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 <log/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(audio_format_t format)95 AC3FrameScanner::AC3FrameScanner(audio_format_t format)
96 : FrameScanner(SPDIF_DATA_TYPE_AC3,
97 AC3FrameScanner::kSyncBytes,
98 sizeof(AC3FrameScanner::kSyncBytes), 6)
99 , mStreamType(0)
100 , mSubstreamID(0)
101 , mFormat(format)
102 {
103 mAudioBlocksPerSyncFrame = 6;
104 memset(mSubstreamBlockCounts, 0, sizeof(mSubstreamBlockCounts));
105 }
106
~AC3FrameScanner()107 AC3FrameScanner::~AC3FrameScanner()
108 {
109 }
110
getSampleFramesPerSyncFrame() const111 int AC3FrameScanner::getSampleFramesPerSyncFrame() const
112 {
113 return mRateMultiplier
114 * AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK * AC3_PCM_FRAMES_PER_BLOCK;
115 }
116
resetBurst()117 void AC3FrameScanner::resetBurst()
118 {
119 for (int i = 0; i < EAC3_MAX_SUBSTREAMS; i++) {
120 if (mSubstreamBlockCounts[i] >= AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK) {
121 mSubstreamBlockCounts[i] -= AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK;
122 } else if (mSubstreamBlockCounts[i] > 0) {
123 ALOGW("EAC3 substream[%d] has only %d audio blocks!",
124 i, mSubstreamBlockCounts[i]);
125 mSubstreamBlockCounts[i] = 0;
126 }
127 }
128 }
129
130 // Per IEC 61973-3:5.3.3, for E-AC3 burst-length shall be in bytes.
convertBytesToLengthCode(uint16_t numBytes) const131 uint16_t AC3FrameScanner::convertBytesToLengthCode(uint16_t numBytes) const
132 {
133 return (mDataType == SPDIF_DATA_TYPE_E_AC3) ? numBytes : numBytes * 8;
134 }
135
136 // per IEC 61973-3 Paragraph 5.3.3
137 // We have to send 6 audio blocks on all active substreams.
138 // Substream zero must be the first.
139 // We don't know if we have all the blocks we need until we see
140 // the 7th block of substream#0.
isFirstInBurst()141 bool AC3FrameScanner::isFirstInBurst()
142 {
143 if (mDataType == SPDIF_DATA_TYPE_E_AC3) {
144 if (((mStreamType == AC3_STREAM_TYPE_0)
145 || (mStreamType == AC3_STREAM_TYPE_2))
146 && (mSubstreamID == 0)
147 // The ">" is intentional. We have to see the beginning
148 // of the block in the next burst before we can send
149 // the current burst.
150 && (mSubstreamBlockCounts[0] > AC3_MAX_BLOCKS_PER_SYNC_FRAME_BLOCK)) {
151 return true;
152 }
153 }
154 return false;
155 }
156
isLastInBurst()157 bool AC3FrameScanner::isLastInBurst()
158 {
159 // For EAC3 we don't know if we are the end until we see a
160 // frame that must be at the beginning. See isFirstInBurst().
161 return (mDataType != SPDIF_DATA_TYPE_E_AC3); // Just one AC3 frame per burst.
162 }
163
164 // TODO Use BitFieldParser
165
166 // Parse AC3 header.
167 // Detect whether the stream is AC3 or EAC3. Extract data depending on type.
168 //
169 // @return true if valid
parseHeader()170 bool AC3FrameScanner::parseHeader()
171 {
172 // Interpret bsid based on paragraph E2.3.1.6 of EAC3 spec.
173 uint32_t bsid = mHeaderBuffer[5] >> 3; // bitstream ID
174 // Check BSID to see if this is EAC3 or regular AC3.
175 // These arbitrary BSID numbers do not have any names in the spec.
176 if ((bsid > 10) && (bsid <= 16)) {
177 mDataType = SPDIF_DATA_TYPE_E_AC3;
178 } else if (bsid <= 8) {
179 mDataType = SPDIF_DATA_TYPE_AC3;
180 } else {
181 ALOGW("AC3 bsid = %d not supported", bsid);
182 return false;
183 }
184
185 // bitstream mode, main, commentary, etc.
186 uint32_t bsmod = mHeaderBuffer[5] & 7;
187 mDataTypeInfo = bsmod; // as per IEC61937-3, table 3.
188
189 // The names fscod, frmsiz are from the AC3 spec.
190 uint32_t fscod = mHeaderBuffer[4] >> 6;
191 if (mDataType == SPDIF_DATA_TYPE_E_AC3) {
192 mStreamType = mHeaderBuffer[2] >> 6; // strmtyp in spec
193 mSubstreamID = (mHeaderBuffer[2] >> 3) & 0x07;
194
195 // Frame size is explicit in EAC3. Paragraph E2.3.1.3
196 uint32_t frmsiz = ((mHeaderBuffer[2] & 0x07) << 8) + mHeaderBuffer[3];
197 mFrameSizeBytes = (frmsiz + 1) * sizeof(int16_t);
198
199 uint32_t numblkscod = 3; // 6 blocks default
200 if (fscod == 3) {
201 uint32_t fscod2 = (mHeaderBuffer[4] >> 4) & 0x03;
202 if (fscod2 >= AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES) {
203 ALOGW("Invalid EAC3 fscod2 = %d", fscod2);
204 return false;
205 } else {
206 mSampleRate = kEAC3ReducedSampleRateTable[fscod2];
207 }
208 } else {
209 mSampleRate = kAC3SampleRateTable[fscod];
210 numblkscod = (mHeaderBuffer[4] >> 4) & 0x03;
211 }
212 mRateMultiplier = EAC3_RATE_MULTIPLIER; // per IEC 61973-3 Paragraph 5.3.3
213 // Don't send data burst until we have 6 blocks per substream.
214 mAudioBlocksPerSyncFrame = kEAC3BlocksPerFrameTable[numblkscod];
215 // Keep track of how many audio blocks we have for each substream.
216 // This should be safe because mSubstreamID is ANDed with 0x07 above.
217 // And the array is allocated as [8].
218 if ((mStreamType == AC3_STREAM_TYPE_0)
219 || (mStreamType == AC3_STREAM_TYPE_2)) {
220 mSubstreamBlockCounts[mSubstreamID] += mAudioBlocksPerSyncFrame;
221 }
222
223 // Print enough so we can see all the substreams.
224 ALOGD_IF((mFormatDumpCount < 3*8 ),
225 "EAC3 mStreamType = %d, mSubstreamID = %d",
226 mStreamType, mSubstreamID);
227 } else { // regular AC3
228 // Extract sample rate and frame size from codes.
229 uint32_t frmsizcod = mHeaderBuffer[4] & 0x3F; // frame size code
230
231 if (fscod >= AC3_NUM_SAMPLE_RATE_TABLE_ENTRIES) {
232 ALOGW("Invalid AC3 sampleRateCode = %d", fscod);
233 return false;
234 } else if (frmsizcod >= AC3_NUM_FRAME_SIZE_TABLE_ENTRIES) {
235 ALOGW("Invalid AC3 frameSizeCode = %d", frmsizcod);
236 return false;
237 } else {
238 mSampleRate = kAC3SampleRateTable[fscod];
239 mRateMultiplier = 1;
240 mFrameSizeBytes = sizeof(uint16_t)
241 * kAC3FrameSizeTable[frmsizcod][fscod];
242 }
243 mAudioBlocksPerSyncFrame = 6;
244 if (mFormat == AUDIO_FORMAT_E_AC3) {
245 ALOGV("Its a Ac3 substream in EAC3 stream");
246 mStreamType = 2;
247 mSubstreamID = 0;
248 mSubstreamBlockCounts[0] += mAudioBlocksPerSyncFrame;
249 mDataType = SPDIF_DATA_TYPE_E_AC3;
250 mRateMultiplier = EAC3_RATE_MULTIPLIER;
251 }
252 }
253 ALOGI_IF((mFormatDumpCount == 0),
254 "AC3 frame rate = %d * %d, size = %zu, audioBlocksPerSyncFrame = %d",
255 mSampleRate, mRateMultiplier, mFrameSizeBytes, mAudioBlocksPerSyncFrame);
256 mFormatDumpCount++;
257 return true;
258 }
259
260 } // namespace android
261