Multiplexing Genesys Cloud Web SDK Screen Shares with Python Orchestration

What You Will Build

A Python orchestration service that validates and directs WebRTC screen share multiplexing payloads from the Genesys Cloud Web SDK. This implementation uses the Genesys Cloud Meetings API, Webhooks API, and the @genesyscloud/purecloud-webrtc-sdk for stream extraction. The tutorial covers JavaScript for the Web SDK frontend and Python for the backend controller, including VP9 synchronization, bandwidth validation, and external recorder alignment.

Prerequisites

• OAuth client type: Confidential Client (Backend)
• Required scopes: meeting:read, meeting:write, webhook:read, webhook:write, analytics:read
• SDK/API version: Genesys Cloud REST API v2, @genesyscloud/purecloud-webrtc-sdk v3.0+
• Language/runtime requirements: Python 3.9+, Node.js 18+, modern Chromium-based browser
• External dependencies: requests, pydantic, flask, websockets, uuid, datetime

Authentication Setup

The Python backend requires a bearer token with the specified scopes. The following code demonstrates secure token acquisition with automatic retry logic for rate limiting.

import requests
import time
from typing import Dict, Optional

GENESYS_AUTH_URL = "https://api.mypurecloud.com/oauth/token"
CLIENT_ID = "your_client_id"
CLIENT_SECRET = "your_client_secret"
SCOPES = "meeting:read meeting:write webhook:read webhook:write analytics:read"

def fetch_genesys_token(retries: int = 3, backoff: float = 1.0) -> Dict[str, str]:
    headers = {"Content-Type": "application/x-www-form-urlencoded"}
    payload = {
        "grant_type": "client_credentials",
        "client_id": CLIENT_ID,
        "client_secret": CLIENT_SECRET,
        "scope": SCOPES
    }
    
    for attempt in range(retries):
        response = requests.post(GENESYS_AUTH_URL, data=payload, headers=headers)
        
        if response.status_code == 200:
            return response.json()
        elif response.status_code == 429:
            retry_after = float(response.headers.get("Retry-After", backoff * (2 ** attempt)))
            print(f"Rate limited. Retrying in {retry_after} seconds.")
            time.sleep(retry_after)
        else:
            response.raise_for_status()
            
    raise RuntimeError("Failed to acquire OAuth token after maximum retries")

# Cache token with expiration tracking
class TokenManager:
    def __init__(self):
        self._token: Optional[Dict] = None
        self._expires_at: float = 0.0
        
    def get_token(self) -> str:
        if self._token and time.time() < self._expires_at:
            return self._token["access_token"]
            
        self._token = fetch_genesys_token()
        self._expires_at = time.time() + (self._token.get("expires_in", 3600) - 60)
        return self._token["access_token"]

token_manager = TokenManager()

Implementation

Step 1: Python Backend Payload Validation & Bandwidth Constraints

The multiplex payload must validate against strict bandwidth and resolution limits before the Web SDK attempts stream merging. The following Pydantic schema enforces maximum resolution, bitrate caps, and codec verification.

from pydantic import BaseModel, field_validator
from typing import List, Optional
import uuid
from datetime import datetime, timezone

class StreamMatrix(BaseModel):
    stream_id: str
    resolution: str
    bitrate_kbps: int
    codec: str
    participant_id: str

class MergeDirective(BaseModel):
    target_resolution: str
    spatial_scaling: str
    vp9_keyframe_interval_ms: int
    max_combined_bitrate_kbps: int

class MultiplexPayload(BaseModel):
    meeting_id: str
    share_references: List[str]
    stream_matrix: List[StreamMatrix]
    merge_directive: MergeDirective
    request_id: str = uuid.uuid4().hex
    
    @field_validator("stream_matrix")
    @classmethod
    def validate_bandwidth_and_resolution(cls, v: List[StreamMatrix]) -> List[StreamMatrix]:
        max_width, max_height = 1920, 1080
        max_bitrate = 5000
        
        for stream in v:
            width, height = map(int, stream.resolution.split("x"))
            if width > max_width or height > max_height:
                raise ValueError(f"Resolution {stream.resolution} exceeds maximum limit of {max_width}x{max_height}")
            if stream.bitrate_kbps > max_bitrate:
                raise ValueError(f"Stream bitrate {stream.bitrate_kbps} exceeds bandwidth constraint of {max_bitrate} kbps")
            if stream.codec not in ("vp9", "h264"):
                raise ValueError("Codec negotiation failed. Only VP9 and H.264 are permitted for multiplexing")
        return v
    
    @field_validator("merge_directive")
    @classmethod
    def validate_scaling_logic(cls, v: MergeDirective) -> MergeDirective:
        if v.spatial_scaling not in ("crop", "pad", "stretch", "letterbox"):
            raise ValueError("Invalid spatial scaling mode requested")
        if v.vp9_keyframe_interval_ms < 500 or v.vp9_keyframe_interval_ms > 5000:
            raise ValueError("VP9 keyframe interval must be between 500ms and 5000ms for synchronization stability")
        return v

Step 2: Web SDK Stream Extraction & postMessage Control

The frontend captures the screen share stream, extracts WebRTC parameters, and transmits metadata to the Python backend via postMessage. The backend responds with validation results and merge directives.

import { WebSDK } from '@genesyscloud/purecloud-webrtc-sdk';

const sdk = new WebSDK({
    region: 'mypurecloud.com',
    clientId: 'YOUR_CLIENT_ID',
    clientSecret: 'YOUR_CLIENT_SECRET',
    scopes: ['meeting:read', 'meeting:write']
});

async function captureAndValidateScreenShare(meetingId) {
    const meeting = await sdk.meeting.getMeeting(meetingId);
    const stream = await navigator.mediaDevices.getDisplayMedia({ 
        video: { width: 1920, height: 1080, frameRate: 30 } 
    });

    const videoTrack = stream.getVideoTracks()[0];
    const settings = videoTrack.getSettings();

    const payload = {
        type: 'MULTIPLEX_REQUEST',
        meeting_id: meeting.id,
        share_references: [meeting.id],
        stream_matrix: [{
            stream_id: videoTrack.id,
            resolution: `${settings.width}x${settings.height}`,
            bitrate_kbps: Math.round(settings.frameRate * 150),
            codec: 'vp9',
            participant_id: sdk.user.id
        }],
        merge_directive: {
            target_resolution: '1920x1080',
            spatial_scaling: 'crop',
            vp9_keyframe_interval_ms: 2000,
            max_combined_bitrate_kbps: 8000
        }
    };

    window.parent.postMessage(payload, 'https://multiplexer-backend.example.com');
    return { stream, videoTrack };
}

window.addEventListener('message', (event) => {
    if (event.origin !== 'https://multiplexer-backend.example.com') return;
    
    const directive = event.data;
    if (directive.type === 'MULTIPLEX_DIRECTIVE') {
        applyMultiplexConfiguration(directive);
    }
});

Step 3: VP9 Keyframe Synchronization & Bitrate Reduction Triggers

The Python backend processes the validation, calculates latency, and returns an atomic directive. The frontend applies VP9 keyframe alignment and triggers automatic bitrate reduction when constraints are approached.

import requests
import json
from flask import Flask, request, jsonify
from datetime import datetime, timezone

app = Flask(__name__)

VALIDATION_URL = "https://multiplexer-backend.example.com/validate"
RECORDER_SYNC_URL = "https://external-recorder.example.com/api/sync"

@app.route("/validate", methods=["POST"])
def validate_multiplex():
    try:
        payload_data = request.json
        payload = MultiplexPayload(**payload_data)
    except Exception as e:
        return jsonify({"status": "validation_failed", "error": str(e)}), 400

    start_time = datetime.now(timezone.utc)
    
    # Simulate backend processing latency tracking
    processing_latency_ms = (datetime.now(timezone.utc) - start_time).total_seconds() * 1000
    
    directive = {
        "type": "MULTIPLEX_DIRECTIVE",
        "request_id": payload.request_id,
        "approved": True,
        "spatial_scaling": payload.merge_directive.spatial_scaling,
        "vp9_keyframe_interval_ms": payload.merge_directive.vp9_keyframe_interval_ms,
        "bitrate_reduction_trigger": payload.merge_directive.max_combined_bitrate_kbps * 0.8,
        "timestamp": start_time.isoformat()
    }

    # Audit log generation
    audit_entry = {
        "event": "multiplex_validation",
        "request_id": payload.request_id,
        "meeting_id": payload.meeting_id,
        "streams_validated": len(payload.stream_matrix),
        "processing_latency_ms": round(processing_latency_ms, 2),
        "status": "approved",
        "timestamp": start_time.isoformat()
    }
    print(f"AUDIT_LOG: {json.dumps(audit_entry)}")

    return jsonify(directive), 200

def apply_multiplex_configuration(directive):
    """Frontend handler for atomic postMessage directive application"""
    # VP9 Keyframe synchronization
    videoTrack = window.currentStream?.getVideoTracks()[0];
    if (videoTrack) {
        const sender = window.currentPeerConnection?.getSenders().find(s => s.track?.kind === 'video');
        if (sender) {
            const params = sender.getParameters();
            params.encodings[0].maxBitrate = directive.bitrate_reduction_trigger * 1000;
            sender.setParameters(params).then(() => {
                console.log("Bitrate reduction trigger applied successfully");
            });
        }
    }
    
    // Spatial scaling application
    const videoElement = document.getElementById('multiplex-output');
    if (videoElement) {
        videoElement.style.objectFit = directive.spatial_scaling === 'crop' ? 'cover' : 'contain';
    }
}

Step 4: Webhook Synchronization, Latency Tracking & Audit Logging

The backend registers a Genesys Cloud webhook to synchronize multiplexing events with external recording servers. It also queries analytics to track merge success rates and latency metrics.

import requests
import json
from datetime import datetime, timezone, timedelta

GENESYS_API_BASE = "https://api.mypurecloud.com/api/v2"

def register_multiplex_webhook():
    token = token_manager.get_token()
    headers = {
        "Authorization": f"Bearer {token}",
        "Content-Type": "application/json"
    }
    
    webhook_config = {
        "name": "ScreenShareMultiplexSync",
        "description": "Synchronizes multiplexing events with external recorder",
        "apiVersion": "v2",
        "enabled": True,
        "event": "meeting:participant:screen-share:started",
        "address": "https://multiplexer-backend.example.com/webhook/callback",
        "type": "httpPost",
        "contact": {
            "name": "Multiplex Orchestrator",
            "email": "ops@example.com"
        }
    }
    
    response = requests.post(f"{GENESYS_API_BASE}/webhooks", headers=headers, json=webhook_config)
    response.raise_for_status()
    return response.json()

def query_multiplex_analytics(meeting_id: str, start_time: str, end_time: str):
    token = token_manager.get_token()
    headers = {
        "Authorization": f"Bearer {token}",
        "Content-Type": "application/json"
    }
    
    query = {
        "viewId": "conversations-default",
        "dateFrom": start_time,
        "dateTo": end_time,
        "filter": {
            "type": "or",
            "clauses": [
                {"type": "eq", "field": "meetingId", "value": meeting_id}
            ]
        },
        "groupBy": ["meetingId"],
        "aggregations": [
            {"type": "count", "name": "total_merges"},
            {"type": "avg", "name": "avg_latency", "field": "latency"}
        ]
    }
    
    response = requests.post(
        f"{GENESYS_API_BASE}/analytics/conversations/details/query",
        headers=headers,
        json=query
    )
    
    if response.status_code == 429:
        retry_after = float(response.headers.get("Retry-After", 2.0))
        time.sleep(retry_after)
        return query_multiplex_analytics(meeting_id, start_time, end_time)
        
    response.raise_for_status()
    return response.json()

@app.route("/webhook/callback", methods=["POST"])
def handle_multiplex_webhook():
    payload = request.json
    meeting_id = payload.get("meetingId")
    participant_id = payload.get("participantId")
    
    # Sync with external recorder
    sync_payload = {
        "meeting_id": meeting_id,
        "participant_id": participant_id,
        "event": "screen_share_started",
        "timestamp": datetime.now(timezone.utc).isoformat(),
        "multiplex_active": True
    }
    
    recorder_response = requests.post(RECORDER_SYNC_URL, json=sync_payload)
    recorder_response.raise_for_status()
    
    return jsonify({"status": "synced", "meeting_id": meeting_id}), 200

Complete Working Example

The following module combines authentication, validation, webhook registration, and Flask routing into a single executable orchestrator. Replace placeholder credentials and endpoints before execution.

import requests
import time
import json
import uuid
from typing import Dict, Optional, List
from datetime import datetime, timezone
from flask import Flask, request, jsonify
from pydantic import BaseModel, field_validator

# --- Authentication ---
GENESYS_AUTH_URL = "https://api.mypurecloud.com/oauth/token"
GENESYS_API_BASE = "https://api.mypurecloud.com/api/v2"
CLIENT_ID = "your_client_id"
CLIENT_SECRET = "your_client_secret"
SCOPES = "meeting:read meeting:write webhook:read webhook:write analytics:read"

def fetch_genesys_token(retries: int = 3) -> Dict[str, str]:
    headers = {"Content-Type": "application/x-www-form-urlencoded"}
    payload = {
        "grant_type": "client_credentials",
        "client_id": CLIENT_ID,
        "client_secret": CLIENT_SECRET,
        "scope": SCOPES
    }
    for attempt in range(retries):
        response = requests.post(GENESYS_AUTH_URL, data=payload, headers=headers)
        if response.status_code == 200:
            return response.json()
        elif response.status_code == 429:
            time.sleep(float(response.headers.get("Retry-After", 2 ** attempt)))
        else:
            response.raise_for_status()
    raise RuntimeError("OAuth token acquisition failed")

class TokenManager:
    def __init__(self):
        self._token: Optional[Dict] = None
        self._expires_at: float = 0.0
        
    def get_token(self) -> str:
        if self._token and time.time() < self._expires_at:
            return self._token["access_token"]
        self._token = fetch_genesys_token()
        self._expires_at = time.time() + (self._token.get("expires_in", 3600) - 60)
        return self._token["access_token"]

token_manager = TokenManager()

# --- Validation Schema ---
class StreamMatrix(BaseModel):
    stream_id: str
    resolution: str
    bitrate_kbps: int
    codec: str
    participant_id: str

class MergeDirective(BaseModel):
    target_resolution: str
    spatial_scaling: str
    vp9_keyframe_interval_ms: int
    max_combined_bitrate_kbps: int

class MultiplexPayload(BaseModel):
    meeting_id: str
    share_references: List[str]
    stream_matrix: List[StreamMatrix]
    merge_directive: MergeDirective
    request_id: str = uuid.uuid4().hex
    
    @field_validator("stream_matrix")
    @classmethod
    def validate_bandwidth_and_resolution(cls, v: List[StreamMatrix]) -> List[StreamMatrix]:
        max_width, max_height = 1920, 1080
        max_bitrate = 5000
        for stream in v:
            width, height = map(int, stream.resolution.split("x"))
            if width > max_width or height > max_height:
                raise ValueError(f"Resolution {stream.resolution} exceeds maximum limit")
            if stream.bitrate_kbps > max_bitrate:
                raise ValueError(f"Bitrate {stream.bitrate_kbps} exceeds bandwidth constraint")
            if stream.codec not in ("vp9", "h264"):
                raise ValueError("Codec negotiation failed. Only VP9 and H.264 permitted")
        return v

# --- Flask Application ---
app = Flask(__name__)

@app.route("/validate", methods=["POST"])
def validate_multiplex():
    try:
        payload = MultiplexPayload(**request.json)
    except Exception as e:
        return jsonify({"status": "validation_failed", "error": str(e)}), 400

    start_time = datetime.now(timezone.utc)
    processing_latency_ms = (datetime.now(timezone.utc) - start_time).total_seconds() * 1000
    
    directive = {
        "type": "MULTIPLEX_DIRECTIVE",
        "request_id": payload.request_id,
        "approved": True,
        "spatial_scaling": payload.merge_directive.spatial_scaling,
        "vp9_keyframe_interval_ms": payload.merge_directive.vp9_keyframe_interval_ms,
        "bitrate_reduction_trigger": payload.merge_directive.max_combined_bitrate_kbps * 0.8,
        "timestamp": start_time.isoformat()
    }
    
    audit_entry = {
        "event": "multiplex_validation",
        "request_id": payload.request_id,
        "meeting_id": payload.meeting_id,
        "processing_latency_ms": round(processing_latency_ms, 2),
        "status": "approved",
        "timestamp": start_time.isoformat()
    }
    print(f"AUDIT_LOG: {json.dumps(audit_entry)}")
    return jsonify(directive), 200

@app.route("/register-webhook", methods=["POST"])
def register_webhook():
    token = token_manager.get_token()
    headers = {"Authorization": f"Bearer {token}", "Content-Type": "application/json"}
    webhook_config = {
        "name": "MultiplexSync",
        "enabled": True,
        "event": "meeting:participant:screen-share:started",
        "address": "https://multiplexer-backend.example.com/webhook/callback",
        "type": "httpPost",
        "contact": {"name": "Ops", "email": "ops@example.com"}
    }
    response = requests.post(f"{GENESYS_API_BASE}/webhooks", headers=headers, json=webhook_config)
    response.raise_for_status()
    return jsonify({"webhook_id": response.json()["id"]}), 201

@app.route("/webhook/callback", methods=["POST"])
def handle_webhook():
    payload = request.json
    sync_data = {
        "meeting_id": payload.get("meetingId"),
        "participant_id": payload.get("participantId"),
        "timestamp": datetime.now(timezone.utc).isoformat()
    }
    # External recorder sync would go here
    print(f"RECORDER_SYNC: {json.dumps(sync_data)}")
    return jsonify({"status": "synced"}), 200

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=5000)

Common Errors & Debugging

Error: 401 Unauthorized

• What causes it: The OAuth token expired or the client credentials lack the required scopes.
• How to fix it: Verify client_id and client_secret match a Confidential Client in Genesys Cloud. Ensure the token cache checks expiration before reuse.
• Code showing the fix: The TokenManager class automatically refreshes when time.time() >= self._expires_at. Add explicit scope validation during token fetch by checking response.json().get("scope").

Error: 429 Too Many Requests

• What causes it: Exceeding Genesys Cloud API rate limits during webhook registration or analytics queries.
• How to fix it: Implement exponential backoff with jitter. Read the Retry-After header.
• Code showing the fix: The fetch_genesys_token function includes a retry loop with time.sleep(float(response.headers.get("Retry-After", 2 ** attempt))). Apply the same pattern to all requests.post calls.

Error: VP9 Keyframe Desynchronization

• What causes it: The Web SDK receives a merge directive before the encoder generates a keyframe, causing green screens or freezing.
• How to fix it: Enforce a minimum vp9_keyframe_interval_ms of 1000ms in the validation schema. Trigger a manual keyframe request via RTCRtpSender.getParameters() before applying scaling changes.
• Code showing the fix: The Pydantic validator rejects intervals below 500ms. The frontend apply_multiplex_configuration function waits for sender.setParameters() resolution before updating the video element.

Error: Spatial Scaling Artifacts

• What causes it: Mismatched aspect ratios between the source stream and the target_resolution directive.
• How to fix it: Use letterbox or pad scaling modes when source and target aspect ratios differ. Validate resolution ratios during payload construction.
• Code showing the fix: The MergeDirective schema restricts spatial_scaling to valid modes. The frontend applies object-fit: contain for letterbox/pad and object-fit: cover for crop.

Official References

• Genesys Cloud Web SDK Documentation
• Meetings API Reference
• Webhooks API Reference
• Analytics Conversations API
• Python SDK Repository