Wednesday,Aug 27 2008, 01:54:49 PMImagination Web Design

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They say a picture is worth a thousand words. In this day and age of digital media, video on your web site can be priceless. Whether you have a corporate, social networking, or video streaming site, video instantly captures your visitor’s attention and describes your product and services quickly and effectively. Due to its large install base, Flash video is now the de-facto standard in internet video delivery. With recent updates to Flash 9, Flash Player adds the capability of playing H264 encoded video in full screen mode, making the delivery of Flash videos on the internet not only practical, but efficient as well. In this article, I will examine a few different techniques for delivering Flash videos over the internet and compare the advantages and disadvantages of each. HTTP Progressive Download If your video file is not encoded in one of Flash’s supported codecs, you will need to transcode your video. The Adobe CS3 Flash Professional development packages offer tools for transcoding video files into Flash-supported formats. Alternatively, you can use an open source tool such as ffmpeg. The simplest and most straightforward approach to delivering Flash video over the internet is using HTTP progressive download. To distribute a Flash video using HTTP progressive download, simply place Flash-compatible video files on your web server and point the Flash player to the URL of the video file. Delivering video using HTTP progressive download does not require any additional software or hardware beyond what is necessary for hosting a standard web site. A Flash video player is required for playing the video. There are quite a few good open source players that can be readily used. If your video is viewed by a large number of users, you probably want to deliver the video over a CDN (Content Distribution Network). HTTP progressive download can work with any CDN service. The disadvantage to HTTP progressive download is that the video content is loaded sequentially, meaning that the user cannot access a later part of the video until the video is completed. For example, a ten minute video may take a couple of minutes to download depending on the user’s bandwidth. If your user only wants to see the last minute of the video, they must wait for the first nine minutes to download before proceeding to the end. Thus, the first nine minutes of the downloaded video are effectively wasted. Another issue to be aware of when using HTTP progressive download is the lack of access privileges. Anyone can point their browser to the video file URL, download, and replay it on their local computer with a Flash compatible video player. In general, HTTP progressive download is a good solution if: • The video files being served are relatively short, e.g. less than 2 minutes long • The video content does not require access control • Your video content is served by online storage services such as Amazon’s S3 RTMP Streaming A more bandwidth-efficient and user-friendly video delivery method is RTMP streaming. RTMP is a proprietary protocol developed by Adobe. In addition to streaming video, RTMP can be used to broadcast live video streams and ingest live Flash audio and video. Streaming Flash video using RTMP requires the Adobe Media Streaming Server or Red5, an open source software package that implements RTMP. In general, RTMP streaming does require more up-front investment in terms of configuring media servers. However, with RTMP streaming, it is possible for a user to jump to different points in the video without having to wait for the entire video to be downloaded. In addition, only video data viewed by the user is delivered. RTMP streaming servers can also restrict access to contents served. So, for example, it is possible to create a pay-per-view service using RTMP streaming. Established CDN providers such as Akamai and Limewire Networks have specific services for optimized streaming of Flash-compatible video files. Use RTMP streaming if: • You need to have access control to the video content being served • The video content receives many views • You are broadcasting live video streams HTTP Streaming A hybrid of the two previous approaches to delivering video, that has some advantages of both, is HTTP streaming. HTTP streaming is based on the idea of HTTP progressive delivery, but it lets users jump to a specific point in the video. Popular web sites such as YouTube and Google Video use HTTP streaming to serve video over the internet. An HTTP streaming-capable server can start streaming from a specific keyframe if the video file is encoded with proper metadata. A commonly used tool for injecting metadata into flv files is flvtools. HTTP streaming does require server configuration in addition to the standard web server. Many open-source tools exist for HTTP streaming. If you are using lighttpd, simply install mod_flv_stream or mod_h264_stream to stream flv or H264-encoded Flash videos. Any web server that supports PHP can use HTTP streaming using PHP streaming. While HTTP streaming does let users jump to a different video quickly, it suffers some of the same drawbacks as HTTP progressive download. Video content may be downloaded without actually being viewed, resulting in inefficient bandwidth usage. In addition, HTTP streaming is not supported by storage services only capable of serving static content such as Amazon’s S3. So, use HTTP streaming if: • You are serving longer video • The video content does not require access control

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