ffmpeg-audio-processing

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name: FFmpeg Audio Processing description: Extract, normalize, mix, and process audio tracks - audio manipulation and analysis

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FFmpeg Audio Processing Skill

Extract, normalize, mix, and process audio tracks from video files.

When to Use

Extract audio from video

Normalize audio levels

Mix multiple audio tracks

Convert audio formats

Extract specific channels

Adjust audio volume

Extract Audio

# Extract as MP3
ffmpeg -i video.mp4 -vn -acodec libmp3lame -q:a 2 audio.mp3
Extract as AAC (copy, no re-encode)
ffmpeg -i video.mp4 -vn -c:a copy audio.aac
Extract as WAV (uncompressed)
ffmpeg -i video.mp4 -vn -acodec pcm_s16le audio.wav
Extract specific audio stream
ffmpeg -i video.mp4 -map 0:a:1 -c:a copy audio2.aac

Normalize Audio

# Normalize loudness (ITU-R BS.1770-4)
ffmpeg -i input.mp4 -af "loudnorm=I=-23:TP=-1.5:LRA=11" output.mp4
Simple normalization
ffmpeg -i input.mp4 -af "volume=2.0" output.mp4
Peak normalization
ffmpeg -i input.mp4 -af "volumedetect" -f null -
Then use the detected peak to normalize
ffmpeg -i input.mp4 -af "volume=0.5" output.mp4

Volume Adjustment

# Increase volume by 6dB
ffmpeg -i input.mp4 -af "volume=6dB" output.mp4
Decrease volume by 3dB
ffmpeg -i input.mp4 -af "volume=-3dB" output.mp4
Set absolute volume
ffmpeg -i input.mp4 -af "volume=0.5" output.mp4

Channel Operations

# Extract left channel
ffmpeg -i stereo.mp3 -map_channel 0.0.0 left.mp3
Extract right channel
ffmpeg -i stereo.mp3 -map_channel 0.0.1 right.mp3
Convert stereo to mono
ffmpeg -i stereo.mp3 -ac 1 mono.mp3
Convert mono to stereo
ffmpeg -i mono.mp3 -ac 2 stereo.mp3

Mix Audio Tracks

# Replace audio track
ffmpeg -i video.mp4 -i audio.mp3 -c:v copy -map 0:v:0 -map 1:a:0 output.mp4
Mix two audio tracks
ffmpeg -i video.mp4 -i audio2.mp3 \
  -filter_complex "[0:a][1:a]amix=inputs=2:duration=first" \
  -c:v copy output.mp4
Mix with volume control
ffmpeg -i video.mp4 -i bgm.mp3 \
  -filter_complex "[0:a]volume=1.0[voice];[1:a]volume=0.3[music];[voice][music]amix=inputs=2:duration=first" \
  -c:v copy output.mp4

Audio Delay

# Delay audio by 0.5 seconds
ffmpeg -i video.mp4 -itsoffset 0.5 -i video.mp4 \
  -map 0:v -map 1:a -c copy output.mp4
Using adelay filter (milliseconds)
ffmpeg -i input.mp4 -af "adelay=500|500" output.mp4

Sample Rate Conversion

# Resample to 48kHz
ffmpeg -i input.mp4 -af "aresample=48000" output.mp4
Resample audio only
ffmpeg -i input.mp4 -vn -af "aresample=48000" -ar 48000 audio.wav

Audio Filters

# High-pass filter (remove low frequencies)
ffmpeg -i input.mp4 -af "highpass=f=200" output.mp4
Low-pass filter (remove high frequencies)
ffmpeg -i input.mp4 -af "lowpass=f=3000" output.mp4
Band-pass filter
ffmpeg -i input.mp4 -af "bandpass=f=1000:width_type=h:w=500" output.mp4
Fade in/out
ffmpeg -i input.mp4 -af "afade=t=in:st=0:d=2,afade=t=out:st=8:d=2" output.mp4

Audio Analysis

# Detect volume levels
ffmpeg -i input.mp4 -af "volumedetect" -f null -
Measure loudness (LUFS)
ffmpeg -i input.mp4 -af "ebur128=peak=true" -f null -
Get audio statistics
ffprobe -v error -select_streams a:0 \
  -show_entries stream=sample_rate,channels,bit_rate \
  -of json input.mp4

Combine Multiple Audio Files

# Concatenate audio files
ffmpeg -i "concat:audio1.mp3|audio2.mp3|audio3.mp3" -c copy output.mp3
Using file list
file 'audio1.mp3'
file 'audio2.mp3'
ffmpeg -f concat -safe 0 -i list.txt -c copy output.mp3

Notes

Use -vn to disable video when extracting audio

-map to select specific streams

-af for audio filters

-ac for channel count

-ar for sample rate

Normalization may require two passes for accurate results

Use -vn to disable video when extracting audio

-map to select specific streams

-af for audio filters

-ac for channel count

-ar for sample rate

Normalization may require two passes for accurate results