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.
AC3FrameScanner()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
~AC3FrameScanner()106 AC3FrameScanner::~AC3FrameScanner()
107 {
108 }
109
getSampleFramesPerSyncFrame() const110 int AC3FrameScanner::getSampleFramesPerSyncFrame() const
111 {
112 return mRateMultiplier
113 * AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK * AC3_PCM_FRAMES_PER_BLOCK;
114 }
115
resetBurst()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.
convertBytesToLengthCode(uint16_t numBytes) const130 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.
isFirstInBurst()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
isLastInBurst()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
parseHeader()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