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/*
* 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_AC3_FRAME_SCANNER_H
#define ANDROID_AUDIO_AC3_FRAME_SCANNER_H
#include <stdint.h>
#include <audio_utils/spdif/FrameScanner.h>
namespace android {
#define AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES 3
#define AC3_NUM_FRAME_SIZE_TABLE_ENTRIES 38
#define AC3_PCM_FRAMES_PER_BLOCK 256
#define AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK 6
#define EAC3_RATE_MULTIPLIER 4
#define EAC3_NUM_SAMPLE_RATE_TABLE_ENTRIES 3
#define EAC3_NUM_BLOCKS_PER_FRAME_TABLE_ENTRIES 38
#define EAC3_MAX_SUBSTREAMS 8
class AC3FrameScanner : public FrameScanner
{
public:
AC3FrameScanner();
virtual ~AC3FrameScanner();
virtual int getMaxChannels() const { return 5 + 1; } // 5.1 surround
virtual int getMaxSampleFramesPerSyncFrame() const { return EAC3_RATE_MULTIPLIER
* AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK * AC3_PCM_FRAMES_PER_BLOCK; }
virtual int getSampleFramesPerSyncFrame() const;
virtual bool isFirstInBurst();
virtual bool isLastInBurst();
virtual void resetBurst();
protected:
// Keep track of how many of each substream blocks have been accumulated.
// We need all of each substream before sending block data burst.
uint8_t mSubstreamBlockCounts[EAC3_MAX_SUBSTREAMS];
int mAudioBlocksPerSyncFrame;
// The type of EAC3 stream as per EAC3 spec paragraph 2.3.1.1
uint32_t mStreamType;
// substream index
uint32_t mSubstreamID;
// used to recognize the start of an AC3 sync frame
static const uint8_t kSyncBytes[];
// sample rates from AC3 spec table 5.1
static const uint16_t kAC3SampleRateTable[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES];
// frame sizes from AC3 spec table 5.13
static const uint16_t kAC3FrameSizeTable[AC3_NUM_FRAME_SIZE_TABLE_ENTRIES]
[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES];
// sample rates from EAC3 spec table E2.3
static const uint16_t kEAC3ReducedSampleRateTable[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES];
// audio blocks per frame from EAC3 spec table E2.4
static const uint16_t kEAC3BlocksPerFrameTable[EAC3_NUM_BLOCKS_PER_FRAME_TABLE_ENTRIES];
virtual bool parseHeader();
};
} // namespace android
#endif // ANDROID_AUDIO_AC3_FRAME_SCANNER_H
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