Flash大师: Streaming with DVR Controls

有一个Flash视频问题? Let 斯特凡•里希特, the Flash guru, help you out. In this monthly series, Richter will answer Flash questions sent in by StreamingMedia.Com阅读器或来自流媒体论坛.

斯特凡•里希特里希特是 Muchosmedia, a UK-based software firm specializing in rich Internet applications. The company works for an international client base that includes ITV, 联合利华, 泰特现代美术馆, and recently launched its first product, Scribblar, an online collaboration tool which is proving popular in the eLearning community. Richter also maintains his personal blog, the popular FlashComGuru.

Stefan's first question this month was e-mailed from Kuldeep:

I am looking for a delay solution after the encoding is done using FMLE for a live event. The way I was approaching is publishing a live stream with DVR option to the local FMS, republish the same stream after 2 minutes to another application on same local FMS using NetStream.播放("streamname"， 0， -1). 我做不到. If I republish the stream after 2 minutes (thinking that the stream will be 2 minutes delayed), it plays for only 2 minutes and stops. This is happening because on republish, the application picks up what is written to the disk and plays only that much and the stream dies.

Can you please suggest me how should I solve this problem?

This questions pops up quite regularly, 斯蒂芬说, and you're on the right track You're doing what he would try, although he's not sure why you would try to republish the stream, since the DVR option itself should be enough. Simply publish your stream with DVR enabled.

When clients request that stream, their request will automatically seek back two minutes. Don't allow the client to seek forwards or backwards; this way you'll get the delay you want.

While Stefan hasn't tried this, he says it's also possible to do the same thing manually. Record the stream and republish it with a delay, doing basically what the DVR option does. 看看这个博客查看代码示例. Try one solution or the other, but don't mix them. 听起来那是你的问题.

Stefan's second question was e-mailed by DGL:

How does HTTP 在线直播 work step by step? And the main difference to FMS, beside the server install and license? Which encoder will broadcast the HTTP live stream?

The HTTP 在线直播 workflow is almost identical to the RTMP streaming workflow, 斯蒂芬说. You're not actually publishing in HTTP; publish as you would normally to Flash Media Server using RTMP. It's the server itself that turns your work into an HTTP stream. The server is a live packager and does its work on the fly. You'll need Flash Media Server 4 to do this, and you'll need the more expensive version.

For live HTTP streaming, you'll use the Adobe Flash Media Interactive Server. The pure streaming server won't work for this. 来测试一下, you can use the free development server, although this is limited to 30 minutes of streaming. 这里有一个 Adobe的链接这应该可以帮助你开始.

Stefan's third question was asked in the forums by Plugues:

Is there a known software that implements a virtual video capture device?

I plan to use a single computer to play video files from a playlist outputting to this device, and to encode and stream with encoding software in real time capturing from the same virtual device. 这是一种“视频循环”."

在理想的情况下, my encoding software would have playlist management with on-the-fly alterations, 但事实并非如此, 所以我想到了这个.

Check out Adobe Visual Communicator 3, 斯蒂芬说, which is a sort of production studio in a box. You can use it to capture video, overlay graphics, add titles, and mix in music. It even works as a teleprompter and can stream live broadcasts. Use it to publish to Flash Media Server and stream your video.

Submit your Flash video questions to 流媒体's 格式、编解码器和播放器 forum, or send them directly to the author at tdreier@nkgx.net.