.265 for ~50% smaller files at same quality (slower to encode)
ffmpeg -i input.mp4 -c:v libx265 -crf 28 -preset medium -c:a aac output.mp4
# Target a specific file size (e.g., 25 MB for a 60s video)
# Calculate bitrate: (25 * 8192) / 60 = ~3413 kbps total. Subtract ~128 for audio.
ffmpeg -i input.mp4 -c:v libx264 -b:v 3285k -pass 1 -an -f null /dev/null && \
ffmpeg -i input.mp4 -c:v libx264 -b:v 3285k -pass 2 -c:a aac -b:a 128k output.mp4
Extract Audio
# Extract audio as MP3
ffmpeg -i input.mp4 -vn -c:a libmp3lame -q:a 2 output.mp3
# Extract audio as AAC (copy if already AAC)
ffmpeg -i input.mp4 -vn -c:a copy output.aac
# Extract audio as WAV (uncompressed)
ffmpeg -i input.mp4 -vn -c:a pcm_s16le output.wav
# Extract audio as FLAC (lossless)
ffmpeg -i input.mp4 -vn -c:a flac output.flac
Convert Audio Formats
# WAV to MP3 (VBR quality 2, roughly 190 kbps)
ffmpeg -i input.wav -c:a libmp3lame -q:a 2 output.mp3
# MP3 to AAC
ffmpeg -i input.mp3 -c:a aac -b:a 192k output.m4a
# FLAC to MP3
ffmpeg -i input.flac -c:a libmp3lame -q:a 0 output.mp3
# WAV to OGG Vorbis
ffmpeg -i input.wav -c:a libvorbis -q:a 5 output.ogg
# WAV to Opus (best quality-to-size ratio)
ffmpeg -i input.wav -c:a libopus -b:a 128k output.opus
# Any audio to WAV (for editing or compatibility)
ffmpeg -i input.mp3 -c:a pcm_s16le -ar 44100 output.wav
Trim and Cut
# Cut from 00:01:30 to 00:03:00 without re-encoding (fast, may have keyframe issues)
ffmpeg -ss 00:01:30 -to 00:03:00 -i input.mp4 -c copy output.mp4
# Cut with re-encoding (frame-accurate)
ffmpeg -ss 00:01:30 -to 00:03:00 -i input.mp4 -c:v libx264 -c:a aac output.mp4
# Cut first 30 seconds
ffmpeg -ss 0 -t 30 -i input.mp4 -c copy output.mp4
# Cut last 30 seconds (requires knowing duration, or use negative start)
ffmpeg -sseof -30 -i input.mp4 -c copy output.mp4
# Remove first 10 seconds
ffmpeg -ss 10 -i input.mp4 -c copy output.mp4
Create GIF
# Basic GIF (low quality, simple)
ffmpeg -i input.mp4 -vf "fps=10,scale=480:-1" output.gif
# High-quality GIF with palette generation (two-pass)
ffmpeg -i input.mp4 -vf "fps=15,scale=480:-1:flags=lanczos,palettegen" palette.png && \
ffmpeg -i input.mp4 -i palette.png -lavfi "fps=15,scale=480:-1:flags=lanczos [x]; [x][1:v] paletteuse" output.gif
# GIF from a specific segment (5 seconds starting at 00:00:30)
ffmpeg -ss 00:00:30 -t 5 -i input.mp4 -vf "fps=15,scale=480:-1:flags=lanczos,palettegen" palette.png && \
ffmpeg -ss 00:00:30 -t 5 -i input.mp4 -i palette.png -lavfi "fps=15,scale=480:-1:flags=lanczos [x]; [x][1:v] paletteuse" output.gif
Scale and Resize
# Scale to 1280x720
ffmpeg -i input.mp4 -vf "scale=1280:720" -c:a copy output.mp4
# Scale width to 1280, keep aspect ratio (-1 auto-calculates, -2 ensures even number)
ffmpeg -i input.mp4 -vf "scale=1280:-2" -c:a copy output.mp4
# Scale to 50% of original size
ffmpeg -i input.mp4 -vf "scale=iw/2:ih/2" -c:a copy output.mp4
# Scale to fit within 1920x1080, preserving aspect ratio (no upscale)
ffmpeg -i input.mp4 -vf "scale='min(1920,iw)':'min(1080,ih)':force_original_aspect_ratio=decrease" -c:a copy output.mp4
Subtitles
# Hardcode subtitles (burn into video, always visible)
ffmpeg -i input.mp4 -vf "subtitles=subs.srt" output.mp4
# Hardcode with custom style
ffmpeg -i input.mp4 -vf "subtitles=subs.srt:force_style='FontSize=24,PrimaryColour=&HFFFFFF'" output.mp4
# Soft subtitles (user can toggle on/off, MP4)
ffmpeg -i input.mp4 -i subs.srt -c copy -c:s mov_text output.mp4
# Soft subtitles (MKV, supports more formats including ASS)
ffmpeg -i input.mp4 -i subs.srt -c copy -c:s srt output.mkv
# Extract subtitles from video
ffmpeg -i input.mkv -map 0:s:0 output.srt
Merge and Concatenate
# Concatenate videos (same codec, resolution, framerate)
# First create a file list:
# file 'part1.mp4'
# file 'part2.mp4'
# file 'part3.mp4'
ffmpeg -f concat -safe 0 -i filelist.txt -c copy output.mp4
# Generate the file list from shell
for f in part*.mp4; do echo "file '$f'"; done > filelist.txt
ffmpeg -f concat -safe 0 -i filelist.txt -c copy output.mp4
# Concatenate with re-encoding (when formats differ)
ffmpeg -f concat -safe 0 -i filelist.txt -c:v libx264 -c:a aac output.mp4
# Combine video and audio from separate files
ffmpeg -i video.mp4 -i audio.mp3 -c:v copy -c:a aac -shortest output.mp4
# Replace audio track in a video
ffmpeg -i video.mp4 -i newaudio.mp3 -c:v copy -c:a aac -map 0:v:0 -map 1:a:0 output.mp4
Extract Frames
# Extract one frame at a specific timestamp
ffmpeg -ss 00:01:30 -i input.mp4 -frames:v 1 frame.png
# Extract one frame every second
ffmpeg -i input.mp4 -vf "fps=1" frames_%04d.png
# Extract one frame every 10 seconds
ffmpeg -i input.mp4 -vf "fps=1/10" frames_%04d.png
# Extract all frames (warning: generates many files)
ffmpeg -i input.mp4 frames_%06d.png
# Create a thumbnail sheet (4x4 grid)
ffmpeg -i input.mp4 -vf "select='not(mod(n\,100))',scale=320:180,tile=4x4" -frames:v 1 thumbnails.png
Screen Recording
# macOS -- record full screen
ffmpeg -f avfoundation -framerate 30 -i "1:0" -c:v libx264 -preset ultrafast -crf 18 output.mp4
# macOS -- list available devices
ffmpeg -f avfoundation -list_devices true -i ""
# macOS -- record screen with audio
ffmpeg -f avfoundation -framerate 30 -i "1:0" -c:v libx264 -preset ultrafast -c:a aac output.mp4
# Linux (X11) -- record full screen
ffmpeg -f x11grab -framerate 30 -video_size 1920x1080 -i :0.0 -c:v libx264 -preset ultrafast -crf 18 output.mp4
# Linux (X11) -- record a region (offset x=100,y=200, size 1280x720)
ffmpeg -f x11grab -framerate 30 -video_size 1280x720 -i :0.0+100,200 -c:v libx264 -preset ultrafast output.mp4
# Linux (PipeWire/Wayland) -- use pipewire screen capture
# Wayland does not support x11grab. Use pw-record or OBS with pipewire.
Speed Up and Slow Down
# Speed up video 2x (drop audio)
ffmpeg -i input.mp4 -vf "setpts=0.5*PTS" -an output.mp4
# Speed up video 2x and audio 2x
ffmpeg -i input.mp4 -vf "setpts=0.5*PTS" -af "atempo=2.0" output.mp4
# Slow down video 2x with audio
ffmpeg -i input.mp4 -vf "setpts=2.0*PTS" -af "atempo=0.5" output.mp4
# Speed up 4x (chain atempo filters; each atempo supports 0.5-2.0 range)
ffmpeg -i input.mp4 -vf "setpts=0.25*PTS" -af "atempo=2.0,atempo=2.0" output.mp4
Remove Audio
# Strip audio track, keep video as-is
ffmpeg -i input.mp4 -an -c:v copy output.mp4
Codec Reference
| Codec | Use Case | Encode Flag | Notes |
|---|---|---|---|
| H.264 | General purpose, widest compatibility | -c:v libx264 | Default choice. Works everywhere. |
| H.265 | Archival, streaming, 4K content | -c:v libx265 | ~50% smaller than H.264. Slower encode. |
| VP9 | Web delivery, YouTube-style hosting | -c:v libvpx-vp9 | Royalty-free. Good browser support. |
| AV1 | Next-gen web/streaming (emerging) | -c:v libaom-av1 | Best compression. Very slow to encode. |
| AAC | Audio in MP4 containers | -c:a aac | Good quality, universal support. |
| Opus | Voice, music, streaming at low bitrates | -c:a libopus | Best quality-per-bit. WebM/OGG container. |
| MP3 | Legacy audio compatibility | -c:a libmp3lame | Use when AAC/Opus not accepted. |
Quick decision guide:
- Sharing on the web or need broad playback? H.264 + AAC in MP4.
- Need smaller files and can wait longer to encode? H.265.
- Targeting browsers specifically? VP9 + Opus in WebM.
- Archiving and storage is a concern? H.265 or AV1.
Useful Flags
-y Overwrite output without asking
-n Never overwrite output
-hide_banner Suppress FFmpeg build info
-v error Only show errors (quieter output)
-movflags +faststart Move MP4 metadata to beginning (better for streaming)
-map 0 Copy all streams from input
-shortest Stop encoding when the shortest stream ends
-threads 0 Use all available CPU threads