DASH Streaming Support

翻译“DASH streaming support” ---》 DASH 流传输支持协议，这是2012的文档，现在应该是已经有部署实施了，权当做学习一下

1- usually a segment is a file, but segments may be concatenated in a single file and retrieved through HTTP byte-ranges. Moreover, the onDemand profile of DASH mandates that a single segment is used, so an onDemand profile file will have only one segements with many subsegments .

2- fragment = a movie fragment = “moof box + mdat box”. This is the terminology from the spec, I cannot say whether other use the term fragment correctly. Note that a fragment may be stored in its own file or concatenated with other fragments. Also note that typically, a segment is made of one or more subsegment, which in turns are made of one or more movie fragments

3- It depends how you transfer your segments/subsegments on the network

segment：片段

subsegment:子片段

fragments: 视频块

StackOVerflow上的总结

1-通常一个片段就是一个文件，但是多个片段可以连接成单个文件，并通过http byte-range 请求来返回。并且 点播的DASH profile文件要求单个片段，所以点播的文件可以有单一个片段，每个片段可以有多个子片段。

2. 在标准的定义中，一个视频块包含了 moof 和 mdat 信息。但是值得我们注意的是：一个视频块可以被存储在一个文件中，也可以被其他的视频段连接起来使用。一个典型的场景是一个片段包含一个或者多个片段，每个片段包含一个或者多个视频块。

3. 协议和软件的实现要依靠你如何在网络上传输片段和子片段数据。