Audio Waveform Editor
This editor displays the decoded audio waveform and assembles multiple manually selected source ranges in row order. Apply a separate linear fade to the beginning and end of each range, listen to the result, and export a 16-bit PCM WAV. The companion JSON records the source SHA-256, exact source and output frame coordinates, and fade frame counts so the edit can be reproduced with the same file and decoder. Unlike a converter that extracts one range or a loop finder that recommends boundaries, this tool assembles multiple user-directed sections.
Key features
- Display the complete waveform and highlighted source ranges for browser-decodable local audio.
- Add or delete between two and sixteen sections and reorder them with accessible controls.
- Apply independent 0–1000 ms linear fades to each section's incoming and outgoing edges.
- Round entered seconds to decoded sample frames and show the exact output frame count.
- Preview the edit and export a 16-bit WAV plus a frame-accurate JSON specification with the source hash.
How to use
- Choose audio up to 8 MiB or load the WAV example.
- Use the waveform to guide start and end times for each section; add more rows as needed.
- Reorder rows and enter fade-in and fade-out lengths for each section.
- Render the WAV, inspect its frame count, then listen and download the WAV or JSON.
Use cases
- Collect several answer clips from an interview in a new order.
- Join two useful parts of a sound effect and soften their boundaries.
- Keep an edit manifest with source SHA-256 and exact frame coordinates.
Frequently asked questions
How are edit boundaries calculated?
Each entered second value is multiplied by the decoded sample rate and rounded with Math.round. The start frame is included and the end frame excluded. JSON stores the exact source and output frame numbers.
Do fades crossfade overlapping sections?
No. Each section receives independent linear gain ramps at its own edges before sections are concatenated. Source ranges can overlap, but there is no automatic crossfade, mixing, or beat alignment. Fade lengths must fit within each section.
How is this different from MP4 to MP3 or the loop seam finder?
MP4 to MP3 extracts audio from video and can trim one time range. The loop seam finder recommends repeat-friendly boundaries. This editor manually selects, rearranges, and fades multiple decoded audio ranges.
What formats and quality are supported?
Input is limited to 8 MiB, then 1–90 decoded seconds, one or two channels, 8–96 kHz, and eight million source frames. The browser must actually decode the file. Output is 16-bit integer WAV, so compressed or higher bit-depth source characteristics are not preserved.
Can a section be repeated or reordered?
Yes. Each row independently refers to a range in the source. You can place the same range more than once and move rows up or down. Reversing playback within one section is not supported.
Is my audio sent to a server?
No. Decoding, editing, and SHA-256 computation happen in your browser. JSON contains source name, size, hash, frame information, and edit instructions, but no audio samples.
Privacy
The selected file stays in browser memory and is not uploaded. JSON includes its name and SHA-256, so check that before sharing. Clearing or leaving the page stops playback and revokes temporary download URLs.
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