第一眼:Flash Media Server 4

[Editor's Note: Want to learn more about what's new in Flash Media Server 4, right from the source? 流媒体的丹·雷伯恩主持了一个问题&9月10日(周五)下午2点，与Adobe的凯文·陶斯(Kevin Towes)举行了一次会议.m. ET的下一部分流媒体的问Adobe Web事件系列. 点击在这里注册.]

Remember those late-night infomercials w在这里 you're guaranteed to add bulk and muscle to your skinny frame? 如果你现在买, they'll also throw in another supplement-free of charge-that guarantees you'll lose weight, 不管你吃什么?

虽然这些类型的报价已经成为许多笑话的笑柄(以及一些诉讼), 这个前提已经足够支撑这些广告多年, even as technology has advanced: From their start in the classifieds section of magazines such as 科普深夜电视节目, 最后, 进入你的垃圾邮件文件夹, 这个前提触及了一个近乎普遍的愿望，那就是让自己变得更好, 无论是通过增加肌肉, 减肥, 或者两者的结合.

Adobe is making a similar offer, although it's studiously avoiding late-night television. 这个提议是这样的:增加我们新的旗舰服务器的容量, Flash Media Server 4系列的一部分, 以高昂的价格升级, and we promise your media delivery budget will go on a bandwidth diet as soon as it's implemented.

听起来好得令人难以置信? After a first look at the Flash Media Server 4 (FMS 4) family of servers, the offer appears valid.

But don't take our word for it: Stay tuned for a testimonial later in the article from a large technology company that put the FMS 4 premise to the test.

构建块
就像我们深夜减肥广告的例子一样, 哪里需要的不仅仅是饮食补充剂来减肥, FMS 4 works hand in hand with several key product rollouts that have become available over the past few months.

允许FMS 4的功能，如快速切换和融合, 我们将在下一节重点介绍, Adobe需要在整个生态系统中进行升级, 从内容保护和HTTP传输到更新的播放器.

破译所有这些推出的时间有点令人费解, 因为每个产品更新似乎都需要另一个尚未准备好黄金时间的产品.

For instance, Adobe could have launched Flash Media Streaming Server (FMSS 4), which supports RTMPE. 但是持久加密, used in Flash Media Interactive Server (FMIS) and Flash Media Enterprise Server (调频) in conjunction with Flash Access, 是否需要额外的工具.

"The move from session encryption with RTMPE to persistent encryption with Flash Access 2.0是关键,弗洛里安·佩斯托尼说, Adobe富媒体解决方案的主要产品经理, 当Flash Access推出时. "Many content owners may choose to download content to AIR-based rich internet applications for offline viewing. 自Flash Access 2以来.0内容将在Flash Player 10上播放.1及AIR 2.0, persistent encryption is an important step toward making offline players ad在这里 to licensing and DRM concerns."

Flash Player 10.在Flash Access 2发布时，1还处于测试阶段.以及HTTP动态流媒体(又名项目西利). Both 最后 launched in June, but HTTP动态流 only supported on-demand content.

FMS 4的出现, 然后, is meant to addresses all aspects of the ecosystem: HTTP动态流 for live encoding, 结合快速切换, 和层云, Adobe's peer-assisted networking for its new Real-Time Media Flow Protocol (RTMFP) delivery protocol.

对Stratus的支持是旗舰调频版本的一个关键卖点. While Stratus was renamed Fusion under FMS 4, the RTMFP protocol's inclusion in Flash Player 10.1意味着Stratus将启用组或用户细分, 仅在组成员之间发送消息. 这是FMS 4实现Fusion的一个重要元素, as application-level multicast "provides one (or a few) -to[o]-many streaming of continuous live video and audio live video chat using RTMFP groups."

Flash Player 10之间的延迟时间.1's availability in mid-June and the October availability of FMS 4 was beneficial in one respect: The typical time for upgrading from one version of a Flash Player to the next can be measured in weeks, while a Flash Media Server can be set up in days; as such, Flash Player 10可能的安装基础.与FMS 3相比，现在能够快速切换的用户数量更高了.5.3.

FMS 4的出现 means that Adobe has almost finalized the move to its new ecosystem, with H.264硬件加速作为唯一仍在测试中的生态系统部分.

FMS 4有什么新功能
Adobe's Flash Media Servers have undergone a radical set of changes in the past few revisions. FMS版本2提供了大量的迭代. 但是Adobe将FMS 3的产品线精简为两个:FMSS和FMIS.

FMS 2和FMS 3之间的价格点也有所下降, 部分原因是竞争, FMSS的基本价格为995美元，4美元,FMIS是995美元. 在FMS 4中，两个低端服务器的价格点是相同的. 但是Adobe增加了第三台服务器, 调频, at a cost many times the FMSS price point; a spokesperson for Adobe says customers should contact the company for quotes.

那么这些额外的钱你得到了什么呢? 总之，多播. 但这不仅仅是传统的IP多播, 在FMIS的第4版中也有, but a combination of IP multicasting and what Adobe is calling application multicasting.

Adobe将这种组合称为融合，而其他人则称之为点对点多播. 不管它叫什么，它是调频的一个关键元素.

FMIS和调频中可用的其他特性包括HTTP流的集成, 直播和点播内容交付, 快速切换.

HTTP动态流
Those who have followed the advent of HTTP streaming delivery for on-demand content will remember Adobe launched a stand-alone HTTP streaming solution, 项目西利, 几个月前. 与它的自适应比特率分割解决方案, Adobe动态流媒体, 以及Adobe的独立内容保护服务器(Flash Access 2)的出现.0), the premise of 项目西利 was to allow progressive downloads to act like streaming delivery via the use of already prevalent HTTP caches and web accelerators.

我们内置了对所有Flash编解码器的支持,——凯文·托斯, Adobe的Flash Media高级产品经理, 在去年年底Zeri项目发布时指出, “包括H.264 vp6 h.263, HE-AAC, VP6, MP3, and all metadata that exists within the formats or live stream. 项目西利 will allow you to stream all the same content regardless if it is live or on-demand with no ... 更改为实时编码技术."

FMS 4的出现允许通过HTTP进行实时流媒体, w在这里 the 项目西利 prerelease version had only allowed on-demand content to be segmented into adaptive bitrate segments. 除了, FMS 4 will support both data pipe encryption (via RTMP-E) as well as persistent bit-level encryption, 当与Flash Access 2相结合时.0服务器.

快速切换
与HTTP流和Adobe动态流携手合作, fms4引入了快速切换的概念.

快速交换最初计划用于FMS 3.5.3. But it was delayed until the advent of FMS 4, in part because the launch of Flash Player 10.需要在客户端机器上支持快速切换. 快速切换使用Flash Player 10中的新功能.1和fms4，以减少自适应比特率段之间的切换时间. 因为用户不再需要等待缓冲区播放完毕, the decreased switching time means that an end user's Flash Player can more rapidly adjust to changing network conditions, 更及时地提高和降低质量, 同时保持不间断的播放体验.

RTMFP或Fusion
实时媒体流协议(RTMFP)非常重要, not just for Adobe but also for the enterprise users at which Adobe is targeting the 调频.

第一个, 让我们看看RTMFP技术，然后看看可能的实现, including a brief discussion of a prerelease test done by a Fortune 100 organization.

在Flash Player 10中提供.1及AIR 2.0 applications, RTMFP is Adobe's foray into User Datagram Protocol (UDP) transmission of content.

Unlike the more widely used Transmission Control Protocol (TCP) that Adobe's RTMP and many other streaming protocols are based on, UDP旨在以较低的延迟锤击家庭内容.

如果TCP和UDP是红脸/红脸喜剧的主角, TCP是比较友好的, 温和的性格衬托了UDP粗暴和霸道的风度.

TCP与其他协议一起工作以保证数据的传递, 授权保证其内容已完整到达, with the option of sending follow-up packets if a few packets went missing along the way. 像这样, TCP is ideal for data delivery when it comes to data that doesn't need to scale or isn't time-sensitive.

另一方面，UDP不能很好地与其他协议兼容. 它的“毫不留情”的方法意味着它可以让内容传递出去, 不管其他类型的内容堵塞了管道. 仍然, for wide-ranging or scalable implementations-especially those that require two-way communication-UDP is more effective that TCP.

TCP中可靠的数据传输是通过重新传输丢失的数据来实现的, 这就引入了延迟,Adobe在RTMFP的常见问题解答中说. "Because minimizing end-to-end delay is one of the most important goals in real-time communications (a few hundred milliseconds' delay may render a conversation unusable), TCP不太适合这个目的."

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