audio_utils/spdif/SPDIFEncoder.cpp - platform/system/media - Git at Google

 /*
  * Copyright 2014, 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.
  */

 #include <stdint.h>
 #include <string.h>

 #define LOG_TAG "AudioSPDIF"
 #include <utils/Log.h>
 #include <audio_utils/spdif/SPDIFEncoder.h>

 #include "AC3FrameScanner.h"
 #include "DTSFrameScanner.h"

 namespace android {

 // Burst Preamble defined in IEC61937-1
 const uint16_t SPDIFEncoder::kSPDIFSync1 = 0xF872; // Pa
 const uint16_t SPDIFEncoder::kSPDIFSync2 = 0x4E1F; // Pb

 static int32_t sEndianDetector = 1;
 #define isLittleEndian()  (*((uint8_t *)&sEndianDetector))

 SPDIFEncoder::SPDIFEncoder(audio_format_t format)
   : mFramer(NULL)
   , mSampleRate(48000)
   , mBurstBuffer(NULL)
   , mBurstBufferSizeBytes(0)
   , mRateMultiplier(1)
   , mBurstFrames(0)
   , mByteCursor(0)
   , mBitstreamNumber(0)
   , mPayloadBytesPending(0)
   , mScanning(true)
 {
     switch(format) {
         case AUDIO_FORMAT_AC3:
         case AUDIO_FORMAT_E_AC3:
             mFramer = new AC3FrameScanner(format);
             break;
         case AUDIO_FORMAT_DTS:
         case AUDIO_FORMAT_DTS_HD:
             mFramer = new DTSFrameScanner();
             break;
         default:
             break;
     }

     // This a programmer error. Call isFormatSupported() first.
     LOG_ALWAYS_FATAL_IF((mFramer == NULL),
         "SPDIFEncoder: invalid audio format = 0x%08X", format);

     mBurstBufferSizeBytes = sizeof(uint16_t)
             * SPDIF_ENCODED_CHANNEL_COUNT
             * mFramer->getMaxSampleFramesPerSyncFrame();

     ALOGI("SPDIFEncoder: mBurstBufferSizeBytes = %zu, littleEndian = %d",
             mBurstBufferSizeBytes, isLittleEndian());
     mBurstBuffer = new uint16_t[mBurstBufferSizeBytes >> 1];
     clearBurstBuffer();
 }

 SPDIFEncoder::SPDIFEncoder()
     : SPDIFEncoder(AUDIO_FORMAT_AC3)
 {
 }

 SPDIFEncoder::~SPDIFEncoder()
 {
     delete[] mBurstBuffer;
     delete mFramer;
 }

 bool SPDIFEncoder::isFormatSupported(audio_format_t format)
 {
     switch(format) {
         case AUDIO_FORMAT_AC3:
         case AUDIO_FORMAT_E_AC3:
         case AUDIO_FORMAT_DTS:
         case AUDIO_FORMAT_DTS_HD:
             return true;
         default:
             return false;
     }
 }

 int SPDIFEncoder::getBytesPerOutputFrame()
 {
     return SPDIF_ENCODED_CHANNEL_COUNT * sizeof(int16_t);
 }

 void SPDIFEncoder::writeBurstBufferShorts(const uint16_t *buffer, size_t numShorts)
 {
     // avoid static analyser warning
     LOG_ALWAYS_FATAL_IF((mBurstBuffer == NULL), "mBurstBuffer never allocated");
     mByteCursor = (mByteCursor + 1) & ~1; // round up to even byte
     size_t bytesToWrite = numShorts * sizeof(uint16_t);
     if ((mByteCursor + bytesToWrite) > mBurstBufferSizeBytes) {
         ALOGE("SPDIFEncoder: Burst buffer overflow!");
         reset();
         return;
     }
     memcpy(&mBurstBuffer[mByteCursor >> 1], buffer, bytesToWrite);
     mByteCursor += bytesToWrite;
 }

 // Pack the bytes into the short buffer in the order:
 //   byte[0] -> short[0] MSB
 //   byte[1] -> short[0] LSB
 //   byte[2] -> short[1] MSB
 //   byte[3] -> short[1] LSB
 //   etcetera
 // This way they should come out in the correct order for SPDIF on both
 // Big and Little Endian CPUs.
 void SPDIFEncoder::writeBurstBufferBytes(const uint8_t *buffer, size_t numBytes)
 {
     size_t bytesToWrite = numBytes;
     if ((mByteCursor + bytesToWrite) > mBurstBufferSizeBytes) {
         ALOGE("SPDIFEncoder: Burst buffer overflow!");
         clearBurstBuffer();
         return;
     }
     uint16_t pad = mBurstBuffer[mByteCursor >> 1];
     for (size_t i = 0; i < bytesToWrite; i++) {
         if (mByteCursor & 1 ) {
             pad |= *buffer++; // put second byte in LSB
             mBurstBuffer[mByteCursor >> 1] = pad;
             pad = 0;
         } else {
             pad |= (*buffer++) << 8; // put first byte in MSB
         }
         mByteCursor++;
     }
     // Save partially filled short.
     if (mByteCursor & 1 ){
         mBurstBuffer[mByteCursor >> 1] = pad;
     }
 }

 void SPDIFEncoder::sendZeroPad()
 {
     // Pad remainder of burst with zeros.
     size_t burstSize = mFramer->getSampleFramesPerSyncFrame() * sizeof(uint16_t)
             * SPDIF_ENCODED_CHANNEL_COUNT;
     if (mByteCursor > burstSize) {
         ALOGE("SPDIFEncoder: Burst buffer, contents too large!");
         clearBurstBuffer();
     } else {
         // We don't have to write zeros because buffer already set to zero
         // by clearBurstBuffer(). Just pretend we wrote zeros by
         // incrementing cursor.
         mByteCursor = burstSize;
     }
 }

 void SPDIFEncoder::reset()
 {
     ALOGV("SPDIFEncoder: reset()");
     clearBurstBuffer();
     if (mFramer != NULL) {
         mFramer->resetBurst();
     }
     mPayloadBytesPending = 0;
     mScanning = true;
 }

 void SPDIFEncoder::flushBurstBuffer()
 {
     const int preambleSize = 4 * sizeof(uint16_t);
     if (mByteCursor > preambleSize) {
         // Set lengthCode for valid payload before zeroPad.
         uint16_t numBytes = (mByteCursor - preambleSize);
         mBurstBuffer[3] = mFramer->convertBytesToLengthCode(numBytes);

         sendZeroPad();
         writeOutput(mBurstBuffer, mByteCursor);
     }
     reset();
 }

 void SPDIFEncoder::clearBurstBuffer()
 {
     if (mBurstBuffer) {
         memset(mBurstBuffer, 0, mBurstBufferSizeBytes);
     }
     mByteCursor = 0;
 }

 void SPDIFEncoder::startDataBurst()
 {
     // Encode IEC61937-1 Burst Preamble
     uint16_t preamble[4];

     uint16_t burstInfo = (mBitstreamNumber << 13)
         | (mFramer->getDataTypeInfo() << 8)
         | mFramer->getDataType();

     mRateMultiplier = mFramer->getRateMultiplier();

     preamble[0] = kSPDIFSync1;
     preamble[1] = kSPDIFSync2;
     preamble[2] = burstInfo;
     preamble[3] = 0; // lengthCode - This will get set after the buffer is full.
     writeBurstBufferShorts(preamble, 4);
 }

 size_t SPDIFEncoder::startSyncFrame()
 {
     // Write start of encoded frame that was buffered in frame detector.
     size_t syncSize = mFramer->getHeaderSizeBytes();
     writeBurstBufferBytes(mFramer->getHeaderAddress(), syncSize);
     return mFramer->getFrameSizeBytes() - syncSize;
 }

 // Wraps raw encoded data into a data burst.
 ssize_t SPDIFEncoder::write( const void *buffer, size_t numBytes )
 {
     size_t bytesLeft = numBytes;
     const uint8_t *data = (const uint8_t *)buffer;
     ALOGV("SPDIFEncoder: mScanning = %d, write(buffer[0] = 0x%02X, numBytes = %zu)",
         mScanning, (uint) *data, numBytes);
     while (bytesLeft > 0) {
         if (mScanning) {
         // Look for beginning of next encoded frame.
             if (mFramer->scan(*data)) {
                 if (mByteCursor == 0) {
                     startDataBurst();
                 } else if (mFramer->isFirstInBurst()) {
                     // Make sure that this frame is at the beginning of the data burst.
                     flushBurstBuffer();
                     startDataBurst();
                 }
                 mPayloadBytesPending = startSyncFrame();
                 mScanning = false;
             }
             data++;
             bytesLeft--;
         } else {
             // Write payload until we hit end of frame.
             size_t bytesToWrite = bytesLeft;
             // Only write as many as we need to finish the frame.
             if (bytesToWrite > mPayloadBytesPending) {
                 bytesToWrite = mPayloadBytesPending;
             }
             writeBurstBufferBytes(data, bytesToWrite);

             data += bytesToWrite;
             bytesLeft -= bytesToWrite;
             mPayloadBytesPending -= bytesToWrite;

             // If we have all the payload then send a data burst.
             if (mPayloadBytesPending == 0) {
                 if (mFramer->isLastInBurst()) {
                     flushBurstBuffer();
                 }
                 mScanning = true;
             }
         }
     }
     return numBytes;
 }

 }  // namespace android
	/*
	* Copyright 2014, 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.
	*/

	#include <stdint.h>
	#include <string.h>

	#define LOG_TAG "AudioSPDIF"
	#include <utils/Log.h>
	#include <audio_utils/spdif/SPDIFEncoder.h>

	#include "AC3FrameScanner.h"
	#include "DTSFrameScanner.h"

	namespace android {

	// Burst Preamble defined in IEC61937-1
	const uint16_t SPDIFEncoder::kSPDIFSync1 = 0xF872; // Pa
	const uint16_t SPDIFEncoder::kSPDIFSync2 = 0x4E1F; // Pb

	static int32_t sEndianDetector = 1;
	#define isLittleEndian() (((uint8_t )&sEndianDetector))

	SPDIFEncoder::SPDIFEncoder(audio_format_t format)
	: mFramer(NULL)
	, mSampleRate(48000)
	, mBurstBuffer(NULL)
	, mBurstBufferSizeBytes(0)
	, mRateMultiplier(1)
	, mBurstFrames(0)
	, mByteCursor(0)
	, mBitstreamNumber(0)
	, mPayloadBytesPending(0)
	, mScanning(true)
	{
	switch(format) {
	case AUDIO_FORMAT_AC3:
	case AUDIO_FORMAT_E_AC3:
	mFramer = new AC3FrameScanner(format);
	break;
	case AUDIO_FORMAT_DTS:
	case AUDIO_FORMAT_DTS_HD:
	mFramer = new DTSFrameScanner();
	break;
	default:
	break;
	}

	// This a programmer error. Call isFormatSupported() first.
	LOG_ALWAYS_FATAL_IF((mFramer == NULL),
	"SPDIFEncoder: invalid audio format = 0x%08X", format);

	mBurstBufferSizeBytes = sizeof(uint16_t)
	* SPDIF_ENCODED_CHANNEL_COUNT
	* mFramer->getMaxSampleFramesPerSyncFrame();

	ALOGI("SPDIFEncoder: mBurstBufferSizeBytes = %zu, littleEndian = %d",
	mBurstBufferSizeBytes, isLittleEndian());
	mBurstBuffer = new uint16_t[mBurstBufferSizeBytes >> 1];
	clearBurstBuffer();
	}

	SPDIFEncoder::SPDIFEncoder()
	: SPDIFEncoder(AUDIO_FORMAT_AC3)
	{
	}

	SPDIFEncoder::~SPDIFEncoder()
	{
	delete[] mBurstBuffer;
	delete mFramer;
	}

	bool SPDIFEncoder::isFormatSupported(audio_format_t format)
	{
	switch(format) {
	case AUDIO_FORMAT_AC3:
	case AUDIO_FORMAT_E_AC3:
	case AUDIO_FORMAT_DTS:
	case AUDIO_FORMAT_DTS_HD:
	return true;
	default:
	return false;
	}
	}

	int SPDIFEncoder::getBytesPerOutputFrame()
	{
	return SPDIF_ENCODED_CHANNEL_COUNT * sizeof(int16_t);
	}

	void SPDIFEncoder::writeBurstBufferShorts(const uint16_t *buffer, size_t numShorts)
	{
	// avoid static analyser warning
	LOG_ALWAYS_FATAL_IF((mBurstBuffer == NULL), "mBurstBuffer never allocated");
	mByteCursor = (mByteCursor + 1) & ~1; // round up to even byte
	size_t bytesToWrite = numShorts * sizeof(uint16_t);
	if ((mByteCursor + bytesToWrite) > mBurstBufferSizeBytes) {
	ALOGE("SPDIFEncoder: Burst buffer overflow!");
	reset();
	return;
	}
	memcpy(&mBurstBuffer[mByteCursor >> 1], buffer, bytesToWrite);
	mByteCursor += bytesToWrite;
	}

	// Pack the bytes into the short buffer in the order:
	// byte[0] -> short[0] MSB
	// byte[1] -> short[0] LSB
	// byte[2] -> short[1] MSB
	// byte[3] -> short[1] LSB
	// etcetera
	// This way they should come out in the correct order for SPDIF on both
	// Big and Little Endian CPUs.
	void SPDIFEncoder::writeBurstBufferBytes(const uint8_t *buffer, size_t numBytes)
	{
	size_t bytesToWrite = numBytes;
	if ((mByteCursor + bytesToWrite) > mBurstBufferSizeBytes) {
	ALOGE("SPDIFEncoder: Burst buffer overflow!");
	clearBurstBuffer();
	return;
	}
	uint16_t pad = mBurstBuffer[mByteCursor >> 1];
	for (size_t i = 0; i < bytesToWrite; i++) {
	if (mByteCursor & 1 ) {
	pad \|= *buffer++; // put second byte in LSB
	mBurstBuffer[mByteCursor >> 1] = pad;
	pad = 0;
	} else {
	pad \|= (*buffer++) << 8; // put first byte in MSB
	}
	mByteCursor++;
	}
	// Save partially filled short.
	if (mByteCursor & 1 ){
	mBurstBuffer[mByteCursor >> 1] = pad;
	}
	}

	void SPDIFEncoder::sendZeroPad()
	{
	// Pad remainder of burst with zeros.
	size_t burstSize = mFramer->getSampleFramesPerSyncFrame() * sizeof(uint16_t)
	* SPDIF_ENCODED_CHANNEL_COUNT;
	if (mByteCursor > burstSize) {
	ALOGE("SPDIFEncoder: Burst buffer, contents too large!");
	clearBurstBuffer();
	} else {
	// We don't have to write zeros because buffer already set to zero
	// by clearBurstBuffer(). Just pretend we wrote zeros by
	// incrementing cursor.
	mByteCursor = burstSize;
	}
	}

	void SPDIFEncoder::reset()
	{
	ALOGV("SPDIFEncoder: reset()");
	clearBurstBuffer();
	if (mFramer != NULL) {
	mFramer->resetBurst();
	}
	mPayloadBytesPending = 0;
	mScanning = true;
	}

	void SPDIFEncoder::flushBurstBuffer()
	{
	const int preambleSize = 4 * sizeof(uint16_t);
	if (mByteCursor > preambleSize) {
	// Set lengthCode for valid payload before zeroPad.
	uint16_t numBytes = (mByteCursor - preambleSize);
	mBurstBuffer[3] = mFramer->convertBytesToLengthCode(numBytes);

	sendZeroPad();
	writeOutput(mBurstBuffer, mByteCursor);
	}
	reset();
	}

	void SPDIFEncoder::clearBurstBuffer()
	{
	if (mBurstBuffer) {
	memset(mBurstBuffer, 0, mBurstBufferSizeBytes);
	}
	mByteCursor = 0;
	}

	void SPDIFEncoder::startDataBurst()
	{
	// Encode IEC61937-1 Burst Preamble
	uint16_t preamble[4];

	uint16_t burstInfo = (mBitstreamNumber << 13)
	\| (mFramer->getDataTypeInfo() << 8)
	\| mFramer->getDataType();

	mRateMultiplier = mFramer->getRateMultiplier();

	preamble[0] = kSPDIFSync1;
	preamble[1] = kSPDIFSync2;
	preamble[2] = burstInfo;
	preamble[3] = 0; // lengthCode - This will get set after the buffer is full.
	writeBurstBufferShorts(preamble, 4);
	}

	size_t SPDIFEncoder::startSyncFrame()
	{
	// Write start of encoded frame that was buffered in frame detector.
	size_t syncSize = mFramer->getHeaderSizeBytes();
	writeBurstBufferBytes(mFramer->getHeaderAddress(), syncSize);
	return mFramer->getFrameSizeBytes() - syncSize;
	}

	// Wraps raw encoded data into a data burst.
	ssize_t SPDIFEncoder::write( const void *buffer, size_t numBytes )
	{
	size_t bytesLeft = numBytes;
	const uint8_t data = (const uint8_t )buffer;
	ALOGV("SPDIFEncoder: mScanning = %d, write(buffer[0] = 0x%02X, numBytes = %zu)",
	mScanning, (uint) *data, numBytes);
	while (bytesLeft > 0) {
	if (mScanning) {
	// Look for beginning of next encoded frame.
	if (mFramer->scan(*data)) {
	if (mByteCursor == 0) {
	startDataBurst();
	} else if (mFramer->isFirstInBurst()) {
	// Make sure that this frame is at the beginning of the data burst.
	flushBurstBuffer();
	startDataBurst();
	}
	mPayloadBytesPending = startSyncFrame();
	mScanning = false;
	}
	data++;
	bytesLeft--;
	} else {
	// Write payload until we hit end of frame.
	size_t bytesToWrite = bytesLeft;
	// Only write as many as we need to finish the frame.
	if (bytesToWrite > mPayloadBytesPending) {
	bytesToWrite = mPayloadBytesPending;
	}
	writeBurstBufferBytes(data, bytesToWrite);

	data += bytesToWrite;
	bytesLeft -= bytesToWrite;
	mPayloadBytesPending -= bytesToWrite;

	// If we have all the payload then send a data burst.
	if (mPayloadBytesPending == 0) {
	if (mFramer->isLastInBurst()) {
	flushBurstBuffer();
	}
	mScanning = true;
	}
	}
	}
	return numBytes;
	}

	} // namespace android