1 /* 2 * Copyright 2014, 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 19 #include <string.h> 20 21 #include <utils/Log.h> 22 #include <audio_utils/spdif/FrameScanner.h> 23 24 #include "AC3FrameScanner.h" 25 26 namespace android { 27 28 // These values are from the AC3 spec. Do not change them. 29 30 const uint8_t AC3FrameScanner::kSyncBytes[] = { 0x0B, 0x77 }; 31 32 const uint16_t AC3FrameScanner::kAC3SampleRateTable[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES] 33 = { 48000, 44100, 32000 }; 34 35 // Table contains number of 16-bit words in an AC3 frame. 36 // From AC3 spec table 5.13 37 const uint16_t AC3FrameScanner::kAC3FrameSizeTable[AC3_NUM_FRAME_SIZE_TABLE_ENTRIES] 38 [AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES] = { 39 { 64, 69, 96 }, 40 { 64, 70, 96 }, 41 { 80, 87, 120 }, 42 { 80, 88, 120 }, 43 { 96, 104, 144 }, 44 { 96, 105, 144 }, 45 { 112, 121, 168 }, 46 { 112, 122, 168 }, 47 { 128, 139, 192 }, 48 { 128, 140, 192 }, 49 { 160, 174, 240 }, 50 { 160, 175, 240 }, 51 { 192, 208, 288 }, 52 { 192, 209, 288 }, 53 { 224, 243, 336 }, 54 { 224, 244, 336 }, 55 { 256, 278, 384 }, 56 { 256, 279, 384 }, 57 { 320, 348, 480 }, 58 { 320, 349, 480 }, 59 { 384, 417, 576 }, 60 { 384, 418, 576 }, 61 { 448, 487, 672 }, 62 { 448, 488, 672 }, 63 { 512, 557, 768 }, 64 { 512, 558, 768 }, 65 { 640, 696, 960 }, 66 { 640, 697, 960 }, 67 { 768, 835, 1152 }, 68 { 768, 836, 1152 }, 69 { 896, 975, 1344 }, 70 { 896, 976, 1344 }, 71 { 1024, 1114, 1536 }, 72 { 1024, 1115, 1536 }, 73 { 1152, 1253, 1728 }, 74 { 1152, 1254, 1728 }, 75 { 1280, 1393, 1920 }, 76 { 1280, 1394, 1920 } 77 }; 78 79 const uint16_t AC3FrameScanner::kEAC3ReducedSampleRateTable[AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES] 80 = { 24000, 22050, 16000 }; 81 82 const uint16_t 83 AC3FrameScanner::kEAC3BlocksPerFrameTable[EAC3_NUM_BLOCKS_PER_FRAME_TABLE_ENTRIES] 84 = { 1, 2, 3, 6 }; 85 86 // Defined in IEC61937-2 87 #define SPDIF_DATA_TYPE_AC3 1 88 #define SPDIF_DATA_TYPE_E_AC3 21 89 #define AC3_STREAM_TYPE_0 0 90 #define AC3_STREAM_TYPE_1 1 91 #define AC3_STREAM_TYPE_2 2 92 // ----------------------------------------------------------------------------- 93 94 // Scanner for AC3 byte streams. 95 AC3FrameScanner::AC3FrameScanner() 96 : FrameScanner(SPDIF_DATA_TYPE_AC3, 97 AC3FrameScanner::kSyncBytes, 98 sizeof(AC3FrameScanner::kSyncBytes), 6) 99 , mStreamType(0) 100 , mSubstreamID(0) 101 { 102 mAudioBlocksPerSyncFrame = 6; 103 memset(mSubstreamBlockCounts, 0, sizeof(mSubstreamBlockCounts)); 104 } 105 106 AC3FrameScanner::~AC3FrameScanner() 107 { 108 } 109 110 int AC3FrameScanner::getSampleFramesPerSyncFrame() const 111 { 112 return mRateMultiplier 113 * AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK * AC3_PCM_FRAMES_PER_BLOCK; 114 } 115 116 void AC3FrameScanner::resetBurst() 117 { 118 for (int i = 0; i < EAC3_MAX_SUBSTREAMS; i++) { 119 if (mSubstreamBlockCounts[i] >= AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK) { 120 mSubstreamBlockCounts[i] -= AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK; 121 } else if (mSubstreamBlockCounts[i] > 0) { 122 ALOGW("EAC3 substream[%d] has only %d audio blocks!", 123 i, mSubstreamBlockCounts[i]); 124 mSubstreamBlockCounts[i] = 0; 125 } 126 } 127 } 128 129 // Per IEC 61973-3:5.3.3, for E-AC3 burst-length shall be in bytes. 130 uint16_t AC3FrameScanner::convertBytesToLengthCode(uint16_t numBytes) const 131 { 132 return (mDataType == SPDIF_DATA_TYPE_E_AC3) ? numBytes : numBytes * 8; 133 } 134 135 // per IEC 61973-3 Paragraph 5.3.3 136 // We have to send 6 audio blocks on all active substreams. 137 // Substream zero must be the first. 138 // We don't know if we have all the blocks we need until we see 139 // the 7th block of substream#0. 140 bool AC3FrameScanner::isFirstInBurst() 141 { 142 if (mDataType == SPDIF_DATA_TYPE_E_AC3) { 143 if (((mStreamType == AC3_STREAM_TYPE_0) 144 || (mStreamType == AC3_STREAM_TYPE_2)) 145 && (mSubstreamID == 0) 146 // The ">" is intentional. We have to see the beginning 147 // of the block in the next burst before we can send 148 // the current burst. 149 && (mSubstreamBlockCounts[0] > AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK)) { 150 return true; 151 } 152 } 153 return false; 154 } 155 156 bool AC3FrameScanner::isLastInBurst() 157 { 158 // For EAC3 we don't know if we are the end until we see a 159 // frame that must be at the beginning. See isFirstInBurst(). 160 return (mDataType != SPDIF_DATA_TYPE_E_AC3); // Just one AC3 frame per burst. 161 } 162 163 // TODO Use BitFieldParser 164 165 // Parse AC3 header. 166 // Detect whether the stream is AC3 or EAC3. Extract data depending on type. 167 // 168 // @return true if valid 169 bool AC3FrameScanner::parseHeader() 170 { 171 // Interpret bsid based on paragraph E2.3.1.6 of EAC3 spec. 172 uint32_t bsid = mHeaderBuffer[5] >> 3; // bitstream ID 173 // Check BSID to see if this is EAC3 or regular AC3. 174 // These arbitrary BSID numbers do not have any names in the spec. 175 if ((bsid > 10) && (bsid <= 16)) { 176 mDataType = SPDIF_DATA_TYPE_E_AC3; 177 } else if (bsid <= 8) { 178 mDataType = SPDIF_DATA_TYPE_AC3; 179 } else { 180 ALOGW("AC3 bsid = %d not supported", bsid); 181 return false; 182 } 183 184 // bitstream mode, main, commentary, etc. 185 uint32_t bsmod = mHeaderBuffer[5] & 7; 186 mDataTypeInfo = bsmod; // as per IEC61937-3, table 3. 187 188 // The names fscod, frmsiz are from the AC3 spec. 189 uint32_t fscod = mHeaderBuffer[4] >> 6; 190 if (mDataType == SPDIF_DATA_TYPE_E_AC3) { 191 mStreamType = mHeaderBuffer[2] >> 6; // strmtyp in spec 192 mSubstreamID = (mHeaderBuffer[2] >> 3) & 0x07; 193 194 // Frame size is explicit in EAC3. Paragraph E2.3.1.3 195 uint32_t frmsiz = ((mHeaderBuffer[2] & 0x07) << 8) + mHeaderBuffer[3]; 196 mFrameSizeBytes = (frmsiz + 1) * sizeof(int16_t); 197 198 uint32_t numblkscod = 3; // 6 blocks default 199 if (fscod == 3) { 200 uint32_t fscod2 = (mHeaderBuffer[4] >> 4) & 0x03; 201 if (fscod2 >= AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES) { 202 ALOGW("Invalid EAC3 fscod2 = %d", fscod2); 203 return false; 204 } else { 205 mSampleRate = kEAC3ReducedSampleRateTable[fscod2]; 206 } 207 } else { 208 mSampleRate = kAC3SampleRateTable[fscod]; 209 numblkscod = (mHeaderBuffer[4] >> 4) & 0x03; 210 } 211 mRateMultiplier = EAC3_RATE_MULTIPLIER; // per IEC 61973-3 Paragraph 5.3.3 212 // Don't send data burst until we have 6 blocks per substream. 213 mAudioBlocksPerSyncFrame = kEAC3BlocksPerFrameTable[numblkscod]; 214 // Keep track of how many audio blocks we have for each substream. 215 // This should be safe because mSubstreamID is ANDed with 0x07 above. 216 // And the array is allocated as [8]. 217 if ((mStreamType == AC3_STREAM_TYPE_0) 218 || (mStreamType == AC3_STREAM_TYPE_2)) { 219 mSubstreamBlockCounts[mSubstreamID] += mAudioBlocksPerSyncFrame; 220 } 221 222 // Print enough so we can see all the substreams. 223 ALOGD_IF((mFormatDumpCount < 3*8 ), 224 "EAC3 mStreamType = %d, mSubstreamID = %d", 225 mStreamType, mSubstreamID); 226 } else { // regular AC3 227 // Extract sample rate and frame size from codes. 228 uint32_t frmsizcod = mHeaderBuffer[4] & 0x3F; // frame size code 229 230 if (fscod >= AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES) { 231 ALOGW("Invalid AC3 sampleRateCode = %d", fscod); 232 return false; 233 } else if (frmsizcod >= AC3_NUM_FRAME_SIZE_TABLE_ENTRIES) { 234 ALOGW("Invalid AC3 frameSizeCode = %d", frmsizcod); 235 return false; 236 } else { 237 mSampleRate = kAC3SampleRateTable[fscod]; 238 mRateMultiplier = 1; 239 mFrameSizeBytes = sizeof(uint16_t) 240 * kAC3FrameSizeTable[frmsizcod][fscod]; 241 } 242 mAudioBlocksPerSyncFrame = 6; 243 } 244 ALOGI_IF((mFormatDumpCount == 0), 245 "AC3 frame rate = %d * %d, size = %zu, audioBlocksPerSyncFrame = %d", 246 mSampleRate, mRateMultiplier, mFrameSizeBytes, mAudioBlocksPerSyncFrame); 247 mFormatDumpCount++; 248 return true; 249 } 250 251 } // namespace android 252
