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      1 /*
      2  * Copyright 2015, The Android Open Source Project
      3  *
      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
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     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.
     15  */
     16 
     17 #define LOG_TAG "AudioSPDIF"
     18 //#define LOG_NDEBUG 0
     19 
     20 #include <assert.h>
     21 #include <string.h>
     22 
     23 #include <utils/Log.h>
     24 #include <audio_utils/spdif/FrameScanner.h>
     25 
     26 #include "BitFieldParser.h"
     27 #include "DTSFrameScanner.h"
     28 
     29 namespace android {
     30 
     31 // TODO Handle termination frames.
     32 // TODO assert if parse past end of header buffer
     33 // TODO Handle DTS_HD
     34 
     35 const uint8_t DTSFrameScanner::kSyncBytes[] =
     36         { 0x7F, 0xFE, 0x80, 0x01 };
     37 
     38 const int32_t DTSFrameScanner::kDTSSampleRateTable[DTS_NUM_SAMPLE_RATE_TABLE_ENTRIES]
     39         = { -1, 8000, 16000, 32000, -1, -1,
     40         11025, 22050, 44100, -1, -1, 12000, 24000, 48000, -1, -1 };
     41 
     42 // Defined in IEC61937-2
     43 #define IEC61937_DATA_TYPE_DTS_I        11
     44 #define IEC61937_DATA_TYPE_DTS_II       12
     45 #define IEC61937_DATA_TYPE_DTS_III      13
     46 #define IEC61937_DATA_TYPE_DTS_IV       17
     47 
     48 #define IEC61937_MAX_SAMPLES_TYPE_I    512
     49 #define IEC61937_MAX_SAMPLES_TYPE_II  1024
     50 #define IEC61937_MAX_SAMPLES_TYPE_III 2048
     51 
     52 // Limits defined in DTS spec paragraph 5.3.1
     53 #define DTS_MINIMUM_NBLKS                5
     54 #define DTS_MINIMUM_FSIZE               95
     55 
     56 #define DTS_HEADER_BYTES_NEEDED         12
     57 
     58 // Scanner for DTS byte streams.
     59 DTSFrameScanner::DTSFrameScanner()
     60  : FrameScanner(IEC61937_DATA_TYPE_DTS_I,
     61     DTSFrameScanner::kSyncBytes,
     62     sizeof(DTSFrameScanner::kSyncBytes),
     63     DTS_HEADER_BYTES_NEEDED)
     64  , mSampleFramesPerSyncFrame(0)
     65 {
     66 }
     67 
     68 DTSFrameScanner::~DTSFrameScanner()
     69 {
     70 }
     71 
     72 // Parse DTS header.
     73 // Detect whether the stream is DTS or DTS_HD. Extract data depending on type.
     74 // Sets mDataType, mFrameSizeBytes,
     75 //      mSampleRate, mRateMultiplier, mLengthCode.
     76 //
     77 // @return true if valid
     78 bool DTSFrameScanner::parseHeader()
     79 {
     80     BitFieldParser parser(&mHeaderBuffer[mSyncLength]);
     81 
     82     // These variables are named after the fields in the DTS spec 5.3.1
     83     // Extract field in order.
     84     (void) /* uint32_t ftype = */ parser.readBits(1);
     85     (void) /* uint32_t deficit = */ parser.readBits(5); // "short"
     86     uint32_t cpf = parser.readBits(1);
     87     uint32_t nblks = parser.readBits(7);
     88     uint32_t fsize = parser.readBits(14);
     89     (void) /* uint32_t amode = */ parser.readBits(6);
     90     uint32_t sfreq = parser.readBits(4);
     91     // make sure we did not read past collected data
     92     ALOG_ASSERT((mSyncLength + ((parser.getBitCursor() + 7) >> 3))
     93             <= mHeaderLength);
     94 
     95     // Validate fields.
     96     if (cpf != 0) {
     97         ALOGE("DTSFrameScanner: ERROR - CPF not zero!");
     98         return false;
     99     }
    100     if (nblks < DTS_MINIMUM_NBLKS) {
    101         ALOGE("DTSFrameScanner: ERROR - nblks = %u", nblks);
    102         return false;
    103     }
    104     if (fsize < DTS_MINIMUM_FSIZE) {
    105         ALOGE("DTSFrameScanner: ERROR - fsize = %u", fsize);
    106         return false;
    107     }
    108 
    109     int32_t sampleRate = kDTSSampleRateTable[sfreq];
    110     if (sampleRate < 0) {
    111         ALOGE("DTSFrameScanner: ERROR - invalid sampleRate[%u] = %d", sfreq, sampleRate);
    112         return false;
    113     }
    114     mSampleRate = (uint32_t) sampleRate;
    115 
    116     mSampleFramesPerSyncFrame = (nblks + 1) * DTS_PCM_FRAMES_PER_BLOCK;
    117     if (mSampleFramesPerSyncFrame <= IEC61937_MAX_SAMPLES_TYPE_I) {
    118         mDataType = IEC61937_DATA_TYPE_DTS_I;
    119     } else if (mSampleFramesPerSyncFrame <= IEC61937_MAX_SAMPLES_TYPE_II) {
    120         mDataType = IEC61937_DATA_TYPE_DTS_II;
    121     } else if (mSampleFramesPerSyncFrame <= IEC61937_MAX_SAMPLES_TYPE_III) {
    122         mDataType = IEC61937_DATA_TYPE_DTS_III;
    123     } else {
    124         mDataType = IEC61937_DATA_TYPE_DTS_IV;
    125         // TODO set bits 8,10
    126     }
    127 
    128     mFrameSizeBytes = fsize + 1;
    129 
    130     mRateMultiplier = 1; // TODO what about "frequency extension"?
    131     ALOGI_IF((mFormatDumpCount == 0),
    132             "DTS frame rate = %d * %d, size = %zu",
    133             mSampleRate, mRateMultiplier, mFrameSizeBytes);
    134     mFormatDumpCount++;
    135     return true;
    136 }
    137 
    138 
    139 }  // namespace android
    140