Index: chromecast/public/media/decoder_config.h |
diff --git a/chromecast/public/media/decoder_config.h b/chromecast/public/media/decoder_config.h |
index e2cf78dcbc6118608f4295c31ae9ff9e939c23ab..d3fc9de85949dca163817dfe25a2668693e49919 100644 |
--- a/chromecast/public/media/decoder_config.h |
+++ b/chromecast/public/media/decoder_config.h |
@@ -87,13 +87,80 @@ enum VideoProfile { |
kVideoProfileMax = kVP9ProfileAny, |
}; |
-// TODO(erickung): Remove constructor once CMA backend implementation does't |
+// Specification of whether and how the stream is encrypted (in whole or part). |
+struct EncryptionScheme { |
+ // Algorithm and mode that was used to encrypt the stream. |
+ enum CipherMode { |
+ kCipherModeNone, |
+ kCipherModeAesCtr, |
+ kCipherModeAesCbc |
+ }; |
+ |
+ // V3 of the CENC standard will add pattern encryption, through two new |
+ // protection schemes 'cens' (with AES-CTR) and 'cbcs' (with AES-CBC). |
+ // The pattern applies only to the 'encrypted' part of the frame (as |
+ // defined by the relevant subsample entries), and reduces further the |
+ // actual encryption applied through a repeating pattern of (encrypt:skip) |
+ // 16 byte blocks. For example, in a (1:9) pattern, the first block is |
+ // encrypted, and the next nine are skipped. This pattern is applied |
+ // repeatedly until the end of the last 16-byte block in the subsample. |
+ // Any remaining bytes are left clear. |
+ // If either or both of encrypt_blocks or skip_blocks is 0, pattern |
+ // encryption is disabled. |
+ struct PatternSpec { |
+ PatternSpec(); |
+ PatternSpec(uint32_t encrypt_blocks, uint32_t skip_blocks); |
+ ~PatternSpec() {} |
+ uint32_t encrypt_blocks; |
+ uint32_t skip_blocks; |
+ }; |
+ |
+ EncryptionScheme(); |
+ explicit EncryptionScheme(bool is_encrypted); |
halliwell
2016/01/13 03:29:41
same comment as ::media::EncryptionScheme construc
dougsteed
2016/02/09 22:58:54
Done.
|
+ explicit EncryptionScheme(CipherMode mode); |
+ EncryptionScheme(CipherMode mode, const PatternSpec& pattern); |
+ ~EncryptionScheme() {} |
+ |
+ CipherMode mode; |
+ PatternSpec pattern; |
+}; |
+ |
+inline EncryptionScheme::PatternSpec::PatternSpec() |
+ : encrypt_blocks(0), skip_blocks(0) { |
+} |
+ |
+inline EncryptionScheme::PatternSpec::PatternSpec(uint32_t encrypt_blocks, |
+ uint32_t skip_blocks) |
+ : encrypt_blocks(encrypt_blocks), skip_blocks(skip_blocks) { |
+} |
+ |
+inline EncryptionScheme::EncryptionScheme() |
+ : mode(kCipherModeNone), pattern() { |
+} |
+ |
+inline EncryptionScheme::EncryptionScheme(bool is_encrypted) |
+ : mode(is_encrypted ? kCipherModeAesCtr : kCipherModeNone), |
halliwell
2016/01/13 03:29:41
Don't like 'true' being implicitly AesCtr. Can we
dougsteed
2016/02/09 22:58:54
Done.
|
+ pattern() { |
+} |
+ |
+inline EncryptionScheme::EncryptionScheme(CipherMode mode) |
+ : mode(mode), pattern() { |
+} |
+ |
+inline EncryptionScheme::EncryptionScheme(CipherMode mode, |
+ const PatternSpec& pattern) |
+ : mode(mode), pattern(pattern) { |
+} |
+ |
+// TODO(erickung): Remove constructor once CMA backend implementation doesn't |
// create a new object to reset the configuration and use IsValidConfig() to |
// determine if the configuration is still valid or not. |
struct AudioConfig { |
AudioConfig(); |
~AudioConfig(); |
+ bool is_encrypted() const; |
+ |
// Stream id. |
StreamId id; |
// Audio codec. |
@@ -108,8 +175,8 @@ struct AudioConfig { |
int samples_per_second; |
// Extra data buffer for certain codec initialization. |
std::vector<uint8_t> extra_data; |
- // content is encrypted or not. |
- bool is_encrypted; |
+ // Encryption scheme (if any) used for the content. |
+ EncryptionScheme encryption_scheme; |
}; |
inline AudioConfig::AudioConfig() |
@@ -119,12 +186,19 @@ inline AudioConfig::AudioConfig() |
bytes_per_channel(0), |
channel_number(0), |
samples_per_second(0), |
- is_encrypted(false) { |
+ encryption_scheme(false) { |
halliwell
2016/01/13 03:29:41
default initialisation of encryption_scheme should
dougsteed
2016/02/09 22:58:54
Done.
|
} |
inline AudioConfig::~AudioConfig() { |
} |
+// Normally a struct would not have a simple function member like this. However, |
+// the member |encryption_scheme| replaced a simple boolean, and a lot of code |
+// sites are only interested in whether encryption has been applied or not. |
halliwell
2016/01/13 03:29:41
let's just delete this comment, doesn't add any va
dougsteed
2016/02/09 22:58:54
Done.
|
+inline bool AudioConfig::is_encrypted() const { |
+ return encryption_scheme.mode != EncryptionScheme::kCipherModeNone; |
+} |
+ |
// TODO(erickung): Remove constructor once CMA backend implementation does't |
// create a new object to reset the configuration and use IsValidConfig() to |
// determine if the configuration is still valid or not. |
@@ -132,6 +206,8 @@ struct VideoConfig { |
VideoConfig(); |
~VideoConfig(); |
+ bool is_encrypted() const; |
+ |
// Stream Id. |
StreamId id; |
// Video codec. |
@@ -144,8 +220,8 @@ struct VideoConfig { |
VideoConfig* additional_config; |
// Extra data buffer for certain codec initialization. |
std::vector<uint8_t> extra_data; |
- // content is encrypted or not. |
- bool is_encrypted; |
+ // Encryption scheme (if any) used for the content. |
+ EncryptionScheme encryption_scheme; |
}; |
inline VideoConfig::VideoConfig() |
@@ -153,12 +229,18 @@ inline VideoConfig::VideoConfig() |
codec(kVideoCodecUnknown), |
profile(kVideoProfileUnknown), |
additional_config(nullptr), |
- is_encrypted(false) { |
+ encryption_scheme(false) { |
} |
inline VideoConfig::~VideoConfig() { |
} |
+// See comment above for AudioConfig::is_encrypted(). |
halliwell
2016/01/13 03:29:41
delete
dougsteed
2016/02/09 22:58:53
Done.
|
+inline bool VideoConfig::is_encrypted() const { |
+ return encryption_scheme.mode != EncryptionScheme::kCipherModeNone; |
+} |
+ |
+ |
// TODO(erickung): Remove following two inline IsValidConfig() functions. These |
// are to keep existing CMA backend implementation consistent until the clean up |
// is done. These SHOULD NOT be used in New CMA backend implementation. |