1 /*
2 * Copyright (C) 2010 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_NDEBUG 0
18 #define LOG_TAG "avc_utils"
19 #include <utils/Log.h>
20
21
22 #include <media/stagefright/foundation/ABitReader.h>
23 #include <media/stagefright/foundation/ADebug.h>
24 #include <media/stagefright/foundation/avc_utils.h>
25 #include <media/stagefright/foundation/hexdump.h>
26 #include <media/stagefright/MediaDefs.h>
27 #include <media/stagefright/MediaErrors.h>
28 #include <media/stagefright/MetaData.h>
29 #include <utils/misc.h>
30
31 namespace android {
32
parseUE(ABitReader * br)33 unsigned parseUE(ABitReader *br) {
34 unsigned numZeroes = 0;
35 while (br->getBits(1) == 0) {
36 ++numZeroes;
37 }
38
39 unsigned x = br->getBits(numZeroes);
40
41 return x + (1u << numZeroes) - 1;
42 }
43
parseUEWithFallback(ABitReader * br,unsigned fallback)44 unsigned parseUEWithFallback(ABitReader *br, unsigned fallback) {
45 unsigned numZeroes = 0;
46 while (br->getBitsWithFallback(1, 1) == 0) {
47 ++numZeroes;
48 }
49 uint32_t x;
50 if (numZeroes < 32) {
51 if (br->getBitsGraceful(numZeroes, &x)) {
52 return x + (1u << numZeroes) - 1;
53 } else {
54 return fallback;
55 }
56 } else {
57 br->skipBits(numZeroes);
58 return fallback;
59 }
60 }
61
parseSE(ABitReader * br)62 signed parseSE(ABitReader *br) {
63 unsigned codeNum = parseUE(br);
64
65 return (codeNum & 1) ? (codeNum + 1) / 2 : -signed(codeNum / 2);
66 }
67
parseSEWithFallback(ABitReader * br,signed fallback)68 signed parseSEWithFallback(ABitReader *br, signed fallback) {
69 // NOTE: parseUE cannot normally return ~0 as the max supported value is 0xFFFE
70 unsigned codeNum = parseUEWithFallback(br, ~0U);
71 if (codeNum == ~0U) {
72 return fallback;
73 }
74 return (codeNum & 1) ? (codeNum + 1) / 2 : -signed(codeNum / 2);
75 }
76
skipScalingList(ABitReader * br,size_t sizeOfScalingList)77 static void skipScalingList(ABitReader *br, size_t sizeOfScalingList) {
78 size_t lastScale = 8;
79 size_t nextScale = 8;
80 for (size_t j = 0; j < sizeOfScalingList; ++j) {
81 if (nextScale != 0) {
82 signed delta_scale = parseSE(br);
83 // ISO_IEC_14496-10_201402-ITU, 7.4.2.1.1.1, The value of delta_scale
84 // shall be in the range of −128 to +127, inclusive.
85 if (delta_scale < -128) {
86 ALOGW("delta_scale (%d) is below range, capped to -128", delta_scale);
87 delta_scale = -128;
88 } else if (delta_scale > 127) {
89 ALOGW("delta_scale (%d) is above range, capped to 127", delta_scale);
90 delta_scale = 127;
91 }
92 nextScale = (lastScale + (delta_scale + 256)) % 256;
93 }
94
95 lastScale = (nextScale == 0) ? lastScale : nextScale;
96 }
97 }
98
99 // Determine video dimensions from the sequence parameterset.
FindAVCDimensions(const sp<ABuffer> & seqParamSet,int32_t * width,int32_t * height,int32_t * sarWidth,int32_t * sarHeight)100 void FindAVCDimensions(
101 const sp<ABuffer> &seqParamSet,
102 int32_t *width, int32_t *height,
103 int32_t *sarWidth, int32_t *sarHeight) {
104 ABitReader br(seqParamSet->data() + 1, seqParamSet->size() - 1);
105
106 unsigned profile_idc = br.getBits(8);
107 br.skipBits(16);
108 parseUE(&br); // seq_parameter_set_id
109
110 unsigned chroma_format_idc = 1; // 4:2:0 chroma format
111
112 if (profile_idc == 100 || profile_idc == 110
113 || profile_idc == 122 || profile_idc == 244
114 || profile_idc == 44 || profile_idc == 83 || profile_idc == 86) {
115 chroma_format_idc = parseUE(&br);
116 if (chroma_format_idc == 3) {
117 br.skipBits(1); // residual_colour_transform_flag
118 }
119 parseUE(&br); // bit_depth_luma_minus8
120 parseUE(&br); // bit_depth_chroma_minus8
121 br.skipBits(1); // qpprime_y_zero_transform_bypass_flag
122
123 if (br.getBits(1)) { // seq_scaling_matrix_present_flag
124 for (size_t i = 0; i < 8; ++i) {
125 if (br.getBits(1)) { // seq_scaling_list_present_flag[i]
126
127 // WARNING: the code below has not ever been exercised...
128 // need a real-world example.
129
130 if (i < 6) {
131 // ScalingList4x4[i],16,...
132 skipScalingList(&br, 16);
133 } else {
134 // ScalingList8x8[i-6],64,...
135 skipScalingList(&br, 64);
136 }
137 }
138 }
139 }
140 }
141
142 parseUE(&br); // log2_max_frame_num_minus4
143 unsigned pic_order_cnt_type = parseUE(&br);
144
145 if (pic_order_cnt_type == 0) {
146 parseUE(&br); // log2_max_pic_order_cnt_lsb_minus4
147 } else if (pic_order_cnt_type == 1) {
148 // offset_for_non_ref_pic, offset_for_top_to_bottom_field and
149 // offset_for_ref_frame are technically se(v), but since we are
150 // just skipping over them the midpoint does not matter.
151
152 br.getBits(1); // delta_pic_order_always_zero_flag
153 parseUE(&br); // offset_for_non_ref_pic
154 parseUE(&br); // offset_for_top_to_bottom_field
155
156 unsigned num_ref_frames_in_pic_order_cnt_cycle = parseUE(&br);
157 for (unsigned i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; ++i) {
158 parseUE(&br); // offset_for_ref_frame
159 }
160 }
161
162 parseUE(&br); // num_ref_frames
163 br.getBits(1); // gaps_in_frame_num_value_allowed_flag
164
165 unsigned pic_width_in_mbs_minus1 = parseUE(&br);
166 unsigned pic_height_in_map_units_minus1 = parseUE(&br);
167 unsigned frame_mbs_only_flag = br.getBits(1);
168
169 *width = pic_width_in_mbs_minus1 * 16 + 16;
170
171 *height = (2 - frame_mbs_only_flag)
172 * (pic_height_in_map_units_minus1 * 16 + 16);
173
174 if (!frame_mbs_only_flag) {
175 br.getBits(1); // mb_adaptive_frame_field_flag
176 }
177
178 br.getBits(1); // direct_8x8_inference_flag
179
180 if (br.getBits(1)) { // frame_cropping_flag
181 unsigned frame_crop_left_offset = parseUE(&br);
182 unsigned frame_crop_right_offset = parseUE(&br);
183 unsigned frame_crop_top_offset = parseUE(&br);
184 unsigned frame_crop_bottom_offset = parseUE(&br);
185
186 unsigned cropUnitX, cropUnitY;
187 if (chroma_format_idc == 0 /* monochrome */) {
188 cropUnitX = 1;
189 cropUnitY = 2 - frame_mbs_only_flag;
190 } else {
191 unsigned subWidthC = (chroma_format_idc == 3) ? 1 : 2;
192 unsigned subHeightC = (chroma_format_idc == 1) ? 2 : 1;
193
194 cropUnitX = subWidthC;
195 cropUnitY = subHeightC * (2 - frame_mbs_only_flag);
196 }
197
198 ALOGV("frame_crop = (%u, %u, %u, %u), cropUnitX = %u, cropUnitY = %u",
199 frame_crop_left_offset, frame_crop_right_offset,
200 frame_crop_top_offset, frame_crop_bottom_offset,
201 cropUnitX, cropUnitY);
202
203
204 // *width -= (frame_crop_left_offset + frame_crop_right_offset) * cropUnitX;
205 if(__builtin_add_overflow(frame_crop_left_offset, frame_crop_right_offset, &frame_crop_left_offset) ||
206 __builtin_mul_overflow(frame_crop_left_offset, cropUnitX, &frame_crop_left_offset) ||
207 __builtin_sub_overflow(*width, frame_crop_left_offset, width) ||
208 *width < 0) {
209 *width = 0;
210 }
211
212 //*height -= (frame_crop_top_offset + frame_crop_bottom_offset) * cropUnitY;
213 if(__builtin_add_overflow(frame_crop_top_offset, frame_crop_bottom_offset, &frame_crop_top_offset) ||
214 __builtin_mul_overflow(frame_crop_top_offset, cropUnitY, &frame_crop_top_offset) ||
215 __builtin_sub_overflow(*height, frame_crop_top_offset, height) ||
216 *height < 0) {
217 *height = 0;
218 }
219 }
220
221 if (sarWidth != NULL) {
222 *sarWidth = 0;
223 }
224
225 if (sarHeight != NULL) {
226 *sarHeight = 0;
227 }
228
229 if (br.getBits(1)) { // vui_parameters_present_flag
230 unsigned sar_width = 0, sar_height = 0;
231
232 if (br.getBits(1)) { // aspect_ratio_info_present_flag
233 unsigned aspect_ratio_idc = br.getBits(8);
234
235 if (aspect_ratio_idc == 255 /* extendedSAR */) {
236 sar_width = br.getBits(16);
237 sar_height = br.getBits(16);
238 } else {
239 static const struct { unsigned width, height; } kFixedSARs[] = {
240 { 0, 0 }, // Invalid
241 { 1, 1 },
242 { 12, 11 },
243 { 10, 11 },
244 { 16, 11 },
245 { 40, 33 },
246 { 24, 11 },
247 { 20, 11 },
248 { 32, 11 },
249 { 80, 33 },
250 { 18, 11 },
251 { 15, 11 },
252 { 64, 33 },
253 { 160, 99 },
254 { 4, 3 },
255 { 3, 2 },
256 { 2, 1 },
257 };
258
259 if (aspect_ratio_idc > 0 && aspect_ratio_idc < NELEM(kFixedSARs)) {
260 sar_width = kFixedSARs[aspect_ratio_idc].width;
261 sar_height = kFixedSARs[aspect_ratio_idc].height;
262 }
263 }
264 }
265
266 ALOGV("sample aspect ratio = %u : %u", sar_width, sar_height);
267
268 if (sarWidth != NULL) {
269 *sarWidth = sar_width;
270 }
271
272 if (sarHeight != NULL) {
273 *sarHeight = sar_height;
274 }
275 }
276 }
277
getNextNALUnit(const uint8_t ** _data,size_t * _size,const uint8_t ** nalStart,size_t * nalSize,bool startCodeFollows)278 status_t getNextNALUnit(
279 const uint8_t **_data, size_t *_size,
280 const uint8_t **nalStart, size_t *nalSize,
281 bool startCodeFollows) {
282 const uint8_t *data = *_data;
283 size_t size = *_size;
284
285 *nalStart = NULL;
286 *nalSize = 0;
287
288 if (size < 3) {
289 return -EAGAIN;
290 }
291
292 size_t offset = 0;
293
294 // A valid startcode consists of at least two 0x00 bytes followed by 0x01.
295 for (; offset + 2 < size; ++offset) {
296 if (data[offset + 2] == 0x01 && data[offset] == 0x00
297 && data[offset + 1] == 0x00) {
298 break;
299 }
300 }
301 if (offset + 2 >= size) {
302 *_data = &data[offset];
303 *_size = 2;
304 return -EAGAIN;
305 }
306 offset += 3;
307
308 size_t startOffset = offset;
309
310 for (;;) {
311 while (offset < size && data[offset] != 0x01) {
312 ++offset;
313 }
314
315 if (offset == size) {
316 if (startCodeFollows) {
317 offset = size + 2;
318 break;
319 }
320
321 return -EAGAIN;
322 }
323
324 if (data[offset - 1] == 0x00 && data[offset - 2] == 0x00) {
325 break;
326 }
327
328 ++offset;
329 }
330
331 size_t endOffset = offset - 2;
332 while (endOffset > startOffset + 1 && data[endOffset - 1] == 0x00) {
333 --endOffset;
334 }
335
336 *nalStart = &data[startOffset];
337 *nalSize = endOffset - startOffset;
338
339 if (offset + 2 < size) {
340 *_data = &data[offset - 2];
341 *_size = size - offset + 2;
342 } else {
343 *_data = NULL;
344 *_size = 0;
345 }
346
347 return OK;
348 }
349
FindNAL(const uint8_t * data,size_t size,unsigned nalType)350 static sp<ABuffer> FindNAL(const uint8_t *data, size_t size, unsigned nalType) {
351 const uint8_t *nalStart;
352 size_t nalSize;
353 while (getNextNALUnit(&data, &size, &nalStart, &nalSize, true) == OK) {
354 if (nalSize > 0 && (nalStart[0] & 0x1f) == nalType) {
355 sp<ABuffer> buffer = new ABuffer(nalSize);
356 memcpy(buffer->data(), nalStart, nalSize);
357 return buffer;
358 }
359 }
360
361 return NULL;
362 }
363
AVCProfileToString(uint8_t profile)364 const char *AVCProfileToString(uint8_t profile) {
365 switch (profile) {
366 case kAVCProfileBaseline:
367 return "Baseline";
368 case kAVCProfileMain:
369 return "Main";
370 case kAVCProfileExtended:
371 return "Extended";
372 case kAVCProfileHigh:
373 return "High";
374 case kAVCProfileHigh10:
375 return "High 10";
376 case kAVCProfileHigh422:
377 return "High 422";
378 case kAVCProfileHigh444:
379 return "High 444";
380 case kAVCProfileCAVLC444Intra:
381 return "CAVLC 444 Intra";
382 default: return "Unknown";
383 }
384 }
385
MakeAVCCodecSpecificData(const sp<ABuffer> & accessUnit,int32_t * width,int32_t * height,int32_t * sarWidth,int32_t * sarHeight)386 sp<ABuffer> MakeAVCCodecSpecificData(
387 const sp<ABuffer> &accessUnit, int32_t *width, int32_t *height,
388 int32_t *sarWidth, int32_t *sarHeight) {
389 const uint8_t *data = accessUnit->data();
390 size_t size = accessUnit->size();
391
392 sp<ABuffer> seqParamSet = FindNAL(data, size, 7);
393 if (seqParamSet == NULL) {
394 return NULL;
395 }
396
397 FindAVCDimensions(
398 seqParamSet, width, height, sarWidth, sarHeight);
399
400 sp<ABuffer> picParamSet = FindNAL(data, size, 8);
401 CHECK(picParamSet != NULL);
402
403 size_t csdSize =
404 1 + 3 + 1 + 1
405 + 2 * 1 + seqParamSet->size()
406 + 1 + 2 * 1 + picParamSet->size();
407
408 sp<ABuffer> csd = new ABuffer(csdSize);
409 uint8_t *out = csd->data();
410
411 *out++ = 0x01; // configurationVersion
412 memcpy(out, seqParamSet->data() + 1, 3); // profile/level...
413
414 uint8_t profile = out[0];
415 uint8_t level = out[2];
416
417 out += 3;
418 *out++ = (0x3f << 2) | 1; // lengthSize == 2 bytes
419 *out++ = 0xe0 | 1;
420
421 *out++ = seqParamSet->size() >> 8;
422 *out++ = seqParamSet->size() & 0xff;
423 memcpy(out, seqParamSet->data(), seqParamSet->size());
424 out += seqParamSet->size();
425
426 *out++ = 1;
427
428 *out++ = picParamSet->size() >> 8;
429 *out++ = picParamSet->size() & 0xff;
430 memcpy(out, picParamSet->data(), picParamSet->size());
431
432 #if 0
433 ALOGI("AVC seq param set");
434 hexdump(seqParamSet->data(), seqParamSet->size());
435 #endif
436
437
438 if (sarWidth != nullptr && sarHeight != nullptr) {
439 if ((*sarWidth > 0 && *sarHeight > 0) && (*sarWidth != 1 || *sarHeight != 1)) {
440 ALOGI("found AVC codec config (%d x %d, %s-profile level %d.%d) "
441 "SAR %d : %d",
442 *width,
443 *height,
444 AVCProfileToString(profile),
445 level / 10,
446 level % 10,
447 *sarWidth,
448 *sarHeight);
449 } else {
450 // We treat *:0 and 0:* (unspecified) as 1:1.
451 *sarWidth = 0;
452 *sarHeight = 0;
453 ALOGI("found AVC codec config (%d x %d, %s-profile level %d.%d)",
454 *width,
455 *height,
456 AVCProfileToString(profile),
457 level / 10,
458 level % 10);
459 }
460 }
461
462 return csd;
463 }
464
IsIDR(const uint8_t * data,size_t size)465 bool IsIDR(const uint8_t *data, size_t size) {
466 // const uint8_t *data = buffer->data();
467 // size_t size = buffer->size();
468 bool foundIDR = false;
469
470 const uint8_t *nalStart;
471 size_t nalSize;
472 while (getNextNALUnit(&data, &size, &nalStart, &nalSize, true) == OK) {
473 if (nalSize == 0u) {
474 ALOGW("skipping empty nal unit from potentially malformed bitstream");
475 continue;
476 }
477
478 unsigned nalType = nalStart[0] & 0x1f;
479
480 if (nalType == 5) {
481 foundIDR = true;
482 break;
483 }
484 }
485
486 return foundIDR;
487 }
488
IsAVCReferenceFrame(const sp<ABuffer> & accessUnit)489 bool IsAVCReferenceFrame(const sp<ABuffer> &accessUnit) {
490 const uint8_t *data = accessUnit->data();
491 size_t size = accessUnit->size();
492 if (data == NULL) {
493 ALOGE("IsAVCReferenceFrame: called on NULL data (%p, %zu)", accessUnit.get(), size);
494 return false;
495 }
496
497 const uint8_t *nalStart;
498 size_t nalSize;
499 while (getNextNALUnit(&data, &size, &nalStart, &nalSize, true) == OK) {
500 if (nalSize == 0) {
501 ALOGE("IsAVCReferenceFrame: invalid nalSize: 0 (%p, %zu)", accessUnit.get(), size);
502 return false;
503 }
504
505 unsigned nalType = nalStart[0] & 0x1f;
506
507 if (nalType == 5) {
508 return true;
509 } else if (nalType == 1) {
510 unsigned nal_ref_idc = (nalStart[0] >> 5) & 3;
511 return nal_ref_idc != 0;
512 }
513 }
514
515 return true;
516 }
517
FindAVCLayerId(const uint8_t * data,size_t size)518 uint32_t FindAVCLayerId(const uint8_t *data, size_t size) {
519 CHECK(data != NULL);
520
521 const unsigned kSvcNalType = 0xE;
522 const unsigned kSvcNalSearchRange = 32;
523 // SVC NAL
524 // |---0 1110|1--- ----|---- ----|iii- ---|
525 // ^ ^
526 // NAL-type = 0xE layer-Id
527 //
528 // layer_id 0 is for base layer, while 1, 2, ... are enhancement layers.
529 // Layer n uses reference frames from layer 0, 1, ..., n-1.
530
531 uint32_t layerId = 0;
532 sp<ABuffer> svcNAL = FindNAL(
533 data, size > kSvcNalSearchRange ? kSvcNalSearchRange : size, kSvcNalType);
534 if (svcNAL != NULL && svcNAL->size() >= 4) {
535 layerId = (*(svcNAL->data() + 3) >> 5) & 0x7;
536 }
537 return layerId;
538 }
539
ExtractDimensionsFromVOLHeader(const uint8_t * data,size_t size,int32_t * width,int32_t * height)540 bool ExtractDimensionsFromVOLHeader(
541 const uint8_t *data, size_t size, int32_t *width, int32_t *height) {
542 ABitReader br(&data[4], size - 4);
543 br.skipBits(1); // random_accessible_vol
544 unsigned video_object_type_indication = br.getBits(8);
545
546 CHECK_NE(video_object_type_indication,
547 0x21u /* Fine Granularity Scalable */);
548
549 if (br.getBits(1)) {
550 br.skipBits(4); //video_object_layer_verid
551 br.skipBits(3); //video_object_layer_priority
552 }
553 unsigned aspect_ratio_info = br.getBits(4);
554 if (aspect_ratio_info == 0x0f /* extended PAR */) {
555 br.skipBits(8); // par_width
556 br.skipBits(8); // par_height
557 }
558 if (br.getBits(1)) { // vol_control_parameters
559 br.skipBits(2); // chroma_format
560 br.skipBits(1); // low_delay
561 if (br.getBits(1)) { // vbv_parameters
562 br.skipBits(15); // first_half_bit_rate
563 CHECK(br.getBits(1)); // marker_bit
564 br.skipBits(15); // latter_half_bit_rate
565 CHECK(br.getBits(1)); // marker_bit
566 br.skipBits(15); // first_half_vbv_buffer_size
567 CHECK(br.getBits(1)); // marker_bit
568 br.skipBits(3); // latter_half_vbv_buffer_size
569 br.skipBits(11); // first_half_vbv_occupancy
570 CHECK(br.getBits(1)); // marker_bit
571 br.skipBits(15); // latter_half_vbv_occupancy
572 CHECK(br.getBits(1)); // marker_bit
573 }
574 }
575 unsigned video_object_layer_shape = br.getBits(2);
576 CHECK_EQ(video_object_layer_shape, 0x00u /* rectangular */);
577
578 CHECK(br.getBits(1)); // marker_bit
579 unsigned vop_time_increment_resolution = br.getBits(16);
580 CHECK(br.getBits(1)); // marker_bit
581
582 if (br.getBits(1)) { // fixed_vop_rate
583 // range [0..vop_time_increment_resolution)
584
585 // vop_time_increment_resolution
586 // 2 => 0..1, 1 bit
587 // 3 => 0..2, 2 bits
588 // 4 => 0..3, 2 bits
589 // 5 => 0..4, 3 bits
590 // ...
591
592 CHECK_GT(vop_time_increment_resolution, 0u);
593 --vop_time_increment_resolution;
594
595 unsigned numBits = 0;
596 while (vop_time_increment_resolution > 0) {
597 ++numBits;
598 vop_time_increment_resolution >>= 1;
599 }
600
601 br.skipBits(numBits); // fixed_vop_time_increment
602 }
603
604 CHECK(br.getBits(1)); // marker_bit
605 unsigned video_object_layer_width = br.getBits(13);
606 CHECK(br.getBits(1)); // marker_bit
607 unsigned video_object_layer_height = br.getBits(13);
608 CHECK(br.getBits(1)); // marker_bit
609
610 br.skipBits(1); // interlaced
611
612 *width = video_object_layer_width;
613 *height = video_object_layer_height;
614
615 return true;
616 }
617
GetMPEGAudioFrameSize(uint32_t header,size_t * frame_size,int * out_sampling_rate,int * out_channels,int * out_bitrate,int * out_num_samples)618 bool GetMPEGAudioFrameSize(
619 uint32_t header, size_t *frame_size,
620 int *out_sampling_rate, int *out_channels,
621 int *out_bitrate, int *out_num_samples) {
622 *frame_size = 0;
623
624 if (out_sampling_rate) {
625 *out_sampling_rate = 0;
626 }
627
628 if (out_channels) {
629 *out_channels = 0;
630 }
631
632 if (out_bitrate) {
633 *out_bitrate = 0;
634 }
635
636 if (out_num_samples) {
637 *out_num_samples = 1152;
638 }
639
640 if ((header & 0xffe00000) != 0xffe00000) {
641 return false;
642 }
643
644 unsigned version = (header >> 19) & 3;
645
646 if (version == 0x01) {
647 return false;
648 }
649
650 unsigned layer = (header >> 17) & 3;
651
652 if (layer == 0x00) {
653 return false;
654 }
655
656 // we can get protection value from (header >> 16) & 1
657
658 unsigned bitrate_index = (header >> 12) & 0x0f;
659
660 if (bitrate_index == 0 || bitrate_index == 0x0f) {
661 // Disallow "free" bitrate.
662 return false;
663 }
664
665 unsigned sampling_rate_index = (header >> 10) & 3;
666
667 if (sampling_rate_index == 3) {
668 return false;
669 }
670
671 static const int kSamplingRateV1[] = { 44100, 48000, 32000 };
672 int sampling_rate = kSamplingRateV1[sampling_rate_index];
673 if (version == 2 /* V2 */) {
674 sampling_rate /= 2;
675 } else if (version == 0 /* V2.5 */) {
676 sampling_rate /= 4;
677 }
678
679 unsigned padding = (header >> 9) & 1;
680
681 if (layer == 3) {
682 // layer I
683
684 static const int kBitrateV1[] = {
685 32, 64, 96, 128, 160, 192, 224, 256,
686 288, 320, 352, 384, 416, 448
687 };
688
689 static const int kBitrateV2[] = {
690 32, 48, 56, 64, 80, 96, 112, 128,
691 144, 160, 176, 192, 224, 256
692 };
693
694 int bitrate =
695 (version == 3 /* V1 */)
696 ? kBitrateV1[bitrate_index - 1]
697 : kBitrateV2[bitrate_index - 1];
698
699 if (out_bitrate) {
700 *out_bitrate = bitrate;
701 }
702
703 *frame_size = (12000 * bitrate / sampling_rate + padding) * 4;
704
705 if (out_num_samples) {
706 *out_num_samples = 384;
707 }
708 } else {
709 // layer II or III
710
711 static const int kBitrateV1L2[] = {
712 32, 48, 56, 64, 80, 96, 112, 128,
713 160, 192, 224, 256, 320, 384
714 };
715
716 static const int kBitrateV1L3[] = {
717 32, 40, 48, 56, 64, 80, 96, 112,
718 128, 160, 192, 224, 256, 320
719 };
720
721 static const int kBitrateV2[] = {
722 8, 16, 24, 32, 40, 48, 56, 64,
723 80, 96, 112, 128, 144, 160
724 };
725
726 int bitrate;
727 if (version == 3 /* V1 */) {
728 bitrate = (layer == 2 /* L2 */)
729 ? kBitrateV1L2[bitrate_index - 1]
730 : kBitrateV1L3[bitrate_index - 1];
731
732 if (out_num_samples) {
733 *out_num_samples = 1152;
734 }
735 } else {
736 // V2 (or 2.5)
737
738 bitrate = kBitrateV2[bitrate_index - 1];
739 if (out_num_samples) {
740 *out_num_samples = (layer == 1 /* L3 */) ? 576 : 1152;
741 }
742 }
743
744 if (out_bitrate) {
745 *out_bitrate = bitrate;
746 }
747
748 if (version == 3 /* V1 */) {
749 *frame_size = 144000 * bitrate / sampling_rate + padding;
750 } else {
751 // V2 or V2.5
752 size_t tmp = (layer == 1 /* L3 */) ? 72000 : 144000;
753 *frame_size = tmp * bitrate / sampling_rate + padding;
754 }
755 }
756
757 if (out_sampling_rate) {
758 *out_sampling_rate = sampling_rate;
759 }
760
761 if (out_channels) {
762 int channel_mode = (header >> 6) & 3;
763
764 *out_channels = (channel_mode == 3) ? 1 : 2;
765 }
766
767 return true;
768 }
769
770 } // namespace android
771
772