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_TAG "XINGSEEKER" 18 #include <utils/Log.h> 19 20 #include "include/XINGSeeker.h" 21 #include "include/avc_utils.h" 22 23 #include <media/stagefright/DataSource.h> 24 #include <media/stagefright/Utils.h> 25 26 namespace android { 27 28 XINGSeeker::XINGSeeker() 29 : mDurationUs(-1), 30 mSizeBytes(0), 31 mEncoderDelay(0), 32 mEncoderPadding(0), 33 mTOCValid(false) { 34 } 35 36 bool XINGSeeker::getDuration(int64_t *durationUs) { 37 if (mDurationUs < 0) { 38 return false; 39 } 40 41 *durationUs = mDurationUs; 42 43 return true; 44 } 45 46 bool XINGSeeker::getOffsetForTime(int64_t *timeUs, off64_t *pos) { 47 if (mSizeBytes == 0 || !mTOCValid || mDurationUs < 0) { 48 return false; 49 } 50 51 float percent = (float)(*timeUs) * 100 / mDurationUs; 52 float fx; 53 if( percent <= 0.0f ) { 54 fx = 0.0f; 55 } else if( percent >= 100.0f ) { 56 fx = 256.0f; 57 } else { 58 int a = (int)percent; 59 float fa, fb; 60 if ( a == 0 ) { 61 fa = 0.0f; 62 } else { 63 fa = (float)mTOC[a-1]; 64 } 65 if ( a < 99 ) { 66 fb = (float)mTOC[a]; 67 } else { 68 fb = 256.0f; 69 } 70 fx = fa + (fb-fa)*(percent-a); 71 } 72 73 *pos = (int)((1.0f/256.0f)*fx*mSizeBytes) + mFirstFramePos; 74 75 return true; 76 } 77 78 // static 79 sp<XINGSeeker> XINGSeeker::CreateFromSource( 80 const sp<DataSource> &source, off64_t first_frame_pos) { 81 sp<XINGSeeker> seeker = new XINGSeeker; 82 83 seeker->mFirstFramePos = first_frame_pos; 84 85 uint8_t buffer[4]; 86 int offset = first_frame_pos; 87 if (source->readAt(offset, &buffer, 4) < 4) { // get header 88 return NULL; 89 } 90 offset += 4; 91 92 int header = U32_AT(buffer);; 93 size_t xingframesize = 0; 94 int sampling_rate = 0; 95 int num_channels; 96 int samples_per_frame = 0; 97 if (!GetMPEGAudioFrameSize(header, &xingframesize, &sampling_rate, &num_channels, 98 NULL, &samples_per_frame)) { 99 return NULL; 100 } 101 seeker->mFirstFramePos += xingframesize; 102 103 uint8_t version = (buffer[1] >> 3) & 3; 104 105 // determine offset of XING header 106 if(version & 1) { // mpeg1 107 if (num_channels != 1) offset += 32; 108 else offset += 17; 109 } else { // mpeg 2 or 2.5 110 if (num_channels != 1) offset += 17; 111 else offset += 9; 112 } 113 114 int xingbase = offset; 115 116 if (source->readAt(offset, &buffer, 4) < 4) { // XING header ID 117 return NULL; 118 } 119 offset += 4; 120 // Check XING ID 121 if ((buffer[0] != 'X') || (buffer[1] != 'i') 122 || (buffer[2] != 'n') || (buffer[3] != 'g')) { 123 if ((buffer[0] != 'I') || (buffer[1] != 'n') 124 || (buffer[2] != 'f') || (buffer[3] != 'o')) { 125 return NULL; 126 } 127 } 128 129 if (source->readAt(offset, &buffer, 4) < 4) { // flags 130 return NULL; 131 } 132 offset += 4; 133 uint32_t flags = U32_AT(buffer); 134 135 if (flags & 0x0001) { // Frames field is present 136 if (source->readAt(offset, buffer, 4) < 4) { 137 return NULL; 138 } 139 int32_t frames = U32_AT(buffer); 140 // only update mDurationUs if the calculated duration is valid (non zero) 141 // otherwise, leave duration at -1 so that getDuration() and getOffsetForTime() 142 // return false when called, to indicate that this xing tag does not have the 143 // requested information 144 if (frames) { 145 seeker->mDurationUs = (int64_t)frames * samples_per_frame * 1000000LL / sampling_rate; 146 } 147 offset += 4; 148 } 149 if (flags & 0x0002) { // Bytes field is present 150 if (source->readAt(offset, buffer, 4) < 4) { 151 return NULL; 152 } 153 seeker->mSizeBytes = U32_AT(buffer); 154 offset += 4; 155 } 156 if (flags & 0x0004) { // TOC field is present 157 if (source->readAt(offset + 1, seeker->mTOC, 99) < 99) { 158 return NULL; 159 } 160 seeker->mTOCValid = true; 161 offset += 100; 162 } 163 164 #if 0 165 if (flags & 0x0008) { // Quality indicator field is present 166 if (source->readAt(offset, buffer, 4) < 4) { 167 return NULL; 168 } 169 // do something with the quality indicator 170 offset += 4; 171 } 172 173 if (source->readAt(xingbase + 0xaf - 0x24, &buffer, 1) < 1) { // encoding flags 174 return false; 175 } 176 177 ALOGV("nogap preceding: %s, nogap continued in next: %s", 178 (buffer[0] & 0x80) ? "true" : "false", 179 (buffer[0] & 0x40) ? "true" : "false"); 180 #endif 181 182 if (source->readAt(xingbase + 0xb1 - 0x24, &buffer, 3) == 3) { 183 seeker->mEncoderDelay = (buffer[0] << 4) + (buffer[1] >> 4); 184 seeker->mEncoderPadding = ((buffer[1] & 0xf) << 8) + buffer[2]; 185 } 186 187 return seeker; 188 } 189 190 int32_t XINGSeeker::getEncoderDelay() { 191 return mEncoderDelay; 192 } 193 194 int32_t XINGSeeker::getEncoderPadding() { 195 return mEncoderPadding; 196 } 197 198 } // namespace android 199 200
