> ## Documentation Index
> Fetch the complete documentation index at: https://docs.acusight.io/llms.txt
> Use this file to discover all available pages before exploring further.

# MSE playback init



## OpenAPI

````yaml /api-spec.json get /core/devices/{device_id}/recordings/{stream_path}/playback/init
openapi: 3.0.0
info:
  contact:
    name: Acusight API Support
  description: >-
    Acusight platform API - custom endpoints + Portainer proxy routes for edge
    AI deployments
  title: Acusight API
  version: 1.0.0
servers:
  - url: https://acusight.io/api
    description: AcuSight Cloud (hosted)
security: []
tags:
  - name: Devices & provisioning
    description: Register, provision, and manage edge devices and their agents.
  - name: Virtual devices
    description: Create and drive simulated devices for testing and demos.
  - name: Alerts & telemetry
    description: Model alerts, alert rules, and product telemetry.
  - name: Organization
    description: Organization-level settings.
  - name: Datasets & data
    description: Projects, batches, datasets, images, annotations, and drift.
  - name: Models & training
    description: Model registry, training jobs, exports, and inference.
  - name: Pipeline data
    description: Detection time-series and aggregated pipeline analytics.
paths:
  /core/devices/{device_id}/recordings/{stream_path}/playback/init:
    get:
      tags:
        - Devices & provisioning
      summary: MSE playback init
      parameters:
        - description: Device ID
          in: path
          name: device_id
          required: true
          schema:
            type: string
        - description: Stream path
          in: path
          name: stream_path
          required: true
          schema:
            type: string
        - description: Session ID (UUID)
          in: query
          name: session_id
          required: true
          schema:
            type: string
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/handlers.PlaybackInitResponse'
        '400':
          description: missing_session_id
          content:
            application/json:
              schema:
                additionalProperties: true
                type: object
        '404':
          description: session_not_found
          content:
            application/json:
              schema:
                additionalProperties: true
                type: object
        '410':
          description: segment_expired
          content:
            application/json:
              schema:
                additionalProperties: true
                type: object
        '500':
          description: storage_error / invalid_fmp4 / db_error
          content:
            application/json:
              schema:
                additionalProperties: true
                type: object
      security:
        - BearerAuth: []
components:
  schemas:
    handlers.PlaybackInitResponse:
      properties:
        init_bytes_b64:
          description: >-
            InitBytesB64 is the base64-encoded ftyp+moov prefix from segment 0.

            The client appends this to a SourceBuffer before queueing media
            segments.
          type: string
        mime_type:
          description: >-
            MimeType is the full codecs string (e.g. `video/mp4;
            codecs="avc1.640029"`).
          type: string
        session_first_ntp_ns:
          description: >-
            SessionFirstNtpNs / SessionLastNtpNs are the session's NTP
            wall-clock

            bounds in nanoseconds, used by the UI to set playback slider
            extents.
          type: integer
        session_last_ntp_ns:
          type: integer
        timescale:
          description: Timescale is the video track's media timescale (units per second).
          type: integer
      type: object
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: >-
        JWT access token. Paste the token only; the Bearer prefix is added
        automatically.

````