---

name: audio-trimmer description: Cut, trim, and edit audio segments with fade effects, speed control, concatenation, and basic audio manipulations.

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

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

trimmer = AudioTrimmer("audio.mp3")

Trimming

# 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

# 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

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

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

Effects

# Reverse audio
trimmer.reverse()

# Loop audio N times
trimmer.loop(3)

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

Volume

# 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

# 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

# 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

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

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

CLI Usage

# 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

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

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

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

# 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

# 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

# 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