CLI Ffmpeg

FFmpeg — Multimedia Framework

Repo: https://github.com/FFmpeg/FFmpeg

Complete multimedia framework for recording, converting, and streaming audio and video. Supports hundreds of formats and codecs. The Swiss Army knife of media processing.

When to Activate

Manual triggers:

• "Convert this video to..."
• "Trim/clip this video"
• "Extract audio from video"
• "Create a GIF from video"
• "Compress this video"
• "Add subtitles"

Auto-detect triggers:

• User has a media file and wants to change its format, size, or content
• User mentions encoding, bitrate, codec, resolution, or framerate
• User wants to batch process video or audio files
• User needs to extract frames or create a thumbnail

Key Commands

Basic Conversion

ffmpeg -i input.mp4 output.mkv           # Convert container format
ffmpeg -i input.mov output.mp4           # MOV to MP4
ffmpeg -i input.mp4 -c copy output.mkv  # Copy streams (no re-encode, fast)
ffmpeg -i input.mp4 output.gif          # Video to GIF (basic)

Inspect Media (ffprobe)

ffprobe input.mp4                                    # Basic info
ffprobe -v quiet -print_format json -show_streams input.mp4  # Full JSON info
ffprobe -v quiet -show_format input.mp4             # Container info only

Codec Selection

ffmpeg -i input.mp4 -c:v libx264 -c:a aac output.mp4   # H.264 video + AAC audio
ffmpeg -i input.mp4 -c:v libx265 -c:a aac output.mp4   # H.265/HEVC (smaller)
ffmpeg -i input.mp4 -c:v libvpx-vp9 -c:a libopus output.webm  # VP9 + Opus (web)
ffmpeg -i input.mp4 -c:v copy -c:a mp3 output.mp4      # Re-encode audio only

Trimming and Cutting

ffmpeg -i input.mp4 -ss 00:01:30 -t 00:00:30 output.mp4  # Start at 1:30, 30s duration
ffmpeg -i input.mp4 -ss 00:01:30 -to 00:02:00 output.mp4 # Start at 1:30, end at 2:00
ffmpeg -ss 00:01:30 -i input.mp4 -t 30 output.mp4        # -ss before -i = faster seek
ffmpeg -i input.mp4 -ss 10 -to 40 -c copy output.mp4    # Keyframe-accurate, no re-encode

Bitrate and Quality

ffmpeg -i input.mp4 -b:v 1M output.mp4              # 1 Mbps video bitrate
ffmpeg -i input.mp4 -crf 23 output.mp4              # CRF quality (0=lossless, 51=worst; 18-28 typical)
ffmpeg -i input.mp4 -b:a 128k output.mp3            # 128 kbps audio
ffmpeg -i input.mp4 -vn -b:a 192k output.mp3        # Extract audio at 192k

Resolution and Framerate

ffmpeg -i input.mp4 -vf scale=1280:720 output.mp4   # Resize to 720p
ffmpeg -i input.mp4 -vf scale=1920:-1 output.mp4    # Width 1920, height auto
ffmpeg -i input.mp4 -vf scale=-1:720 output.mp4     # Height 720, width auto
ffmpeg -i input.mp4 -r 30 output.mp4                # Set framerate to 30fps
ffmpeg -i input.mp4 -r 24 -vf fps=24 output.mp4    # Force 24fps

Stream Selection (-map)

ffmpeg -i input.mkv -map 0:v:0 -map 0:a:1 output.mp4  # First video, second audio
ffmpeg -i input.mkv -map 0 -map -0:s output.mp4        # All streams except subtitles
ffmpeg -i input.mkv -vn output.mp3                      # Audio only (-vn = no video)
ffmpeg -i input.mp4 -an output.mp4                      # Video only (-an = no audio)

Advanced Patterns

High-Quality GIF from Video

# Two-pass GIF: generate palette first, then encode
ffmpeg -i input.mp4 -ss 5 -t 4 -vf "fps=15,scale=480:-1:flags=lanczos,palettegen" palette.png
ffmpeg -i input.mp4 -i palette.png -ss 5 -t 4 \
  -filter_complex "fps=15,scale=480:-1:flags=lanczos[x];[x][1:v]paletteuse" output.gif

Batch Conversion

# Convert all MKV files to MP4
for f in *.mkv; do ffmpeg -i "$f" -c:v libx264 -c:a aac "${f%.mkv}.mp4"; done

# With fd
fd -e mkv | while read f; do
  ffmpeg -i "$f" -c:v libx264 -c:a aac "${f%.mkv}.mp4"
done

Video Concatenation

# Create a list file
printf "file '%s'\n" *.mp4 > filelist.txt
ffmpeg -f concat -safe 0 -i filelist.txt -c copy output.mp4

# Concatenate with re-encoding (for different formats/codecs)
ffmpeg -i "concat:part1.ts|part2.ts" -c copy output.ts

Video Filters (-vf)

ffmpeg -i input.mp4 -vf crop=640:480:100:50 output.mp4     # Crop: w:h:x:y
ffmpeg -i input.mp4 -vf rotate=PI/4 output.mp4              # Rotate 45 degrees
ffmpeg -i input.mp4 -vf transpose=1 output.mp4              # Rotate 90° clockwise
ffmpeg -i input.mp4 -vf hflip output.mp4                    # Horizontal flip
ffmpeg -i input.mp4 -vf vflip output.mp4                    # Vertical flip
ffmpeg -i input.mp4 -vf "eq=brightness=0.1:contrast=1.2" output.mp4  # Brightness/contrast
ffmpeg -i input.mp4 -vf unsharp output.mp4                  # Sharpen
ffmpeg -i input.mp4 -vf "hue=s=0" output.mp4               # Grayscale

Add Text Overlay

ffmpeg -i input.mp4 -vf \
  "drawtext=text='Hello World':fontsize=48:fontcolor=white:x=(w-text_w)/2:y=h-50" \
  output.mp4

# With timestamp
ffmpeg -i input.mp4 -vf \
  "drawtext=text='%{pts\:hms}':fontsize=24:fontcolor=white:x=10:y=10" \
  output.mp4

Add Subtitles

ffmpeg -i input.mp4 -i subtitles.srt -c copy -c:s mov_text output.mp4   # Soft subtitles
ffmpeg -i input.mp4 -vf subtitles=subtitles.srt output.mp4              # Burn in subtitles

Extract Frames / Create Thumbnails

ffmpeg -i input.mp4 -vf fps=1 frame_%04d.png         # 1 frame per second
ffmpeg -i input.mp4 -ss 00:01:00 -frames:v 1 thumb.jpg  # Single frame at 1:00
ffmpeg -i input.mp4 -vf "thumbnail,scale=320:-1" -frames:v 1 thumb.jpg  # Best thumbnail

Thumbnail Sprite Sheet

ffmpeg -i input.mp4 -vf "fps=1/10,scale=160:-1,tile=5x5" sprite.jpg

Audio Filters (-af)

ffmpeg -i input.mp3 -af "volume=2.0" output.mp3              # Double volume
ffmpeg -i input.mp3 -af "loudnorm" output.mp3                # Normalize loudness
ffmpeg -i input.mp3 -af "afade=t=in:st=0:d=3" output.mp3   # Fade in over 3s
ffmpeg -i input.mp3 -af "silenceremove=1:0:-50dB" output.mp3  # Remove silence
ffmpeg -i input.mp4 -af "equalizer=f=1000:width_type=o:width=2:g=10" output.mp4  # EQ boost

Complex Filter Graph (-filter_complex)

# Overlay logo on video
ffmpeg -i input.mp4 -i logo.png \
  -filter_complex "overlay=W-w-10:H-h-10" \
  output.mp4

# Side-by-side video
ffmpeg -i left.mp4 -i right.mp4 \
  -filter_complex "[0:v][1:v]hstack=inputs=2[v];[0:a][1:a]amerge=inputs=2[a]" \
  -map "[v]" -map "[a]" output.mp4

# Picture-in-picture
ffmpeg -i main.mp4 -i overlay.mp4 \
  -filter_complex "[1:v]scale=320:180[pip];[0:v][pip]overlay=W-w-10:H-h-10" \
  output.mp4

Screen Recording (macOS)

# List input devices
ffmpeg -f avfoundation -list_devices true -i ""

# Record screen + audio
ffmpeg -f avfoundation -i "1:0" -r 30 -c:v libx264 -preset ultrafast screen.mp4

Streaming to RTMP

ffmpeg -i input.mp4 -c:v libx264 -preset fast -b:v 3000k \
  -c:a aac -b:a 128k -f flv rtmp://live.twitch.tv/app/STREAM_KEY

Hardware Acceleration

# macOS VideoToolbox
ffmpeg -hwaccel videotoolbox -i input.mp4 -c:v h264_videotoolbox output.mp4

# NVIDIA NVENC
ffmpeg -hwaccel cuda -i input.mp4 -c:v h264_nvenc output.mp4

# Intel QSV
ffmpeg -hwaccel qsv -i input.mp4 -c:v h264_qsv output.mp4

Compress for Web

# H.264, good quality, web-compatible
ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset medium \
  -c:a aac -b:a 128k -movflags +faststart output.mp4

# VP9 for web (better compression, open codec)
ffmpeg -i input.mp4 -c:v libvpx-vp9 -crf 30 -b:v 0 \
  -c:a libopus -b:a 96k output.webm

Format Coverage

Chaining with Other Skills

• cli-imagemagick: Extract frames with FFmpeg (-vf fps=1), then batch-process them with ImageMagick (resize, watermark, color correct)
• fd: Use fd -e mp4 to find all video files, pipe into a shell loop with FFmpeg for batch conversion
• fzf (cli-fzf): Use fd -e mp4 | fzf to interactively select a video file before running an FFmpeg command