Merge "handle emulation_prevention_three_bytes for AVC" (718cee5f) · Commits · e / os / android_frameworks_av

include/media/stagefright/foundation/ABitReader.h

+19 −3

Original line number	Diff line number	Diff line
		@@ -25,8 +25,10 @@

		namespace android {

		struct ABitReader {
		class ABitReader {
		public:
		ABitReader(const uint8_t *data, size_t size);
		virtual ~ABitReader();

		uint32_t getBits(size_t n);
		void skipBits(size_t n);
		@@ -37,18 +39,32 @@ struct ABitReader {

		const uint8_t *data() const;

		private:
		protected:
		const uint8_t *mData;
		size_t mSize;

		uint32_t mReservoir; // left-aligned bits
		size_t mNumBitsLeft;

		void fillReservoir();
		virtual void fillReservoir();

		DISALLOW_EVIL_CONSTRUCTORS(ABitReader);
		};

		class NALBitReader : public ABitReader {
		public:
		NALBitReader(const uint8_t *data, size_t size);

		bool atLeastNumBitsLeft(size_t n) const;

		private:
		int32_t mNumZeros;

		virtual void fillReservoir();

		DISALLOW_EVIL_CONSTRUCTORS(NALBitReader);
		};

		} // namespace android

		#endif // A_BIT_READER_H_

+2 −2

Original line number	Diff line number	Diff line
		@@ -674,9 +674,9 @@ bool NuPlayer::CCDecoder::extractFromSEI(const sp<ABuffer> &accessUnit) {

		bool hasCC = false;

		ABitReader br(sei->data() + 1, sei->size() - 1);
		NALBitReader br(sei->data() + 1, sei->size() - 1);
		// sei_message()
		while (br.numBitsLeft() >= 16) { // at least 16-bit for sei_message()
		while (br.atLeastNumBitsLeft(16)) { // at least 16-bit for sei_message()
		uint32_t payload_type = 0;
		size_t payload_size = 0;
		uint8_t last_byte;

+68 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,9 @@ ABitReader::ABitReader(const uint8_t *data, size_t size)
		mNumBitsLeft(0) {
		}

		ABitReader::~ABitReader() {
		}

		void ABitReader::fillReservoir() {
		CHECK_GT(mSize, 0u);

		@@ -99,4 +102,69 @@ const uint8_t *ABitReader::data() const {
		return mData - (mNumBitsLeft + 7) / 8;
		}

		NALBitReader::NALBitReader(const uint8_t *data, size_t size)
		: ABitReader(data, size),
		mNumZeros(0) {
		}

		bool NALBitReader::atLeastNumBitsLeft(size_t n) const {
		// check against raw size and reservoir bits first
		size_t numBits = numBitsLeft();
		if (n > numBits) {
		return false;
		}

		ssize_t numBitsRemaining = n - mNumBitsLeft;

		size_t size = mSize;
		const uint8_t *data = mData;
		int32_t numZeros = mNumZeros;
		while (size > 0 && numBitsRemaining > 0) {
		bool isEmulationPreventionByte = (numZeros >= 2 && *data == 3);

		if (*data == 0) {
		++numZeros;
		} else {
		numZeros = 0;
		}

		if (!isEmulationPreventionByte) {
		numBitsRemaining -= 8;
		}

		++data;
		--size;
		}

		return (numBitsRemaining <= 0);
		}

		void NALBitReader::fillReservoir() {
		CHECK_GT(mSize, 0u);

		mReservoir = 0;
		size_t i = 0;
		while (mSize > 0 && i < 4) {
		bool isEmulationPreventionByte = (mNumZeros >= 2 && *mData == 3);

		if (*mData == 0) {
		++mNumZeros;
		} else {
		mNumZeros = 0;
		}

		// skip emulation_prevention_three_byte
		if (!isEmulationPreventionByte) {
		mReservoir = (mReservoir << 8) \| *mData;
		++i;
		}

		++mData;
		--mSize;
		}

		mNumBitsLeft = 8 * i;
		mReservoir <<= 32 - mNumBitsLeft;
		}

		} // namespace android