{ "title": "Change audio speed", "human_url": "https://happytails.ai/en/media-tools/change-audio-speed/", "agent_url": "https://happytails.ai/agents/en/media-tools/change-audio-speed/", "language": "en", "markdown_url": "https://happytails.ai/en/media-tools/change-audio-speed.md", "content": "Change audio speed\nChange audio playback speed while preserving pitch.\nUseful next steps\nMP4 to MP3\nConvert MP4 files to MP3 with the available format settings.\nWAV to MP3\nConvert WAV files to MP3 with the available format settings.\nM4a to MP3\nConvert M4A files to MP3 with the available format settings.\nHow to use Change audio speed\nChoose a file in MP3, WAV, M4A, AAC, FLAC, OGG or OPUS.\nReview the settings, then choose Run Change audio speed.\nReview the result, then use Copy result or a download link when available.\nWhat to expect\nChange audio playback speed while preserving pitch. Browser processing keeps files on this device. Choosing Local server sends files to this website’s own processor. Preserves pitch and exports WAV.", "content_format": "text/plain", "visibility": "public", "links": [ { "name": "MP4 to MP3 Convert MP4 files to MP3 with the available format settings.", "url": "https://happytails.ai/en/media-tools/mp4-to-mp3/" }, { "name": "WAV to MP3 Convert WAV files to MP3 with the available format settings.", "url": "https://happytails.ai/en/media-tools/wav-to-mp3/" }, { "name": "M4a to MP3 Convert M4A files to MP3 with the available format settings.", "url": "https://happytails.ai/en/media-tools/m4a-to-mp3/" } ], "tool": { "id": "change-audio-speed", "category": "media-tools", "built": true, "requirements": "Playback speed with optional pitch preservation and output preview.", "implementation": { "fields": [ { "key": "speed", "label": "Speed multiplier", "value": 1.25, "type": "number", "min": 0.5, "max": 2, "step": "any" }, { "key": "engine", "label": "Processing location", "type": "select", "value": "browser", "values": [ "browser", "server" ], "labels": { "browser": "Browser (files stay here)", "server": "Local server (larger files)" } } ], "files": true, "accept": ".mp3,.wav,.m4a,.aac,.flac,.ogg,.opus", "multiple": false, "input": false, "processing": "Browser or server", "native": true, "maxFileBytes": 20971520, "note": "Browser processing keeps files on this device. Choosing Local server sends files to this website’s own processor. Preserves pitch and exports WAV.", "hybrid": true, "experience": { "automatic": false, "single": false, "label": "Your text", "placeholder": "Type or paste your input…", "help": "Up to 1,000,000 characters. Review the settings before running.", "action": null }, "mode": "explicit", "interactive": false }, "execution": "POST /api/v1/tools/change-audio-speed/run", "api": { "id": "change-audio-speed", "name": "Change audio speed", "category": "media-tools", "description": "Change audio playback speed while preserving pitch.", "notes": "Browser processing keeps files on this device. Choosing Local server sends files to this website’s own processor. Preserves pitch and exports WAV.", "human_path": "/en/media-tools/change-audio-speed/", "method": "POST", "endpoint": "/api/v1/tools/change-audio-speed/run", "schema_url": "/api/v1/tools/change-audio-speed", "input_schema": { "type": "object", "additionalProperties": false, "properties": { "input": { "type": "string", "maxLength": 1000000, "default": "", "description": "Plain text input. File tools use files instead unless otherwise documented." }, "options": { "type": "object", "additionalProperties": false, "properties": { "speed": { "type": "number", "description": "Speed multiplier", "default": 1.25, "minimum": 0.5, "maximum": 2 }, "engine": { "type": "string", "description": "Processing location", "default": "browser", "enum": [ "browser", "server" ] } } }, "files": { "type": "array", "maxItems": 1, "items": { "type": "object", "required": [ "name", "base64" ], "additionalProperties": false, "properties": { "name": { "type": "string", "maxLength": 200, "description": "Filename only, no path." }, "mime": { "type": "string", "maxLength": 150 }, "bytes": { "type": "integer", "minimum": 0, "description": "Optional decoded byte count; must match content if supplied." }, "base64": { "type": "string", "contentEncoding": "base64", "description": "File bytes as padded base64. Use the tool-specific limits.files_bytes value for the total decoded input size." } } } } } }, "output_schema": { "type": "object", "required": [ "tool", "result" ], "properties": { "tool": { "type": "string" }, "result": { "type": "object", "required": [ "text", "files" ], "properties": { "text": { "type": [ "string", "null" ] }, "data": { "description": "Parsed JSON when the textual result is JSON." }, "name": { "type": "string" }, "mime": { "type": "string" }, "files": { "type": "array", "items": { "type": "object", "required": [ "name", "mime", "bytes", "base64" ], "properties": { "name": { "type": "string" }, "mime": { "type": "string" }, "bytes": { "type": "integer" }, "base64": { "type": "string", "contentEncoding": "base64" } } } } } } } }, "processing": "Server; self-hosted native engine, no external conversion service", "limits": { "request_bytes": 31457280, "input_characters": 1000000, "files_bytes": 20971520, "max_files": 1, "timeout_seconds": 90 } }, "agent_processing": "Server; self-hosted native engine, no external conversion service", "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" } }, "markdown": "# Change audio speed\n\n- Human page: https://happytails.ai/en/media-tools/change-audio-speed/\n- Markdown: https://happytails.ai/en/media-tools/change-audio-speed.md\n- Structured JSON: https://happytails.ai/agents/en/media-tools/change-audio-speed/index.json\n- Visibility: public\n\n## Tool capabilities\n\n| Property | Value |\n| --- | --- |\n| Tool ID | `change-audio-speed` |\n| Category | media-tools |\n| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |\n| Browser execution | Use the visible action or interactive controls. |\n| Browser processing | Browser or server |\n| HTTP API | /api/v1/tools/change-audio-speed/run |\n| Browser-agent interface | run_current_tool |\n\n### Implementation notes\n\nBrowser processing keeps files on this device. Choosing Local server sends files to this website’s own processor. Preserves pitch and exports WAV.\n\n### Inputs and settings\n\nNo free-text input is required. Use the file inputs and/or settings below.\n\nAccepted browser files: `.mp3,.wav,.m4a,.aac,.flac,.ogg,.opus`. Choose one file.\n\nBrowser file-input limit: 20971520 bytes in total. HTTP limits can differ.\n\n| Setting | Meaning | Control type | Default | Constraints |\n| --- | --- | --- | --- | --- |\n| `speed` | Speed multiplier | number | 1.25 | min=0.5 max=2 step=any |\n| `engine` | Processing location | select | \"browser\" | Allowed: browser, server |\n\n### HTTP contract\n\nAPI calls process supplied data on the server. The website origin is `https://happytails.ai`. Server API hosting is not connected on the public website yet. Use your local server origin to test these requests.\n\n```http\nPOST https://happytails.ai/api/v1/tools/change-audio-speed/run\nContent-Type: application/json\n```\n\n[Detailed operation reference](https://happytails.ai/en/api/tools/change-audio-speed.md) · [Shared API guide](https://happytails.ai/en/api.md)\n\n#### Limits\n\n| Limit | Value |\n| --- | --- |\n| request_bytes | 31457280 |\n| input_characters | 1000000 |\n| files_bytes | 20971520 |\n| max_files | 1 |\n| timeout_seconds | 90 |\n\n#### Complete input schema\n\n```json\n{\n \"type\": \"object\",\n \"additionalProperties\": false,\n \"properties\": {\n \"input\": {\n \"type\": \"string\",\n \"maxLength\": 1000000,\n \"default\": \"\",\n \"description\": \"Plain text input. File tools use files instead unless otherwise documented.\"\n },\n \"options\": {\n \"type\": \"object\",\n \"additionalProperties\": false,\n \"properties\": {\n \"speed\": {\n \"type\": \"number\",\n \"description\": \"Speed multiplier\",\n \"default\": 1.25,\n \"minimum\": 0.5,\n \"maximum\": 2\n },\n \"engine\": {\n \"type\": \"string\",\n \"description\": \"Processing location\",\n \"default\": \"browser\",\n \"enum\": [\n \"browser\",\n \"server\"\n ]\n }\n }\n },\n \"files\": {\n \"type\": \"array\",\n \"maxItems\": 1,\n \"items\": {\n \"type\": \"object\",\n \"required\": [\n \"name\",\n \"base64\"\n ],\n \"additionalProperties\": false,\n \"properties\": {\n \"name\": {\n \"type\": \"string\",\n \"maxLength\": 200,\n \"description\": \"Filename only, no path.\"\n },\n \"mime\": {\n \"type\": \"string\",\n \"maxLength\": 150\n },\n \"bytes\": {\n \"type\": \"integer\",\n \"minimum\": 0,\n \"description\": \"Optional decoded byte count; must match content if supplied.\"\n },\n \"base64\": {\n \"type\": \"string\",\n \"contentEncoding\": \"base64\",\n \"description\": \"File bytes as padded base64. Use the tool-specific limits.files_bytes value for the total decoded input size.\"\n }\n }\n }\n }\n }\n}\n```\n\n#### Complete output schema\n\n```json\n{\n \"type\": \"object\",\n \"required\": [\n \"tool\",\n \"result\"\n ],\n \"properties\": {\n \"tool\": {\n \"type\": \"string\"\n },\n \"result\": {\n \"type\": \"object\",\n \"required\": [\n \"text\",\n \"files\"\n ],\n \"properties\": {\n \"text\": {\n \"type\": [\n \"string\",\n \"null\"\n ]\n },\n \"data\": {\n \"description\": \"Parsed JSON when the textual result is JSON.\"\n },\n \"name\": {\n \"type\": \"string\"\n },\n \"mime\": {\n \"type\": \"string\"\n },\n \"files\": {\n \"type\": \"array\",\n \"items\": {\n \"type\": \"object\",\n \"required\": [\n \"name\",\n \"mime\",\n \"bytes\",\n \"base64\"\n ],\n \"properties\": {\n \"name\": {\n \"type\": \"string\"\n },\n \"mime\": {\n \"type\": \"string\"\n },\n \"bytes\": {\n \"type\": \"integer\"\n },\n \"base64\": {\n \"type\": \"string\",\n \"contentEncoding\": \"base64\"\n }\n }\n }\n }\n }\n }\n }\n}\n```\n\n#### Error and retry handling\n\nFailures return a non-200 status and `error.code` plus `error.message`. Correct invalid input before retrying; retry server-busy responses with bounded backoff. Returned files contain Base64 data, not persistent download URLs. Decode and inspect the output before treating conversion as successful. See the shared API guide for the complete status and timeout rules.\n\n### Browser-agent workflow\n\n1. Open the human page in a browser that supports WebMCP.\n2. Discover the interface exposed by that page; use its actual schema.\n3. Select files on the page first when the tool requires files.\n4. Call `run_current_tool` with valid input and settings.\n5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.\n\nCalls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.\n\n### Planning specification\n\nPlayback speed with optional pitch preservation and output preview.\n\nThis describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.\n\n### Complete machine-readable capability record\n\n```json\n{\n \"id\": \"change-audio-speed\",\n \"category\": \"media-tools\",\n \"built\": true,\n \"requirements\": \"Playback speed with optional pitch preservation and output preview.\",\n \"implementation\": {\n \"fields\": [\n {\n \"key\": \"speed\",\n \"label\": \"Speed multiplier\",\n \"value\": 1.25,\n \"type\": \"number\",\n \"min\": 0.5,\n \"max\": 2,\n \"step\": \"any\"\n },\n {\n \"key\": \"engine\",\n \"label\": \"Processing location\",\n \"type\": \"select\",\n \"value\": \"browser\",\n \"values\": [\n \"browser\",\n \"server\"\n ],\n \"labels\": {\n \"browser\": \"Browser (files stay here)\",\n \"server\": \"Local server (larger files)\"\n }\n }\n ],\n \"files\": true,\n \"accept\": \".mp3,.wav,.m4a,.aac,.flac,.ogg,.opus\",\n \"multiple\": false,\n \"input\": false,\n \"processing\": \"Browser or server\",\n \"native\": true,\n \"maxFileBytes\": 20971520,\n \"note\": \"Browser processing keeps files on this device. Choosing Local server sends files to this website’s own processor. Preserves pitch and exports WAV.\",\n \"hybrid\": true,\n \"experience\": {\n \"automatic\": false,\n \"single\": false,\n \"label\": \"Your text\",\n \"placeholder\": \"Type or paste your input…\",\n \"help\": \"Up to 1,000,000 characters. Review the settings before running.\",\n \"action\": null\n },\n \"mode\": \"explicit\",\n \"interactive\": false\n },\n \"execution\": \"POST /api/v1/tools/change-audio-speed/run\",\n \"api\": {\n \"id\": \"change-audio-speed\",\n \"name\": \"Change audio speed\",\n \"category\": \"media-tools\",\n \"description\": \"Change audio playback speed while preserving pitch.\",\n \"notes\": \"Browser processing keeps files on this device. Choosing Local server sends files to this website’s own processor. Preserves pitch and exports WAV.\",\n \"human_path\": \"/en/media-tools/change-audio-speed/\",\n \"method\": \"POST\",\n \"endpoint\": \"/api/v1/tools/change-audio-speed/run\",\n \"schema_url\": \"/api/v1/tools/change-audio-speed\",\n \"input_schema\": {\n \"type\": \"object\",\n \"additionalProperties\": false,\n \"properties\": {\n \"input\": {\n \"type\": \"string\",\n \"maxLength\": 1000000,\n \"default\": \"\",\n \"description\": \"Plain text input. File tools use files instead unless otherwise documented.\"\n },\n \"options\": {\n \"type\": \"object\",\n \"additionalProperties\": false,\n \"properties\": {\n \"speed\": {\n \"type\": \"number\",\n \"description\": \"Speed multiplier\",\n \"default\": 1.25,\n \"minimum\": 0.5,\n \"maximum\": 2\n },\n \"engine\": {\n \"type\": \"string\",\n \"description\": \"Processing location\",\n \"default\": \"browser\",\n \"enum\": [\n \"browser\",\n \"server\"\n ]\n }\n }\n },\n \"files\": {\n \"type\": \"array\",\n \"maxItems\": 1,\n \"items\": {\n \"type\": \"object\",\n \"required\": [\n \"name\",\n \"base64\"\n ],\n \"additionalProperties\": false,\n \"properties\": {\n \"name\": {\n \"type\": \"string\",\n \"maxLength\": 200,\n \"description\": \"Filename only, no path.\"\n },\n \"mime\": {\n \"type\": \"string\",\n \"maxLength\": 150\n },\n \"bytes\": {\n \"type\": \"integer\",\n \"minimum\": 0,\n \"description\": \"Optional decoded byte count; must match content if supplied.\"\n },\n \"base64\": {\n \"type\": \"string\",\n \"contentEncoding\": \"base64\",\n \"description\": \"File bytes as padded base64. Use the tool-specific limits.files_bytes value for the total decoded input size.\"\n }\n }\n }\n }\n }\n },\n \"output_schema\": {\n \"type\": \"object\",\n \"required\": [\n \"tool\",\n \"result\"\n ],\n \"properties\": {\n \"tool\": {\n \"type\": \"string\"\n },\n \"result\": {\n \"type\": \"object\",\n \"required\": [\n \"text\",\n \"files\"\n ],\n \"properties\": {\n \"text\": {\n \"type\": [\n \"string\",\n \"null\"\n ]\n },\n \"data\": {\n \"description\": \"Parsed JSON when the textual result is JSON.\"\n },\n \"name\": {\n \"type\": \"string\"\n },\n \"mime\": {\n \"type\": \"string\"\n },\n \"files\": {\n \"type\": \"array\",\n \"items\": {\n \"type\": \"object\",\n \"required\": [\n \"name\",\n \"mime\",\n \"bytes\",\n \"base64\"\n ],\n \"properties\": {\n \"name\": {\n \"type\": \"string\"\n },\n \"mime\": {\n \"type\": \"string\"\n },\n \"bytes\": {\n \"type\": \"integer\"\n },\n \"base64\": {\n \"type\": \"string\",\n \"contentEncoding\": \"base64\"\n }\n }\n }\n }\n }\n }\n }\n },\n \"processing\": \"Server; self-hosted native engine, no external conversion service\",\n \"limits\": {\n \"request_bytes\": 31457280,\n \"input_characters\": 1000000,\n \"files_bytes\": 20971520,\n \"max_files\": 1,\n \"timeout_seconds\": 90\n }\n },\n \"agent_processing\": \"Server; self-hosted native engine, no external conversion service\",\n \"browser_agent\": {\n \"supported\": true,\n \"name\": \"run_current_tool\",\n \"discovery\": \"WebMCP on the human page in a supporting browser\",\n \"verification\": \"See audit/API-AUDIT.md; availability is not verification\"\n }\n}\n```\n\n## Page guide\n\nChange audio playback speed while preserving pitch.\n\n## Useful next steps\n\n- [MP4 to MP3](https://happytails.ai/en/media-tools/mp4-to-mp3/): Convert MP4 files to MP3 with the available format settings. ([Markdown](https://happytails.ai/en/media-tools/mp4-to-mp3.md))\n\n- [WAV to MP3](https://happytails.ai/en/media-tools/wav-to-mp3/): Convert WAV files to MP3 with the available format settings. ([Markdown](https://happytails.ai/en/media-tools/wav-to-mp3.md))\n\n- [M4a to MP3](https://happytails.ai/en/media-tools/m4a-to-mp3/): Convert M4A files to MP3 with the available format settings. ([Markdown](https://happytails.ai/en/media-tools/m4a-to-mp3.md))\n\n## How to use Change audio speed\n\n1. Choose a file in MP3, WAV, M4A, AAC, FLAC, OGG or OPUS.\n2. Review the settings, then choose Run Change audio speed.\n3. Review the result, then use Copy result or a download link when available.\n\n## What to expect\n\nChange audio playback speed while preserving pitch. Browser processing keeps files on this device. Choosing Local server sends files to this website’s own processor. Preserves pitch and exports WAV.\n" }