About

Manually splitting audio files introduces timing errors measured in milliseconds that cascade into sync failures in multi-track production. This tool decodes audio natively in the browser using the Web Audio API, renders a per-pixel peak waveform on Canvas, and lets you place split markers at sample-accurate positions. Each segment is exported as a standalone WAV file with a proper 44-byte RIFF header. An optional linear crossfade of configurable duration t_fade prevents click artifacts at cut boundaries. The tool handles mono and stereo sources at any sample rate f_s up to 192 kHz.

Limitations: decoding relies on the browser's built-in codec support. Chromium handles MP3, WAV, OGG, FLAC, and AAC. Safari may reject OGG Vorbis. Output is always uncompressed PCM WAV at the source file's native bit depth of 16 bit (float-to-int16 conversion). Files above 500 MB may cause memory pressure on devices with limited RAM.

Formulas

Each audio segment is extracted as raw PCM and encoded into a WAV container. The output file size in bytes:

S = f_s × ch × b8 × t + 44

Where f_s = sample rate in Hz, ch = number of channels, b = bits per sample (16), t = duration in seconds, and 44 is the RIFF header size in bytes.

The optional linear crossfade applies an amplitude ramp at each cut boundary:

A_out(n) = x(n) × N_fade − nN_fade

A_in(n) = x(n) × nN_fade

Where N_fade = f_s × t_fade is the fade length in samples, and n is the sample index within the fade region. Float32 samples are clamped to [−1, 1] before conversion to Int16 via: s₁₆ = round(x × 32767).

Reference Data

Audio Format	Extension	Chrome	Firefox	Safari	Typical Bitrate	Lossless
WAV (PCM)	.wav	✓	✓	✓	1411 kbps (CD)	Yes
MP3	.mp3	✓	✓	✓	128 - 320 kbps	No
AAC	.m4a / .aac	✓	✓	✓	96 - 256 kbps	No
OGG Vorbis	.ogg	✓	✓	✗	64 - 500 kbps	No
FLAC	.flac	✓	✓	✓ (11+)	400 - 1200 kbps	Yes
WebM (Opus)	.webm	✓	✓	✗	6 - 510 kbps	No
AIFF	.aiff	✗	✗	✓	1411 kbps	Yes
WAV Output Specs (this tool)
Bit Depth	16 bit signed integer (PCM)
Header Size	44 bytes (standard RIFF/WAVE)
Max Channels	2 (stereo)
Sample Rate	Preserved from source (8000 - 192000 Hz)
Byte Order	Little-endian
Max Safe Duration	~3 hours at 44100 Hz stereo
File Size Formula	S = f_s × ch × 2 × t + 44

Frequently Asked Questions

Browsers decode compressed formats (MP3, AAC, OGG) into raw PCM via the Web Audio API, but re-encoding back to a lossy format requires a codec library. WAV is uncompressed PCM with a simple 44-byte header that can be constructed natively in JavaScript. This avoids quality loss from a second compression pass. If you need MP3 output, import the WAV segments into any audio editor for re-encoding.

All metadata is discarded during decoding. The Web Audio API extracts only the raw sample data. The output WAV files contain no ID3, Vorbis Comment, or other metadata frames. You must re-tag segments manually using a metadata editor.

If a segment's duration is less than twice the configured fade duration, the fade is automatically reduced to half the segment length. For a segment of 200 ms with a 150 ms fade, the effective fade becomes 100 ms. This prevents the fade-out and fade-in from overlapping within the same segment.

A 2-hour stereo file at 44100 Hz occupies approximately 1.27 GB in memory as Float32 PCM. Most modern devices with 8 GB RAM handle this. On low-memory devices, close other tabs first. The tool decodes progressively and renders the waveform from the decoded buffer. Export is done segment-by-segment to limit peak allocation.

Safari's AudioContext does not support OGG Vorbis or WebM Opus codecs. The decodeAudioData call rejects with an EncodingError. Convert your file to MP3 or WAV before loading, or use Chrome/Firefox. The tool detects this failure and shows a specific toast message identifying the codec incompatibility.

Splits operate on individual PCM samples, not on codec frames. After decoding, the audio exists as a continuous Float32Array. Marker positions are converted to sample indices via i = round(t × f_s). This gives sample-level precision - typically 22.7 μs at 44100 Hz.