The Flash Guru: Streaming with DVR Controls
Got a Flash video question? Let Stefan Richter, the Flash guru, help you out. In this monthly series, Richter will answer Flash questions sent in by StreamingMedia.com readers or from the Streaming Media forums.
Richter is the founding director of Muchosmedia, a UK-based software firm specializing in rich Internet applications. The company works for an international client base that includes ITV, Unilever, and the Tate Modern, 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.Play ("streamname", 0, -1). I am not able to do the same. 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, says Stefan, 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. Check out this blog post for code samples. Try one solution or the other, but don't mix them. It sounds like that's your problem.
Stefan's second question was e-mailed by DGL:
How does HTTP Live Streaming 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 Live Streaming workflow is almost identical to the RTMP streaming workflow, says Stefan. 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. To test it out, you can use the free development server, although this is limited to 30 minutes of streaming. Here's an Adobe link that should help you get started.
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. It's a sort of "video loop."
Ideally, my encoding software would have playlist management with on-the-fly alterations, but it doesn't, so I thought of this.
Check out Adobe Visual Communicator 3, says Stefan, 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 Streaming Media's Formats, Codecs, and Players forum, or send them directly to the author at firstname.lastname@example.org.
In this month's installment, Stefan Richter answers questions about Flash and HTTP streaming, sending Skype video with Flash, and building a Flash server
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