Agent skill

audio-trimmer

Cut, trim, and edit audio segments with fade effects, speed control, concatenation, and basic audio manipulations.

View SKILL.md on GitHub Repository
Stars 163
Forks 31

Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/development/audio-trimmer

SKILL.md

Audio Trimmer

Edit audio files with precise cutting, trimming, and effects. Extract segments, add fades, adjust speed, concatenate clips, and apply basic audio manipulations.

Quick Start

python
from scripts.audio_trimmer import AudioTrimmer

# Trim to segment
trimmer = AudioTrimmer("podcast.mp3")
trimmer.trim(start="00:05:30", end="00:10:00")
trimmer.save("segment.mp3")

# Add fades and save
trimmer = AudioTrimmer("song.mp3")
trimmer.fade_in(3000).fade_out(5000).save("song_faded.mp3")

# Concatenate multiple files
AudioTrimmer.concatenate(["intro.mp3", "main.mp3", "outro.mp3"], "full_episode.mp3")

Features

  • Precise Trimming: Cut segments by timestamp or milliseconds
  • Fade Effects: Fade in/out with customizable duration
  • Speed Control: Speed up or slow down audio
  • Concatenation: Join multiple audio files
  • Basic Effects: Reverse, loop, overlay
  • Silence Operations: Add silence, remove silence
  • Volume Adjustment: Gain control, normalization

API Reference

Initialization

python
trimmer = AudioTrimmer("audio.mp3")

Trimming

python
# By timestamp (HH:MM:SS or MM:SS)
trimmer.trim(start="01:30", end="05:00")

# By milliseconds
trimmer.trim(start_ms=90000, end_ms=300000)

# From start to timestamp
trimmer.trim(end="02:00")

# From timestamp to end
trimmer.trim(start="10:00")

Fade Effects

python
# Fade in at start (milliseconds)
trimmer.fade_in(3000)  # 3 second fade in

# Fade out at end
trimmer.fade_out(5000)  # 5 second fade out

# Crossfade (for concatenation)
AudioTrimmer.concatenate_with_crossfade(files, output, crossfade_ms=2000)

Speed Control

python
# Speed up (1.5x)
trimmer.speed(1.5)

# Slow down (0.75x)
trimmer.speed(0.75)

Effects

python
# Reverse audio
trimmer.reverse()

# Loop audio N times
trimmer.loop(3)

# Overlay another audio
trimmer.overlay("background.mp3", position_ms=0, volume=-6)

Volume

python
# Adjust volume (dB)
trimmer.gain(6)   # Increase by 6 dB
trimmer.gain(-3)  # Decrease by 3 dB

# Normalize to target level
trimmer.normalize(-3)  # Normalize to -3 dBFS

Silence Operations

python
# Add silence at start
trimmer.add_silence_start(2000)  # 2 seconds

# Add silence at end
trimmer.add_silence_end(1000)

# Strip leading/trailing silence
trimmer.strip_silence(threshold=-50)  # dBFS threshold

Concatenation

python
# Simple concatenation
AudioTrimmer.concatenate(
    ["file1.mp3", "file2.mp3", "file3.mp3"],
    "output.mp3"
)

# With crossfade
AudioTrimmer.concatenate_with_crossfade(
    ["intro.mp3", "main.mp3", "outro.mp3"],
    "output.mp3",
    crossfade_ms=2000
)

Save

python
# Save to file (format from extension)
trimmer.save("output.mp3")

# Explicit format and quality
trimmer.save("output.mp3", format="mp3", bitrate=320)

CLI Usage

bash
# Trim segment
python audio_trimmer.py --input podcast.mp3 --output segment.mp3 --start 05:30 --end 10:00

# Add fades
python audio_trimmer.py --input song.mp3 --output faded.mp3 --fade-in 3000 --fade-out 5000

# Speed up
python audio_trimmer.py --input lecture.mp3 --output fast.mp3 --speed 1.5

# Concatenate files
python audio_trimmer.py --concat file1.mp3 file2.mp3 file3.mp3 --output merged.mp3

# Extract multiple segments
python audio_trimmer.py --input podcast.mp3 --segments "00:00-05:00,10:00-15:00,20:00-25:00" --output-dir ./clips/

CLI Arguments

Argument Description Default
--input Input audio file Required
--output Output file path Required
--start Start timestamp (HH:MM:SS or MM:SS) -
--end End timestamp -
--fade-in Fade in duration (ms) -
--fade-out Fade out duration (ms) -
--speed Speed multiplier 1.0
--gain Volume adjustment (dB) 0
--reverse Reverse audio False
--normalize Normalize to dBFS level -
--concat Files to concatenate -
--crossfade Crossfade duration for concat (ms) 0
--segments Multiple segments to extract -

Examples

Extract Podcast Segment

python
trimmer = AudioTrimmer("episode_42.mp3")
trimmer.trim(start="15:30", end="22:45")
trimmer.fade_in(1000)
trimmer.fade_out(2000)
trimmer.save("highlight_clip.mp3")

Create Ringtone

python
trimmer = AudioTrimmer("song.mp3")
trimmer.trim(start="01:15", end="01:45")  # 30-second segment
trimmer.fade_in(500)
trimmer.fade_out(1000)
trimmer.normalize(-3)
trimmer.save("ringtone.mp3", bitrate=192)

Speed Up Lecture

python
trimmer = AudioTrimmer("lecture.mp3")
trimmer.speed(1.25)  # 25% faster
trimmer.normalize(-16)  # Podcast-friendly level
trimmer.save("lecture_fast.mp3")

Build Episode from Segments

python
# With crossfades between segments
AudioTrimmer.concatenate_with_crossfade(
    files=[
        "intro_music.mp3",
        "sponsor_read.mp3",
        "main_content.mp3",
        "outro_music.mp3"
    ],
    output="full_episode.mp3",
    crossfade_ms=1500
)

Extract Multiple Highlights

python
# Extract several segments from a long recording
trimmer = AudioTrimmer("meeting_recording.mp3")

segments = [
    ("00:05:00", "00:08:30", "intro"),
    ("00:25:00", "00:32:00", "discussion"),
    ("01:15:00", "01:20:00", "conclusion")
]

for start, end, name in segments:
    t = AudioTrimmer("meeting_recording.mp3")
    t.trim(start=start, end=end)
    t.fade_in(500)
    t.fade_out(500)
    t.save(f"{name}.mp3")

Add Background Music

python
# Overlay quiet background music
trimmer = AudioTrimmer("podcast.mp3")
trimmer.overlay(
    "ambient_music.mp3",
    position_ms=0,
    volume=-15,  # 15 dB quieter
    loop=True    # Loop to fill duration
)
trimmer.save("podcast_with_music.mp3")

Time Format Reference

The trimmer accepts these timestamp formats:

Format Example Meaning
MM:SS 05:30 5 minutes 30 seconds
HH:MM:SS 01:30:00 1 hour 30 minutes
SS 90 90 seconds
SS.ms 90.500 90.5 seconds

Dependencies

pydub>=0.25.0

Note: Requires FFmpeg installed on system.

Limitations

  • Speed adjustment may affect pitch (no pitch preservation)
  • Very large files may consume significant memory
  • Crossfade works best with similar audio levels

Didn't find tool you were looking for?

Be as detailed as possible for better results