FFmpeg Format Conversion

benchflow-ai

•

9392423 months ago

Source Raw

Convert media files between formats - video containers, audio formats, and codec transcoding

Quick Install

npxskills add benchflow-ai/skillsbench--skill "FFmpeg Format Conversion"

Instructions

FFmpeg Format Conversion Skill

Convert media files between different formats and containers.

When to Use

Convert video containers (MP4, MKV, AVI, etc.)
Convert audio formats (MP3, AAC, WAV, etc.)
Transcode to different codecs
Copy streams without re-encoding (fast)

Basic Conversion

# Convert container format (re-encode)
ffmpeg -i input.avi output.mp4

# Copy streams without re-encoding (fast, no quality loss)
ffmpeg -i input.mp4 -c copy output.mkv

# Convert with specific codec
ffmpeg -i input.mp4 -c:v libx264 -c:a aac output.mp4

Video Codec Conversion

# H.264
ffmpeg -i input.mp4 -c:v libx264 output.mp4

# H.265 (better compression)
ffmpeg -i input.mp4 -c:v libx265 output.mp4

# VP9 (web optimized)
ffmpeg -i input.mp4 -c:v libvpx-vp9 output.webm

# AV1 (modern codec)
ffmpeg -i input.mp4 -c:v libaom-av1 output.mp4

Audio Format Conversion

# MP3
ffmpeg -i input.wav -acodec libmp3lame -q:a 2 output.mp3

# AAC
ffmpeg -i input.wav -c:a aac -b:a 192k output.m4a

# Opus (best quality/bitrate)
ffmpeg -i input.wav -c:a libopus -b:a 128k output.opus

# FLAC (lossless)
ffmpeg -i input.wav -c:a flac output.flac

Quality Settings

# CRF (Constant Rate Factor) - lower is better quality
ffmpeg -i input.mp4 -c:v libx264 -crf 23 output.mp4

# Bitrate
ffmpeg -i input.mp4 -b:v 2M -b:a 192k output.mp4

# Two-pass encoding (best quality)
ffmpeg -i input.mp4 -c:v libx264 -b:v 2M -pass 1 -f null /dev/null
ffmpeg -i input.mp4 -c:v libx264 -b:v 2M -pass 2 output.mp4

Presets

# Encoding speed presets (faster = larger file)
ffmpeg -i input.mp4 -c:v libx264 -preset fast output.mp4
# Options: ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow

# Quality presets
ffmpeg -i input.mp4 -c:v libx264 -preset slow -crf 18 output.mp4

Batch Conversion

# Convert all MKV to MP4
for f in *.mkv; do
  ffmpeg -i "$f" -c copy "${f%.mkv}.mp4"
done

# Convert with re-encoding
for f in *.avi; do
  ffmpeg -i "$f" -c:v libx264 -c:a aac "${f%.avi}.mp4"
done

Common Codecs

Video

H.264 (libx264) - Universal compatibility
H.265 (libx265) - Better compression
VP9 (libvpx-vp9) - Open standard
AV1 (libaom-av1) - Modern codec

Audio

AAC (aac) - Universal
MP3 (libmp3lame) - Legacy
Opus (libopus) - Best quality/bitrate
FLAC (flac) - Lossless

Notes

Use -c copy when possible for speed (no re-encoding)
Re-encoding is slower but allows codec/quality changes
CRF 18-23 is good quality range for H.264
Preset affects encoding speed vs file size tradeoff

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