Added in API level 16

Summary: Nested Classes | Fields | Ctors | Methods | Inherited Methods

MediaCodec.CryptoInfo

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Kotlin |Java

public static final class MediaCodec.CryptoInfo
extends Object

java.lang.Object
↳	android.media.MediaCodec.CryptoInfo

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Metadata describing the structure of an encrypted input sample.

A buffer's data is considered to be partitioned into "subSamples". Each subSample starts with a run of plain, unencrypted bytes followed by a run of encrypted bytes. Either of these runs may be empty. If pattern encryption applies, each of the encrypted runs is encrypted only partly, according to a repeating pattern of "encrypt" and "skip" blocks. numBytesOfClearData can be null to indicate that all data is encrypted, and numBytesOfEncryptedData can be null to indicate that all data is clear. At least one of numBytesOfClearData and numBytesOfEncryptedData must be non-null.

This information encapsulates per-sample metadata as outlined in ISO/IEC FDIS 23001-7:2016 "Common encryption in ISO base media file format files".

ISO-CENC Schemes

ISO/IEC FDIS 23001-7:2016 defines four possible schemes by which media may be encrypted, corresponding to each possible combination of an AES mode with the presence or absence of patterned encryption.

	AES-CTR	AES-CBC
Without Patterns	cenc	cbc1
With Patterns	cens	cbcs

For CryptoInfo, the scheme is selected implicitly by the combination of the mode field and the value set with setPattern(Pattern). For the pattern, setting the pattern to all zeroes (that is, both blocksToEncrypt and blocksToSkip are zero) is interpreted as turning patterns off completely. A scheme that does not use patterns will be selected, either cenc or cbc1. Setting the pattern to any nonzero value will choose one of the pattern-supporting schemes, cens or cbcs. The default pattern if setPattern(Pattern) is never called is all zeroes.

HLS SAMPLE-AES Audio

HLS SAMPLE-AES audio is encrypted in a manner compatible with the cbcs scheme, except that it does not use patterned encryption. However, if setPattern(Pattern) is used to set the pattern to all zeroes, this will be interpreted as selecting the cbc1 scheme. The cbc1 scheme cannot successfully decrypt HLS SAMPLE-AES audio because of differences in how the IVs are handled. For this reason, it is recommended that a pattern of 1 encrypted block and 0 skip blocks be used with HLS SAMPLE-AES audio. This will trigger decryption to use cbcs mode while still decrypting every block.

Summary

Nested classes
class	MediaCodec.CryptoInfo.Pattern Metadata describing an encryption pattern for the protected bytes in a subsample.

Fields
public byte[]	iv A 16-byte initialization vector
public byte[]	key A 16-byte key id
public int	mode The type of encryption that has been applied, see MediaCodec.CRYPTO_MODE_UNENCRYPTED, MediaCodec.CRYPTO_MODE_AES_CTR and MediaCodec.CRYPTO_MODE_AES_CBC
public int[]	numBytesOfClearData The number of leading unencrypted bytes in each subSample.
public int[]	numBytesOfEncryptedData The number of trailing encrypted bytes in each subSample.
public int	numSubSamples The number of subSamples that make up the buffer's contents.

Public constructors
CryptoInfo()

Public methods
MediaCodec.CryptoInfo.Pattern	getPattern() Returns the encryption pattern.
void	set(int newNumSubSamples, int[] newNumBytesOfClearData, int[] newNumBytesOfEncryptedData, byte[] newKey, byte[] newIV, int newMode) Set the subsample count, clear/encrypted sizes, key, IV and mode fields of a MediaCodec.CryptoInfo instance.
void	setPattern(MediaCodec.CryptoInfo.Pattern newPattern) Set the encryption pattern on a MediaCodec.CryptoInfo instance.
String	toString() Returns a string representation of the object.

Inherited methods

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Fields

iv

Added in API level 16

public byte[] iv

A 16-byte initialization vector

key

Added in API level 16

public byte[] key

A 16-byte key id

mode

Added in API level 16

public int mode

The type of encryption that has been applied, see MediaCodec.CRYPTO_MODE_UNENCRYPTED, MediaCodec.CRYPTO_MODE_AES_CTR and MediaCodec.CRYPTO_MODE_AES_CBC

numBytesOfClearData

Added in API level 16

public int[] numBytesOfClearData

The number of leading unencrypted bytes in each subSample. If null, all bytes are treated as encrypted and numBytesOfEncryptedData must be specified.

numBytesOfEncryptedData

Added in API level 16

public int[] numBytesOfEncryptedData

The number of trailing encrypted bytes in each subSample. If null, all bytes are treated as clear and numBytesOfClearData must be specified.

numSubSamples

Added in API level 16

public int numSubSamples

The number of subSamples that make up the buffer's contents.

Public constructors

CryptoInfo

public CryptoInfo ()

Public methods

getPattern

Added in API level 31

public MediaCodec.CryptoInfo.Pattern getPattern ()

Returns the encryption pattern.

Returns
MediaCodec.CryptoInfo.Pattern	This value cannot be null.

set

Added in API level 16

public void set (int newNumSubSamples, 
                int[] newNumBytesOfClearData, 
                int[] newNumBytesOfEncryptedData, 
                byte[] newKey, 
                byte[] newIV, 
                int newMode)

Set the subsample count, clear/encrypted sizes, key, IV and mode fields of a MediaCodec.CryptoInfo instance.

Parameters
newNumSubSamples	int
newNumBytesOfClearData	int: This value cannot be null.
newNumBytesOfEncryptedData	int: This value cannot be null.
newKey	byte: This value cannot be null.
newIV	byte: This value cannot be null.
newMode	int

setPattern

Added in API level 24

public void setPattern (MediaCodec.CryptoInfo.Pattern newPattern)

Set the encryption pattern on a MediaCodec.CryptoInfo instance. See Pattern.

Parameters
newPattern	MediaCodec.CryptoInfo.Pattern

toString

Added in API level 16

public String toString ()

Returns a string representation of the object.

Returns
String	a string representation of the object.