There are two important capacity values:
Storage -- how much disk space is available to hold your Video-on-Demand (VoD) files
Bandwidth -- how much bandwidth is available to deliver both live and VoD
Understanding Storage
The amount of storage needed for video on-demand files stored on a server is based on the bitrate and frame size the video is encoded at and the duration of the video. For example, a 1-hour video encoded at 500 Kbps will result in a file that is approximately 220 MB in size. A video encoded at 1 Mbps (or 1,000 Kbps) would generally be about twice that size, or 440 MB. At that rate, you will be able to store nearly 2,300 hours of video on a 1 TB drive.
Understanding Bandwidth
There are two ways to calculate bandwidth usage:
Simultaneous Bandwidth - How much bandwidth is needed at any given instant in time, or how many 1's and 0's are moving over the network interface.
Cumulative Bandwidth - How much bandwidth is consumed over a period of time, or how much total bandwidth is consumed by the system.
Simultaneous bandwidth usage for live streaming is calculated by using a straight-line calculation multiplying the bitrate of the live stream times the number of viewers who are currently watching. This is typically calculated in bits per second, or bps for short. Based on most networks, the available bandwidth would typically be measured in either Mbps (mebabits per second) or Gbps (gigabits per second. For example, if a live stream is encoded at 1 Mbps and there are 100 people watching, the amount of bandwidth being used by the server on the network will be 100 Mbps (1 Mbps X 100 simultaneous viewers).
When calculating live streaming bandwidth, keep in mind that the measurement uses bits, not bytes. Each byte is made up of 8 bits, so to convert a measurement such as Mbps to bytes, simply divide the number of bits by 8.
Cumulative bandwidth takes the simultaneous bandwidth used by each viewer's connection over time. Also, cumulative bandwidth is typically measured in bytes instead of bits. If the previous example was a live stream that lasted for 1 hour, the 100 Mbps of live bandwidth used per second would cumulatively use 45 MB of bandwidth over that hour (100 Mbps x 60 seconds x 60 minutes / 8).
DEVOS on the Premises
For hardware servers on the premises, cumulative bandwidth is typically not a concern. The main concern on the premises is simultaneous bandwidth since every internal network has a maximum amount of available bandwidth that must be spread over all users and uses of the network. Typically, there are two maximum bandwidth limits on any network, which are as follows:
- Internal Bandwidth - the amount of bandwidth allowed for network traffic within the local area network (LAN).
- External Bandwidth - the amount of available bandwidth coming in to the network from the public internet and the amount of available bandwidth going out of the LAN to the public internet.
Typically, internal bandwidth limits are much higher than external bandwidth limits. This is one reason a DEVOS server on the premises provides for better control and scalability of usage within your LAN.
DEVOS Cloud
For DEVOS servers hosted in the cloud, both simultaneous and cumulative bandwidth apply. The DEVOS cloud-based solution is sold based on the size of the server and capacity desired. That means the available storage for video on-demand could be anywhere from 10 GB to 1 TB or more. As for simultaneous bandwidth, DEVOS in the cloud can typically support up to a maximum of approximately 2500 simultaneous live viewers depending on the bit rate of the delivered live stream or video on-demand video. DEVOS Cloud can support a virtually unlimited number of live viewers when used in conjunction with the Arcus hosted streaming solution for high volume live events.
For either DEVOS on the premises or DEVOS in the cloud, StreamPumps can be deployed at multiple local locations to mirror live streams and cache on-demand content locally to increase viewer capacity.
Calculating Bandwidth
Discover Video offers an easy-to-use bandwidth calculator to calculate both simultaneous bandwidth usage for live streaming and a file size calculator for video on-demand files. The bandwidth calculator can be found
here.