SampleIterator.cpp revision 170056540e9ce65261b45efd15f67e72e2df1bed 
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 "SampleIterator"
18//#define LOG_NDEBUG 0
19#include <utils/Log.h>
20
21#include "include/SampleIterator.h"
22
23#include <arpa/inet.h>
24
25#include <media/stagefright/foundation/ADebug.h>
26#include <media/stagefright/DataSource.h>
27#include <media/stagefright/Utils.h>
28
29#include "include/SampleTable.h"
30
31namespace android {
32
33SampleIterator::SampleIterator(SampleTable *table)
34    : mTable(table),
35      mInitialized(false),
36      mTimeToSampleIndex(0),
37      mTTSSampleIndex(0),
38      mTTSSampleTime(0),
39      mTTSCount(0),
40      mTTSDuration(0) {
41    reset();
42}
43
44void SampleIterator::reset() {
45    mSampleToChunkIndex = 0;
46    mFirstChunk = 0;
47    mFirstChunkSampleIndex = 0;
48    mStopChunk = 0;
49    mStopChunkSampleIndex = 0;
50    mSamplesPerChunk = 0;
51    mChunkDesc = 0;
52}
53
54status_t SampleIterator::seekTo(uint32_t sampleIndex) {
55    ALOGV("seekTo(%d)", sampleIndex);
56
57    if (sampleIndex >= mTable->mNumSampleSizes) {
58        return ERROR_END_OF_STREAM;
59    }
60
61    if (mTable->mSampleToChunkOffset < 0
62            || mTable->mChunkOffsetOffset < 0
63            || mTable->mSampleSizeOffset < 0
64            || mTable->mTimeToSampleCount == 0) {
65
66        return ERROR_MALFORMED;
67    }
68
69    if (mInitialized && mCurrentSampleIndex == sampleIndex) {
70        return OK;
71    }
72
73    if (!mInitialized || sampleIndex < mFirstChunkSampleIndex) {
74        reset();
75    }
76
77    if (sampleIndex >= mStopChunkSampleIndex) {
78        status_t err;
79        if ((err = findChunkRange(sampleIndex)) != OK) {
80            ALOGE("findChunkRange failed");
81            return err;
82        }
83    }
84
85    CHECK(sampleIndex < mStopChunkSampleIndex);
86
87    uint32_t chunk =
88        (sampleIndex - mFirstChunkSampleIndex) / mSamplesPerChunk
89        + mFirstChunk;
90
91    if (!mInitialized || chunk != mCurrentChunkIndex) {
92        mCurrentChunkIndex = chunk;
93
94        status_t err;
95        if ((err = getChunkOffset(chunk, &mCurrentChunkOffset)) != OK) {
96            ALOGE("getChunkOffset return error");
97            return err;
98        }
99
100        mCurrentChunkSampleSizes.clear();
101
102        uint32_t firstChunkSampleIndex =
103            mFirstChunkSampleIndex
104                + mSamplesPerChunk * (mCurrentChunkIndex - mFirstChunk);
105
106        for (uint32_t i = 0; i < mSamplesPerChunk; ++i) {
107            size_t sampleSize;
108            if ((err = getSampleSizeDirect(
109                            firstChunkSampleIndex + i, &sampleSize)) != OK) {
110                ALOGE("getSampleSizeDirect return error");
111                return err;
112            }
113
114            mCurrentChunkSampleSizes.push(sampleSize);
115        }
116    }
117
118    uint32_t chunkRelativeSampleIndex =
119        (sampleIndex - mFirstChunkSampleIndex) % mSamplesPerChunk;
120
121    mCurrentSampleOffset = mCurrentChunkOffset;
122    for (uint32_t i = 0; i < chunkRelativeSampleIndex; ++i) {
123        mCurrentSampleOffset += mCurrentChunkSampleSizes[i];
124    }
125
126    mCurrentSampleSize = mCurrentChunkSampleSizes[chunkRelativeSampleIndex];
127    if (sampleIndex < mTTSSampleIndex) {
128        mTimeToSampleIndex = 0;
129        mTTSSampleIndex = 0;
130        mTTSSampleTime = 0;
131        mTTSCount = 0;
132        mTTSDuration = 0;
133    }
134
135    status_t err;
136    if ((err = findSampleTimeAndDuration(
137            sampleIndex, &mCurrentSampleTime, &mCurrentSampleDuration)) != OK) {
138        ALOGE("findSampleTime return error");
139        return err;
140    }
141
142    mCurrentSampleIndex = sampleIndex;
143
144    mInitialized = true;
145
146    return OK;
147}
148
149status_t SampleIterator::findChunkRange(uint32_t sampleIndex) {
150    CHECK(sampleIndex >= mFirstChunkSampleIndex);
151
152    while (sampleIndex >= mStopChunkSampleIndex) {
153        if (mSampleToChunkIndex == mTable->mNumSampleToChunkOffsets) {
154            return ERROR_OUT_OF_RANGE;
155        }
156
157        mFirstChunkSampleIndex = mStopChunkSampleIndex;
158
159        const SampleTable::SampleToChunkEntry *entry =
160            &mTable->mSampleToChunkEntries[mSampleToChunkIndex];
161
162        mFirstChunk = entry->startChunk;
163        mSamplesPerChunk = entry->samplesPerChunk;
164        mChunkDesc = entry->chunkDesc;
165
166        if (mSampleToChunkIndex + 1 < mTable->mNumSampleToChunkOffsets) {
167            mStopChunk = entry[1].startChunk;
168
169            mStopChunkSampleIndex =
170                mFirstChunkSampleIndex
171                    + (mStopChunk - mFirstChunk) * mSamplesPerChunk;
172        } else {
173            mStopChunk = 0xffffffff;
174            mStopChunkSampleIndex = 0xffffffff;
175        }
176
177        ++mSampleToChunkIndex;
178    }
179
180    return OK;
181}
182
183status_t SampleIterator::getChunkOffset(uint32_t chunk, off64_t *offset) {
184    *offset = 0;
185
186    if (chunk >= mTable->mNumChunkOffsets) {
187        return ERROR_OUT_OF_RANGE;
188    }
189
190    if (mTable->mChunkOffsetType == SampleTable::kChunkOffsetType32) {
191        uint32_t offset32;
192
193        if (mTable->mDataSource->readAt(
194                    mTable->mChunkOffsetOffset + 8 + 4 * chunk,
195                    &offset32,
196                    sizeof(offset32)) < (ssize_t)sizeof(offset32)) {
197            return ERROR_IO;
198        }
199
200        *offset = ntohl(offset32);
201    } else {
202        CHECK_EQ(mTable->mChunkOffsetType, SampleTable::kChunkOffsetType64);
203
204        uint64_t offset64;
205        if (mTable->mDataSource->readAt(
206                    mTable->mChunkOffsetOffset + 8 + 8 * chunk,
207                    &offset64,
208                    sizeof(offset64)) < (ssize_t)sizeof(offset64)) {
209            return ERROR_IO;
210        }
211
212        *offset = ntoh64(offset64);
213    }
214
215    return OK;
216}
217
218status_t SampleIterator::getSampleSizeDirect(
219        uint32_t sampleIndex, size_t *size) {
220    *size = 0;
221
222    if (sampleIndex >= mTable->mNumSampleSizes) {
223        return ERROR_OUT_OF_RANGE;
224    }
225
226    if (mTable->mDefaultSampleSize > 0) {
227        *size = mTable->mDefaultSampleSize;
228        return OK;
229    }
230
231    switch (mTable->mSampleSizeFieldSize) {
232        case 32:
233        {
234            if (mTable->mDataSource->readAt(
235                        mTable->mSampleSizeOffset + 12 + 4 * sampleIndex,
236                        size, sizeof(*size)) < (ssize_t)sizeof(*size)) {
237                return ERROR_IO;
238            }
239
240            *size = ntohl(*size);
241            break;
242        }
243
244        case 16:
245        {
246            uint16_t x;
247            if (mTable->mDataSource->readAt(
248                        mTable->mSampleSizeOffset + 12 + 2 * sampleIndex,
249                        &x, sizeof(x)) < (ssize_t)sizeof(x)) {
250                return ERROR_IO;
251            }
252
253            *size = ntohs(x);
254            break;
255        }
256
257        case 8:
258        {
259            uint8_t x;
260            if (mTable->mDataSource->readAt(
261                        mTable->mSampleSizeOffset + 12 + sampleIndex,
262                        &x, sizeof(x)) < (ssize_t)sizeof(x)) {
263                return ERROR_IO;
264            }
265
266            *size = x;
267            break;
268        }
269
270        default:
271        {
272            CHECK_EQ(mTable->mSampleSizeFieldSize, 4);
273
274            uint8_t x;
275            if (mTable->mDataSource->readAt(
276                        mTable->mSampleSizeOffset + 12 + sampleIndex / 2,
277                        &x, sizeof(x)) < (ssize_t)sizeof(x)) {
278                return ERROR_IO;
279            }
280
281            *size = (sampleIndex & 1) ? x & 0x0f : x >> 4;
282            break;
283        }
284    }
285
286    return OK;
287}
288
289status_t SampleIterator::findSampleTimeAndDuration(
290        uint32_t sampleIndex, uint32_t *time, uint32_t *duration) {
291    if (sampleIndex >= mTable->mNumSampleSizes) {
292        return ERROR_OUT_OF_RANGE;
293    }
294
295    while (sampleIndex >= mTTSSampleIndex + mTTSCount) {
296        if (mTimeToSampleIndex == mTable->mTimeToSampleCount) {
297            return ERROR_OUT_OF_RANGE;
298        }
299
300        mTTSSampleIndex += mTTSCount;
301        mTTSSampleTime += mTTSCount * mTTSDuration;
302
303        mTTSCount = mTable->mTimeToSample[2 * mTimeToSampleIndex];
304        mTTSDuration = mTable->mTimeToSample[2 * mTimeToSampleIndex + 1];
305
306        ++mTimeToSampleIndex;
307    }
308
309    *time = mTTSSampleTime + mTTSDuration * (sampleIndex - mTTSSampleIndex);
310
311    *time += mTable->getCompositionTimeOffset(sampleIndex);
312
313    *duration = mTTSDuration;
314
315    return OK;
316}
317
318}  // namespace android
319
320