Subtitle Synchronization
Open Subtitle Synchronization 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": "subtitle-alignment",
"category": "subtitle-tools",
"built": true,
"requirements": "Align a supplied transcript to audio and produce word or segment timestamps; flag unmatched text; forced alignment does not create speaker labels or fix wrong source words.",
"implementation": {
"fields": [
{
"key": "transcript",
"label": "Matching English transcript or lyrics",
"type": "textarea",
"value": ""
}
],
"files": true,
"accept": ".wav,.mp3,.m4a,.flac,.mp4,.webm",
"multiple": false,
"input": false,
"processing": "Server required",
"native": true,
"extra": true,
"maxFileBytes": 20971520,
"note": "Local Whisper forced alignment. English, up to one minute and 5,000 transcript characters. Review word timing; singing and overlapping voices may align poorly.",
"experience": {
"automatic": false,
"single": false,
"inputMaxLength": 1000000,
"inputMode": "text",
"label": "Your text",
"placeholder": "Type or paste your input…",
"help": "Up to 1,000,000 characters. Review the settings before running.",
"helpParts": [
"Up to 1,000,000 characters.",
"Review the settings before running."
],
"action": null
},
"mode": "explicit",
"interactive": false
},
"execution": "POST /api/v1/tools/subtitle-alignment/run",
"api": {
"id": "subtitle-alignment",
"name": "Subtitle alignment",
"category": "subtitle-tools",
"description": "Align a matching English transcript to recorded speech.",
"notes": "Local Whisper forced alignment. English, up to one minute and 5,000 transcript characters. Review word timing; singing and overlapping voices may align poorly.",
"human_path": "/en/subtitle-tools/subtitle-alignment/",
"method": "POST",
"endpoint": "/api/v1/tools/subtitle-alignment/run",
"schema_url": "/api/v1/tools/subtitle-alignment",
"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": {
"transcript": {
"type": "string",
"description": "Matching English transcript or lyrics",
"default": ""
}
}
},
"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"
}
}Page guide
Match an English transcript to the timing of recorded speech.
This tool needs server processing
The public server is not connected yet. File selection and processing are unavailable on this website.
Browse other tools in this categoryHow to use Subtitle alignment
- Choose a file in WAV, MP3, M4A, FLAC, MP4 or WEBM.
- Review the settings, then choose Run Subtitle alignment.
- Review the result, then use Copy result or a download link when available.
Useful next steps
What to expect
Align a matching English transcript to recorded speech. Local Whisper forced alignment. English, up to one minute and 5,000 transcript characters. Review word timing; singing and overlapping voices may align poorly.