# POST /v1/dubbing/project/{project_id}/transcript/segment (ElevenLabs API)
Base URL: https://api.elevenlabs.io
Auth: xi-api-key: <ELEVENLABS_API_KEY>
Last verified: 2026-09-03

> Add Dubbing Transcript Segment

## Critical Gotchas
* Authentication uses the non-standard `xi-api-key` header, not `Authorization: Bearer`. Sending a Bearer token returns HTTP 401.
* Text-to-speech responses are raw binary audio, not JSON. Write the body to a file (`--output speech.mp3`) rather than parsing it.

## cURL
curl -X POST 'https://api.elevenlabs.io/v1/dubbing/project/project-id/transcript/segment' \
  -H "xi-api-key: $ELEVENLABS_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"text":"string","speaker_id":"string","start_s":0,"end_s":0}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| project_id | path | string | Yes | Identifier of the dubbing project. |
| text | body | string | Yes | The text of the new segment. |
| speaker_id | body | string | Yes | Identifier of the segment's speaker. |
| start_s | body | number | Yes | Start time of the segment, in seconds. |

## Response (200 OK)
{"segment":{"id":"string","text":"string"},"revision":0}

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