happytails.ai

Audio crossfade mixer

Open Audio crossfade mixer 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-crossfade-mixer",
  "category": "media-tools",
  "built": true,
  "requirements": "Exactly two recordings, each up to 256 MiB and 10 minutes, with an overlap from 0.01 to 60 seconds that fits in both and a result of at most 60 million samples. 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 (24-bit by default, 16-bit or 32-bit float) and a JSON report.",
  "implementation": {
    "fields": [
      {
        "key": "overlap",
        "label": "Overlap (seconds)",
        "value": "3",
        "type": "number",
        "min": 0.01,
        "max": 60,
        "step": 0.01
      },
      {
        "key": "curve",
        "label": "Fade curve",
        "value": "equal-power",
        "type": "select",
        "values": [
          "equal-power",
          "linear",
          "s-curve"
        ]
      },
      {
        "key": "preventClipping",
        "label": "Lower the level if the joined audio would clip",
        "value": true,
        "type": "checkbox"
      },
      {
        "key": "encoding",
        "label": "WAV sample format",
        "value": "pcm24",
        "type": "select",
        "values": [
          "pcm24",
          "pcm16",
          "float32"
        ]
      }
    ],
    "registrationFamily": "audio-dsp-edit",
    "presentation": "metrics",
    "files": true,
    "multiple": 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. Joins two recordings up to 10 minutes each with a crossfade of up to 60 seconds.",
    "experience": {
      "automatic": false,
      "single": false,
      "inputMaxLength": 1000000,
      "inputMode": "text",
      "label": "Two audio files",
      "placeholder": "Choose the outgoing and the incoming recording",
      "help": "The first file fades out and the second fades in. Up to 1,000,000 characters. Review the settings before running.",
      "helpParts": [
        "The first file fades out and the second fades in.",
        "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

Join two recordings so the first fades out while the second fades in, with the overlap length and fade curve you choose.

How to use Audio crossfade mixer
  1. Choose two recordings: the first plays out, the second comes in.
  2. Set the overlap in seconds and choose a fade curve.
  3. Join them and check the peak and headroom in the report.
  4. Download the joined WAV and the JSON report.

Useful next steps

Merge audioAudio fade editorTrim audio

How the join works

The last part of the first recording and the first part of the second play at the same time for the overlap you set. The first fades out along the chosen curve while the second fades in along its mirror image, so the result is as long as both recordings minus the overlap.

Curves

Equal power keeps the loudness steady when the two recordings are different. Linear keeps the level steady when they are very similar, such as two takes of the same sound. S-curve holds each side longer before handing over.

Matching the files

The second recording is resampled to the rate of the first if they differ. A mono file is copied to both sides when the other is stereo. If the joined audio would clip, the whole file is lowered just enough, and the report gives that headroom gain.