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 "VBRISeeker"
19
20 #include <inttypes.h>
21
22 #include <utils/Log.h>
23
24 #include "VBRISeeker.h"
25
26 #include <media/stagefright/foundation/avc_utils.h>
27
28 #include <media/stagefright/foundation/ADebug.h>
29 #include <media/stagefright/foundation/ByteUtils.h>
30 #include <media/DataSourceBase.h>
31
32 namespace android {
33
U24_AT(const uint8_t * ptr)34 static uint32_t U24_AT(const uint8_t *ptr) {
35 return ptr[0] << 16 | ptr[1] << 8 | ptr[2];
36 }
37
38 // static
CreateFromSource(DataSourceBase * source,off64_t post_id3_pos)39 VBRISeeker *VBRISeeker::CreateFromSource(
40 DataSourceBase *source, off64_t post_id3_pos) {
41 off64_t pos = post_id3_pos;
42
43 uint8_t header[4];
44 ssize_t n = source->readAt(pos, header, sizeof(header));
45 if (n < (ssize_t)sizeof(header)) {
46 return NULL;
47 }
48
49 uint32_t tmp = U32_AT(&header[0]);
50 size_t frameSize;
51 int sampleRate;
52 if (!GetMPEGAudioFrameSize(tmp, &frameSize, &sampleRate)) {
53 return NULL;
54 }
55
56 // VBRI header follows 32 bytes after the header _ends_.
57 pos += sizeof(header) + 32;
58
59 uint8_t vbriHeader[26];
60 n = source->readAt(pos, vbriHeader, sizeof(vbriHeader));
61 if (n < (ssize_t)sizeof(vbriHeader)) {
62 return NULL;
63 }
64
65 if (memcmp(vbriHeader, "VBRI", 4)) {
66 return NULL;
67 }
68
69 size_t numFrames = U32_AT(&vbriHeader[14]);
70
71 int64_t durationUs =
72 numFrames * 1000000ll * (sampleRate >= 32000 ? 1152 : 576) / sampleRate;
73
74 ALOGV("duration = %.2f secs", durationUs / 1E6);
75
76 size_t numEntries = U16_AT(&vbriHeader[18]);
77 size_t entrySize = U16_AT(&vbriHeader[22]);
78 size_t scale = U16_AT(&vbriHeader[20]);
79
80 ALOGV("%zu entries, scale=%zu, size_per_entry=%zu",
81 numEntries,
82 scale,
83 entrySize);
84
85 if (entrySize > 4) {
86 ALOGE("invalid VBRI entry size: %zu", entrySize);
87 return NULL;
88 }
89
90 VBRISeeker *seeker = new (std::nothrow) VBRISeeker;
91 if (seeker == NULL) {
92 ALOGW("Couldn't allocate VBRISeeker");
93 return NULL;
94 }
95
96 size_t totalEntrySize = numEntries * entrySize;
97 uint8_t *buffer = new (std::nothrow) uint8_t[totalEntrySize];
98 if (!buffer) {
99 ALOGW("Couldn't allocate %zu bytes", totalEntrySize);
100 delete seeker;
101 return NULL;
102 }
103
104 n = source->readAt(pos + sizeof(vbriHeader), buffer, totalEntrySize);
105 if (n < (ssize_t)totalEntrySize) {
106 delete[] buffer;
107 buffer = NULL;
108 delete seeker;
109 return NULL;
110 }
111
112 seeker->mBasePos = post_id3_pos + frameSize;
113 // only update mDurationUs if the calculated duration is valid (non zero)
114 // otherwise, leave duration at -1 so that getDuration() and getOffsetForTime()
115 // return false when called, to indicate that this vbri tag does not have the
116 // requested information
117 if (durationUs) {
118 seeker->mDurationUs = durationUs;
119 }
120
121 off64_t offset = post_id3_pos;
122 for (size_t i = 0; i < numEntries; ++i) {
123 uint32_t numBytes;
124 switch (entrySize) {
125 case 1: numBytes = buffer[i]; break;
126 case 2: numBytes = U16_AT(buffer + 2 * i); break;
127 case 3: numBytes = U24_AT(buffer + 3 * i); break;
128 default:
129 {
130 CHECK_EQ(entrySize, 4u);
131 numBytes = U32_AT(buffer + 4 * i); break;
132 }
133 }
134
135 numBytes *= scale;
136
137 seeker->mSegments.push(numBytes);
138
139 ALOGV("entry #%zu: %u offset %#016llx", i, numBytes, (long long)offset);
140 offset += numBytes;
141 }
142
143 delete[] buffer;
144 buffer = NULL;
145
146 ALOGI("Found VBRI header.");
147
148 return seeker;
149 }
150
VBRISeeker()151 VBRISeeker::VBRISeeker()
152 : mDurationUs(-1) {
153 }
154
getDuration(int64_t * durationUs)155 bool VBRISeeker::getDuration(int64_t *durationUs) {
156 if (mDurationUs < 0) {
157 return false;
158 }
159
160 *durationUs = mDurationUs;
161
162 return true;
163 }
164
getOffsetForTime(int64_t * timeUs,off64_t * pos)165 bool VBRISeeker::getOffsetForTime(int64_t *timeUs, off64_t *pos) {
166 if (mDurationUs < 0 || mSegments.size() == 0) {
167 return false;
168 }
169
170 int64_t segmentDurationUs = mDurationUs / mSegments.size();
171
172 int64_t nowUs = 0;
173 *pos = mBasePos;
174 size_t segmentIndex = 0;
175 while (segmentIndex < mSegments.size() && nowUs < *timeUs) {
176 nowUs += segmentDurationUs;
177 *pos += mSegments.itemAt(segmentIndex++);
178 }
179
180 ALOGV("getOffsetForTime %lld us => 0x%016llx", (long long)*timeUs, (long long)*pos);
181
182 *timeUs = nowUs;
183
184 return true;
185 }
186
187 } // namespace android
188
189