{
  "slug": "audio-time-stretch",
  "name": "gizza-ai/audio-time-stretch",
  "version": "0.1.0",
  "title": "Change Audio Speed Online (Keep Pitch) — gizza.ai",
  "description": "Free online audio speed & tempo changer — speed up or slow down any track without changing the pitch. Set a factor, BPM ratio, or percentage in your browser.",
  "tags": [
    "audio",
    "speed",
    "tempo",
    "time stretch",
    "bpm",
    "slow down",
    "speed up",
    "podcast",
    "transcription",
    "pitch preserved",
    "factor",
    "playback"
  ],
  "category": "audio",
  "urls": {
    "page": "https://gizza.ai/tools/audio-time-stretch/",
    "markdown": "https://gizza.ai/tools/audio-time-stretch/index.md",
    "descriptor": "https://gizza.ai/tools/audio-time-stretch/tool.json",
    "deep_link_example": "https://gizza.ai/tools/audio-time-stretch/?url=https://example.com/input&factor=1.5&format=mp3"
  },
  "cli": "gizza tool audio-time-stretch 'url=https://example.com/input' 'factor=1.5' 'format=mp3'",
  "tool": {
    "description": "Speed an audio file up or slow it down by a playback factor without changing its pitch (a time stretch): make a podcast play at 1.5x, slow a solo to half speed for transcription, or hit a target BPM. Provide either url (HTTP/HTTPS) or ref (id from a prior tool call). factor is the speed multiplier: 2 = twice as fast, 0.5 = half speed, 1.5 = 50% faster (150%); as BPM, factor = target BPM / source BPM. Range 0.25 to 4 (1 is rejected as a no-op). Pitch is preserved via ffmpeg's atempo WSOLA time-stretch; output is re-encoded to mp3 (192 kbps), wav, ogg, flac or m4a.",
    "parameters": {
      "additionalProperties": false,
      "oneOf": [
        {
          "required": [
            "url"
          ]
        },
        {
          "required": [
            "ref"
          ]
        }
      ],
      "properties": {
        "factor": {
          "description": "Playback-speed multiplier (tempo/BPM factor). 2 = twice as fast (half the duration), 0.5 = half speed (double the duration), 1.5 = 50% faster. As a percentage, 150% = 1.5; as BPM, factor = target BPM / source BPM. Range 0.25 to 4; 1 is rejected as a no-op. Pitch is preserved.",
          "maximum": 4,
          "minimum": 0.25,
          "type": "number"
        },
        "format": {
          "default": "mp3",
          "description": "Output audio format. Default mp3 (192 kbps).",
          "enum": [
            "mp3",
            "wav",
            "ogg",
            "flac",
            "m4a"
          ],
          "type": "string"
        },
        "ref": {
          "description": "Reference id from a prior tool call. Use either url or ref.",
          "type": "string"
        },
        "url": {
          "description": "Audio URL (HTTP/HTTPS). Use either url or ref.",
          "type": "string"
        }
      },
      "required": [
        "factor"
      ],
      "type": "object"
    }
  }
}