Transcoding Genesys Cloud Recordings to WebM Format On-The-Fly Using the Media API and a Go FFmpeg Service

What You Will Build

• A Go HTTP service that accepts a Genesys Cloud recording identifier, fetches the raw media stream via the Media API, pipes it directly to an FFmpeg subprocess, and returns a WebM-encoded stream to the requesting client.
• Uses the Genesys Cloud Media API endpoints /api/v2/media/recordings/{id} and /api/v2/media/recordings/{id}/download for retrieval and validation.
• Covers Go 1.21+ with net/http, os/exec, golang.org/x/oauth2, and standard process piping for zero-disk transcoding.

Prerequisites

• Genesys Cloud OAuth Client ID and Client Secret configured with the media:recording:view scope
• Genesys Cloud API version: v2 (Media API)
• Go 1.21 or later installed on the build host
• FFmpeg compiled with libvpx and libopus codecs available on the execution host
• External dependencies: golang.org/x/oauth2, golang.org/x/oauth2/clientcredentials

Authentication Setup

Genesys Cloud uses OAuth 2.0 for all API access. For server-side media processing, the Client Credentials flow is the standard choice. The Go oauth2 package handles token acquisition and automatic refresh. You must configure the token source with the correct environment endpoint and the media:recording:view scope. The HTTP client created from this configuration will attach the Authorization: Bearer <token> header to every request and refresh the token before expiration.

package main

import (
	"context"
	"net/http"
	"time"

	"golang.org/x/oauth2/clientcredentials"
)

type GenesysConfig struct {
	ClientID     string
	ClientSecret string
	Environment  string // Example: "mypurecloud.com" or "api.developer.mypurecloud.com"
}

func buildGenesysClient(cfg GenesysConfig) *http.Client {
	conf := &clientcredentials.Config{
		ClientID:     cfg.ClientID,
		ClientSecret: cfg.ClientSecret,
		TokenURL:     "https://" + cfg.Environment + "/oauth/token",
		Scopes:       []string{"media:recording:view"},
	}

	ctx := context.Background()
	// conf.Client() returns an *http.Client that automatically refreshes tokens
	return conf.Client(ctx)
}

The clientcredentials package caches the token in memory and triggers a refresh when the server returns a 401 with an error: invalid_token response. You do not need to implement manual expiration tracking. If you deploy behind a load balancer, initialize the client once during startup and reuse it across all goroutines to avoid concurrent token refresh races.

Implementation

Step 1: Validate Recording Metadata Before Streaming

You must verify that the recording exists, is in an available status, and contains a format compatible with FFmpeg input. The Media API returns JSON metadata at /api/v2/media/recordings/{recordingId}. You will check the status field and the format field. Genesys Cloud stores recordings as wav, mp4, or opus. All three transcode cleanly to WebM.

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

type RecordingMetadata struct {
	ID     string `json:"id"`
	Status string `json:"status"`
	Format string `json:"format"`
}

func fetchRecordingMetadata(client *http.Client, env, recordingID string) (*RecordingMetadata, error) {
	url := fmt.Sprintf("https://%s/api/v2/media/recordings/%s", env, recordingID)
	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create metadata request: %w", err)
	}

	resp, err := client.Do(req)
	if err != nil {
		return nil, fmt.Errorf("metadata request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusNotFound {
		return nil, fmt.Errorf("recording %s not found", recordingID)
	}
	if resp.StatusCode == http.StatusForbidden {
		return nil, fmt.Errorf("insufficient permissions for recording %s", recordingID)
	}
	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("metadata request returned %d: %s", resp.StatusCode, string(body))
	}

	var meta RecordingMetadata
	if err := json.NewDecoder(resp.Body).Decode(&meta); err != nil {
		return nil, fmt.Errorf("failed to decode metadata: %w", err)
	}

	if meta.Status != "available" {
		return nil, fmt.Errorf("recording status is %s, expected available", meta.Status)
	}

	return &meta, nil
}

The media:recording:view scope is required for this endpoint. If you receive a 403, verify that the OAuth client has the scope assigned in the Genesys Cloud admin console under Security > OAuth Applications.

Step 2: Stream Raw Audio to FFmpeg Stdin with 429 Retry Logic

The Media API download endpoint streams the raw file directly. You must handle rate limiting gracefully. Genesys Cloud returns 429 when you exceed the Media API quota. The response includes a Retry-After header. You will implement an exponential backoff loop that respects this header.

import (
	"net/http"
	"strconv"
	"time"
)

func downloadRecordingWithRetry(client *http.Client, env, recordingID string) (*http.Response, error) {
	url := fmt.Sprintf("https://%s/api/v2/media/recordings/%s/download", env, recordingID)
	maxRetries := 3
	baseDelay := 2 * time.Second

	var lastErr error
	for attempt := 0; attempt <= maxRetries; attempt++ {
		req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
		if err != nil {
			return nil, fmt.Errorf("failed to create download request: %w", err)
		}

		resp, err := client.Do(req)
		if err != nil {
			lastErr = fmt.Errorf("download request failed: %w", err)
			time.Sleep(baseDelay)
			baseDelay *= 2
			continue
		}

		if resp.StatusCode == http.StatusTooManyRequests {
			retryAfter := 5
			if ra := resp.Header.Get("Retry-After"); ra != "" {
				if parsed, parseErr := strconv.Atoi(ra); parseErr == nil {
					retryAfter = parsed
				}
			}
			time.Sleep(time.Duration(retryAfter) * time.Second)
			resp.Body.Close()
			continue
		}

		if resp.StatusCode != http.StatusOK {
			body, _ := io.ReadAll(resp.Body)
			resp.Body.Close()
			return nil, fmt.Errorf("download failed with %d: %s", resp.StatusCode, string(body))
		}

		return resp, nil
	}

	return nil, fmt.Errorf("download failed after %d attempts: %w", maxRetries, lastErr)
}

This function returns an open *http.Response with the Body stream ready for piping. You must close the response body after the transcoding pipeline completes. The Retry-After header parsing ensures compliance with Genesys Cloud rate limit enforcement.

Step 3: Pipe FFmpeg Output to HTTP Response Writer

You will spawn an FFmpeg subprocess that reads from pipe:0 (stdin) and writes to pipe:1 (stdout). The HTTP response writer receives the WebM stream directly. You must set the Content-Type header to video/webm before writing any bytes. FFmpeg will block until it receives enough data to write headers, so you should flush the response writer periodically or rely on the standard library chunked transfer encoding.

import (
	"fmt"
	"io"
	"net/http"
	"os/exec"
)

func pipeFFmpegToResponse(w http.ResponseWriter, ffmpegStdin io.WriteCloser, ffmpegStdout io.Reader) {
	w.Header().Set("Content-Type", "video/webm")
	w.Header().Set("Cache-Control", "no-store")
	w.WriteHeader(http.StatusOK)

	if _, err := io.Copy(w, ffmpegStdout); err != nil {
		// Client disconnected or pipe broken
		fmt.Printf("stream copy failed: %v\n", err)
	}
}

func executeTranscodePipeline(meta *RecordingMetadata, w http.ResponseWriter, downloadResp *http.Response) {
	cmd := exec.Command(
		"ffmpeg",
		"-y",
		"-i", "pipe:0",
		"-c:v", "libvpx-vp9",
		"-c:a", "libopus",
		"-b:v", "1M",
		"-b:a", "128k",
		"-f", "webm",
		"pipe:1",
	)

	stdin, err := cmd.StdinPipe()
	if err != nil {
		http.Error(w, "failed to create ffmpeg stdin pipe", http.StatusInternalServerError)
		return
	}
	defer stdin.Close()

	stdout := cmd.StdoutPipe()
	defer stdout.Close()

	// Pipe FFmpeg stderr to os.Stderr for debugging
	cmd.Stderr = os.Stderr

	if err := cmd.Start(); err != nil {
		http.Error(w, "failed to start ffmpeg", http.StatusInternalServerError)
		return
	}
	defer cmd.Wait()

	// Start streaming in a separate goroutine to avoid deadlock
	go func() {
		if _, err := io.Copy(stdin, downloadResp.Body); err != nil {
			fmt.Printf("ffmpeg stdin copy failed: %v\n", err)
		}
		stdin.Close()
	}()

	pipeFFmpegToResponse(w, stdin, stdout)
}

The -y flag forces output file overwrite, which is harmless for pipes but prevents FFmpeg from prompting on interactive terminals. The -c:v libvpx-vp9 and -c:a libopus flags select the WebM standard codecs. The -b:v 1M and -b:a 128k flags cap bitrate to ensure predictable bandwidth usage for web playback. FFmpeg will automatically handle format conversion from WAV/MP4/Opus to WebM.

Complete Working Example

The following script combines authentication, metadata validation, retry logic, and FFmpeg piping into a single runnable HTTP server. Replace the configuration values with your Genesys Cloud credentials.

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"strconv"
	"time"

	"golang.org/x/oauth2/clientcredentials"
)

type GenesysConfig struct {
	ClientID     string
	ClientSecret string
	Environment  string
}

type RecordingMetadata struct {
	ID     string `json:"id"`
	Status string `json:"status"`
	Format string `json:"format"`
}

func buildGenesysClient(cfg GenesysConfig) *http.Client {
	conf := &clientcredentials.Config{
		ClientID:     cfg.ClientID,
		ClientSecret: cfg.ClientSecret,
		TokenURL:     "https://" + cfg.Environment + "/oauth/token",
		Scopes:       []string{"media:recording:view"},
	}
	return conf.Client(context.Background())
}

func fetchRecordingMetadata(client *http.Client, env, recordingID string) (*RecordingMetadata, error) {
	url := fmt.Sprintf("https://%s/api/v2/media/recordings/%s", env, recordingID)
	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create metadata request: %w", err)
	}

	resp, err := client.Do(req)
	if err != nil {
		return nil, fmt.Errorf("metadata request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusNotFound {
		return nil, fmt.Errorf("recording %s not found", recordingID)
	}
	if resp.StatusCode == http.StatusForbidden {
		return nil, fmt.Errorf("insufficient permissions for recording %s", recordingID)
	}
	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("metadata request returned %d: %s", resp.StatusCode, string(body))
	}

	var meta RecordingMetadata
	if err := json.NewDecoder(resp.Body).Decode(&meta); err != nil {
		return nil, fmt.Errorf("failed to decode metadata: %w", err)
	}

	if meta.Status != "available" {
		return nil, fmt.Errorf("recording status is %s, expected available", meta.Status)
	}

	return &meta, nil
}

func downloadRecordingWithRetry(client *http.Client, env, recordingID string) (*http.Response, error) {
	url := fmt.Sprintf("https://%s/api/v2/media/recordings/%s/download", env, recordingID)
	maxRetries := 3
	baseDelay := 2 * time.Second

	var lastErr error
	for attempt := 0; attempt <= maxRetries; attempt++ {
		req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
		if err != nil {
			lastErr = fmt.Errorf("failed to create download request: %w", err)
			time.Sleep(baseDelay)
			baseDelay *= 2
			continue
		}

		resp, err := client.Do(req)
		if err != nil {
			lastErr = fmt.Errorf("download request failed: %w", err)
			time.Sleep(baseDelay)
			baseDelay *= 2
			continue
		}

		if resp.StatusCode == http.StatusTooManyRequests {
			retryAfter := 5
			if ra := resp.Header.Get("Retry-After"); ra != "" {
				if parsed, parseErr := strconv.Atoi(ra); parseErr == nil {
					retryAfter = parsed
				}
			}
			time.Sleep(time.Duration(retryAfter) * time.Second)
			resp.Body.Close()
			continue
		}

		if resp.StatusCode != http.StatusOK {
			body, _ := io.ReadAll(resp.Body)
			resp.Body.Close()
			return nil, fmt.Errorf("download failed with %d: %s", resp.StatusCode, string(body))
		}

		return resp, nil
	}

	return nil, fmt.Errorf("download failed after %d attempts: %w", maxRetries, lastErr)
}

func handleTranscode(cfg GenesysConfig, client *http.Client) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		recordingID := r.URL.Query().Get("id")
		if recordingID == "" {
			http.Error(w, "missing id parameter", http.StatusBadRequest)
			return
		}

		meta, err := fetchRecordingMetadata(client, cfg.Environment, recordingID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusForbidden)
			return
		}

		downloadResp, err := downloadRecordingWithRetry(client, cfg.Environment, recordingID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer downloadResp.Body.Close()

		cmd := exec.Command(
			"ffmpeg",
			"-y",
			"-i", "pipe:0",
			"-c:v", "libvpx-vp9",
			"-c:a", "libopus",
			"-b:v", "1M",
			"-b:a", "128k",
			"-f", "webm",
			"pipe:1",
		)

		stdin, err := cmd.StdinPipe()
		if err != nil {
			http.Error(w, "failed to create ffmpeg stdin pipe", http.StatusInternalServerError)
			return
		}
		defer stdin.Close()

		stdout := cmd.StdoutPipe()
		defer stdout.Close()
		cmd.Stderr = os.Stderr

		if err := cmd.Start(); err != nil {
			http.Error(w, "failed to start ffmpeg", http.StatusInternalServerError)
			return
		}
		defer cmd.Wait()

		go func() {
			if _, err := io.Copy(stdin, downloadResp.Body); err != nil {
				fmt.Printf("ffmpeg stdin copy failed: %v\n", err)
			}
			stdin.Close()
		}()

		w.Header().Set("Content-Type", "video/webm")
		w.Header().Set("Cache-Control", "no-store")
		w.WriteHeader(http.StatusOK)
		if _, err := io.Copy(w, stdout); err != nil {
			fmt.Printf("stream copy failed: %v\n", err)
		}
	}
}

func main() {
	cfg := GenesysConfig{
		ClientID:     "YOUR_CLIENT_ID",
		ClientSecret: "YOUR_CLIENT_SECRET",
		Environment:  "api.mypurecloud.com",
	}

	client := buildGenesysClient(cfg)
	http.HandleFunc("/transcode", handleTranscode(cfg, client))

	log.Println("Server listening on :8080")
	if err := http.ListenAndServe(":8080", nil); err != nil {
		log.Fatalf("Server failed: %v", err)
	}
}

Run the service with go run main.go. Request a transcoded stream with curl "http://localhost:8080/transcode?id=YOUR_RECORDING_ID" --output sample.webm. The browser or media player will receive a valid WebM stream without any intermediate disk writes.

Common Errors & Debugging

Error: 401 Unauthorized

• What causes it: The OAuth token has expired, the client credentials are incorrect, or the token endpoint URL does not match your Genesys Cloud environment.
• How to fix it: Verify ClientID and ClientSecret match the OAuth application in Genesys Cloud. Ensure the TokenURL points to the correct environment domain. The clientcredentials package will automatically retry with a fresh token, but persistent 401s indicate credential mismatch.
• Code showing the fix: Check the response body for error: invalid_client or error: unauthorized_client. Log the exact error string returned by the /oauth/token endpoint.

Error: 403 Forbidden

• What causes it: The OAuth client lacks the media:recording:view scope, or the recording belongs to a division the client cannot access.
• How to fix it: Navigate to Security > OAuth Applications in the Genesys Cloud admin console. Edit your application and add media:recording:view to the scopes list. Save and restart your service to pick up the new scope.
• Code showing the fix: The metadata fetch function explicitly checks for 403 and returns a clear message. Add division filtering to the query if you use query parameters, though the recording endpoint does not support division scoping in the URL.

Error: 429 Too Many Requests

• What causes it: The Media API enforces per-client and per-environment rate limits. Bulk transcription or high-frequency playback requests trigger this limit.
• How to fix it: Implement the retry loop shown in Step 2. Respect the Retry-After header. Distribute requests across multiple OAuth clients if you require higher throughput.
• Code showing the fix: The downloadRecordingWithRetry function parses Retry-After, sleeps for the specified duration, and retries up to three times with exponential backoff.

Error: FFmpeg Exit Code 1 or Broken Pipe

• What causes it: FFmpeg cannot decode the input format, missing codecs, or the HTTP client disconnects before the stream completes.
• How to fix it: Verify FFmpeg supports libvpx-vp9 and libopus by running ffmpeg -codecs | grep libvpx. For broken pipes, wrap the io.Copy call in a context-aware reader that cancels when the HTTP request context expires.
• Code showing the fix: Pipe cmd.Stderr to os.Stderr during development to capture FFmpeg error messages. In production, redirect stderr to a log buffer and monitor for Invalid data found or Stream mapping error.

Official References

• Genesys Cloud Media API Reference
• Genesys Cloud OAuth 2.0 Documentation
• Go OAuth2 Client Credentials Package
• FFmpeg WebM Encoding Guide