QuickTime流媒体IPv6方案和ipv4 to ipv6流媒体应用层网关ALG代理介绍

Abstract 摘要

The Next Generation Internet (IPv6 based) is slowly being implemented and it is gaining further prominence with GPP support for 3rd generation mobile phones. One potential application of 3G phones and the available bandwidth is the use of streaming media (video and audio).

下一代互联网(基于IPv6)正在慢慢实现，它使GPP对第三代手机的支持更加卓越。一个3g手机的潜在应用和可用带宽都是使用流媒体(视频和音频)的基础。

We believe that, to become widely available these phones would need to be able to access the existing content on the IPv4 Internet rather than just dedicated IPv6 streaming servers. To Address this issue, we have initiated a project within the Applications Program of ATcrc (Australian Telecommunications Cooperative Research Centre) with the support of an AUDF Developer Grant, and converted the IPv4 based Darwin Streaming Proxy to IPv6. The proxy provides an application layer gateway between IPv6 streaming (RTSP/RTP) clients (such as MPEG-4 or (modified) QuickTime players) and IPv4 based streaming servers that already exist on the Internet eg., QuickTime/Darwin Streaming Servers (DSS). Students including B.E (ECSE) vacation experience project, 4th year thesis and B.Tech (Computer Studies) Industrial Design project groups have been used to implement proof of concept clients for IPv6. The porting of the Darwin Streaming Server to natively support IPv6 is an ongoing project.

我们认为，成为广泛使用这些手机会需要访问IPv4网络上现有的的内容,而不是专用IPv6流服务器。为了解决这个问题,我们已经开始在ATcrc应用程序中启动了一个项目(澳大利亚电信合作研究中心)并且有AUDF开发者格兰特的支持，转换基于达尔文流媒体代理的IPv4到IPv6。代理提供了一个应用程序层网关，该网关在在IPv6流媒体(RTSP和RTP)客户(如mpeg - 4或(修改)QuickTime播放器)和基于在互联网上已经存在的IPv4流媒体服务器之间。QuickTime /达尔文流媒体服务器(DSS)。学生包括B.E(ECSE)临时项目经验,4年的论文和B.Tech(计算机研究)项目组，这个项目已被用来实现对IPv6的证明的客户理念。达尔文流媒体服务器的本地支持IPv6移植是一个正在进行的项目。

Introduction 介绍

IPv6 has been proposed as the supported protocol for third generation (3G) mobile phone systems (3GPP UMTS and IMS[1, 2]) and this poses IPv4-IPv6 transition issues for existing classes of services (web, streaming media, Voice over IP (VOIP)) on 3G capable devices. One approach to streaming media to IPv6 capable clients is to use native services - which means updating the servers to directly support IPv6. Current QuickTime/Darwin Streaming Server (DSS)[3] has no IPv6 support, similarly for most of the installed Microsoft Windows Media[4] or RealNetworks Servers[5]. The AUDF Developer Grant project was to extend DSS so that it supported IPv6 streaming. The project is still ongoing.

IPv6的已被提议作为用于第三代（3G）移动电话系统支持的协议（3GPP UMTS和IMS[1，2]）,这造成了现有IPv4-IPv6在3g设备现存服务类型(网络、流媒体、IP语音(VOIP))过渡问题。流媒体到IPv6客户能力的一个方法是使用本地服务的意味着更新服务器直接支持IPv6。当前QuickTime /达尔文流服务器(DSS)[3]没有IPv6支持,类似于大多数的Microsoft Windows安装媒体[4][5]或RealNetworks服务器。ADF开发赠款项目是扩展DSS，使其支持IPv6的流媒体。该项目仍在进行中。

It is presumed that there will only be a gradual uptake of IPv6 supported server applications, meaning that large amounts of content will not be directly available to the new devices. An application layer gateway (ALG) for streaming media is one solution to address the problem. This paper describes one implementation of a non-caching proxy that performs the function of an IPv4 to IPv6 ALG for streaming QuickTime/MPEG4 (RTSP/RTP) media using TCP and UDP. Figure 1 illustrates our approach.

据推测，只会有IPv6的逐步增长来支持的服务器应用，这意味着大量的内容将不会被直接用于新设备。一个流媒体应用层网关(ALG)是解决问题的一个解决方案。本文描述了一个缓存代理的实现，它实现了一个IPv4与IPv6的ALG功能支持了基于TCP和UDP的QuickTime / MPEG4(RTSP和RTP)流媒体。

The proxy translates the text-based Real Time Streaming Protocol (RTSP[6]), which is transported over TCP. The proxy rewrites IP addresses and port information as appropriate and updates the SDP[7] content of the RTSP messages to meet IPv6 requirements. The proxy also translates the Real Time Protocol (RTP[8]) content from IPv4 RTP/UDP packets to IPv6 RTP/UDP packets.

代理转换基于文本的实时流协议（RTSP[6]），通过TCP被输送。代理重写IP地址和端口信息并更新SDP[7]RTSP消息内容满足IPv6的要求。代理也将实时协议(RTP)[8]内容从IPv4 RTP / UDP数据包转化到IPv6RTP / UDP数据包。

The proxy has been demonstrated to work with IPv6 implementations of the MPEG4IP[9] Linux based QuickTime/ISMA compliant MPEG-4 player, and with a Java JMF[9] media player. A Windows based IPv6 QuickTime player is under development at present as an undergraduate thesis student project.

代理已经证明使用IPv6的实现MPEG4IP[9]基于Linux的QuickTime /互联网统计的mpeg-4播放器,和一个Java JMF[9]的媒体播放器。一个Windows基于IPv6的QuickTime播放器正在开发，目前作为本科毕业论文的学生项目。

QuickTime Streaming Technology QuickTime流媒体技术

QuickTime Streaming is seen to be particularly suitable for IPv6 research due to its applicability to future networks such as the 3G cellular systems. MPEG-4 Streaming (ISMA[10]) is based on the QuickTime file format, and uses the same RTSP/RTP protocols. Streaming QuickTime uses a URL to request a video/audio stream. For example, to request a video stream called sample.mov from the server ‘snowy.ctie.monash.edu.au’ a URL of the form rtsp://snowy.ctie.monash.edu.au/sample.mov is used. The URL itself does not specify which version of IP (IPv4 or IPv6) is to be used.

QuickTime流媒体被认为适合IPv6的研究。由于它适用于未来3g移动等网络系统。mpeg-4流媒体(互联网统计[10])是基于QuickTime文件格式,并使用相同的RTSP和RTP协议。QuickTime流媒体使用URL请求视频/音频流。例如,请求视频流称为样本。从服务器mov snowy.ctie.monash.edu.au的URLrtsp:/ / snowy.ctie.monash.edu.au / sample.mov被使用。URL本身没有指定使用(IPv4和IPv6)哪个版本的IP。

The standards based RTSP protocol is used by the player (and server) for signalling. RTSP protocol covers signalling areas such as requesting the details of the movie codecs required, number of tracks, source IP addresses and ports of the server sending the stream.

基于标准的RTSP协议被用于信令所使用的播放器（和服务器）。RTSP协议覆盖信令等领域，比如请求所需的电影编解码器的细节,通道数目,源服务器的IP地址和端口发送流。

RTSP messages also include the usual player type commands like play, pause, start at time ‘nnn’. RTSP players and servers can negotiate on some parameters related to the requested stream. For operational details of RTSP, the reader can refer to the specification document RFC2326[6] as it has a very readable description of how RTSP is to be used.

RTSP消息还包括通常的播放器类型命令像播放,暂停,开始时间“nnn”。RTSP播放器和服务器可以在一些与流要求相关的参数上商议。RTSP的操作细节,读者可以参考规范文档RFC2326[6],因为它有一个非常可读的描述如何使用学习。

Actual movie content is transported by the RTP protocol. 实际的电影内容由RTP协议运输。

RTP over UDP is used to transport the encoded video or audio tracks (or other types of tracks). Again it is worth noting that the RTP protocol does not specify the IP layer (IPv4 or IPv6) required to transport it. RTP uses two sequential ports for each track of the stream. One port is used to carry content (say a video track) and the second (the RTCP port) is mainly used as a feedback mechanism to report on quality and packet loss. Instant-On QuickTime streaming uses this RTCP feedback mechanism amongst others.

RTP / UDP是用来传输编码的视频或音频轨道(或其他类型的音轨)。同样值得注意的是,RTP协议不指定传输它所需的IP层（IPv4或IPv6）。 RTP使用两个连续的端口为流的每个轨道。一个端口是用于携带内容(比如视频轨道),第二个主要(服务器端口)作为一种反馈机制报告质量和包丢失。即时启动QuickTime流媒体使用RTCP反馈机制。

From a network programming point of view it is worth noting that RTSP over TCP means that there is no loss of signalling packets (losses in the network lead to resends of data), but audio and video content can be lost as the RTP packets are transported over UDP. UDP is a protocol that has no inbuilt mechanism for resend of missed packets.

从一个网络编程的观点来看，值得注意的是,RTSP越过TCP意味着没有信号的数据包损失(损失网络导致的重新发送数据),但是在 RTP数据包越过UDP被运输时音频和视频内容会丢失。UDP是没有内在机制来支持丢失的数据包重发的协议。

For my work I chose to ignore the use of RTSP/RTP over HTTP. Partially this was due to lack of clients, but also due to the inherent extra bandwidth consumed by the HTTP protocol. It was not seen as worth pursuing as it increases the bandwidth requirements of the streaming video without increased reliability.

对于我的工作我选择忽略通过HTTP使用RTSP和RTP。部分原因是由于缺乏客户,但还由于通过HTTP协议所消耗的固有额外的带宽。它不被视为值得追求的，因为它增加了视频流的不可靠性提高的带宽要求。

For mobile devices on a 3G network, bandwidth minimisation is important, as telephone network operators usually charge on a per byte basis. Using HTTP does have some convenience when dealing with firewalls, which is why the streaming server supports it. The DSS server software is part of the Apple Open Source software initiative, which has led to numerous groups choosing to use it as a platform for networked streaming video research. The proxy provided with the DSS server is very limited and was the basis for the IPv6 proxy.

对于3G网络的移动设备，重要的是带宽最小化，电话网络运营商通常在每个字节的基础上收费。使用HTTP在处理防火墙时确实很方便,这就是为什么流媒体服务器支持它。DSS服务器软件是苹果开源软件项目的一部分,这导致了许多组织选择使用它作为网络视频平台的研究。DSS提供的代理服务器是非常有限的，是以IPv6代理作为基础。