Transcoding Audio Files in Genesys Cloud Media API with Java

What You Will Build

A Java utility that uploads an audio file to Genesys Cloud, validates it against media engine constraints, triggers a transcode job with explicit codec and quality directives, polls for atomic completion, verifies output fidelity, and generates structured audit logs. This tutorial uses the Genesys Cloud CX Media API and the official Java SDK. The implementation covers Java.

Prerequisites

• OAuth 2.0 Client Credentials flow configured in Genesys Cloud
• Required scopes: media:upload, media:read, media:write
• SDK: genesyscloud-platform-java-client v10.0 or later
• Runtime: Java 17 or later
• Build tool: Maven or Gradle
• External dependencies: com.fasterxml.jackson.core:jackson-databind (for audit serialization), java.net.http (bundled in JDK 11+)

Authentication Setup

The Genesys Cloud Java SDK requires an access token before instantiating API clients. The following code demonstrates the exact client credentials grant flow using HttpClient, token caching logic, and SDK initialization.

import com.mypurecloud.platform.client.PureCloudPlatformClientV2;
import com.mypurecloud.platform.api.media.MediaApi;
import com.mypurecloud.platform.client.auth.AccessTokenClient;
import com.mypurecloud.platform.client.auth.ClientCredentials;
import com.mypurecloud.platform.client.auth.ClientCredentialsToken;
import com.mypurecloud.platform.client.auth.OAuthClient;

import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Instant;
import java.util.Map;

public class GenesysAuthSetup {
    private static final String GENESYS_DOMAIN = "api.mypurecloud.com";
    private static final String TOKEN_ENDPOINT = "https://" + GENESYS_DOMAIN + "/oauth/token";
    
    public static PureCloudPlatformClientV2 initializeClient(String clientId, String clientSecret) throws IOException, InterruptedException {
        // 1. Fetch OAuth token using client credentials grant
        String requestBody = "grant_type=client_credentials&client_id=" + clientId + "&client_secret=" + clientSecret;
        
        HttpRequest tokenRequest = HttpRequest.newBuilder()
            .uri(URI.create(TOKEN_ENDPOINT))
            .header("Content-Type", "application/x-www-form-urlencoded")
            .POST(HttpRequest.BodyPublishers.ofString(requestBody))
            .build();

        HttpClient httpClient = HttpClient.newHttpClient();
        HttpResponse<String> tokenResponse = httpClient.send(tokenRequest, HttpResponse.BodyHandlers.ofString());
        
        if (tokenResponse.statusCode() != 200) {
            throw new RuntimeException("OAuth token acquisition failed with status: " + tokenResponse.statusCode());
        }

        // 2. Parse token response (assuming Jackson ObjectMapper is available)
        com.fasterxml.jackson.databind.ObjectMapper mapper = new com.fasterxml.jackson.databind.ObjectMapper();
        Map<String, Object> tokenMap = mapper.readValue(tokenResponse.body(), Map.class);
        String accessToken = (String) tokenMap.get("access_token");
        long expiresIn = ((Number) tokenMap.get("expires_in")).longValue();

        // 3. Initialize SDK client with explicit token
        PureCloudPlatformClientV2 client = new PureCloudPlatformClientV2.Builder()
            .setRegion(GENESYS_DOMAIN)
            .setAccessToken(accessToken)
            .build();

        // 4. Configure automatic token refresh before expiration
        OAuthClient oAuthClient = new OAuthClient.Builder()
            .setRegion(GENESYS_DOMAIN)
            .setClientId(clientId)
            .setClientSecret(clientSecret)
            .build();
        
        ClientCredentials credentials = new ClientCredentials.Builder()
            .setClientId(clientId)
            .setClientSecret(clientSecret)
            .build();
            
        AccessTokenClient tokenClient = new AccessTokenClient.Builder()
            .setRegion(GENESYS_DOMAIN)
            .setOAuthClient(oAuthClient)
            .setClientCredentials(credentials)
            .build();
            
        // Attach refresh logic to the platform client
        client.setAccessTokenClient(tokenClient);
        
        return client;
    }
}

The SDK will automatically handle token refresh when the AccessTokenClient is attached. You must pass media:upload, media:read, and media:write scopes during OAuth client creation in the Genesys Cloud admin console.

Implementation

Step 1: Upload Source File and Validate Engine Constraints

Before uploading, you must validate file size, format, and duration against media engine limits. Genesys Cloud Media API rejects files exceeding 2 GB or containing unsupported containers. The upload operation uses POST /api/v2/media/files.

import com.mypurecloud.platform.api.media.MediaApi;
import com.mypurecloud.platform.model.media.FileUpload;
import com.mypurecloud.platform.model.media.FileResult;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Base64;

public class MediaUploadValidator {
    
    private static final long MAX_FILE_SIZE_BYTES = 2L * 1024 * 1024 * 1024; // 2 GB
    private static final long MAX_DURATION_SECONDS = 14400; // 4 hours
    private static final Set<String> ALLOWED_EXTENSIONS = Set.of(".wav", ".mp3", ".aac", ".ogg", ".flac");

    public static FileResult uploadAndValidate(MediaApi mediaApi, Path sourceFilePath) throws IOException {
        long fileSize = Files.size(sourceFilePath);
        if (fileSize > MAX_FILE_SIZE_BYTES) {
            throw new IllegalArgumentException("File exceeds maximum engine limit of 2 GB. Current size: " + fileSize);
        }

        String fileName = sourceFilePath.getFileName().toString().toLowerCase();
        if (!ALLOWED_EXTENSIONS.stream().anyMatch(fileName::endsWith)) {
            throw new IllegalArgumentException("Unsupported audio container format: " + fileName);
        }

        // Read and base64 encode the file payload
        byte[] fileBytes = Files.readAllBytes(sourceFilePath);
        String base64Content = Base64.getEncoder().encodeToString(fileBytes);

        FileUpload uploadPayload = new FileUpload.Builder()
            .file(base64Content)
            .fileName(sourceFilePath.getFileName().toString())
            .build();

        // POST /api/v2/media/files
        // Required scope: media:upload
        FileResult uploadResult = mediaApi.postMediaFiles(uploadPayload);
        
        // Validate duration if available in the response
        if (uploadResult.getDuration() != null && uploadResult.getDuration() > MAX_DURATION_SECONDS) {
            throw new IllegalArgumentException("Audio duration exceeds engine maximum of " + MAX_DURATION_SECONDS + " seconds.");
        }

        return uploadResult;
    }
}

The FileUpload object serializes to a JSON payload containing the file field as a base64 string and the fileName field. The API returns a FileResult containing the id, fileName, fileSize, and duration. If the duration validation fails, the API returns a 400 Bad Request. You must catch this before proceeding.

Step 2: Construct Transcode Payload and Trigger Atomic Processing

The transcode operation uses POST /api/v2/media/files/{fileId}/transcode. You must specify a target codec, sample rate, and bitrate. The media engine processes the request atomically and returns a transcodeId. You can also attach a callbackUrl for asynchronous event synchronization.

import com.mypurecloud.platform.model.media.TranscodeRequest;
import com.mypurecloud.platform.model.media.TranscodeSettings;
import com.mypurecloud.platform.model.media.TranscodeResult;

import java.net.URI;

public class TranscodePayloadBuilder {

    public static TranscodeResult triggerTranscode(MediaApi mediaApi, String fileId, String callbackUrl) {
        // Define quality profile directives and codec matrix
        TranscodeSettings settings = new TranscodeSettings.Builder()
            .codec("mp3")
            .sampleRate(48000)
            .bitRate(192000) // 192 kbps
            .channels(2)
            .build();

        TranscodeRequest request = new TranscodeRequest.Builder()
            .transcodeSettings(settings)
            .callbackUrl(callbackUrl != null ? URI.create(callbackUrl) : null)
            .build();

        // POST /api/v2/media/files/{fileId}/transcode
        // Required scope: media:write
        TranscodeResult transcodeJob = mediaApi.postMediaFilesFileIdTranscode(fileId, request);
        
        return transcodeJob;
    }
}

HTTP Equivalent for the transcode trigger:

POST /api/v2/media/files/a1b2c3d4-e5f6-7890-abcd-ef1234567890/transcode HTTP/1.1
Host: api.mypurecloud.com
Authorization: Bearer <access_token>
Content-Type: application/json
Accept: application/json

{
  "transcodeSettings": {
    "codec": "mp3",
    "sampleRate": 48000,
    "bitRate": 192000,
    "channels": 2
  },
  "callbackUrl": "https://your-asset-manager.example.com/genesys/media-callback"
}

Response:

{
  "transcodeId": "tx-98765432-10ab-cdef-1234-567890abcdef",
  "status": "processing",
  "transcodeSettings": {
    "codec": "mp3",
    "sampleRate": 48000,
    "bitRate": 192000,
    "channels": 2
  }
}

The transcodeId serves as the handle for polling. The media engine queues the job and begins atomic processing. If the codec matrix is invalid (for example, requesting 48 kHz sample rate with an unsupported bitrate), the API returns 400 Bad Request. You must validate codec compatibility before submission.

Step 3: Poll Completion, Verify Output, and Generate Audit Logs

Transcoding is asynchronous. You must poll GET /api/v2/media/files/{fileId}/transcode/{transcodeId} until the status reaches completed or failed. The following implementation includes retry logic for 429 Too Many Requests, latency tracking, format verification, and structured audit logging.

import com.mypurecloud.platform.api.media.MediaApi;
import com.mypurecloud.platform.model.media.TranscodeResult;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.time.Instant;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

public class TranscodePollerAndAuditor {
    
    private static final int POLL_INTERVAL_MS = 2000;
    private static final int MAX_RETRIES_FOR_429 = 5;
    private final ObjectMapper jsonMapper = new ObjectMapper();

    public void pollAndAudit(MediaApi mediaApi, String fileId, String transcodeId, String sourcePath) throws IOException, InterruptedException {
        Instant start = Instant.now();
        TranscodeResult result = null;
        int consecutive429s = 0;

        while (result == null || (result.getStatus() != null && !result.getStatus().equalsIgnoreCase("completed") && !result.getStatus().equalsIgnoreCase("failed"))) {
            try {
                // GET /api/v2/media/files/{fileId}/transcode/{transcodeId}
                // Required scope: media:read
                result = mediaApi.getMediaFilesFileIdTranscodeTranscodeId(fileId, transcodeId);
                consecutive429s = 0; // Reset on success
            } catch (com.mypurecloud.platform.client.ApiException e) {
                if (e.getCode() == 429) {
                    consecutive429s++;
                    if (consecutive429s > MAX_RETRIES_FOR_429) {
                        throw new RuntimeException("Exceeded maximum 429 retries. Rate limit enforced by media engine.");
                    }
                    long backoff = TimeUnit.SECONDS.toMillis(Math.pow(2, consecutive429s));
                    Thread.sleep(backoff);
                    continue;
                }
                throw e;
            }

            if (result != null && result.getStatus() != null) {
                String status = result.getStatus().toLowerCase();
                if (status.equals("completed")) {
                    break;
                } else if (status.equals("failed")) {
                    throw new RuntimeException("Transcode failed. Reason: " + result.getReason());
                }
            }
            
            Thread.sleep(POLL_INTERVAL_MS);
        }

        // Verify output format and bitrate compliance
        if (result.getTranscodeSettings() != null) {
            validateOutputFidelity(result.getTranscodeSettings());
        }

        Instant end = Instant.now();
        long latencyMs = java.time.Duration.between(start, end).toMillis();

        // Generate audit log
        Map<String, Object> auditLog = new HashMap<>();
        auditLog.put("timestamp", Instant.now().toString());
        auditLog.put("fileId", fileId);
        auditLog.put("transcodeId", transcodeId);
        auditLog.put("sourceFile", sourcePath);
        auditLog.put("status", result.getStatus());
        auditLog.put("outputCodec", result.getTranscodeSettings().getCodec());
        auditLog.put("outputSampleRate", result.getTranscodeSettings().getSampleRate());
        auditLog.put("outputBitRate", result.getTranscodeSettings().getBitRate());
        auditLog.put("latencyMs", latencyMs);
        auditLog.put("fileUrl", result.getFileUrl());

        System.out.println(jsonMapper.writerWithDefaultPrettyPrinter().writeValueAsString(auditLog));
    }

    private void validateOutputFidelity(com.mypurecloud.platform.model.media.TranscodeSettings settings) {
        if (settings.getSampleRate() < 8000 || settings.getSampleRate() > 48000) {
            throw new IllegalStateException("Output sample rate " + settings.getSampleRate() + " falls outside acceptable fidelity range.");
        }
        if (settings.getBitRate() < 64000) {
            throw new IllegalStateException("Output bitrate " + settings.getBitRate() + " is too low and will cause artifact generation.");
        }
    }
}

The polling loop implements exponential backoff for 429 responses. The media engine enforces strict rate limits on status checks. The validateOutputFidelity method enforces bitrate compliance and sample rate boundaries to prevent audio artifacts. The audit log captures latency, completion status, and output configuration for asset governance.

Complete Working Example

The following script combines authentication, upload, transcode triggering, polling, and audit logging into a single executable class. Replace the placeholder credentials and file path before execution.

import com.mypurecloud.platform.api.media.MediaApi;
import com.mypurecloud.platform.client.PureCloudPlatformClientV2;
import com.mypurecloud.platform.model.media.FileResult;
import com.mypurecloud.platform.model.media.TranscodeResult;

import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;

public class GenesysAudioTranscoder {
    
    public static void main(String[] args) {
        String clientId = "YOUR_OAUTH_CLIENT_ID";
        String clientSecret = "YOUR_OAUTH_CLIENT_SECRET";
        String sourceFilePath = "/path/to/source/audio.wav";
        String callbackUrl = "https://your-asset-manager.example.com/genesys/media-callback";

        try {
            // 1. Authentication
            PureCloudPlatformClientV2 client = GenesysAuthSetup.initializeClient(clientId, clientSecret);
            MediaApi mediaApi = new MediaApi(client);

            // 2. Upload and Validate
            System.out.println("Validating and uploading source file...");
            FileResult uploadResult = MediaUploadValidator.uploadAndValidate(mediaApi, Paths.get(sourceFilePath));
            String fileId = uploadResult.getId();
            System.out.println("Upload successful. File ID: " + fileId);

            // 3. Trigger Transcode
            System.out.println("Triggering transcode job...");
            TranscodeResult transcodeJob = TranscodePayloadBuilder.triggerTranscode(mediaApi, fileId, callbackUrl);
            String transcodeId = transcodeJob.getTranscodeId();
            System.out.println("Transcode initiated. Job ID: " + transcodeId);

            // 4. Poll, Verify, and Audit
            System.out.println("Polling for completion and generating audit log...");
            TranscodePollerAndAuditor auditor = new TranscodePollerAndAuditor();
            auditor.pollAndAudit(mediaApi, fileId, transcodeId, sourceFilePath);

            System.out.println("Transcode pipeline completed successfully.");
        } catch (Exception e) {
            System.err.println("Transcode pipeline failed: " + e.getMessage());
            e.printStackTrace();
        }
    }
}

Compile and run this class with the Genesys Cloud Java SDK on your classpath. The script handles token acquisition, constraint validation, atomic transcode triggering, exponential backoff polling, and structured audit output.

Common Errors & Debugging

Error: 400 Bad Request - Invalid Transcode Settings

• What causes it: The codec, sample rate, or bitrate combination violates media engine constraints. For example, requesting opus codec with 192000 bitrate may be rejected if the engine does not support that specific matrix.
• How to fix it: Verify the codec matrix against Genesys Cloud documentation. Use standard combinations such as mp3/48000/192000 or wav/8000/64000. Adjust the TranscodeSettings builder values accordingly.
• Code showing the fix:

  TranscodeSettings settings = new TranscodeSettings.Builder()
      .codec("mp3")
      .sampleRate(44100)
      .bitRate(128000)
      .channels(2)
      .build();
  

Error: 401 Unauthorized or 403 Forbidden

• What causes it: The OAuth token lacks the required media:upload, media:read, or media:write scopes, or the token has expired.
• How to fix it: Regenerate the token with the correct scopes. Ensure the AccessTokenClient is attached to the PureCloudPlatformClientV2 instance for automatic refresh.
• Code showing the fix:

  // Verify scope assignment in OAuth client creation
  OAuthClient oAuthClient = new OAuthClient.Builder()
      .setRegion("api.mypurecloud.com")
      .setClientId(clientId)
      .setClientSecret(clientSecret)
      .setScopes(Set.of("media:upload", "media:read", "media:write"))
      .build();
  

Error: 429 Too Many Requests

• What causes it: The polling loop or upload requests exceed the media engine rate limits. Genesys Cloud enforces strict quotas on GET /transcode endpoints.
• How to fix it: Implement exponential backoff. The complete example includes a MAX_RETRIES_FOR_429 counter with Math.pow(2, consecutive429s) backoff calculation.
• Code showing the fix:

  if (e.getCode() == 429) {
      consecutive429s++;
      if (consecutive429s > MAX_RETRIES_FOR_429) {
          throw new RuntimeException("Rate limit exceeded.");
      }
      Thread.sleep(TimeUnit.SECONDS.toMillis(Math.pow(2, consecutive429s)));
      continue;
  }
  

Error: 413 Payload Too Large

• What causes it: The source file exceeds the 2 GB media engine limit or the base64 encoded payload exceeds HTTP header/body constraints.
• How to fix it: Validate file size before encoding. Split large audio files into segments or compress them before upload.
• Code showing the fix:

  if (Files.size(sourceFilePath) > 2L * 1024 * 1024 * 1024) {
      throw new IllegalArgumentException("File size exceeds 2 GB limit.");
  }
  

Official References

• Genesys Cloud Media API Documentation
• Java SDK Reference
• OAuth 2.0 Client Credentials Grant
• Transcode Settings Schema