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 "XINGSeeker.h"
21#include <media/stagefright/foundation/avc_utils.h>
22
23#include <media/stagefright/foundation/ByteUtils.h>
24#include <media/DataSourceBase.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
79XINGSeeker *XINGSeeker::CreateFromSource(
80        DataSourceBase *source, off64_t first_frame_pos) {
81
82    uint8_t buffer[4];
83    int offset = first_frame_pos;
84    if (source->readAt(offset, &buffer, 4) < 4) { // get header
85        return NULL;
86    }
87    offset += 4;
88
89    int header = U32_AT(buffer);;
90    size_t xingframesize = 0;
91    int sampling_rate = 0;
92    int num_channels;
93    int samples_per_frame = 0;
94    if (!GetMPEGAudioFrameSize(header, &xingframesize, &sampling_rate, &num_channels,
95                               NULL, &samples_per_frame)) {
96        return NULL;
97    }
98    uint8_t version = (buffer[1] >> 3) & 3;
99
100    // determine offset of XING header
101    if(version & 1) { // mpeg1
102        if (num_channels != 1) offset += 32;
103        else offset += 17;
104    } else { // mpeg 2 or 2.5
105        if (num_channels != 1) offset += 17;
106        else offset += 9;
107    }
108
109    int xingbase = offset;
110
111    if (source->readAt(offset, &buffer, 4) < 4) { // XING header ID
112        return NULL;
113    }
114    offset += 4;
115    // Check XING ID
116    if ((buffer[0] != 'X') || (buffer[1] != 'i')
117                || (buffer[2] != 'n') || (buffer[3] != 'g')) {
118        if ((buffer[0] != 'I') || (buffer[1] != 'n')
119                    || (buffer[2] != 'f') || (buffer[3] != 'o')) {
120            return NULL;
121        }
122    }
123
124    if (source->readAt(offset, &buffer, 4) < 4) { // flags
125        return NULL;
126    }
127    offset += 4;
128    uint32_t flags = U32_AT(buffer);
129
130    XINGSeeker *seeker = new XINGSeeker;
131    seeker->mFirstFramePos = first_frame_pos + xingframesize;
132
133    if (flags & 0x0001) {  // Frames field is present
134        if (source->readAt(offset, buffer, 4) < 4) {
135            delete seeker;
136            return NULL;
137        }
138        int32_t frames = U32_AT(buffer);
139        // only update mDurationUs if the calculated duration is valid (non zero)
140        // otherwise, leave duration at -1 so that getDuration() and getOffsetForTime()
141        // return false when called, to indicate that this xing tag does not have the
142        // requested information
143        if (frames) {
144            seeker->mDurationUs = (int64_t)frames * samples_per_frame * 1000000LL / sampling_rate;
145        }
146        offset += 4;
147    }
148    if (flags & 0x0002) {  // Bytes field is present
149        if (source->readAt(offset, buffer, 4) < 4) {
150            delete seeker;
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            delete seeker;
159            return NULL;
160        }
161        seeker->mTOCValid = true;
162        offset += 100;
163    }
164
165#if 0
166    if (flags & 0x0008) {  // Quality indicator field is present
167        if (source->readAt(offset, buffer, 4) < 4) {
168            delete seeker;
169            return NULL;
170        }
171        // do something with the quality indicator
172        offset += 4;
173    }
174
175    if (source->readAt(xingbase + 0xaf - 0x24, &buffer, 1) < 1) { // encoding flags
176        delete seeker;
177        return false;
178    }
179
180    ALOGV("nogap preceding: %s, nogap continued in next: %s",
181              (buffer[0] & 0x80) ? "true" : "false",
182              (buffer[0] & 0x40) ? "true" : "false");
183#endif
184
185    if (source->readAt(xingbase + 0xb1 - 0x24, &buffer, 3) == 3) {
186        seeker->mEncoderDelay = (buffer[0] << 4) + (buffer[1] >> 4);
187        seeker->mEncoderPadding = ((buffer[1] & 0xf) << 8) + buffer[2];
188    }
189
190    return seeker;
191}
192
193int32_t XINGSeeker::getEncoderDelay() {
194    return mEncoderDelay;
195}
196
197int32_t XINGSeeker::getEncoderPadding() {
198    return mEncoderPadding;
199}
200
201}  // namespace android
202
203