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; 
			 } 
		 } 
	}