Fully document ExoMediaDrm

PiperOrigin-RevId: 351771497

library/common/src/main/java/com/google/android/exoplayer2/drm/ExoMediaCrypto.java

@@ -15,5 +15,5 @@
  */
 package com.google.android.exoplayer2.drm;
 
-/** An opaque {@link android.media.MediaCrypto} equivalent. */
+/** Enables decoding of encrypted data using keys in a DRM session. */
 public interface ExoMediaCrypto {}

library/core/src/main/java/com/google/android/exoplayer2/drm/ExoMediaDrm.java

@@ -20,6 +20,7 @@ import android.media.MediaCryptoException;
 import android.media.MediaDrm;
 import android.media.MediaDrmException;
 import android.media.NotProvisionedException;
+import android.media.ResourceBusyException;
 import android.os.Handler;
 import android.os.PersistableBundle;
 import androidx.annotation.IntDef;
@@ -34,7 +35,7 @@ import java.util.Map;
 import java.util.UUID;
 
 /**
- * Used to obtain keys for decrypting protected media streams. See {@link android.media.MediaDrm}.
+ * Used to obtain keys for decrypting protected media streams.
  *
  * <h3>Reference counting</h3>
  *
@@ -45,16 +46,18 @@ import java.util.UUID;
  * <p>Each new instance has an initial reference count of 1. Hence application code that creates a
  * new instance does not normally need to call {@link #acquire()}, and must call {@link #release()}
  * when the instance is no longer required.
+ *
+ * @see MediaDrm
  */
 public interface ExoMediaDrm {
 
-  /** {@link ExoMediaDrm} instances provider. */
+  /** Provider for {@link ExoMediaDrm} instances. */
   interface Provider {
 
     /**
      * Returns an {@link ExoMediaDrm} instance with an incremented reference count. When the caller
-     * no longer needs to use the instance, it must call {@link ExoMediaDrm#release()} to decrement
+     * no longer needs the instance, it must call {@link ExoMediaDrm#release()} to decrement the
-     * the reference count.
+     * reference count.
      */
     ExoMediaDrm acquireExoMediaDrm(UUID uuid);
   }
@@ -82,37 +85,37 @@ public interface ExoMediaDrm {
     }
   }
 
-  /** @see MediaDrm#EVENT_KEY_REQUIRED */
+  /** Event indicating that keys need to be requested from the license server. */
   @SuppressWarnings("InlinedApi")
   int EVENT_KEY_REQUIRED = MediaDrm.EVENT_KEY_REQUIRED;
-  /**
+  /** Event indicating that keys have expired, and are no longer usable. */
-   * @see MediaDrm#EVENT_KEY_EXPIRED
-   */
   @SuppressWarnings("InlinedApi")
   int EVENT_KEY_EXPIRED = MediaDrm.EVENT_KEY_EXPIRED;
-  /**
+  /** Event indicating that a certificate needs to be requested from the provisioning server. */
-   * @see MediaDrm#EVENT_PROVISION_REQUIRED
-   */
   @SuppressWarnings("InlinedApi")
   int EVENT_PROVISION_REQUIRED = MediaDrm.EVENT_PROVISION_REQUIRED;
 
   /**
-   * @see MediaDrm#KEY_TYPE_STREAMING
+   * Key request type for keys that will be used for online use. Streaming keys will not be saved to
+   * the device for subsequent use when the device is not connected to a network.
    */
   @SuppressWarnings("InlinedApi")
   int KEY_TYPE_STREAMING = MediaDrm.KEY_TYPE_STREAMING;
   /**
-   * @see MediaDrm#KEY_TYPE_OFFLINE
+   * Key request type for keys that will be used for offline use. They will be saved to the device
+   * for subsequent use when the device is not connected to a network.
    */
   @SuppressWarnings("InlinedApi")
   int KEY_TYPE_OFFLINE = MediaDrm.KEY_TYPE_OFFLINE;
-  /**
+  /** Key request type indicating that saved offline keys should be released. */
-   * @see MediaDrm#KEY_TYPE_RELEASE
-   */
   @SuppressWarnings("InlinedApi")
   int KEY_TYPE_RELEASE = MediaDrm.KEY_TYPE_RELEASE;
 
-  /** @see android.media.MediaDrm.OnEventListener */
+  /**
+   * Called when a DRM event occurs.
+   *
+   * @see MediaDrm.OnEventListener
+   */
   interface OnEventListener {
     /**
      * Called when an event occurs that requires the app to be notified
@@ -131,7 +134,11 @@ public interface ExoMediaDrm {
         @Nullable byte[] data);
   }
 
-  /** @see android.media.MediaDrm.OnKeyStatusChangeListener */
+  /**
+   * Called when the keys in a DRM session change state.
+   *
+   * @see MediaDrm.OnKeyStatusChangeListener
+   */
   interface OnKeyStatusChangeListener {
     /**
      * Called when the keys in a session change status, such as when the license is renewed or
@@ -149,12 +156,16 @@ public interface ExoMediaDrm {
         boolean hasNewUsableKey);
   }
 
-  /** @see android.media.MediaDrm.OnExpirationUpdateListener */
+  /**
+   * Called when a session expiration update occurs.
+   *
+   * @see MediaDrm.OnExpirationUpdateListener
+   */
   interface OnExpirationUpdateListener {
 
     /**
      * Called when a session expiration update occurs, to inform the app about the change in
-     * expiration time
+     * expiration time.
      *
      * @param mediaDrm The {@link ExoMediaDrm} object on which the event occurred.
      * @param sessionId The DRM session ID on which the event occurred
@@ -165,31 +176,43 @@ public interface ExoMediaDrm {
     void onExpirationUpdate(ExoMediaDrm mediaDrm, byte[] sessionId, long expirationTimeMs);
   }
 
-  /** @see android.media.MediaDrm.KeyStatus */
+  /**
+   * Defines the status of a key.
+   *
+   * @see MediaDrm.KeyStatus
+   */
   final class KeyStatus {
 
     private final int statusCode;
     private final byte[] keyId;
 
+    /**
+     * Creates an instance.
+     *
+     * @param statusCode The status code of the key, as defined by {@link
+     *     MediaDrm.KeyStatus#getStatusCode()}.
+     * @param keyId The ID of the key.
+     */
     public KeyStatus(int statusCode, byte[] keyId) {
       this.statusCode = statusCode;
       this.keyId = keyId;
     }
 
+    /** Returns the status of the key, as defined by {@link MediaDrm.KeyStatus#getStatusCode()}. */
     public int getStatusCode() {
       return statusCode;
     }
 
+    /** Returns the ID of the key. */
     public byte[] getKeyId() {
       return keyId;
     }
-
   }
 
   /**
    * Contains data used to request keys from a license server.
    *
-   * @see android.media.MediaDrm.KeyRequest
+   * @see MediaDrm.KeyRequest
    */
   final class KeyRequest {
 
@@ -281,25 +304,40 @@ public interface ExoMediaDrm {
     }
   }
 
-  /** @see android.media.MediaDrm.ProvisionRequest */
+  /**
+   * Contains data to request a certificate from a provisioning server.
+   *
+   * @see MediaDrm.ProvisionRequest
+   */
   final class ProvisionRequest {
 
     private final byte[] data;
     private final String defaultUrl;
 
+    /**
+     * Creates an instance.
+     *
+     * @param data The opaque provisioning request data.
+     * @param defaultUrl The default URL of the provisioning server to which the request can be
+     *     made, or the empty string if not known.
+     */
     public ProvisionRequest(byte[] data, String defaultUrl) {
       this.data = data;
       this.defaultUrl = defaultUrl;
     }
 
+    /** Returns the opaque provisioning request data. */
     public byte[] getData() {
       return data;
     }
 
+    /**
+     * Returns the default URL of the provisioning server to which the request can be made, or the
+     * empty string if not known.
+     */
     public String getDefaultUrl() {
       return defaultUrl;
     }
-
   }
 
   /**
@@ -338,11 +376,20 @@ public interface ExoMediaDrm {
    */
   void setOnExpirationUpdateListener(@Nullable OnExpirationUpdateListener listener);
 
-  /** @see MediaDrm#openSession() */
+  /**
+   * Opens a new DRM session. A session ID is returned.
+   *
+   * @return The session ID.
+   * @throws NotProvisionedException If provisioning is needed.
+   * @throws ResourceBusyException If required resources are in use.
+   * @throws MediaDrmException If the session could not be opened.
+   */
   byte[] openSession() throws MediaDrmException;
 
   /**
-   * @see MediaDrm#closeSession(byte[])
+   * Closes a DRM session.
+   *
+   * @param sessionId The ID of the session to close.
    */
   void closeSession(byte[] sessionId);
 
@@ -350,8 +397,8 @@ public interface ExoMediaDrm {
    * Generates a key request.
    *
    * @param scope If {@code keyType} is {@link #KEY_TYPE_STREAMING} or {@link #KEY_TYPE_OFFLINE},
-   *     the session id that the keys will be provided to. If {@code keyType} is {@link
+   *     the ID of the session that the keys will be provided to. If {@code keyType} is {@link
-   *     #KEY_TYPE_RELEASE}, the keySetId of the keys to release.
+   *     #KEY_TYPE_RELEASE}, the {@code keySetId} of the keys to release.
    * @param schemeDatas If key type is {@link #KEY_TYPE_STREAMING} or {@link #KEY_TYPE_OFFLINE}, a
    *     list of {@link SchemeData} instances extracted from the media. Null otherwise.
    * @param keyType The type of the request. Either {@link #KEY_TYPE_STREAMING} to acquire keys for
@@ -371,23 +418,45 @@ public interface ExoMediaDrm {
       @Nullable HashMap<String, String> optionalParameters)
       throws NotProvisionedException;
 
-  /** @see MediaDrm#provideKeyResponse(byte[], byte[]) */
+  /**
+   * Provides a key response for the last request to be generated using {@link #getKeyRequest}.
+   *
+   * @param scope If the request had type {@link #KEY_TYPE_STREAMING} or {@link #KEY_TYPE_OFFLINE},
+   *     the ID of the session to provide the keys to. If {@code keyType} is {@link
+   *     #KEY_TYPE_RELEASE}, the {@code keySetId} of the keys being released.
+   * @param response The response data from the server.
+   * @return If the request had type {@link #KEY_TYPE_OFFLINE}, the {@code keySetId} for the offline
+   *     keys. An empty byte array or {@code null} may be returned for other cases.
+   * @throws NotProvisionedException If the response indicates that provisioning is needed.
+   * @throws DeniedByServerException If the response indicates that the server rejected the request.
+   */
   @Nullable
   byte[] provideKeyResponse(byte[] scope, byte[] response)
       throws NotProvisionedException, DeniedByServerException;
 
   /**
-   * @see MediaDrm#getProvisionRequest()
+   * Generates a provisioning request.
+   *
+   * @return The generated provisioning request.
    */
   ProvisionRequest getProvisionRequest();
 
   /**
-   * @see MediaDrm#provideProvisionResponse(byte[])
+   * Provides a provisioning response for the last request to be generated using {@link
+   * #getProvisionRequest()}.
+   *
+   * @param response The response data from the server.
+   * @throws DeniedByServerException If the response indicates that the server rejected the request.
    */
   void provideProvisionResponse(byte[] response) throws DeniedByServerException;
 
   /**
-   * @see MediaDrm#queryKeyStatus(byte[])
+   * Returns the key status for a given session, as {name, value} pairs. Since DRM license policies
+   * vary by vendor, the returned entries depend on the DRM plugin being used. Refer to your DRM
+   * provider's documentation for more information.
+   *
+   * @param sessionId The ID of the session being queried.
+   * @return The key status for the session.
    */
   Map<String, String> queryKeyStatus(byte[] sessionId);
 
@@ -407,43 +476,64 @@ public interface ExoMediaDrm {
   void release();
 
   /**
-   * @see MediaDrm#restoreKeys(byte[], byte[])
+   * Restores persisted offline keys into a session.
+   *
+   * @param sessionId The ID of the session into which the keys will be restored.
+   * @param keySetId The {@code keySetId} of the keys to restore, as provided by the call to {@link
+   *     #provideKeyResponse} that persisted them.
    */
   void restoreKeys(byte[] sessionId, byte[] keySetId);
 
   /**
-   * Returns drm metrics. May be null if unavailable.
+   * Returns metrics data for this ExoMediaDrm instance, or {@code null} if metrics are unavailable.
-   *
-   * @see MediaDrm#getMetrics()
    */
   @Nullable
   PersistableBundle getMetrics();
 
   /**
-   * @see MediaDrm#getPropertyString(String)
+   * Returns the value of a string property. For standard property names, see {@link
+   * MediaDrm#getPropertyString}.
+   *
+   * @param propertyName The property name.
+   * @return The property value.
+   * @throws IllegalArgumentException If the underlying DRM plugin does not support the property.
    */
   String getPropertyString(String propertyName);
 
   /**
-   * @see MediaDrm#getPropertyByteArray(String)
+   * Returns the value of a byte array property. For standard property names, see {@link
+   * MediaDrm#getPropertyByteArray}.
+   *
+   * @param propertyName The property name.
+   * @return The property value.
+   * @throws IllegalArgumentException If the underlying DRM plugin does not support the property.
    */
   byte[] getPropertyByteArray(String propertyName);
 
   /**
-   * @see MediaDrm#setPropertyString(String, String)
+   * Sets the value of a string property.
+   *
+   * @param propertyName The property name.
+   * @param value The value.
+   * @throws IllegalArgumentException If the underlying DRM plugin does not support the property.
    */
   void setPropertyString(String propertyName, String value);
 
   /**
-   * @see MediaDrm#setPropertyByteArray(String, byte[])
+   * Sets the value of a byte array property.
+   *
+   * @param propertyName The property name.
+   * @param value The value.
+   * @throws IllegalArgumentException If the underlying DRM plugin does not support the property.
    */
   void setPropertyByteArray(String propertyName, byte[] value);
 
   /**
-   * @see android.media.MediaCrypto#MediaCrypto(UUID, byte[])
+   * Creates an {@link ExoMediaCrypto} for a given session.
-   * @param sessionId The DRM session ID.
+   *
-   * @return An object extends {@link ExoMediaCrypto}, using opaque crypto scheme specific data.
+   * @param sessionId The ID of the session.
-   * @throws MediaCryptoException If the instance can't be created.
+   * @return An {@link ExoMediaCrypto} for the given session.
+   * @throws MediaCryptoException If an {@link ExoMediaCrypto} could not be created.
    */
   ExoMediaCrypto createMediaCrypto(byte[] sessionId) throws MediaCryptoException;