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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.mp4;
import androidx.annotation.Nullable;
import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.TrackOutput;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Log;
/**
* Encapsulates information parsed from a track encryption (tenc) box or sample group description
* (sgpd) box in an MP4 stream.
*/
public final class TrackEncryptionBox {
private static final String TAG = "TrackEncryptionBox";
/**
* Indicates the encryption state of the samples in the sample group.
*/
public final boolean isEncrypted;
/**
* The protection scheme type, as defined by the 'schm' box, or null if unknown.
*/
@Nullable public final String schemeType;
/**
* A {@link TrackOutput.CryptoData} instance containing the encryption information from this
* {@link TrackEncryptionBox}.
*/
public final TrackOutput.CryptoData cryptoData;
/** The initialization vector size in bytes for the samples in the corresponding sample group. */
public final int perSampleIvSize;
/**
* If {@link #perSampleIvSize} is 0, holds the default initialization vector as defined in the
* track encryption box or sample group description box. Null otherwise.
*/
@Nullable public final byte[] defaultInitializationVector;
/**
* @param isEncrypted See {@link #isEncrypted}.
* @param schemeType See {@link #schemeType}.
* @param perSampleIvSize See {@link #perSampleIvSize}.
* @param keyId See {@link TrackOutput.CryptoData#encryptionKey}.
* @param defaultEncryptedBlocks See {@link TrackOutput.CryptoData#encryptedBlocks}.
* @param defaultClearBlocks See {@link TrackOutput.CryptoData#clearBlocks}.
* @param defaultInitializationVector See {@link #defaultInitializationVector}.
*/
public TrackEncryptionBox(
boolean isEncrypted,
@Nullable String schemeType,
int perSampleIvSize,
byte[] keyId,
int defaultEncryptedBlocks,
int defaultClearBlocks,
@Nullable byte[] defaultInitializationVector) {
Assertions.checkArgument(perSampleIvSize == 0 ^ defaultInitializationVector == null);
this.isEncrypted = isEncrypted;
this.schemeType = schemeType;
this.perSampleIvSize = perSampleIvSize;
this.defaultInitializationVector = defaultInitializationVector;
cryptoData = new TrackOutput.CryptoData(schemeToCryptoMode(schemeType), keyId,
defaultEncryptedBlocks, defaultClearBlocks);
}
@C.CryptoMode
private static int schemeToCryptoMode(@Nullable String schemeType) {
if (schemeType == null) {
// If unknown, assume cenc.
return C.CRYPTO_MODE_AES_CTR;
}
switch (schemeType) {
case C.CENC_TYPE_cenc:
case C.CENC_TYPE_cens:
return C.CRYPTO_MODE_AES_CTR;
case C.CENC_TYPE_cbc1:
case C.CENC_TYPE_cbcs:
return C.CRYPTO_MODE_AES_CBC;
default:
Log.w(TAG, "Unsupported protection scheme type '" + schemeType + "'. Assuming AES-CTR "
+ "crypto mode.");
return C.CRYPTO_MODE_AES_CTR;
}
}
}
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