Agent-Skills.md

Agent Skills: FFmpeg Fundamentals (2025)

Complete FFmpeg core knowledge system for FFmpeg 7.1 LTS and 8.0.1 (latest stable, released 2025-11-20). PROACTIVELY activate for: (1) Basic transcoding and format conversion, (2) Command syntax questions, (3) Codec selection (H.264, H.265, VVC, AV1, VP9, APV), (4) Quality settings (CRF, bitrate, presets), (5) Video/audio filter chains, (6) Trimming, splitting, concatenating, (7) Resolution scaling and aspect ratios, (8) FFmpeg 8.0 features (Whisper AI, Vulkan codecs, APV, WHIP), (9) Version checking and update guidance. Provides: Command syntax reference, codec comparison tables, filter examples, format conversion recipes, probing commands, Whisper transcription examples, version checking commands. Ensures: Correct FFmpeg usage with 2025 best practices and latest stable version.

UncategorizedID: josiahsiegel/claude-plugin-marketplace/ffmpeg-fundamentals-2025

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josiahsiegel/claude-plugin-marketplace
JosiahSiegelLicense: MIT
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Skill Metadata

Name
ffmpeg-fundamentals-2025
Description
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FFmpeg Fundamentals (2025)

Foundational FFmpeg knowledge for 7.1 LTS and 8.0.1. This SKILL is a lean orchestrator; detailed recipes and tables live under references/.

When to Use This Skill

Use for foundational FFmpeg operations:

  • First-time FFmpeg users needing syntax help
  • Basic transcoding between formats (MP4, WebM, MKV, MOV)
  • Understanding codec options and quality settings
  • Simple filter operations (scale, crop, rotate)
  • File analysis with ffprobe

For specialized topics see related skills: hardware encoding -> ffmpeg-hardware-acceleration, streaming -> ffmpeg-streaming, Docker -> ffmpeg-docker-containers, advanced filter graphs -> ffmpeg-filter-complex-patterns.

Quick Reference

| Task | Command Pattern | |------|-----------------| | Convert format | ffmpeg -i input.ext output.ext | | Set quality (CRF) | -c:v libx264 -crf 23 | | Scale video | -vf "scale=1920:1080" | | Trim video | -ss 00:00:10 -t 00:00:30 | | Extract audio | -vn -c:a aac output.m4a | | Probe file | ffprobe -v error -show_format -show_streams file |

Core Workflow

  1. Verify your FFmpeg version with ffmpeg -version. Prefer the latest stable (8.0.1) or the 7.1 LTS.
  2. Probe the input with ffprobe to inspect codecs, container, resolution, and duration.
  3. Decide whether to remux (-c copy) or transcode (specify encoders, quality).
  4. Pick encoders and quality settings (see Codec Reference below).
  5. Add filters as needed (see references/filter-essentials.md and references/frame-manipulation.md).
  6. Verify the output: re-probe, check duration, A/V sync, and pixel format.

Basic Command Syntax

ffmpeg [global_options] {[input_options] -i input} ... {[output_options] output} ...

Common examples:

# Basic transcode
ffmpeg -i input.mp4 output.mkv

# Specify codecs
ffmpeg -i input.mp4 -c:v libx264 -c:a aac output.mp4

# Copy streams without re-encoding (remux)
ffmpeg -i input.mkv -c copy output.mp4

# CRF quality mode
ffmpeg -i input.mp4 -c:v libx264 -crf 23 output.mp4

# Bitrate mode
ffmpeg -i input.mp4 -c:v libx264 -b:v 5M output.mp4

# Overwrite without prompting
ffmpeg -y -i input.mp4 output.mp4

# Show progress as parseable stats
ffmpeg -progress - -i input.mp4 output.mp4

For exhaustive option ordering rules, stream specifiers, and per-format option tables, see the ffmpeg-command-syntax skill.

Codec Reference (2025)

Video Codecs (Software)

| Codec | Encoder | Use Case | Quality | Speed | |-------|---------|----------|---------|-------| | H.264/AVC | libx264 | Universal compatibility | Excellent | Medium | | H.265/HEVC | libx265 | 4K, HDR, storage efficiency | Excellent | Slow | | H.266/VVC | libvvenc | Next-gen, 8K | Best | Very Slow | | AV1 | libsvtav1, libaom-av1 | Web streaming, royalty-free | Excellent | Slow-Medium | | VP9 | libvpx-vp9 | WebM, YouTube | Very Good | Slow | | ProRes | prores_ks | Professional editing | Lossless | Fast |

Hardware Encoders

| Platform | H.264 | H.265 | AV1 | VVC | FFv1 | |----------|-------|-------|-----|-----|------| | NVIDIA | h264_nvenc | hevc_nvenc | av1_nvenc | - | - | | Intel | h264_qsv | hevc_qsv | av1_qsv | - | - | | AMD | h264_amf | hevc_amf | av1_amf | - | - | | Apple | h264_videotoolbox | hevc_videotoolbox | - | - | - | | Vulkan | h264_vulkan | hevc_vulkan | av1_vulkan (8.0+) | - | ffv1_vulkan (8.0+) |

Hardware Decoders (FFmpeg 8.0+)

| Platform | VVC/H.266 | VP9 | ProRes RAW | |----------|-----------|-----|------------| | VAAPI | vvc (8.0+) | Yes | - | | QSV | vvc_qsv (7.1+) | Yes | - | | Vulkan | - | vp9 (8.0+) | Yes (8.0+) |

Audio Codecs

| Codec | Encoder | Use Case | Bitrate Range | |-------|---------|----------|---------------| | AAC | aac, libfdk_aac | Universal, streaming | 96-320 kbps | | MP3 | libmp3lame | Legacy compatibility | 128-320 kbps | | Opus | libopus | VoIP, streaming, WebM | 32-256 kbps | | FLAC | flac | Lossless archival | ~900 kbps | | AC3 | ac3 | DVD, Blu-ray | 384-640 kbps | | EAC3 | eac3 | Streaming, Dolby Digital+ | 192-768 kbps |

Probing & Analysis

# Get media info as JSON
ffprobe -v quiet -print_format json -show_format -show_streams input.mp4

# Get duration
ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 input.mp4

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

# Get codec
ffprobe -v error -select_streams v:0 -show_entries stream=codec_name -of default=noprint_wrappers=1:nokey=1 input.mp4

# Validate file
ffprobe -v error input.mp4 && echo "Valid" || echo "Invalid"

Best Practices

Performance

  1. Use -threads 0 to auto-detect optimal thread count.
  2. Place -ss before -i for fast seeking (may be less accurate); after -i for frame-accurate seek.
  3. Use -c copy when possible to avoid re-encoding.
  4. Use hardware acceleration when available.

Quality

  1. Prefer CRF over bitrate for single-pass encoding.
  2. Use -preset slow or slower for better compression.
  3. Use -tune options (film, animation, grain) when appropriate.
  4. Keep -pix_fmt yuv420p for broad compatibility.

Compatibility

  1. Use -movflags +faststart for web MP4 files.
  2. Use -vtag hvc1 for HEVC on Apple devices.
  3. Test on target devices before mass conversion.
  4. Provide fallback formats for older browsers.

Error Prevention

  1. Test commands on a sample file first.
  2. Use -report for detailed logging.
  3. Check output file size and duration.
  4. Verify A/V sync after conversion.

Capability Discovery

ffmpeg -encoders          # List encoders
ffmpeg -decoders          # List decoders
ffmpeg -formats           # List formats
ffmpeg -filters           # List filters
ffmpeg -hwaccels          # List hardware acceleration methods
ffmpeg -h encoder=libx264 # Encoder-specific options

Exit codes:

  • 0: success
  • 1: error (check stderr)
  • 255: interrupted (Ctrl+C)

Reference Map

Detailed recipes, option tables, and FFmpeg 8.0-specific guides:

  • references/version-history.md - Full FFmpeg 8.0 / 7.1 LTS feature lists, update strategy, official resources
  • references/common-operations.md - Format conversion, scaling, trimming, concat, audio, subtitles, Whisper recipe, image ops, output optimization (web/iOS/Android)
  • references/filter-essentials.md - Video filters (-vf), audio filters (-af), complex filtergraphs, filter_complex syntax reference
  • references/frame-manipulation.md - Frame rate, setpts, select, thumbnails, tiles, freezing, looping, reversing
  • references/whisper-transcription.md - Whisper AI filter for speech recognition and subtitle generation
  • references/vvc-h266-encoding.md - VVC/H.266 encoding with libvvenc plus hardware decode
  • references/vulkan-compute-codecs.md - Vulkan compute-based codecs (FFv1, AV1, VP9, ProRes RAW)

For deeper dives: ffmpeg-filter-complex-patterns, ffmpeg-hardware-acceleration, ffmpeg-streaming, ffmpeg-captions-subtitles, ffmpeg-audio-processing.