Budgets: Bandwidth and Transfer Rates
Flash-based video offers a unique experience for Web site visitors to view a wide range of video content: full episodes of TV shows, movie trailers, how-to videos and tutorials, music videos, home-grown video clips, and more. As long as Flash Player 6 or newer is installed on the user’s computer, you can serve some type of video for their enjoyment.
But all video, regardless of whether its format is Flash-compatible video, has a financial price. Depending on your content length and audience, the additional cost of hosting and serving video can range from zero to thousands—if not millions—of dollars per month. The more popular your video content, the more likely you’ll need to pay extra hosting fees on top of your regular bill. Let’s look at how you can estimate how much video deployment could end up costing you.
Before you encode your video content, you should determine how much of your site budget will be used for video and estimate how much traffic you want to accommodate.
Real-time streaming video
To calculate the average transfer rate of real-time streaming video from your site per month, use the following formula for each video file to determine the number of bytes:
( Bit rate in bps 8 ) Average viewing time in seconds Viewers
So, if you have 3,000 users (100 users a day over a 30-day period) watching a 500 Kbps video clip for an average duration of 3 minutes, the Flash Media Server (or equivalent streaming video service provider) would have streamed around 31.4 GB of data:
(500,000 8) 180 seconds 3,000 = 33,750,000,000 bytes = 32,186 MB = 31.4 GB
Depending on your service plan, this one video clip could cost you more than $150 per month.
To calculate the average transfer rate of video from a Web server per month, use the following formula for each video file:
File size of video clip Viewers
If 3,000 users (100 users a day over a 30-day period) watch a video clip that is 35 MB (roughly 500 Kbps at 10 minutes in length), the Web server streams around 102.5 GB of data:
35 3,000 = 105,000 MB = 102.5 GB
Depending on your Web hosting plan, this one video clip could cost you anywhere from $3 to $10 a month to host with popular Web hosting packages.
Why should you use the total file size for the progressive video calculation and not the average time watched by the viewer? Remember, with progressive video file formats, after Flash Player begins to download the video file to the browser cache, it doesn’t stop. The file continues to load in the background while the viewer watches the content. Regardless of how much of the video the viewer watches, the entire video file might download to the cache—unless the viewer unloads the Flash movie and continues to another Web page or closes the browser window.
Bottom line: estimate your transfer rates
Regardless of which method of delivery you use for your video content, prepare transfer estimates so you can forecast how much of your budget you need to allocate to video. If you’re developing Web video for a business client, include these data-transfer estimates in your project plans. Each client will have a different hosting agreement with their CDNs, and those agreements vary dramatically based on the size of the company, the size of their audience, and the type of content they’re providing.