> ## Documentation Index > Fetch the complete documentation index at: https://www.tella.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Get the beats of an audio or video source > Returns the tempo, every beat and every bar's first beat (downbeat) of an audio or video source owned by the caller or their workspace, in ms of source time. Each source is analyzed once and cached; the first request can take a few seconds, and answers 503 `unavailable` if the analysis is still running, so retry. ## OpenAPI ````yaml /openapi.json get /v1/sources/{sourceId}/beats openapi: 3.0.3 info: description: >- The Tella Public API allows you to programmatically access your videos and playlists, including transcripts, chapters, and thumbnails. ## Authentication All requests require a Bearer token in the Authorization header: ``` Authorization: Bearer tella_pk_xxxxx... ``` API keys can be generated in your Tella workspace settings. ## Rate Limiting The API is rate-limited to 200 requests per minute per user within a workspace. Rate limit information is returned in response headers: - `RateLimit-Policy`: Named quota, request limit, and window in seconds - `RateLimit`: Remaining quota and seconds until reset - `X-RateLimit-Limit`: Maximum requests per window - `X-RateLimit-Remaining`: Remaining requests in current window - `X-RateLimit-Reset`: Unix timestamp in milliseconds when the window resets A `429 Too Many Requests` response also includes `Retry-After` in seconds. title: Tella Public API version: 1.0.0 servers: - description: Production url: https://api.tella.com security: [] tags: - description: Video operations name: Videos - description: Sections of a video name: Clips - description: Playlist operations name: Playlists - description: Sidebar groups for organizing playlists name: Playlist Groups - description: Tags for categorizing and filtering videos name: Tags - description: 'Tella''s editor agent, working in a video: start a chat and follow it' name: Agent chats - description: >- Viewing analytics for a video or across the workspace: plays, watch time, retention, geography, referrers name: Analytics - description: The signed-in user, their workspace, its plan and agent credits name: Account - description: Personal, workspace, and default video backgrounds name: Backgrounds - description: >- Reusable media saved to a workspace, plus Tella's curated sound effect and background music catalogs — the same items the editor's media panels show name: Library - description: >- Motion graphics documents a video plays live as a Tella Motion clip, overlay or b-roll, edited with the editor's own commands name: Tella Motion - description: >- Screen walkthroughs an agent films of a web page with no one recording. Takes are started and read over the MCP server name: Auto Capture - description: Webhook endpoint management name: Webhooks externalDocs: description: API versioning and deprecation policy url: https://www.tella.com/docs/versioning paths: /v1/sources/{sourceId}/beats: get: tags: - Sources summary: Get the beats of an audio or video source description: >- Returns the tempo, every beat and every bar's first beat (downbeat) of an audio or video source owned by the caller or their workspace, in ms of source time. Each source is analyzed once and cached; the first request can take a few seconds, and answers 503 `unavailable` if the analysis is still running, so retry. operationId: getSourceBeats parameters: - description: Streaming upload source identifier in: path name: sourceId required: true schema: description: Streaming upload source identifier example: su_abc123def456 type: string responses: '200': content: application/json: schema: $ref: '#/components/schemas/MusicBeatsResponse' description: OK headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '400': content: application/json: example: docsUrl: https://docs.tella.com/ error: bad_request message: The request was malformed or contained invalid parameters. schema: $ref: '#/components/schemas/ErrorResponse' description: The request was malformed or contained invalid parameters. headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '401': content: application/json: example: docsUrl: https://docs.tella.com/ error: unauthorized message: Authentication is required. Provide a valid API key. schema: $ref: '#/components/schemas/ErrorResponse' description: Authentication is required. Provide a valid API key. headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '403': content: application/json: example: docsUrl: https://docs.tella.com/ error: forbidden message: You don't have permission to access this resource. schema: $ref: '#/components/schemas/ErrorResponse' description: You don't have permission to access this resource. headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '404': content: application/json: example: docsUrl: https://docs.tella.com/ error: not_found message: The requested resource was not found. schema: $ref: '#/components/schemas/ErrorResponse' description: The requested resource was not found. headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '409': content: application/json: example: docsUrl: https://docs.tella.com/ error: conflict message: >- The request conflicts with the resource's current state, e.g. an Idempotency-Key whose first request is still in progress. Retry once it settles. schema: $ref: '#/components/schemas/ErrorResponse' description: >- The request conflicts with the resource's current state, e.g. an Idempotency-Key whose first request is still in progress. Retry once it settles. headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '429': content: application/json: example: docsUrl: https://docs.tella.com/ error: rate_limited message: You have exceeded the rate limit. Please slow down. schema: $ref: '#/components/schemas/ErrorResponse' description: You have exceeded the rate limit. Please slow down. headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Retry-After: $ref: '#/components/headers/RetryAfter' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '500': content: application/json: example: docsUrl: https://docs.tella.com/ error: server_error message: An unexpected error occurred schema: $ref: '#/components/schemas/ErrorResponse' description: An unexpected error occurred headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '501': content: application/json: example: docsUrl: https://docs.tella.com/ error: not_implemented message: The requested operation is not implemented. schema: $ref: '#/components/schemas/ErrorResponse' description: The requested operation is not implemented. headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' '503': content: application/json: example: docsUrl: https://docs.tella.com/ error: unavailable message: >- A dependency was unavailable and the request was not executed. Safe to resend unchanged after the Retry-After delay. schema: $ref: '#/components/schemas/ErrorResponse' description: >- A dependency was unavailable and the request was not executed. Safe to resend unchanged after the Retry-After delay. headers: Deprecation: $ref: '#/components/headers/Deprecation' RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimitPolicy' Sunset: $ref: '#/components/headers/Sunset' X-RateLimit-Limit: $ref: '#/components/headers/XRateLimitLimit' X-RateLimit-Remaining: $ref: '#/components/headers/XRateLimitRemaining' X-RateLimit-Reset: $ref: '#/components/headers/XRateLimitReset' security: - BearerAuth: [] components: schemas: MusicBeatsResponse: additionalProperties: false description: >- Tempo, beats and bars of a music track, analyzed once per track and cached properties: beatsMs: description: >- Every beat, in ms: on the video's playback timeline for background music (the same times as `get_timeline`), in source time for a source example: - 512 - 1012 - 1512 - 2012 items: minimum: 0 type: number type: array beatsPerBar: description: 'Beats in each bar: 4, or 3 for a waltz-like meter' example: 4 maximum: 9007199254740991 minimum: -9007199254740991 type: integer bpm: description: Tempo in beats per minute. 0 when the track has no beat at all example: 120 minimum: 0 type: number confidence: description: >- How clearly the track has a pulse, 0 to 1. Steady produced music is usually above 0.4; beatless ambient music below 0.1, where the beats are only a guess example: 0.86 maximum: 1 minimum: 0 type: number downbeatsMs: description: >- The first beat of every bar, a subset of `beatsMs`. Cut or start a motion on these for the strongest musical accents example: - 512 - 2512 items: minimum: 0 type: number type: array durationMs: description: >- Length of the timeline the beats are on: the video's playback duration for background music, the source's duration for a source example: 95200 minimum: 0 type: number trackDurationMs: description: >- Length of one pass of the track. Background music restarts after it, so its beat grid restarts too example: 180036 minimum: 0 type: number required: - bpm - beatsPerBar - confidence - trackDurationMs - durationMs - beatsMs - downbeatsMs type: object ErrorResponse: additionalProperties: false description: Standard error response format properties: docsUrl: description: Link to Tella API documentation example: https://docs.tella.com/ format: uri type: string error: description: Machine-readable error code enum: - bad_request - unauthorized - forbidden - not_found - rate_limited - server_error - conflict - edit_conflict - not_implemented - unavailable example: not_found type: string message: description: Human-readable error message example: Resource not found type: string required: - error - message - docsUrl type: object headers: Deprecation: description: Indicates that an API operation is deprecated, following RFC 9745 example: '@1767225600' schema: type: string RateLimit: description: >- Current quota with remaining requests (`r`) and seconds until reset (`t`) example: '"public-api";r=95;t=42' schema: type: string RateLimitPolicy: description: >- Named quota policy with the request limit (`q`) and window in seconds (`w`) example: '"public-api";q=100;w=60' schema: type: string Sunset: description: >- Indicates when a deprecated API operation will become unavailable, following RFC 8594 example: Tue, 30 Jun 2026 23:59:59 GMT schema: type: string XRateLimitLimit: description: Maximum requests allowed in the current window example: 100 schema: type: integer XRateLimitRemaining: description: Requests remaining in the current window example: 95 schema: type: integer XRateLimitReset: description: Unix timestamp in milliseconds when the window resets example: 1704067200000 schema: format: int64 type: integer RetryAfter: description: Seconds to wait before retrying a rate-limited request example: 45 schema: minimum: 1 type: integer securitySchemes: BearerAuth: description: API key obtained from your Tella account settings scheme: bearer type: http ```` ## Related topics - [Get the audio waveform JSON for a source](https://www.tella.com/docs/api-reference/clips/get-the-audio-waveform-json-for-a-source.md) - [Get the audio waveform JSON for a source on no clip](https://www.tella.com/docs/api-reference/sources/get-the-audio-waveform-json-for-a-source-on-no-clip.md) - [Create a source upload (video, audio, image, or LUT)](https://www.tella.com/docs/api-reference/sources/create-a-source-upload-video-audio-image-or-lut.md) - [Background Music](https://www.tella.com/docs/mcp-tools/background-music.md) - [Get the beats of the background music](https://www.tella.com/docs/api-reference/videos/get-the-beats-of-the-background-music.md) This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.