mirror of
https://github.com/DKJone/DKWechatHelper.git
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397 lines
11 KiB
Objective-C
397 lines
11 KiB
Objective-C
// QGMP4Box.m
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// Tencent is pleased to support the open source community by making vap available.
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//
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// Copyright (C) 2020 THL A29 Limited, a Tencent company. All rights reserved.
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//
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// Licensed under the MIT License (the "License"); you may not use this file except in
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// compliance with the License. You may obtain a copy of the License at
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//
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// http://opensource.org/licenses/MIT
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//
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// Unless required by applicable law or agreed to in writing, software distributed under the License is
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// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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// either express or implied. See the License for the specific language governing permissions and
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// limitations under the License.
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#import "QGMP4Box.h"
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#import "QGMP4Parser.h"
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NSInteger const kQGBoxSizeLengthInBytes = 4;
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NSInteger const kQGBoxTypeLengthInBytes = 4;
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#pragma mark - boxes
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#pragma mark -- base box
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@implementation QGMP4Box
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- (instancetype)initWithType:(QGMP4BoxType)type startIndex:(unsigned long long)startIndexInBytes length:(unsigned long long)length {
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if (self = [super init]) {
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_type = type;
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_startIndexInBytes = startIndexInBytes;
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_length = length;
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}
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return self;
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}
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/**
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前序遍历递归查找指定类型的子box，不包含自身。
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@param type box类型
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@return 符合条件的第一个子box
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*/
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- (id)subBoxOfType:(QGMP4BoxType)type {
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if (self.subBoxes) {
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for (QGMP4Box *subBox in self.subBoxes) {
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if (subBox.type == type) {
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return subBox;
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}
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QGMP4Box *box = [subBox subBoxOfType:type];
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if (box) {
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return box;
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}
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}
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}
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return nil;
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}
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/**
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向上查找指定类型的box，不包含自身
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@param type box类型
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@return h符合条件的第一个box
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*/
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- (id)superBoxOfType:(QGMP4BoxType)type {
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if (self.superBox) {
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if (self.superBox.type == type) {
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return self.superBox;
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}
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QGMP4Box *box = [self.superBox superBoxOfType:type];
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if (box) {
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return box;
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}
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}
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return nil;
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}
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- (NSString *)description {
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return [self descriptionForRecursionLevel:0];
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}
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- (NSString *)descriptionForRecursionLevel:(NSInteger)level {
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__block NSString *des = [NSString stringWithFormat:@"Box:%@ offset:%@ size:%@ ",self.typeString,@(self.startIndexInBytes),@(self.length)];
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for (int i = 0; i < level; i++) {
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des = [NSString stringWithFormat:@"|--%@",des];
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}
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des = [NSString stringWithFormat:@"\n%@",des];
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[self.subBoxes enumerateObjectsUsingBlock:^(QGMP4Box *obj, NSUInteger idx, BOOL * _Nonnull stop) {
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des = [des stringByAppendingString:[obj descriptionForRecursionLevel:(level+1)]];
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}];
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return des;
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}
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- (NSString *)typeString {
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NSUInteger value = self.type;
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NSString *des = @"";
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while (value > 0) {
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NSUInteger hexValue = value&0xff;
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value = value>>8;
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des = [NSString stringWithFormat:@"%c%@",(int)hexValue,des];
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}
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return des;
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}
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@end
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#pragma mark -- hvcc box
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/**
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* QGMP4HvccBox
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*/
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@implementation QGMP4HvccBox
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@end
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/**
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* QGCttsEntry 通过dts计算pts
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*/
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@implementation QGCttsEntry
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@end
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/**
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* QGMP4CttsBox 通过dts计算pts
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*/
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@implementation QGMP4CttsBox
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- (void)boxDidParsed:(QGMp4BoxDataFetcher)datablock {
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if (!_compositionOffsets) {
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_compositionOffsets = [NSMutableArray new];
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}
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NSData *cttsData = datablock(self);
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const char *bytes = cttsData.bytes;
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uint32_t entryCount = READ32BIT(&bytes[12]);
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for (int i = 0; i < entryCount; ++i) {
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uint32_t sampleCount = READ32BIT(&bytes[16+i*8]);
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uint32_t compositionOffset = READ32BIT(&bytes[16+i*8+4]);
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for (int j = 0; j < sampleCount; j++) {
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[_compositionOffsets addObject:@(compositionOffset)];
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}
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}
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}
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@end
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#pragma mark -- mdat box
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@implementation QGMP4MdatBox
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@end
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#pragma mark -- avcc box
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@implementation QGMP4AvccBox
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@end
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@implementation QGMP4MvhdBox
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@end
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/**
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在video track中，stsd包含了sps&pps等编解码数据
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stsd是⼀个必不可少的atom，在它的 header和version字段后会有⼀个entry count字段，
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根据entry的个数，每个entry会有type信息，根据type不同sample description会提供不
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同的信息，例如对于video track，会有“VisualSampleEntry”类型信息，对于audio track
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会有“AudioSampleEntry”类型信息。视频的关键信息如SPS和PPS，编码类型、宽⾼、
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⻓度，⾳频的声道、采样等信息都会出现在这个box中。
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*/
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@implementation QGMP4StsdBox
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@end
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/**
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There are two variants of the sample size box. The first variant has a fixed size 32-bit field for representing the sample sizes; it permits defining a constant size for all samples in a track. The second variant permits smaller size fields, to save space when the sizes are varying but small. One of these boxes must be present; the first version is preferred for maximum compatibility.
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记录了每个sample的大小
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*/
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@implementation QGMP4StszBox
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- (void)boxDidParsed:(QGMp4BoxDataFetcher)datablock {
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if (!_sampleSizes) {
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_sampleSizes = [NSMutableArray new];
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}
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NSData *stszData = datablock(self);
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const char *bytes = stszData.bytes;
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uint32_t sampleSize = READ32BIT(&bytes[12]);
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uint32_t sampleCount = READ32BIT(&bytes[16]);
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self.sampleCount = sampleCount;
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for (int i = 0; i < sampleCount; i ++) {
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if (sampleSize > 0) {
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[self.sampleSizes addObject:@(sampleSize)];
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} else {
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uint32_t entryValue = READ32BIT(&bytes[20+i*4]);
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[self.sampleSizes addObject:@(entryValue)];
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}
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}
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}
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@end
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/**
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Samples within the media data are grouped into chunks. Chunks can be of different sizes, and the samples within a chunk can have different sizes. This table can be used to find the chunk that contains a sample, its position, and the associated sample description.
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stsc记录了每个chunk有多少个Sample https://img-blog.csdn.net/20140613154636296
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*/
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@implementation QGStscEntry
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@end
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/*
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stsc，记录了每个chunk有多少个sample，通过这个表可以找到指定的sample
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*/
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@implementation QGMP4StscBox
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- (void)boxDidParsed:(QGMp4BoxDataFetcher)datablock {
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if (!_entries) {
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_entries = [NSMutableArray new];
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}
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NSData *stscData = datablock(self);
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const char *bytes = stscData.bytes;
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uint32_t entry_count = READ32BIT(&bytes[12]);
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for (int i = 0; i < entry_count; ++i) {
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QGStscEntry *entry = [QGStscEntry new];
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entry.firstChunk = READ32BIT(&bytes[16+i*12]);
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entry.samplesPerChunk = READ32BIT(&bytes[16+i*12+4]);
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entry.sampleDescriptionIndex = READ32BIT(&bytes[16+i*12+8]);
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[_entries addObject:entry];
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}
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}
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@end
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/**
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stco 记录每个chunk位置信息，与stsc结合可以算出每个sample的位置和大小
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entry_count is an integer that gives the number of entries in the following table
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chunk_offset is a 32 or 64 bit integer that gives the offset of the start of a chunk into its containing
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media file.
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*/
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@implementation QGMP4StcoBox
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- (void)boxDidParsed:(QGMp4BoxDataFetcher)datablock {
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if (!_chunkOffsets) {
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_chunkOffsets = [NSMutableArray new];
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}
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NSData *stcoData = datablock(self);
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const char *bytes = stcoData.bytes;
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uint32_t entry_count = READ32BIT(&bytes[12]);
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self.chunkCount = entry_count;
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for (int i = 0; i < entry_count; ++i) {
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[self.chunkOffsets addObject:@(READ32BIT(&bytes[16+i*4]))];
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}
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}
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@end
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/**
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Decoding Time to Sample Box
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用来计算dts
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*/
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@implementation QGSttsEntry
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@end
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/*
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stts记录了sample的时间信息，⾥⾯有多个entry，每个entry⾥⾯的的sample的时⻓都是
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对应这个entry的delta值，通过这个atom可以得到⼀个时间和sample的映射表。
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*/
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@implementation QGMP4SttsBox
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- (void)boxDidParsed:(QGMp4BoxDataFetcher)datablock {
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if (!_entries) {
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_entries = [NSMutableArray new];
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}
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NSData *sttsData = datablock(self);
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const char *bytes = sttsData.bytes;
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uint32_t entry_count = READ32BIT(&bytes[12]);
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for (int i = 0; i < entry_count; ++i) {
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QGSttsEntry *entry = [QGSttsEntry new];
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entry.sampleCount = READ32BIT(&bytes[16+i*8]);;
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entry.sampleDelta = READ32BIT(&bytes[16+i*8+4]);
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[_entries addObject:entry];
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}
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}
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@end
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@implementation QGMP4TrackBox
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@end
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@implementation QGMP4HdlrBox
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- (void)boxDidParsed:(QGMp4BoxDataFetcher)datablock {
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NSData *hdlrData = datablock(self);
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const char *bytes = hdlrData.bytes;
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uint32_t trackType = READ32BIT(&bytes[16]);
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self.trackType = trackType;
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}
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@end
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@implementation QGMP4Sample
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@end
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@implementation QGChunkOffsetEntry
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@end
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@implementation QGMP4BoxFactory
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+ (QGMP4Box *)createBoxForType:(QGMP4BoxType)type startIndex:(unsigned long long)startIndexInBytes length:(unsigned long long)length {
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Class boxClass = [self boxClassForType:type] ?: [QGMP4Box class];
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QGMP4Box *box = [[boxClass alloc] initWithType:type startIndex:startIndexInBytes length:length];
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return box;
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}
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+ (Class)boxClassForType:(QGMP4BoxType)type {
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switch (type) {
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case QGMP4BoxType_ftyp:
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case QGMP4BoxType_free:
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case QGMP4BoxType_moov:
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case QGMP4BoxType_mvhd:
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case QGMP4BoxType_trak:
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case QGMP4BoxType_tkhd:
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case QGMP4BoxType_edts:
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case QGMP4BoxType_elst:
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case QGMP4BoxType_mdia:
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case QGMP4BoxType_minf:
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case QGMP4BoxType_vmhd:
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case QGMP4BoxType_dinf:
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case QGMP4BoxType_dref:
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case QGMP4BoxType_url:
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case QGMP4BoxType_stbl:
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case QGMP4BoxType_avc1:
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case QGMP4BoxType_stss:
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case QGMP4BoxType_udta:
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case QGMP4BoxType_meta:
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case QGMP4BoxType_ilst:
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case QGMP4BoxType_data:
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case QGMP4BoxType_iods:
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case QGMP4BoxType_wide:
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case QGMP4BoxType_loci:
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case QGMP4BoxType_smhd:
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return [QGMP4Box class];
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case QGMP4BoxType_mdat:
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return [QGMP4MdatBox class];
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case QGMP4BoxType_avcC:
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return [QGMP4AvccBox class];
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case QGMP4BoxType_mdhd:
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return [QGMP4MvhdBox class];
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case QGMP4BoxType_stsd:
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return [QGMP4StsdBox class];
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case QGMP4BoxType_stsz:
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return [QGMP4StszBox class];
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case QGMP4BoxType_hdlr:
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return [QGMP4HdlrBox class];
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case QGMP4BoxType_stsc:
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return [QGMP4StscBox class];
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case QGMP4BoxType_stts:
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return [QGMP4SttsBox class];
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case QGMP4BoxType_stco:
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return [QGMP4StcoBox class];
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case QGMP4BoxType_hvcC:
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return [QGMP4HvccBox class];
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case QGMP4BoxType_ctts:
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return [QGMP4CttsBox class];
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default:
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return nil;
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}
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}
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/**
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根据boxClassForType:方法的返回判断是否为一个合法的box类型
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@param type box类型
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@return 除QGMP4BoxType定义的类型（不包含QGMP4BoxType_unknown）外全部为不合法类型
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*/
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+ (BOOL)isTypeValueValid:(QGMP4BoxType)type {
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Class class = [self boxClassForType:type];
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if (class) {
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return YES;
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}
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return NO;
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}
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@end
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