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#include "include/avc_utils.h"
22
23#include <media/stagefright/foundation/ABitReader.h>
24#include <media/stagefright/foundation/ADebug.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
30namespace android {
31
32unsigned parseUE(ABitReader *br) {
33    unsigned numZeroes = 0;
34    while (br->getBits(1) == 0) {
35        ++numZeroes;
36    }
37
38    unsigned x = br->getBits(numZeroes);
39
40    return x + (1u << numZeroes) - 1;
41}
42
43signed parseSE(ABitReader *br) {
44    unsigned codeNum = parseUE(br);
45
46    return (codeNum & 1) ? (codeNum + 1) / 2 : -(codeNum / 2);
47}
48
49static void skipScalingList(ABitReader *br, size_t sizeOfScalingList) {
50    size_t lastScale = 8;
51    size_t nextScale = 8;
52    for (size_t j = 0; j < sizeOfScalingList; ++j) {
53        if (nextScale != 0) {
54            signed delta_scale = parseSE(br);
55            nextScale = (lastScale + delta_scale + 256) % 256;
56        }
57
58        lastScale = (nextScale == 0) ? lastScale : nextScale;
59    }
60}
61
62// Determine video dimensions from the sequence parameterset.
63void FindAVCDimensions(
64        const sp<ABuffer> &seqParamSet,
65        int32_t *width, int32_t *height,
66        int32_t *sarWidth, int32_t *sarHeight) {
67    ABitReader br(seqParamSet->data() + 1, seqParamSet->size() - 1);
68
69    unsigned profile_idc = br.getBits(8);
70    br.skipBits(16);
71    parseUE(&br);  // seq_parameter_set_id
72
73    unsigned chroma_format_idc = 1;  // 4:2:0 chroma format
74
75    if (profile_idc == 100 || profile_idc == 110
76            || profile_idc == 122 || profile_idc == 244
77            || profile_idc == 44 || profile_idc == 83 || profile_idc == 86) {
78        chroma_format_idc = parseUE(&br);
79        if (chroma_format_idc == 3) {
80            br.skipBits(1);  // residual_colour_transform_flag
81        }
82        parseUE(&br);  // bit_depth_luma_minus8
83        parseUE(&br);  // bit_depth_chroma_minus8
84        br.skipBits(1);  // qpprime_y_zero_transform_bypass_flag
85
86        if (br.getBits(1)) {  // seq_scaling_matrix_present_flag
87            for (size_t i = 0; i < 8; ++i) {
88                if (br.getBits(1)) {  // seq_scaling_list_present_flag[i]
89
90                    // WARNING: the code below has not ever been exercised...
91                    // need a real-world example.
92
93                    if (i < 6) {
94                        // ScalingList4x4[i],16,...
95                        skipScalingList(&br, 16);
96                    } else {
97                        // ScalingList8x8[i-6],64,...
98                        skipScalingList(&br, 64);
99                    }
100                }
101            }
102        }
103    }
104
105    parseUE(&br);  // log2_max_frame_num_minus4
106    unsigned pic_order_cnt_type = parseUE(&br);
107
108    if (pic_order_cnt_type == 0) {
109        parseUE(&br);  // log2_max_pic_order_cnt_lsb_minus4
110    } else if (pic_order_cnt_type == 1) {
111        // offset_for_non_ref_pic, offset_for_top_to_bottom_field and
112        // offset_for_ref_frame are technically se(v), but since we are
113        // just skipping over them the midpoint does not matter.
114
115        br.getBits(1);  // delta_pic_order_always_zero_flag
116        parseUE(&br);  // offset_for_non_ref_pic
117        parseUE(&br);  // offset_for_top_to_bottom_field
118
119        unsigned num_ref_frames_in_pic_order_cnt_cycle = parseUE(&br);
120        for (unsigned i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; ++i) {
121            parseUE(&br);  // offset_for_ref_frame
122        }
123    }
124
125    parseUE(&br);  // num_ref_frames
126    br.getBits(1);  // gaps_in_frame_num_value_allowed_flag
127
128    unsigned pic_width_in_mbs_minus1 = parseUE(&br);
129    unsigned pic_height_in_map_units_minus1 = parseUE(&br);
130    unsigned frame_mbs_only_flag = br.getBits(1);
131
132    *width = pic_width_in_mbs_minus1 * 16 + 16;
133
134    *height = (2 - frame_mbs_only_flag)
135        * (pic_height_in_map_units_minus1 * 16 + 16);
136
137    if (!frame_mbs_only_flag) {
138        br.getBits(1);  // mb_adaptive_frame_field_flag
139    }
140
141    br.getBits(1);  // direct_8x8_inference_flag
142
143    if (br.getBits(1)) {  // frame_cropping_flag
144        unsigned frame_crop_left_offset = parseUE(&br);
145        unsigned frame_crop_right_offset = parseUE(&br);
146        unsigned frame_crop_top_offset = parseUE(&br);
147        unsigned frame_crop_bottom_offset = parseUE(&br);
148
149        unsigned cropUnitX, cropUnitY;
150        if (chroma_format_idc == 0  /* monochrome */) {
151            cropUnitX = 1;
152            cropUnitY = 2 - frame_mbs_only_flag;
153        } else {
154            unsigned subWidthC = (chroma_format_idc == 3) ? 1 : 2;
155            unsigned subHeightC = (chroma_format_idc == 1) ? 2 : 1;
156
157            cropUnitX = subWidthC;
158            cropUnitY = subHeightC * (2 - frame_mbs_only_flag);
159        }
160
161        ALOGV("frame_crop = (%u, %u, %u, %u), cropUnitX = %u, cropUnitY = %u",
162             frame_crop_left_offset, frame_crop_right_offset,
163             frame_crop_top_offset, frame_crop_bottom_offset,
164             cropUnitX, cropUnitY);
165
166        *width -=
167            (frame_crop_left_offset + frame_crop_right_offset) * cropUnitX;
168        *height -=
169            (frame_crop_top_offset + frame_crop_bottom_offset) * cropUnitY;
170    }
171
172    if (sarWidth != NULL) {
173        *sarWidth = 0;
174    }
175
176    if (sarHeight != NULL) {
177        *sarHeight = 0;
178    }
179
180    if (br.getBits(1)) {  // vui_parameters_present_flag
181        unsigned sar_width = 0, sar_height = 0;
182
183        if (br.getBits(1)) {  // aspect_ratio_info_present_flag
184            unsigned aspect_ratio_idc = br.getBits(8);
185
186            if (aspect_ratio_idc == 255 /* extendedSAR */) {
187                sar_width = br.getBits(16);
188                sar_height = br.getBits(16);
189            } else if (aspect_ratio_idc > 0 && aspect_ratio_idc < 14) {
190                static const int32_t kFixedSARWidth[] = {
191                    1, 12, 10, 16, 40, 24, 20, 32, 80, 18, 15, 64, 160
192                };
193
194                static const int32_t kFixedSARHeight[] = {
195                    1, 11, 11, 11, 33, 11, 11, 11, 33, 11, 11, 33, 99
196                };
197
198                sar_width = kFixedSARWidth[aspect_ratio_idc - 1];
199                sar_height = kFixedSARHeight[aspect_ratio_idc - 1];
200            }
201        }
202
203        ALOGV("sample aspect ratio = %u : %u", sar_width, sar_height);
204
205        if (sarWidth != NULL) {
206            *sarWidth = sar_width;
207        }
208
209        if (sarHeight != NULL) {
210            *sarHeight = sar_height;
211        }
212    }
213}
214
215status_t getNextNALUnit(
216        const uint8_t **_data, size_t *_size,
217        const uint8_t **nalStart, size_t *nalSize,
218        bool startCodeFollows) {
219    const uint8_t *data = *_data;
220    size_t size = *_size;
221
222    *nalStart = NULL;
223    *nalSize = 0;
224
225    if (size < 3) {
226        return -EAGAIN;
227    }
228
229    size_t offset = 0;
230
231    // A valid startcode consists of at least two 0x00 bytes followed by 0x01.
232    for (; offset + 2 < size; ++offset) {
233        if (data[offset + 2] == 0x01 && data[offset] == 0x00
234                && data[offset + 1] == 0x00) {
235            break;
236        }
237    }
238    if (offset + 2 >= size) {
239        *_data = &data[offset];
240        *_size = 2;
241        return -EAGAIN;
242    }
243    offset += 3;
244
245    size_t startOffset = offset;
246
247    for (;;) {
248        while (offset < size && data[offset] != 0x01) {
249            ++offset;
250        }
251
252        if (offset == size) {
253            if (startCodeFollows) {
254                offset = size + 2;
255                break;
256            }
257
258            return -EAGAIN;
259        }
260
261        if (data[offset - 1] == 0x00 && data[offset - 2] == 0x00) {
262            break;
263        }
264
265        ++offset;
266    }
267
268    size_t endOffset = offset - 2;
269    while (endOffset > startOffset + 1 && data[endOffset - 1] == 0x00) {
270        --endOffset;
271    }
272
273    *nalStart = &data[startOffset];
274    *nalSize = endOffset - startOffset;
275
276    if (offset + 2 < size) {
277        *_data = &data[offset - 2];
278        *_size = size - offset + 2;
279    } else {
280        *_data = NULL;
281        *_size = 0;
282    }
283
284    return OK;
285}
286
287static sp<ABuffer> FindNAL(const uint8_t *data, size_t size, unsigned nalType) {
288    const uint8_t *nalStart;
289    size_t nalSize;
290    while (getNextNALUnit(&data, &size, &nalStart, &nalSize, true) == OK) {
291        if ((nalStart[0] & 0x1f) == nalType) {
292            sp<ABuffer> buffer = new ABuffer(nalSize);
293            memcpy(buffer->data(), nalStart, nalSize);
294            return buffer;
295        }
296    }
297
298    return NULL;
299}
300
301const char *AVCProfileToString(uint8_t profile) {
302    switch (profile) {
303        case kAVCProfileBaseline:
304            return "Baseline";
305        case kAVCProfileMain:
306            return "Main";
307        case kAVCProfileExtended:
308            return "Extended";
309        case kAVCProfileHigh:
310            return "High";
311        case kAVCProfileHigh10:
312            return "High 10";
313        case kAVCProfileHigh422:
314            return "High 422";
315        case kAVCProfileHigh444:
316            return "High 444";
317        case kAVCProfileCAVLC444Intra:
318            return "CAVLC 444 Intra";
319        default:   return "Unknown";
320    }
321}
322
323sp<MetaData> MakeAVCCodecSpecificData(const sp<ABuffer> &accessUnit) {
324    const uint8_t *data = accessUnit->data();
325    size_t size = accessUnit->size();
326
327    sp<ABuffer> seqParamSet = FindNAL(data, size, 7);
328    if (seqParamSet == NULL) {
329        return NULL;
330    }
331
332    int32_t width, height;
333    int32_t sarWidth, sarHeight;
334    FindAVCDimensions(
335            seqParamSet, &width, &height, &sarWidth, &sarHeight);
336
337    sp<ABuffer> picParamSet = FindNAL(data, size, 8);
338    CHECK(picParamSet != NULL);
339
340    size_t csdSize =
341        1 + 3 + 1 + 1
342        + 2 * 1 + seqParamSet->size()
343        + 1 + 2 * 1 + picParamSet->size();
344
345    sp<ABuffer> csd = new ABuffer(csdSize);
346    uint8_t *out = csd->data();
347
348    *out++ = 0x01;  // configurationVersion
349    memcpy(out, seqParamSet->data() + 1, 3);  // profile/level...
350
351    uint8_t profile = out[0];
352    uint8_t level = out[2];
353
354    out += 3;
355    *out++ = (0x3f << 2) | 1;  // lengthSize == 2 bytes
356    *out++ = 0xe0 | 1;
357
358    *out++ = seqParamSet->size() >> 8;
359    *out++ = seqParamSet->size() & 0xff;
360    memcpy(out, seqParamSet->data(), seqParamSet->size());
361    out += seqParamSet->size();
362
363    *out++ = 1;
364
365    *out++ = picParamSet->size() >> 8;
366    *out++ = picParamSet->size() & 0xff;
367    memcpy(out, picParamSet->data(), picParamSet->size());
368
369#if 0
370    ALOGI("AVC seq param set");
371    hexdump(seqParamSet->data(), seqParamSet->size());
372#endif
373
374    sp<MetaData> meta = new MetaData;
375    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_AVC);
376
377    meta->setData(kKeyAVCC, kTypeAVCC, csd->data(), csd->size());
378    meta->setInt32(kKeyWidth, width);
379    meta->setInt32(kKeyHeight, height);
380
381    if (sarWidth > 1 || sarHeight > 1) {
382        // We treat 0:0 (unspecified) as 1:1.
383
384        meta->setInt32(kKeySARWidth, sarWidth);
385        meta->setInt32(kKeySARHeight, sarHeight);
386
387        ALOGI("found AVC codec config (%d x %d, %s-profile level %d.%d) "
388              "SAR %d : %d",
389             width,
390             height,
391             AVCProfileToString(profile),
392             level / 10,
393             level % 10,
394             sarWidth,
395             sarHeight);
396    } else {
397        ALOGI("found AVC codec config (%d x %d, %s-profile level %d.%d)",
398             width,
399             height,
400             AVCProfileToString(profile),
401             level / 10,
402             level % 10);
403    }
404
405    return meta;
406}
407
408bool IsIDR(const sp<ABuffer> &buffer) {
409    const uint8_t *data = buffer->data();
410    size_t size = buffer->size();
411
412    bool foundIDR = false;
413
414    const uint8_t *nalStart;
415    size_t nalSize;
416    while (getNextNALUnit(&data, &size, &nalStart, &nalSize, true) == OK) {
417        CHECK_GT(nalSize, 0u);
418
419        unsigned nalType = nalStart[0] & 0x1f;
420
421        if (nalType == 5) {
422            foundIDR = true;
423            break;
424        }
425    }
426
427    return foundIDR;
428}
429
430bool IsAVCReferenceFrame(const sp<ABuffer> &accessUnit) {
431    const uint8_t *data = accessUnit->data();
432    size_t size = accessUnit->size();
433
434    const uint8_t *nalStart;
435    size_t nalSize;
436    while (getNextNALUnit(&data, &size, &nalStart, &nalSize, true) == OK) {
437        CHECK_GT(nalSize, 0u);
438
439        unsigned nalType = nalStart[0] & 0x1f;
440
441        if (nalType == 5) {
442            return true;
443        } else if (nalType == 1) {
444            unsigned nal_ref_idc = (nalStart[0] >> 5) & 3;
445            return nal_ref_idc != 0;
446        }
447    }
448
449    return true;
450}
451
452sp<MetaData> MakeAACCodecSpecificData(
453        unsigned profile, unsigned sampling_freq_index,
454        unsigned channel_configuration) {
455    sp<MetaData> meta = new MetaData;
456    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_AAC);
457
458    CHECK_LE(sampling_freq_index, 11u);
459    static const int32_t kSamplingFreq[] = {
460        96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050,
461        16000, 12000, 11025, 8000
462    };
463    meta->setInt32(kKeySampleRate, kSamplingFreq[sampling_freq_index]);
464    meta->setInt32(kKeyChannelCount, channel_configuration);
465
466    static const uint8_t kStaticESDS[] = {
467        0x03, 22,
468        0x00, 0x00,     // ES_ID
469        0x00,           // streamDependenceFlag, URL_Flag, OCRstreamFlag
470
471        0x04, 17,
472        0x40,                       // Audio ISO/IEC 14496-3
473        0x00, 0x00, 0x00, 0x00,
474        0x00, 0x00, 0x00, 0x00,
475        0x00, 0x00, 0x00, 0x00,
476
477        0x05, 2,
478        // AudioSpecificInfo follows
479
480        // oooo offf fccc c000
481        // o - audioObjectType
482        // f - samplingFreqIndex
483        // c - channelConfig
484    };
485    sp<ABuffer> csd = new ABuffer(sizeof(kStaticESDS) + 2);
486    memcpy(csd->data(), kStaticESDS, sizeof(kStaticESDS));
487
488    csd->data()[sizeof(kStaticESDS)] =
489        ((profile + 1) << 3) | (sampling_freq_index >> 1);
490
491    csd->data()[sizeof(kStaticESDS) + 1] =
492        ((sampling_freq_index << 7) & 0x80) | (channel_configuration << 3);
493
494    meta->setData(kKeyESDS, 0, csd->data(), csd->size());
495
496    return meta;
497}
498
499bool ExtractDimensionsFromVOLHeader(
500        const uint8_t *data, size_t size, int32_t *width, int32_t *height) {
501    ABitReader br(&data[4], size - 4);
502    br.skipBits(1);  // random_accessible_vol
503    unsigned video_object_type_indication = br.getBits(8);
504
505    CHECK_NE(video_object_type_indication,
506             0x21u /* Fine Granularity Scalable */);
507
508    unsigned video_object_layer_verid;
509    unsigned video_object_layer_priority;
510    if (br.getBits(1)) {
511        video_object_layer_verid = br.getBits(4);
512        video_object_layer_priority = br.getBits(3);
513    }
514    unsigned aspect_ratio_info = br.getBits(4);
515    if (aspect_ratio_info == 0x0f /* extended PAR */) {
516        br.skipBits(8);  // par_width
517        br.skipBits(8);  // par_height
518    }
519    if (br.getBits(1)) {  // vol_control_parameters
520        br.skipBits(2);  // chroma_format
521        br.skipBits(1);  // low_delay
522        if (br.getBits(1)) {  // vbv_parameters
523            br.skipBits(15);  // first_half_bit_rate
524            CHECK(br.getBits(1));  // marker_bit
525            br.skipBits(15);  // latter_half_bit_rate
526            CHECK(br.getBits(1));  // marker_bit
527            br.skipBits(15);  // first_half_vbv_buffer_size
528            CHECK(br.getBits(1));  // marker_bit
529            br.skipBits(3);  // latter_half_vbv_buffer_size
530            br.skipBits(11);  // first_half_vbv_occupancy
531            CHECK(br.getBits(1));  // marker_bit
532            br.skipBits(15);  // latter_half_vbv_occupancy
533            CHECK(br.getBits(1));  // marker_bit
534        }
535    }
536    unsigned video_object_layer_shape = br.getBits(2);
537    CHECK_EQ(video_object_layer_shape, 0x00u /* rectangular */);
538
539    CHECK(br.getBits(1));  // marker_bit
540    unsigned vop_time_increment_resolution = br.getBits(16);
541    CHECK(br.getBits(1));  // marker_bit
542
543    if (br.getBits(1)) {  // fixed_vop_rate
544        // range [0..vop_time_increment_resolution)
545
546        // vop_time_increment_resolution
547        // 2 => 0..1, 1 bit
548        // 3 => 0..2, 2 bits
549        // 4 => 0..3, 2 bits
550        // 5 => 0..4, 3 bits
551        // ...
552
553        CHECK_GT(vop_time_increment_resolution, 0u);
554        --vop_time_increment_resolution;
555
556        unsigned numBits = 0;
557        while (vop_time_increment_resolution > 0) {
558            ++numBits;
559            vop_time_increment_resolution >>= 1;
560        }
561
562        br.skipBits(numBits);  // fixed_vop_time_increment
563    }
564
565    CHECK(br.getBits(1));  // marker_bit
566    unsigned video_object_layer_width = br.getBits(13);
567    CHECK(br.getBits(1));  // marker_bit
568    unsigned video_object_layer_height = br.getBits(13);
569    CHECK(br.getBits(1));  // marker_bit
570
571    unsigned interlaced = br.getBits(1);
572
573    *width = video_object_layer_width;
574    *height = video_object_layer_height;
575
576    return true;
577}
578
579bool GetMPEGAudioFrameSize(
580        uint32_t header, size_t *frame_size,
581        int *out_sampling_rate, int *out_channels,
582        int *out_bitrate, int *out_num_samples) {
583    *frame_size = 0;
584
585    if (out_sampling_rate) {
586        *out_sampling_rate = 0;
587    }
588
589    if (out_channels) {
590        *out_channels = 0;
591    }
592
593    if (out_bitrate) {
594        *out_bitrate = 0;
595    }
596
597    if (out_num_samples) {
598        *out_num_samples = 1152;
599    }
600
601    if ((header & 0xffe00000) != 0xffe00000) {
602        return false;
603    }
604
605    unsigned version = (header >> 19) & 3;
606
607    if (version == 0x01) {
608        return false;
609    }
610
611    unsigned layer = (header >> 17) & 3;
612
613    if (layer == 0x00) {
614        return false;
615    }
616
617    unsigned protection = (header >> 16) & 1;
618
619    unsigned bitrate_index = (header >> 12) & 0x0f;
620
621    if (bitrate_index == 0 || bitrate_index == 0x0f) {
622        // Disallow "free" bitrate.
623        return false;
624    }
625
626    unsigned sampling_rate_index = (header >> 10) & 3;
627
628    if (sampling_rate_index == 3) {
629        return false;
630    }
631
632    static const int kSamplingRateV1[] = { 44100, 48000, 32000 };
633    int sampling_rate = kSamplingRateV1[sampling_rate_index];
634    if (version == 2 /* V2 */) {
635        sampling_rate /= 2;
636    } else if (version == 0 /* V2.5 */) {
637        sampling_rate /= 4;
638    }
639
640    unsigned padding = (header >> 9) & 1;
641
642    if (layer == 3) {
643        // layer I
644
645        static const int kBitrateV1[] = {
646            32, 64, 96, 128, 160, 192, 224, 256,
647            288, 320, 352, 384, 416, 448
648        };
649
650        static const int kBitrateV2[] = {
651            32, 48, 56, 64, 80, 96, 112, 128,
652            144, 160, 176, 192, 224, 256
653        };
654
655        int bitrate =
656            (version == 3 /* V1 */)
657                ? kBitrateV1[bitrate_index - 1]
658                : kBitrateV2[bitrate_index - 1];
659
660        if (out_bitrate) {
661            *out_bitrate = bitrate;
662        }
663
664        *frame_size = (12000 * bitrate / sampling_rate + padding) * 4;
665
666        if (out_num_samples) {
667            *out_num_samples = 384;
668        }
669    } else {
670        // layer II or III
671
672        static const int kBitrateV1L2[] = {
673            32, 48, 56, 64, 80, 96, 112, 128,
674            160, 192, 224, 256, 320, 384
675        };
676
677        static const int kBitrateV1L3[] = {
678            32, 40, 48, 56, 64, 80, 96, 112,
679            128, 160, 192, 224, 256, 320
680        };
681
682        static const int kBitrateV2[] = {
683            8, 16, 24, 32, 40, 48, 56, 64,
684            80, 96, 112, 128, 144, 160
685        };
686
687        int bitrate;
688        if (version == 3 /* V1 */) {
689            bitrate = (layer == 2 /* L2 */)
690                ? kBitrateV1L2[bitrate_index - 1]
691                : kBitrateV1L3[bitrate_index - 1];
692
693            if (out_num_samples) {
694                *out_num_samples = 1152;
695            }
696        } else {
697            // V2 (or 2.5)
698
699            bitrate = kBitrateV2[bitrate_index - 1];
700            if (out_num_samples) {
701                *out_num_samples = (layer == 1 /* L3 */) ? 576 : 1152;
702            }
703        }
704
705        if (out_bitrate) {
706            *out_bitrate = bitrate;
707        }
708
709        if (version == 3 /* V1 */) {
710            *frame_size = 144000 * bitrate / sampling_rate + padding;
711        } else {
712            // V2 or V2.5
713            size_t tmp = (layer == 1 /* L3 */) ? 72000 : 144000;
714            *frame_size = tmp * bitrate / sampling_rate + padding;
715        }
716    }
717
718    if (out_sampling_rate) {
719        *out_sampling_rate = sampling_rate;
720    }
721
722    if (out_channels) {
723        int channel_mode = (header >> 6) & 3;
724
725        *out_channels = (channel_mode == 3) ? 1 : 2;
726    }
727
728    return true;
729}
730
731}  // namespace android
732
733