114 lines
3.5 KiB
C++
114 lines
3.5 KiB
C++
|
/*
|
||
|
|
* 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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifndef ANDROID_AUDIO_SPDIF_ENCODER_H
|
||
|
|
#define ANDROID_AUDIO_SPDIF_ENCODER_H
|
||
|
|
|
||
|
|
#include <stdint.h>
|
||
|
|
#include "FrameScanner.h"
|
||
|
|
|
||
|
|
namespace android {
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Scan the incoming byte stream for a frame sync.
|
||
|
|
* Then wrap the encoded frame in a data burst and send it as if it were PCM.
|
||
|
|
* The receiver will see the data burst header and decode the wrapped frame.
|
||
|
|
*/
|
||
|
|
#define SPDIF_MAX_CHANNELS 8
|
||
|
|
#define SPDIF_ENCODED_CHANNEL_COUNT 2
|
||
|
|
|
||
|
|
class SPDIFEncoder {
|
||
|
|
public:
|
||
|
|
|
||
|
|
explicit SPDIFEncoder(audio_format_t format);
|
||
|
|
// Defaults to AC3 format. Was in original API.
|
||
|
|
SPDIFEncoder();
|
||
|
|
|
||
|
|
virtual ~SPDIFEncoder();
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Write encoded data to be wrapped for SPDIF.
|
||
|
|
* The compressed frames do not have to be aligned.
|
||
|
|
* @return number of bytes written or negative error
|
||
|
|
*/
|
||
|
|
ssize_t write( const void* buffer, size_t numBytes );
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Called by SPDIFEncoder when it is ready to output a data burst.
|
||
|
|
* Must be implemented in the subclass.
|
||
|
|
* @return number of bytes written or negative error
|
||
|
|
*/
|
||
|
|
virtual ssize_t writeOutput( const void* buffer, size_t numBytes ) = 0;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Get ratio of the encoded data burst sample rate to the encoded rate.
|
||
|
|
* For example, EAC3 data bursts are 4X the encoded rate.
|
||
|
|
*/
|
||
|
|
uint32_t getRateMultiplier() const { return mRateMultiplier; }
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @return number of PCM frames in a data burst
|
||
|
|
*/
|
||
|
|
uint32_t getBurstFrames() const { return mBurstFrames; }
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @return number of bytes per PCM frame for the data burst
|
||
|
|
*/
|
||
|
|
int getBytesPerOutputFrame();
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @return true if we can wrap this format in an SPDIF stream
|
||
|
|
*/
|
||
|
|
static bool isFormatSupported(audio_format_t format);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Discard any data in the buffer. Reset frame scanners.
|
||
|
|
* This should be called when seeking to a new position in the stream.
|
||
|
|
*/
|
||
|
|
void reset();
|
||
|
|
|
||
|
|
protected:
|
||
|
|
void clearBurstBuffer();
|
||
|
|
void writeBurstBufferShorts(const uint16_t* buffer, size_t numBytes);
|
||
|
|
void writeBurstBufferBytes(const uint8_t* buffer, size_t numBytes);
|
||
|
|
void sendZeroPad();
|
||
|
|
void flushBurstBuffer();
|
||
|
|
void startDataBurst();
|
||
|
|
size_t startSyncFrame();
|
||
|
|
|
||
|
|
// Works with various formats including AC3.
|
||
|
|
FrameScanner *mFramer;
|
||
|
|
|
||
|
|
uint32_t mSampleRate;
|
||
|
|
size_t mFrameSize; // size of sync frame in bytes
|
||
|
|
uint16_t *mBurstBuffer; // ALSA wants to get SPDIF data as shorts.
|
||
|
|
size_t mBurstBufferSizeBytes;
|
||
|
|
uint32_t mRateMultiplier;
|
||
|
|
uint32_t mBurstFrames;
|
||
|
|
size_t mByteCursor; // cursor into data burst
|
||
|
|
int mBitstreamNumber;
|
||
|
|
size_t mPayloadBytesPending; // number of bytes needed to finish burst
|
||
|
|
// state variable, true if scanning for start of frame
|
||
|
|
bool mScanning;
|
||
|
|
|
||
|
|
static const uint16_t kSPDIFSync1; // Pa
|
||
|
|
static const uint16_t kSPDIFSync2; // Pb
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace android
|
||
|
|
|
||
|
|
#endif // ANDROID_AUDIO_SPDIF_ENCODER_H
|