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
26namespace android {
27
28XINGSeeker::XINGSeeker()
29    : mDurationUs(-1),
30      mSizeBytes(0),
31      mEncoderDelay(0),
32      mEncoderPadding(0),
33      mTOCValid(false) {
34}
35
36bool XINGSeeker::getDuration(int64_t *durationUs) {
37    if (mDurationUs < 0) {
38        return false;
39    }
40
41    *durationUs = mDurationUs;
42
43    return true;
44}
45
46bool 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
79sp<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
190int32_t XINGSeeker::getEncoderDelay() {
191    return mEncoderDelay;
192}
193
194int32_t XINGSeeker::getEncoderPadding() {
195    return mEncoderPadding;
196}
197
198}  // namespace android
199
200