一：介绍
MP4(MPEG-4 Part 14)是一种常见的多媒体容器格式，它是在“ISO/IEC 14496-14”标准文件中定义的，属于MPEG-4的一部分，是“ISO/IEC 14496-12(MPEG-4 Part 12 ISO base media file format)”标准中所定义的媒体格式的一种实现，后者定义了一种通用的媒体文件结构标准。MP4是一种描述较为全面的容器格式，被认为可以在其中嵌入任何形式的数据，各种编码的视频、音频等都不在话下，不过我们常见的大部分的MP4文件存放的AVC(H.264)或MPEG-4(Part 2)编码的视频和AAC编码的音频。MP4格式的官方文件后缀名是“.mp4”，还有其他的以mp4为基础进行的扩展或者是缩水版本的格式，包括：M4V, 3GP, F4V等。
二：BOX结构
mp4是由一个个“box”组成的，大box中存放小box，一级嵌套一级来存放媒体信息。box的基本结构是：
三：BOX类型
MP4的Box种类繁多，以下为参照（√为必须包含的Box）：
MP4 FormatBox TypeOptionDescriptionftyp √file type and compatibilitypdin progressive download informationmoov √container for all the metadata mvhd √movie header, overall declarations trak √container for an individual track or stream tkhd √track header, overall information about the track tref track reference container edts edit list container elst an edit list mdia √container for the media information in a track mdhd √media header, overall information about the media hdlr √handler, declares the media (handler) type minf √media information container vmhd video media header, overall information (video track only) smhd sound media header, overall information (sound track only) hmhd hint media header, overall information (hint track only) nmhd Null media header, overall information (some tracks only) dinf √data information box, container dref√data reference box, declares source(s) of media data in track stbl √sample table box, container for the time/space map stsd√sample descriptions (codec types, initialization etc.) stts√(decoding) time-to-sample ctts (composition) time to sample stsc√sample-to-chunk, partial data-offset information stsz sample sizes (framing) stz2 compact sample sizes (framing) stco√chunk offset, partial data-offset information co64 64-bit chunk offset stss sync sample table (random access points) stsh shadow sync sample table padb sample padding bits stdp sample degradation priority sdtp independent and disposable samples sbgp sample-to-group sgpd sample group description subs sub-sample information mvex movie extends box mehd movie extends header box trex √track extends defaults ipmc IPMP Control Boxmoof movie fragment mfhd √movie fragment header traf track fragment tfhd √track fragment header trun track fragment run sdtp independent and disposable samples sbgp sample-to-group subs sub-sample informationmfra movie fragment random access tfra track fragment random access mfro √movie fragment random access offsetmdat media data containerfree free spaceskip free space udta user-data cprt copyright etcmeta metadata hdlr √handler, declares the metadata (handler) type dinf data information box, container dref data reference box, declares source(s) of metadata items ipmc IPMP Control Box iloc item location ipro item protection sinf protection scheme information box frma original format box imif IPMP Information box schm scheme type box schi scheme information box iinf item information xml XML container bxml primary item reference pitm primary item reference fiin file delivery item information paen partition entry fpar FEC reservoir fecr FEC reservoir segr file delivery session group gitn group id to name tsel track selectionmeco additional metadata container mere metabox relation
四：示例
补充：具体的各种Box结构需另外参考。
参考：
http://blog.163.com/niuxiangshan@126/blog/static/1705965952012102011316978/
http://blog.csdn.NET/pirateleo/article/details/7061452
http://www.cnblogs.com/haibindev/archive/2011/10/17/2214518.html
http://www.xuebuyuan.com/1799539.html
