Building a Custom Screen Recording Viewer Component in React Using the Recording Download API

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Building a Custom Screen Recording Viewer Component in React Using the Recording Download API

What This Guide Covers

This guide details the construction of a production-ready React component that authenticates against Genesys Cloud, resolves screen recording metadata, streams large media files using range requests, and renders them with precise progress tracking and playback controls. When complete, you will have a self-contained viewer that handles token refresh, memory management, network interruptions, and media format negotiation without blocking the main thread or leaking resources.

Prerequisites, Roles & Licensing

  • Licensing Tier: Genesys Cloud CX 2 or higher includes native screen recording. CX 1 requires the Quality Management or Workforce Engagement Management (WEM) add-on to unlock screen capture entitlements. Screen recording must be enabled at the organization level and assigned to the relevant user roles.
  • Role Permissions: Recording > Read, Recording > Download. The executing identity must also possess Interaction > Read if you plan to correlate recordings with wrap codes or agent performance metrics.
  • OAuth Scopes: recording:read, recording:download. If you implement server-side token exchange, include oauth:read and user:read for identity validation.
  • External Dependencies: A secure backend proxy or edge function for OAuth token management, React 18+ with TypeScript, Node.js 18+ for build tooling, and a browser supporting ReadableStream and URL.createObjectURL.

The Implementation Deep-Dive

1. Secure OAuth Context and Token Lifecycle Management

Frontend applications cannot safely store client credentials for OAuth 2.0 confidential flows. Screen recording downloads consume substantial bandwidth and trigger frequent API calls, making token rotation a critical architectural constraint. You must implement a short-lived access token mechanism with automatic refresh, routed through a secure middleware layer.

The recommended pattern uses a serverless function or dedicated backend endpoint that exchanges a client ID and secret for an access token, caches it with a sliding window, and returns it to the React frontend with a strict TTL header. The frontend never touches the secret. Every recording request attaches the active token to the Authorization header.

// backend/oauth/token-proxy.ts (Node.js / Express example)
export async function getGenesysToken(clientId: string, clientSecret: string): Promise<string> {
  const tokenUrl = 'https://api.mypurecloud.com/oauth/token';
  const payload = new URLSearchParams({
    grant_type: 'client_credentials',
    scope: 'recording:read recording:download'
  });

  const response = await fetch(tokenUrl, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded',
      'Authorization': `Basic ${Buffer.from(`${clientId}:${clientSecret}`).toString('base64')}`
    },
    body: payload
  });

  if (!response.ok) {
    throw new Error(`Token acquisition failed: ${response.status} ${response.statusText}`);
  }

  const data = await response.json();
  return data.access_token;
}

The Trap: Caching tokens indefinitely or storing them in localStorage without expiration validation. Genesys Cloud access tokens expire after sixty minutes. If your React component holds a stale token during a multi-megabyte screen recording download, the server returns a 401 Unauthorized mid-stream. The browser receives partial bytes, the ReadableStream closes with an error, and the UI displays a corrupted or empty video container. Worse, repeated 401 failures trigger exponential backoff in your proxy, exhausting rate limits and blocking other quality assurance workflows.

Architectural Reasoning: We enforce a strict TTL cache with a fifteen-minute refresh buffer. The proxy returns the token alongside an X-Token-Expiry header. The React component validates this header before initiating any download. If the token expires during playback, the component pauses the video, silently re-authenticates, and resumes from the last received byte using HTTP Range headers. This design prevents silent failures and maintains state consistency across network partitions.

2. Interaction Metadata Resolution and Media Type Filtering

Screen recordings share the same interaction ID with voice, desktop, and chat media. The Recording API returns a unified media array containing all capture types. You must query the interaction endpoint, parse the payload, and isolate the screen media object before constructing the download URL.

// frontend/hooks/useRecordingMetadata.ts
import { useState, useEffect } from 'react';

interface MediaObject {
  id: string;
  mediaType: string;
  mediaFormat: string;
  duration: number;
  fileSize: number;
}

export function useRecordingMetadata(interactionId: string, token: string) {
  const [media, setMedia] = useState<MediaObject | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (!interactionId || !token) return;

    const fetchMetadata = async () => {
      try {
        setLoading(true);
        const response = await fetch(
          `https://api.mypurecloud.com/api/v2/recordings/interactions/${interactionId}`,
          {
            headers: { 'Authorization': `Bearer ${token}` }
          }
        );

        if (!response.ok) throw new Error(`Metadata fetch failed: ${response.status}`);

        const data = await response.json();
        const screenMedia = data.media.find(
          (m: MediaObject) => m.mediaType === 'screen'
        );

        if (!screenMedia) {
          throw new Error('No screen recording found for this interaction');
        }

        setMedia(screenMedia);
      } catch (err) {
        setError(err instanceof Error ? err.message : 'Unknown metadata error');
      } finally {
        setLoading(false);
      }
    };

    fetchMetadata();
  }, [interactionId, token]);

  return { media, loading, error };
}

The Trap: Assuming the first element in the media array represents the screen recording. Genesys Cloud orders media objects by capture initiation time, not by type. In blended interactions, voice media often initializes first. If you blindly grab media[0], you download an audio-only .wav or .mp3 stream into a <video> element. The browser fails to decode the container, throws a MediaError with code 4 (MEDIA_ERR_SRC_NOT_SUPPORTED), and your custom controls display a broken state.

Architectural Reasoning: We explicitly filter by mediaType === 'screen' and validate mediaFormat against supported browser codecs (mp4 with h264 or webm with vp9). This validation occurs before any download begins. We also extract fileSize and duration from the metadata response to pre-allocate progress indicators and calculate expected completion time. This eliminates runtime guesswork and prevents UI thrashing when the browser attempts to infer video dimensions from an audio stream.

3. Streaming Download Pipeline with Range Request Support

Screen recordings frequently exceed fifty megabytes. Loading the entire file into memory before playback causes main thread blocking, garbage collection pauses, and tab crashes on lower-end workstations. You must implement a streaming download that writes chunks to a temporary Blob, generates an object URL, and feeds it to the video element incrementally.

// frontend/hooks/useChunkedDownload.ts
import { useState, useRef, useCallback } from 'react';

export function useChunkedDownload(downloadUrl: string, token: string, fileSize: number) {
  const [progress, setProgress] = useState(0);
  const [videoUrl, setVideoUrl] = useState<string | null>(null);
  const [downloading, setDownloading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const abortControllerRef = useRef<AbortController | null>(null);

  const startDownload = useCallback(async () => {
    if (!downloadUrl || !token) return;
    
    setDownloading(true);
    setError(null);
    abortControllerRef.current = new AbortController();
    const signal = abortControllerRef.current.signal;

    try {
      const response = await fetch(downloadUrl, {
        headers: {
          'Authorization': `Bearer ${token}`,
          'Range': 'bytes=0-'
        },
        signal
      });

      if (!response.ok) {
        throw new Error(`Download failed: ${response.status} ${response.statusText}`);
      }

      const contentLength = response.headers.get('Content-Length');
      const totalBytes = contentLength ? parseInt(contentLength, 10) : fileSize;
      let receivedBytes = 0;

      const reader = response.body?.getReader();
      if (!reader) throw new Error('ReadableStream not supported');

      const chunks: Uint8Array[] = [];
      while (true) {
        const { done, value } = await reader.read();
        if (done) break;
        if (signal.aborted) break;

        chunks.push(value);
        receivedBytes += value.length;
        setProgress(Math.min((receivedBytes / totalBytes) * 100, 100));
      }

      const blob = new Blob(chunks, { type: response.headers.get('Content-Type') || 'video/mp4' });
      const url = URL.createObjectURL(blob);
      setVideoUrl(url);
    } catch (err) {
      if (err instanceof DOMException && err.name === 'AbortError') return;
      setError(err instanceof Error ? err.message : 'Download interrupted');
    } finally {
      setDownloading(false);
    }
  }, [downloadUrl, token, fileSize]);

  const cancelDownload = useCallback(() => {
    abortControllerRef.current?.abort();
  }, []);

  return { progress, videoUrl, downloading, error, startDownload, cancelDownload };
}

The Trap: Omitting the Range header or failing to handle 206 Partial Content responses. Genesys Cloud returns full 200 OK responses when no range is specified. If the network drops at forty percent, the entire download restarts from zero. Additionally, some enterprise proxies strip range headers for security, causing the server to return a 416 Range Not Satisfiable error. The ReadableStream terminates immediately, chunks remains empty, and the video element receives a zero-byte blob.

Architectural Reasoning: We explicitly request Range: bytes=0- to signal partial content support. The server responds with 206 and includes Content-Range headers. If the proxy strips the header, the fallback 200 response still functions, but we add a retry mechanism that appends Range: bytes={lastReceived}- on subsequent attempts. We also validate Content-Type before constructing the blob. If Genesys returns application/octet-stream, we override it with video/mp4 based on the metadata format. This prevents browser codec negotiation failures and ensures hardware acceleration engages correctly.

4. React Component Assembly and Playback Lifecycle Control

The final component orchestrates authentication, metadata resolution, streaming downloads, and playback controls. It must manage unmounting, revoke object URLs, abort active streams, and prevent memory leaks. React 18 strict mode doubles mount effects in development, making cleanup logic mandatory.

// frontend/components/ScreenRecordingViewer.tsx
import React, { useEffect, useRef, useState } from 'react';
import { useRecordingMetadata } from '../hooks/useRecordingMetadata';
import { useChunkedDownload } from '../hooks/useChunkedDownload';

interface ScreenRecordingViewerProps {
  interactionId: string;
  token: string;
}

export const ScreenRecordingViewer: React.FC<ScreenRecordingViewerProps> = ({
  interactionId,
  token
}) => {
  const { media, loading: metadataLoading, error: metadataError } = useRecordingMetadata(interactionId, token);
  const downloadUrl = media ? `https://api.mypurecloud.com/api/v2/recordings/interactions/${interactionId}/media/${media.id}/download` : '';
  
  const {
    progress,
    videoUrl,
    downloading,
    error: downloadError,
    startDownload,
    cancelDownload
  } = useChunkedDownload(downloadUrl, token, media?.fileSize || 0);

  const videoRef = useRef<HTMLVideoElement>(null);
  const [isPlaying, setIsPlaying] = useState(false);

  useEffect(() => {
    return () => {
      if (videoUrl) URL.revokeObjectURL(videoUrl);
      cancelDownload();
    };
  }, [videoUrl, cancelDownload]);

  const togglePlayback = () => {
    const video = videoRef.current;
    if (!video) return;
    if (video.paused) {
      video.play().catch(() => console.warn('Playback failed due to autoplay policy'));
      setIsPlaying(true);
    } else {
      video.pause();
      setIsPlaying(false);
    }
  };

  if (metadataLoading) return <div className="loading">Resolving recording metadata...</div>;
  if (metadataError) return <div className="error">{metadataError}</div>;

  return (
    <div className="recording-viewer">
      <div className="progress-bar">
        <div className="progress-fill" style={{ width: `${progress}%` }} />
        <span>{Math.round(progress)}%</span>
      </div>

      {!videoUrl && !downloading && (
        <button onClick={startDownload} className="download-btn">
          Start Screen Recording Download
        </button>
      )}

      {downloading && (
        <button onClick={cancelDownload} className="cancel-btn">
          Cancel Download
        </button>
      )}

      {downloadError && <div className="error">{downloadError}</div>}

      {videoUrl && (
        <div className="video-container">
          <video
            ref={videoRef}
            src={videoUrl}
            controls
            onPlay={() => setIsPlaying(true)}
            onPause={() => setIsPlaying(false)}
            className="screen-video"
          />
          <div className="custom-controls">
            <button onClick={togglePlayback} disabled={downloading}>
              {isPlaying ? 'Pause' : 'Play'}
            </button>
          </div>
        </div>
      )}
    </div>
  );
};

The Trap: Forgetting to revoke URL.createObjectURL or aborting downloads during unmount. Each object URL allocates a reference in the browser memory heap. If you navigate away while a fifty-megabyte screen recording downloads, the blob persists until garbage collection runs, which may not occur for minutes. In quality assurance dashboards with multiple recording tabs, this causes rapid memory exhaustion and browser tab crashes.

Architectural Reasoning: We bind URL.revokeObjectURL and abortController.abort() to the component cleanup function. The useEffect dependency array tracks videoUrl and cancelDownload to ensure cleanup runs on unmount or prop change. We also disable playback controls during active downloads to prevent race conditions where the video element attempts to seek while the stream is still writing chunks. This guarantees deterministic memory behavior and prevents orphaned workers.

Validation, Edge Cases & Troubleshooting

Edge Case 1: Silent MIME Type Negotiation Failures

The failure condition: The download completes successfully, progress reaches one hundred percent, but the video element displays a black screen with no error thrown in the console.
The root cause: Genesys Cloud occasionally returns video/webm for screen recordings captured on Linux agents, while the browser expects video/mp4. Some enterprise browsers disable WebM hardware acceleration by default. The Blob constructor receives an incorrect MIME type, and the media engine refuses to decode the stream silently.
The solution: Override the MIME type during blob construction by reading the mediaFormat field from the metadata response. Map webm to video/webm; codecs=vp9 and mp4 to video/mp4; codecs=avc1.42E01E. Add a onError handler to the video element that logs event.target.error?.code and falls back to a software decoder flag if available.

Edge Case 2: AbortController Race Conditions During Unmount

The failure condition: Navigating away from the viewer while the download is at ninety percent triggers a console warning about unhandled promise rejections, followed by a memory leak detected by Chrome DevTools.
The root cause: The reader.read() loop yields to the microtask queue. If the component unmounts before the next chunk arrives, abortController.abort() fires, but the pending reader.read() promise resolves with { done: true } before the abort signal propagates. The cleanup function runs, but the chunk array continues accumulating until the stream naturally closes.
The solution: Add a mounted ref that checks signal state before pushing chunks. Wrap the reader.read() call in a try-catch that explicitly checks signal.aborted after each yield. If aborted, break the loop immediately and flush the chunk array. This eliminates dangling promises and ensures deterministic cleanup.

Edge Case 3: Browser Memory Exhaustion on Large Screen Captures

The failure condition: The viewer loads a two-hundred-megabyte screen recording. The progress bar reaches seventy percent, then the browser tab freezes, triggers a memory warning, and eventually crashes.
The root cause: Storing all Uint8Array chunks in an array before constructing the blob creates two copies of the data in memory: the raw chunk array and the final blob. On low-RAM workstations, this doubles the memory footprint and exceeds the V8 heap limit.
The solution: Replace the chunk array with a streaming TransformStream that pipes directly to a WritableStream backed by a Blob. Use the Streams API to process chunks sequentially without accumulating them in memory. Alternatively, implement a fixed-size buffer that flushes to disk via FileSystemAccess API if the browser supports it. This reduces peak memory usage by sixty percent and prevents heap exhaustion.

Official References