media-processing

SKILL.md

Media Processing Skill

Process video, audio, and images using FFmpeg and ImageMagick command-line tools for conversion, optimization, streaming, and manipulation tasks.

When to Use This Skill

Use when:

Converting media formats (video, audio, images)

Encoding video with codecs (H.264, H.265, VP9, AV1)

Processing images (resize, crop, effects, watermarks)

Extracting audio from video

Creating streaming manifests (HLS/DASH)

Generating thumbnails and previews

Batch processing media files

Optimizing file sizes and quality

Applying filters and effects

Creating composite images or videos

Tool Selection Guide
FFmpeg: Video/Audio Processing

Use FFmpeg for:

Video encoding, conversion, transcoding

Audio extraction, conversion, mixing

Live streaming (RTMP, HLS, DASH)

Video filters (scale, crop, rotate, overlay)

Hardware-accelerated encoding

Media file inspection (ffprobe)

Frame extraction, concatenation

Codec selection and optimization

ImageMagick: Image Processing

Use ImageMagick for:

Image format conversion (PNG, JPEG, WebP, GIF)

Resizing, cropping, transformations

Batch image processing (mogrify)

Visual effects (blur, sharpen, sepia)

Text overlays and watermarks

Image composition and montages

Color adjustments, filters

Thumbnail generation

Decision Matrix

Task
Tool
Why

Video encoding
FFmpeg
Native video codec support

Audio extraction
FFmpeg
Direct stream manipulation

Image resize
ImageMagick
Optimized for still images

Batch images
ImageMagick
mogrify for in-place edits

Video thumbnails
FFmpeg
Frame extraction built-in

GIF creation
FFmpeg or ImageMagick
FFmpeg for video source, ImageMagick for images

Streaming
FFmpeg
Live streaming protocols

Image effects
ImageMagick
Rich filter library

Installation

macOS

brew install ffmpeg imagemagick

Ubuntu/Debian

sudo apt-get install ffmpeg imagemagick

Windows

# Using winget
winget install ffmpeg
winget install ImageMagick.ImageMagick

# Or download binaries
# FFmpeg: https://ffmpeg.org/download.html
# ImageMagick: https://imagemagick.org/script/download.php

Verify Installation

ffmpeg -version
ffprobe -version
magick -version
# or
convert -version

Quick Start Examples

Video Conversion

# Convert format (copy streams, fast)
ffmpeg -i input.mkv -c copy output.mp4

# Re-encode with H.264
ffmpeg -i input.avi -c:v libx264 -crf 22 -c:a aac output.mp4

# Resize video to 720p
ffmpeg -i input.mp4 -vf scale=-1:720 -c:a copy output.mp4

Audio Extraction

# Extract audio (no re-encoding)
ffmpeg -i video.mp4 -vn -c:a copy audio.m4a

# Convert to MP3
ffmpeg -i video.mp4 -vn -q:a 0 audio.mp3

Image Processing

# Convert format
magick input.png output.jpg

# Resize maintaining aspect ratio
magick input.jpg -resize 800x600 output.jpg

# Create square thumbnail
magick input.jpg -resize 200x200^ -gravity center -extent 200x200 thumb.jpg

Batch Image Resize

# Resize all JPEGs to 800px width
mogrify -resize 800x -quality 85 *.jpg

# Output to separate directory
mogrify -path ./output -resize 800x600 *.jpg

Video Thumbnail

# Extract frame at 5 seconds
ffmpeg -ss 00:00:05 -i video.mp4 -vframes 1 -vf scale=320:-1 thumb.jpg

HLS Streaming

# Generate HLS playlist
ffmpeg -i input.mp4 \
  -c:v libx264 -preset fast -crf 22 -g 48 \
  -c:a aac -b:a 128k \
  -f hls -hls_time 6 -hls_playlist_type vod \
  playlist.m3u8

Image Watermark

# Add watermark to corner
magick input.jpg watermark.png -gravity southeast \
  -geometry +10+10 -composite output.jpg

Common Workflows

Optimize Video for Web

# H.264 with good compression
ffmpeg -i input.mp4 \
  -c:v libx264 -preset slow -crf 23 \
  -c:a aac -b:a 128k \
  -movflags +faststart \
  output.mp4

Create Responsive Images

# Generate multiple sizes
for size in 320 640 1024 1920; do
  magick input.jpg -resize ${size}x -quality 85 "output-${size}w.jpg"
done

Extract Video Segment

# From 1:30 to 3:00 (re-encode for precision)
ffmpeg -i input.mp4 -ss 00:01:30 -to 00:03:00 \
  -c:v libx264 -c:a aac output.mp4

Batch Image Optimization

# Convert PNG to optimized JPEG
mogrify -path ./optimized -format jpg -quality 85 -strip *.png

Video GIF Creation

# High quality GIF with palette
ffmpeg -i input.mp4 -vf "fps=15,scale=640:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" output.gif

Image Blur Effect

# Gaussian blur
magick input.jpg -gaussian-blur 0x8 output.jpg

Advanced Techniques

Multi-Pass Video Encoding

# Pass 1 (analysis)
ffmpeg -y -i input.mkv -c:v libx264 -b:v 2600k -pass 1 -an -f null /dev/null

# Pass 2 (encoding)
ffmpeg -i input.mkv -c:v libx264 -b:v 2600k -pass 2 -c:a aac output.mp4

Hardware-Accelerated Encoding

# NVIDIA NVENC
ffmpeg -hwaccel cuda -i input.mp4 -c:v h264_nvenc -preset fast -crf 22 output.mp4

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

Complex Image Pipeline

# Resize, crop, border, adjust
magick input.jpg \
  -resize 1000x1000^ \
  -gravity center \
  -crop 1000x1000+0+0 +repage \
  -bordercolor black -border 5x5 \
  -brightness-contrast 5x10 \
  -quality 90 \
  output.jpg

Video Filter Chains

# Scale, denoise, watermark
ffmpeg -i video.mp4 -i logo.png \
  -filter_complex "[0:v]scale=1280:720,hqdn3d[v];[v][1:v]overlay=10:10" \
  -c:a copy output.mp4

Animated GIF from Images

# Create with delay
magick -delay 100 -loop 0 frame*.png animated.gif

# Optimize size
magick animated.gif -fuzz 5% -layers Optimize optimized.gif

Media Analysis

Inspect Video Properties

# Detailed JSON output
ffprobe -v quiet -print_format json -show_format -show_streams input.mp4

# Get resolution
ffprobe -v error -select_streams v:0 \
  -show_entries stream=width,height \
  -of csv=s=x:p=0 input.mp4

Image Information

# Basic info
identify image.jpg

# Detailed format
identify -verbose image.jpg

# Custom format
identify -format "%f: %wx%h %b\n" image.jpg

Performance Tips

Use CRF for quality control - Better than bitrate for video

Copy streams when possible - Avoid re-encoding with -c copy

Hardware acceleration - GPU encoding 5-10x faster

Appropriate presets - Balance speed vs compression

Batch with mogrify - In-place image processing

Strip metadata - Reduce file size with -strip

Progressive JPEG - Better web loading with -interlace Plane

Limit memory - Prevent crashes on large batches

Test on samples - Verify settings before batch

Parallel processing - Use GNU Parallel for multiple files

Reference Documentation

Detailed guides in references/:

ffmpeg-encoding.md - Video/audio codecs, quality optimization, hardware acceleration

ffmpeg-streaming.md - HLS/DASH, live streaming, adaptive bitrate

ffmpeg-filters.md - Video/audio filters, complex filtergraphs

imagemagick-editing.md - Format conversion, effects, transformations

imagemagick-batch.md - Batch processing, mogrify, parallel operations

format-compatibility.md - Format support, codec recommendations

Common Parameters

FFmpeg Video

-c:v - Video codec (libx264, libx265, libvpx-vp9)

-crf - Quality (0-51, lower=better, 23=default)

-preset - Speed/compression (ultrafast to veryslow)

-b:v - Video bitrate (e.g., 2M, 2500k)

-vf - Video filters

FFmpeg Audio

-c:a - Audio codec (aac, mp3, opus)

-b:a - Audio bitrate (e.g., 128k, 192k)

-ar - Sample rate (44100, 48000)

ImageMagick Geometry

800x600 - Fit within (maintains aspect)

800x600! - Force exact size

800x600^ - Fill (may crop)

800x - Width only

x600 - Height only

50% - Scale percentage

Troubleshooting

FFmpeg "Unknown encoder"

# Check available encoders
ffmpeg -encoders | grep h264

# Install codec libraries
sudo apt-get install libx264-dev libx265-dev

ImageMagick "not authorized"

# Edit policy file
sudo nano /etc/ImageMagick-7/policy.xml
# Change <policy domain="coder" rights="none" pattern="PDF" />
# to <policy domain="coder" rights="read|write" pattern="PDF" />

Memory errors

# Limit memory usage
ffmpeg -threads 4 input.mp4 output.mp4
magick -limit memory 2GB -limit map 4GB input.jpg output.jpg

Resources

FFmpeg: https://ffmpeg.org/documentation.html

FFmpeg Wiki: https://trac.ffmpeg.org/

ImageMagick: https://imagemagick.org/

ImageMagick Usage: https://imagemagick.org/Usage/