happytails.ai

Audio fade editor

Open Audio fade editor on Happytails.ai. This view has the same page content and links, with explicit tool capabilities. Read the processing notes before using a tool.

Tool capabilities

{
  "id": "audio-fade-editor",
  "category": "media-tools",
  "built": true,
  "requirements": "One recording up to 256 MiB and 10 minutes, with fades from 0 to 600 seconds that together fit inside it. WAV is read with every sample intact; other formats are decoded by your browser at 48 kHz. Everything is processed on your device and nothing is uploaded. Download: WAV in the source format or the format you choose, and a JSON report.",
  "implementation": {
    "fields": [
      {
        "key": "fadeIn",
        "label": "Fade in (seconds)",
        "value": "1",
        "type": "number",
        "min": 0,
        "max": 600,
        "step": 0.01
      },
      {
        "key": "fadeOut",
        "label": "Fade out (seconds)",
        "value": "2",
        "type": "number",
        "min": 0,
        "max": 600,
        "step": 0.01
      },
      {
        "key": "curve",
        "label": "Fade curve",
        "value": "equal-power",
        "type": "select",
        "values": [
          "equal-power",
          "linear",
          "s-curve",
          "logarithmic"
        ]
      },
      {
        "key": "encoding",
        "label": "WAV sample format",
        "value": "match",
        "type": "select",
        "values": [
          "match",
          "pcm16",
          "pcm24",
          "float32"
        ],
        "labels": {
          "match": "Match source sample format"
        }
      }
    ],
    "registrationFamily": "audio-dsp-edit",
    "presentation": "metrics",
    "files": true,
    "input": false,
    "accept": ".wav,.mp3,.m4a,.aac,.flac,.ogg,.oga,.opus,.webm,audio/*",
    "maxFileBytes": 268435456,
    "inputErrorCode": "AUDIO_DSP_EDIT_TOO_LONG",
    "note": "Runs locally in your browser. Fades one recording up to 10 minutes and 256 MiB and leaves every sample between the fades unchanged.",
    "experience": {
      "automatic": false,
      "single": false,
      "inputMaxLength": 1000000,
      "inputMode": "text",
      "label": "Audio file",
      "placeholder": "Choose a recording",
      "help": "The fades are applied to the start and end of this file. Up to 1,000,000 characters. Review the settings before running.",
      "helpParts": [
        "The fades are applied to the start and end of this file.",
        "Up to 1,000,000 characters.",
        "Review the settings before running."
      ],
      "action": null
    },
    "mode": "explicit",
    "interactive": false
  },
  "execution": "Browser interface",
  "api": null,
  "browser_agent": {
    "supported": true,
    "name": "run_current_tool",
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}

Page guide

Add a fade in and a fade out to a recording, with a choice of four fade curves, while every sample between the fades stays exactly as it was.

How to use Audio fade editor
  1. Choose the recording to fade.
  2. Enter the fade in and fade out lengths in seconds.
  3. Pick a fade curve and the WAV sample format.
  4. Apply the fades and download the WAV file and the JSON report.

Useful next steps

Trim audioAudio crossfade mixerIncrease audio volume

Fade curves

Linear changes the gain at a steady rate. Equal power follows a quarter sine, which sounds even when the fade overlaps other audio. S-curve starts and ends gently. Logarithmic moves at a steady rate in decibels over 60 dB, which sounds natural for long fade outs.

What stays unchanged

Only the samples inside the fade in and fade out are multiplied. With the sample format set to match, a 16-bit or 24-bit WAV is written in its own format, so every sample between the fades is bit for bit the same as the source.

Lengths

Fade lengths are rounded to the nearest sample. The two fades together cannot be longer than the recording; set a fade to 0 to skip it.