MP4

这是本文档旧的修订版！

https://www.cnblogs.com/chyingp/p/mp4-file-format.html
https://lucius0.github.io/2018/01/16/archivers/media-study-08/
ffmpeg\libavformat\movenc.c

参考：https://www.cnblogs.com/codertian/p/8277965.html
文档下载：https://standards.iso.org/ittf/PubliclyAvailableStandards/index.html
14496-12 14496-14 14496-15 下载要收费了， csdn 解决

14496-15 涉及h264 h265 流的 stsd box 封装

14496-15-2017 5.4.2 讲述 h264 的 avc1-avcC box 结构， avcC主要是AVCDecoderConfigurationRecord, 这个见 5.3.3.1.2
avc1 是 AVCSampleEntry ，继承 VisualSampleEntry

VisualSampleEntry 结构见 14496-12_2015 12.1.3.2

class VisualSampleEntry(codingname) extends SampleEntry (codingname){ 
 unsigned int(16) pre_defined = 0; 
 const unsigned int(16) reserved = 0; 
 unsigned int(32)[3] pre_defined = 0; 
 unsigned int(16) width; 
 unsigned int(16) height; 
 template unsigned int(32) horizresolution = 0x00480000; // 72 dpi 
 template unsigned int(32) vertresolution = 0x00480000; // 72 dpi 
 const unsigned int(32) reserved = 0; 
 template unsigned int(16) frame_count = 1; 
 string[32] compressorname; 
 template unsigned int(16) depth = 0x0018; 
 int(16) pre_defined = -1; 
 // other boxes from derived specifications 
 CleanApertureBox clap; // optional 
 PixelAspectRatioBox pasp; // optional 
}

aligned(8) abstract class SampleEntry (unsigned int(32) format) extends Box(format){ const unsigned int(8)[6] reserved = 0; unsigned int(16) data_reference_index; }

- H265 的 hev1 - hvcC box 结构  14496-15_2013 就有提及，在 8.4.1 章节， hvcC box 包含 `HEVCDecoderConfigurationRecord` 结构，具体见 8.3.3.1 章节
- `Compressorname` in the base class VisualSampleEntry indicates the name of the compressor used with the value "\013HEVC Coding" being recommended (\013 is 11, the length of the string in 
bytes).
- `HEVCDecoderConfigurationRecord` 结构：

aligned(8) class HEVCDecoderConfigurationRecord {

 unsigned int(8) configurationVersion = 1; 
 unsigned int(2) general_profile_space; 
 unsigned int(1) general_tier_flag; 
 unsigned int(5) general_profile_idc; 
 unsigned int(32) general_profile_compatibility_flags; 
 unsigned int(48) general_constraint_indicator_flags; 
 unsigned int(8) general_level_idc; 
 bit(4) reserved = ‘1111’b; 
 unsigned int(12) min_spatial_segmentation_idc; 
 bit(6) reserved = ‘111111’b; 
 unsigned int(2) parallelismType; 
 bit(6) reserved = ‘111111’b; 
 unsigned int(2) chromaFormat; 
 bit(5) reserved = ‘11111’b; 
 unsigned int(3) bitDepthLumaMinus8; 
 bit(5) reserved = ‘11111’b; 
 unsigned int(3) bitDepthChromaMinus8; 
 bit(16) avgFrameRate; 
 bit(2) constantFrameRate; 
 bit(3) numTemporalLayers; 
 bit(1) temporalIdNested; 
 unsigned int(2) lengthSizeMinusOne; 
 unsigned int(8) numOfArrays; 
 for (j=0; j < numOfArrays; j++) { 
	 bit(1) array_completeness; 
	 unsigned int(1) reserved = 0; 
	 unsigned int(6) NAL_unit_type; 
	 unsigned int(16) numNalus; 
	 for (i=0; i< numNalus; i++) { 
		 unsigned int(16) nalUnitLength; 
		 bit(8*nalUnitLength) nalUnit; 
	 } 
 }

}