AacAdtsExtractor.cpp revision 4efb2aa0d563b86b3c95d418d6d61d97f51c0bbb
1/* 2 * Copyright (C) 2011 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#include "sllog.h" 18#include <utils/Log.h> 19 20#include "android/include/AacAdtsExtractor.h" 21#include "include/avc_utils.h" 22 23 24namespace android { 25 26#define ADTS_HEADER_LENGTH 7 27// ADTS header size is 7, but frame size information ends on byte 6 (when counting from byte 1) 28#define ADTS_HEADER_SIZE_UP_TO_FRAMESIZE 6 29 30//////////////////////////////////////////////////////////////////////////////// 31 32// Returns the sample rate based on the sampling frequency index 33static uint32_t get_sample_rate(const uint8_t sf_index) 34{ 35 static const uint32_t sample_rates[] = 36 { 37 96000, 88200, 64000, 48000, 44100, 32000, 38 24000, 22050, 16000, 12000, 11025, 8000 39 }; 40 41 if (sf_index < sizeof(sample_rates) / sizeof(sample_rates[0])) { 42 return sample_rates[sf_index]; 43 } 44 45 return 0; 46} 47 48static size_t getFrameSize(const sp<DataSource> &source, off64_t offset) { 49 size_t frameSize = 0; 50 51 uint8_t syncHeader[ADTS_HEADER_SIZE_UP_TO_FRAMESIZE]; 52 const uint8_t *syncword = syncHeader; 53 const uint8_t *header = syncHeader + 3; 54 55 ssize_t readSize = source->readAt(offset, &syncHeader, ADTS_HEADER_SIZE_UP_TO_FRAMESIZE); 56 if (readSize == 0) { 57 // EOS is normal, not an error 58 SL_LOGV("AacAdtsExtractor::getFrameSize EOS"); 59 return 0; 60 } 61 if (readSize != ADTS_HEADER_SIZE_UP_TO_FRAMESIZE) { 62 SL_LOGE("AacAdtsExtractor:: getFrameSize() returns %d (syncword and header read error)", 63 (int) readSize); 64 return 0; 65 } 66 67 if ((syncword[0] != 0xff) || ((syncword[1] & 0xf6) != 0xf0)) { 68 SL_LOGE("AacAdtsExtractor:: getFrameSize() returns 0 (syncword pb)"); 69 return 0; 70 } 71 72 const uint8_t protectionAbsent = syncword[1] & 0x1; 73 74 frameSize = (header[0] & 0x3) << 11 | header[1] << 3 | header[2] >> 5; 75 // the frame size read already contains the size of the ADTS header, so no need to add it here 76 77 // protectionAbsent is 0 if there is CRC 78 static const size_t kAdtsHeaderLengthNoCrc = 7; 79 static const size_t kAdtsHeaderLengthWithCrc = 9; 80 size_t headSize = protectionAbsent ? kAdtsHeaderLengthNoCrc : kAdtsHeaderLengthWithCrc; 81 if (headSize > frameSize) { 82 SL_LOGE("AacAdtsExtractor:: getFrameSize() returns 0 (frameSize %u < headSize %u)", 83 frameSize, headSize); 84 return 0; 85 } 86 87 //SL_LOGV("AacAdtsExtractor:: getFrameSize() returns %u", frameSize); 88 89 return frameSize; 90} 91 92 93AacAdtsExtractor::AacAdtsExtractor(const sp<DataSource> &source) 94 : mDataSource(source), 95 mInitCheck(NO_INIT), 96 mFrameDurationUs(0) { 97 98 // difference with framework's AAC Extractor: we have already validated the data 99 // upon enqueueing, so no need to sniff the data: 100 // String8 mimeType; 101 // float confidence; 102 // if (!SniffAAC(mDataSource, &mimeType, &confidence, NULL)) { 103 // return; 104 // } 105 106 uint8_t profile, sf_index, channel, header[2]; 107 if (mDataSource->readAt(2, &header, 2) < 2) { 108 return; 109 } 110 111 profile = (header[0] >> 6) & 0x3; 112 sf_index = (header[0] >> 2) & 0xf; 113 uint32_t sr = get_sample_rate(sf_index); 114 115 if (sr == 0) { 116 return; 117 } 118 channel = (header[0] & 0x1) << 2 | (header[1] >> 6); 119 120 SL_LOGV("AacAdtsExtractor has found sr=%d channel=%d", sr, channel); 121 122 mMeta = MakeAACCodecSpecificData(profile, sf_index, channel); 123 124 // Round up and get the duration of each frame 125 mFrameDurationUs = (1024 * 1000000ll + (sr - 1)) / sr; 126 127 off64_t streamSize; 128 if (mDataSource->getSize(&streamSize) == OK) { 129 off64_t offset = 0, numFrames = 0; 130 while (offset < streamSize) { 131 size_t frameSize; 132 if ((frameSize = getFrameSize(mDataSource, offset)) == 0) { 133 //SL_LOGV("AacAdtsExtractor() querying framesize at offset=%lld", offset); 134 return; 135 } 136 137 offset += frameSize; 138 numFrames ++; 139 } 140 141 // Compute total duration 142 int64_t duration = numFrames * mFrameDurationUs; 143 mMeta->setInt64(kKeyDuration, duration); 144 } 145 146 mInitCheck = OK; 147 148} 149 150 151AacAdtsExtractor::~AacAdtsExtractor() { 152} 153 154 155sp<MetaData> AacAdtsExtractor::getMetaData() { 156 sp<MetaData> meta = new MetaData; 157 158 if (mInitCheck != OK) { 159 return meta; 160 } 161 162 meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_AUDIO_AAC_ADTS); 163 164 return meta; 165} 166 167 168size_t AacAdtsExtractor::countTracks() { 169 return mInitCheck == OK ? 1 : 0; 170} 171 172 173sp<MediaSource> AacAdtsExtractor::getTrack(size_t index) { 174 if (mInitCheck != OK || index != 0) { 175 return NULL; 176 } 177 178 return new AacAdtsSource(mDataSource, mMeta, mFrameDurationUs); 179} 180 181 182sp<MetaData> AacAdtsExtractor::getTrackMetaData(size_t index, uint32_t flags) { 183 if (mInitCheck != OK || index != 0) { 184 return NULL; 185 } 186 187 return mMeta; 188} 189 190 191//////////////////////////////////////////////////////////////////////////////// 192 193// 8192 = 2^13, 13bit AAC frame size (in bytes) 194const size_t AacAdtsSource::kMaxFrameSize = 8192; 195 196AacAdtsSource::AacAdtsSource( 197 const sp<DataSource> &source, const sp<MetaData> &meta, 198 int64_t frame_duration_us) 199 : mDataSource(source), 200 mMeta(meta), 201 mOffset(0), 202 mCurrentTimeUs(0), 203 mStarted(false), 204 mGroup(NULL), 205 mFrameDurationUs(frame_duration_us) { 206} 207 208 209AacAdtsSource::~AacAdtsSource() { 210 if (mStarted) { 211 stop(); 212 } 213} 214 215 216status_t AacAdtsSource::start(MetaData *params) { 217 CHECK(!mStarted); 218 219 mOffset = 0; 220 mCurrentTimeUs = 0; 221 mGroup = new MediaBufferGroup; 222 mGroup->add_buffer(new MediaBuffer(kMaxFrameSize)); 223 mStarted = true; 224 225 return OK; 226} 227 228 229status_t AacAdtsSource::stop() { 230 CHECK(mStarted); 231 232 delete mGroup; 233 mGroup = NULL; 234 235 mStarted = false; 236 return OK; 237} 238 239 240sp<MetaData> AacAdtsSource::getFormat() { 241 return mMeta; 242} 243 244 245status_t AacAdtsSource::read( 246 MediaBuffer **out, const ReadOptions *options) { 247 *out = NULL; 248 249 int64_t seekTimeUs; 250 ReadOptions::SeekMode mode; 251 if (options && options->getSeekTo(&seekTimeUs, &mode)) { 252 // difference with framework's AAC Extractor: no seeking 253 SL_LOGE("Can't seek in AAC ADTS buffer queue"); 254 } 255 256 size_t frameSize, frameSizeWithoutHeader; 257 SL_LOGV("AacAdtsSource::read() offset=%lld", mOffset); 258 if ((frameSize = getFrameSize(mDataSource, mOffset)) == 0) { 259 SL_LOGV("AacAdtsSource::read() returns EOS"); 260 return ERROR_END_OF_STREAM; 261 } 262 263 MediaBuffer *buffer; 264 status_t err = mGroup->acquire_buffer(&buffer); 265 if (err != OK) { 266 return err; 267 } 268 269 frameSizeWithoutHeader = frameSize - ADTS_HEADER_LENGTH; 270 ssize_t readSize = mDataSource->readAt(mOffset + ADTS_HEADER_LENGTH, buffer->data(), 271 frameSizeWithoutHeader); 272 //SL_LOGV("AacAdtsSource::read() readAt returned %u bytes", readSize); 273 if (readSize != (ssize_t)frameSizeWithoutHeader) { 274 SL_LOGW("AacAdtsSource::read() readSize != frameSizeWithoutHeader"); 275 buffer->release(); 276 buffer = NULL; 277 return ERROR_IO; 278 } 279 280 buffer->set_range(0, frameSizeWithoutHeader); 281 buffer->meta_data()->setInt64(kKeyTime, mCurrentTimeUs); 282 buffer->meta_data()->setInt32(kKeyIsSyncFrame, 1); 283 284 mOffset += frameSize; 285 mCurrentTimeUs += mFrameDurationUs; 286 287 *out = buffer; 288 return OK; 289} 290 291} // namespace android 292