A Crash Course in Flash Video

使用这些新工具的唯一潜在缺点是它们需要Flash Player 9来查看. 然而，在撰写本文时，该版本的渗透率高达83.4% (according to Adobe) and growing daily. Adobe还提供了一个快速安装功能供您实现, 对于大多数访问者来说，如何快速无缝地升级.

Why Would I Want to Use Flash Video?
为什么选择Flash视频而不是其他视频格式为您的项目? There are a few good reasons:
• Good video quality. 当然，其他视频格式的支持者说他们的格式比Flash视频要好. However, when encoded well, 质量相当好，甚至被用于高质量的电影预告片和全长的在线功能. Besides, 大多数观众都不期望在网络上看到高清质量的视频(尽管Flash视频可以在高比特率下提供接近高清质量的视频).
• Interactivity. Buttons, overlays, dynamic features, user-applied bookmarks, 播放列表——所有这些东西都可以被编程到Flash视频播放器中. 在Flash中可以做的任何事情，都可以添加到视频应用程序中. Try that with RealPlayer, QuickTime, or Windows Media. 即使微软推出了用于视频和交互性的Silverlight, 如今，Flash仍然为开发人员提供了丰富得多的工具集.
• It just works. Nothing beats Flash for ubiquity. With a 98.视频播放器版本7及更高版本的渗透率为7%, no special codecs or plugins to download, and fully cross-platform compatibility, Flash is the clear winner in transparency and ease of use.
Since Flash Video players can be skinned so easily, 它并不总是清楚，你正在观看一个Flash视频文件. There’s one easy way to find out, however. 如果你在浏览器中右键点击(或者在Mac上按ctrl)正在播放的视频, and the dialog box says "About Adobe Flash Player . . . " you know that it’s Flash. (See Figure 1 for an example.)

Figure 1 (below). 你可以通过在浏览器中右键点击视频来判断视频是Flash.

How Do I Encode FLVs?
有许多将视频编码为FLV格式的选项. The commercial-grade solutions are:
• Sorensen Squeeze
• On2 Flix Pro
• Adobe Flash Video Encoder

这些应用程序可用于PC和Mac，并提供全套功能. You can add cue points, enter custom metadata, set up encoding profiles, and much more with these applications. Sorensen Squeeze和On2 Flix Pro在功能和编码速度上非常相似, 但提供一些具体的好处，可能会影响你选择其中一个. 例如，Squeeze具有健壮的批处理编码和分析功能，而On2的成本稍低一些. Both offer two-pass encoding, 哪一种编码比单次编码能提供更好的整体质量和文件大小优化. The Adobe Flash Video Encoder, which ships with the Flash authoring tool, 只提供单通道编码，但可以为大多数小型视频项目.

For those just getting started with Flash Video, or who have a limited budget, 有一个叫做RIVA编码器的免费工具，可以让你对AVI进行转码, MPEG, QuickTime, and WMV formats into FLV. 不幸的是，RIVA编码器仅适用于Windows，并且它使用单通道编码进行编码. But, hey, you can’t beat the price!

目前还有两种命令行编码器可以在服务器端将视频转码为FLV格式:ffmpeg (PC)和ffmpegX (Mac)。. 这些被用户生成的视频网站(如YouTube)广泛用于自动将上传的视频转换为FLV. Both of these tools are open source, and free.

How Do I Serve Flash Video?
有两种方式为你的用户提供Flash视频:渐进式下载或流媒体.
• Progressive Download. Progressive video is served from a standard web server. 像在浏览器中查看的任何其他文件一样，它被缓存并在下载时查看. 您不需要任何特殊的软件或服务器技术来通过渐进式交付部署Flash Video.
• Streaming. 流式传输使用RTMP(实时消息传递协议), rather than the standard HTTP, to send over the video file. 这听起来很复杂，但它实际上只是向浏览器发送数据的一种不同方式. It’s real time, as the name states, 这意味着视频数据是在接收到的时候显示的吗, rather than cached.
目前部署流媒体Flash视频有三种选择:
• Adobe’s Flash Media Server
• Wowza Media Server
• Red5

显然，首选是Adobe的Flash Media Server (FMS)。. FMS runs on Windows or Linux servers, and provides video and audio streaming, and two-way data sharing capabilities. With FMS and Flash, you can create applications such as live videoconferences, text chat, or pre-recorded video feeds. 甚至还有一个边缘源服务器可以处理大规模、高流量的视频流.

The Wowza Media Server is a commercial competitor to FMS. It has a fewer bells and whistles, but also allows for live or pre-recorded audio, video and data streaming. It’s more affordable than FMS, 它正在获得一些公司的支持，这些公司正在进入流媒体领域，但可能不需要FMS的所有功能，并希望节省一两美元. 它还可以在Windows和Linux上运行，以及其他平台，如Mac OS X.

Red5是一个流媒体Flash视频的开源解决方案. It’s also a whole lot more. It streams FLVs, yes, 但它也为定制化打开了服务器端开发的大门, which the other two options don’t do. There’s also a stripped-down version, 叫做Red5-minimal，它只提供流媒体功能，如果你需要的话. Red5和Red5-minimal可以编译为在几乎任何操作系统上工作. 如果你是一个服务器极客(或有一个工作人员)，Red5可能是一个很好的解决方案。. The best part? It’s free.

So, Should I Use Streaming or Progressive Download?
The answer depends on several factors:
• How long are your videos? 渐进式下载最适合短视频，一般为5分钟或更短. 流媒体视频最有效的方式是传送较长的视频，比如研讨会, feature-length films, or shorts.
•你是否需要让你的观众顺利浏览视频? 渐进式下载在导航方面有一些限制. 只有当你要查找的点已经下载到浏览器缓存中时，你才能在视频中向前查找. This means that you can’t jump to the middle of a video as soon as it loads; you have to wait until that video data is downloaded first. Streaming video, however, doesn’t have this restriction. Since you’re displaying the video data as it’s received, you can jump around as much as you like, 你会在你选择的地方开始接收视频数据.