ffmpeg_skill

Overview

This skill is a practical guide for using FFmpeg to encode, convert, stream, filter, and inspect multimedia files. It focuses on common commands, workflows, and tips to get reliable results quickly. Use it to optimize video/audio quality, automate batch jobs, or set up streaming and HLS outputs.

How this skill works

The guide explains core FFmpeg tools (ffmpeg, ffprobe, ffplay) and key libraries used for codecs, containers, and filters. It shows how to transcode with CRF or bitrate targets, apply video/audio filters, extract or replace streams, and leverage hardware acceleration. It also covers streaming (RTMP/HLS/UDP), media analysis, and performance tuning for batch and parallel processing.

When to use it

• Convert between containers or codecs (MP4, MKV, WebM, H.264/HEVC/VP9/AV1).
• Extract or transcode audio, create thumbnails, GIFs, or image sequences.
• Prepare live streams for Twitch/YouTube or generate HLS/DASH outputs.
• Batch convert or resize many files, including parallel processing.
• Apply filters: denoise, crop, scale, subtitles, watermarking, speed changes.
• Analyze file properties and automate quality/size trade-offs.

Best practices

• Prefer CRF encoding for quality-focused results; use 17–28 range depending on needs.
• Use -c copy when you don’t need re-encoding to save time and avoid quality loss.
• Test settings on short clips before running large batches or long encodes.
• Choose appropriate presets (ultrafast → veryslow) to balance speed and compression.
• Use hardware acceleration (NVENC/QSV/AMF) for faster encodes, but verify quality.
• Match output resolution/bitrate to source to avoid unnecessary upscaling.

Example use cases

• Convert a folder of MKV files to MP4 with H.264 and AAC for universal playback.
• Stream desktop audio/video to Twitch in real time with -re and rtmp output.
• Create adaptive HLS with multiple bitrates and a master playlist for streaming.
• Extract lossless audio tracks or convert to MP3/Opus for podcasts.
• Resize and denoise old footage, then burn subtitles or overlay a watermark.