2 * Copyright 2014, The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #ifndef ANDROID_AUDIO_AC3_FRAME_SCANNER_H
18 #define ANDROID_AUDIO_AC3_FRAME_SCANNER_H
21 #include <system/audio.h>
22 #include <audio_utils/spdif/FrameScanner.h>
26 #define AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES 3
27 #define AC3_NUM_FRAME_SIZE_TABLE_ENTRIES 38
28 #define AC3_PCM_FRAMES_PER_BLOCK 256
29 #define AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK 6
30 #define EAC3_RATE_MULTIPLIER 4
31 #define EAC3_NUM_SAMPLE_RATE_TABLE_ENTRIES 3
32 #define EAC3_NUM_BLOCKS_PER_FRAME_TABLE_ENTRIES 38
33 #define EAC3_MAX_SUBSTREAMS 8
35 class AC3FrameScanner : public FrameScanner
38 explicit AC3FrameScanner(audio_format_t format);
39 virtual ~AC3FrameScanner();
41 virtual int getMaxChannels() const { return 5 + 1; } // 5.1 surround
43 virtual int getMaxSampleFramesPerSyncFrame() const { return EAC3_RATE_MULTIPLIER
44 * AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK * AC3_PCM_FRAMES_PER_BLOCK; }
45 virtual int getSampleFramesPerSyncFrame() const;
47 virtual bool isFirstInBurst();
48 virtual bool isLastInBurst();
49 virtual void resetBurst();
51 virtual uint16_t convertBytesToLengthCode(uint16_t numBytes) const;
54 // Keep track of how many of each substream blocks have been accumulated.
55 // We need all of each substream before sending block data burst.
56 uint8_t mSubstreamBlockCounts[EAC3_MAX_SUBSTREAMS];
57 int mAudioBlocksPerSyncFrame;
58 // The type of EAC3 stream as per EAC3 spec paragraph 2.3.1.1
61 uint32_t mSubstreamID;
62 audio_format_t mFormat;
64 // used to recognize the start of an AC3 sync frame
65 static const uint8_t kSyncBytes[];
66 // sample rates from AC3 spec table 5.1
67 static const uint16_t kAC3SampleRateTable[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES];
68 // frame sizes from AC3 spec table 5.13
69 static const uint16_t kAC3FrameSizeTable[AC3_NUM_FRAME_SIZE_TABLE_ENTRIES]
70 [AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES];
71 // sample rates from EAC3 spec table E2.3
72 static const uint16_t kEAC3ReducedSampleRateTable[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES];
73 // audio blocks per frame from EAC3 spec table E2.4
74 static const uint16_t kEAC3BlocksPerFrameTable[EAC3_NUM_BLOCKS_PER_FRAME_TABLE_ENTRIES];
76 virtual bool parseHeader();
79 } // namespace android
81 #endif // ANDROID_AUDIO_AC3_FRAME_SCANNER_H