As I field questions from potential customers about adding video to their digital asset management system, I tend to field the same type of question. “I have a QuickTime file. Is that good?” That is really a loaded question. The next statement is….”It is 100 Megabytes. Is that good?”
I will attempt to explain how video bandwidth is the intersection where time length avenue and storage size street cross. Unlike an image file, video is a time-based media. It not only has a resolution, but it has a time length, over which the resolution is maintained. Compression is used to help keep quality up and files size down, but that is for another blog topic.
“Storage” is static….a 100 MB video file sitting in your video asset management system is much like a one gallon bucket of water sitting on a counter. “Bandwidth” has motion to it. If the video is 1 minute long, and you are watching it online, your internet connection (or pipe) will have exactly 60 seconds to pull through 100 MB of data. If we think of the water in the bucket, we will poor that water into the sink. The opening of the drain will need to be wide enough to let exactly 1 gallon of water through its opening in 60 second. Anything less will result in stuttered playback of the video.
Therefore, “bandwidth” is simply storage size divided by the total run time (TRT). For example, let’s say 10 people want to simultaneously watch a 7.5 MB (storage size), 60 second video (TRT). One thing to note is the difference between Megabyte (MB) and Megabit (bit). Storage is usually expressed in Bytes, and bandwidth is usually expressed in bits per second (bps). Note the use of lower case and upper case letter “b.” Also, there are 8 bits in one Byte.
Here’s the math for our example:
7.5 MB (total file size) ÷ 60 seconds (TRT) = 0.125 MBps X 8 (there are 8 bits in one Byte) = 1 Mbps (bandwidth)
1 Mbps is the “bandwidth” of the video. If 10 people simultaneously watch the video, you will need 1 Mbps X 10 people = 10 Mbps worth of available bandwidth for all 10 people to watch the video without stuttered playback. If we convert this to water in the sink, we would have 7.5 MB (file size) X 10 = 75 MB worth of water in the sink. The drain opening would need to be sized to allow 10 Mb of water through the drain per second (or 10 Mbps). This would allow all 75 MB worth of water to flow through the drain in exactly 60 seconds.
Your video asset management system may have enough storage to keep every video asset you have, but do you have enough bandwidth to facilitate the number of viewers you may have?
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