What is Video Bandwidth?
Video bandwidth is a metric in streaming that describes the amount of data that can be transferred per time. Bandwidth refers to both the capacity of your server in terms of how much stress and traffic it can handle and how much data you actually used. Understanding video bandwidth will help you understand the cost of streaming.
It is important to have an understanding of video bandwidth because bandwidth usage is one of the main costs associated with live streaming setups. Generally speaking, the more you stream, the more bandwidth you use. However, other factors influence bandwidth consumption. We will take a close look at these factors later on in this post.
Metrics Related to Bandwidth for Broadcasting
Before we get further into video bandwidth, it’s important to understand the different metrics and settings. These are different things that you can control at the encoder level.
Let’s shift gears to check out a couple of related metrics that are important to understanding bandwidth’s role in live streaming, including bitrate, frame rate, and resolution.
Video bitrate is the amount of data transferred over the internet at any given time. In layman’s terms, bitrate is the speed that your video files travel from the server to the internet.
Bitrate is measured in bits per second (bps), kilobits per second (kbps), and megabits per second (Mbps).
In the context of online video streaming, bitrate affects the overall quality of your live stream. Higher bitrate settings will yield higher resolution streams. That said, streaming at a higher bitrate consumes a larger amount of bandwidth.
Frame Rate
Every video is made up of a series of still images called “frames.” These still frames move quickly to create a fluid appearance that becomes a video.
Frame rate is the speed at which each frame is shown. This metric uses the units frames per second (fps). The minimum frame rate for live video streaming is about 30 fps.
If you are streaming videos with a low amount of action and motion, you can get away with a lower frame rate. However, high action streams, like sporting events, require a higher frame rate.
Frame rate and bandwidth consumption are directly correlated. The higher the frame rate, the more bandwidth you’ll use.
Video Resolution
Use your required resolution, to calculate your expected bandwidth usage and come up with an appropriate budget.
Video resolution is the measurement of a video’s width by height in pixels. For example, a video with a 2560 × 1440 aspect ratio would measure 2560 pixels along the bottom and 1440 pixels in height.
Video resolution is determined by a few things. First, it is determined by the camera that it is captured by. When it comes to a specific stream, however, it is determined largely in part by your encoder settings, such as bitrate and frame rate.
Higher resolution videos require more bandwidth to stream since they are larger files.
How to Calculate Bandwidth Usage for Video Streaming
There are a few factors that go into calculating bandwidth usage for video streaming. The primary factors include how often you will stream, how long you’ll stream, how many viewers you’ll have, and what bitrate you stream in.
Dacast offers a video bandwidth calculator that allows you to plug these criteria in to generate an estimate of how much bandwidth you’ll need each month and approximately how much that will cost.
How Much Bandwidth is Required for Video Streaming?
As we discussed, bandwidth usage depends on a number of factors, so there is not an all-encompassing answer to the question of how much bandwidth is necessary for streaming.
In order to give you a better understanding of how much bandwidth is required for streaming, let’s take a look at a few different hypothetical streaming scenarios and how much bandwidth they’d require.
1. Low Bandwidth Usage
For this example, let’s assume you’re streaming live lectures to your college students.
You’re not too concerned about streaming at a high resolution since you’re simply streaming from your webcam in your office. In order to stream live video in standard definition, your average bitrate will be around 0.8 to 1.2 Mbps.
Your class has 30 students, and your lecture will last an hour. Each lecture you stream with these specs will use between 11 and 17 GB of bandwidth.
2. Average Bandwidth Usage
Now, let’s assume that you’re streaming a city council town hall. This sort of event also requires a moderate video quality, so a bitrate of 0.8 to 1.2 Mbps will suffice.
If the event is an hour and a half long and 200 constituents tune in, you can count on using 108 to 162 GB for this stream.
3. High Bandwidth Usage
For this example, we’re streaming a very popular concert. High-resolution streaming is a must since fans are paying for access to his event and their expectations are high. They want to feel like they are there.
In order to achieve an HD stream, you’re going to want to use a bitrate of at least 1.9 Mbps. If 20,000 people tune in and the concert lasts two hours, you’re looking at using 36,765 GB of bandwidth.
How to Control Bandwidth Consumption
Bandwidth consumption can be controlled at the encoder level.
One of the best ways to control bandwidth consumption without limiting your number of viewers or abiding by strict time limits is to reduce the resolution that you’re streaming at. That said, it is important to note that streaming in a lower resolution makes more sense in some situations than it does in others.
For example, if you’re streaming a sporting event or concert that would benefit from feeling more lifelike, you may want to absorb the cost of the bandwidth for the sake of producing a full high definition stream. On the other hand, a lower quality would suffice for lectures for a college course or an internal training video.
Encoder Settings for Controlling Video Quality
You can control your bandwidth consumption by changing your video quality. For example, if you’re looking to conserve bandwidth, you might opt to stream in standard definition rather than full high definition.
Broadcasters can change their video quality by manipulating their encoder settings. Specifically, you’re going to want to focus on the bitrate and resolution settings. Reducing your bitrate and resolution will reduce the quality of your video, and your stream will consume less bandwidth.
Here are a few bitrate and resolution setting combinations that you can use to achieve ultra-low definition, low definition, standard definition, high definition, and full high definition streams.
Multi-bitrate streaming is streaming multiple renditions of a video to suit different viewers’ internet speeds. Paired with an adaptive bitrate video player, multi-bitrate streaming is designed to improve the viewer experience since it helps to avoid buffering and lagging.
Multi-bitrate streaming will affect your bandwidth consumption in the sense that streaming smaller renditions consumes less bandwidth and streaming larger renditions consumes more bandwidth.
However, since you likely calculated your anticipated bandwidth requirements based on an average bitrate setting, you don’t really have to worry about your estimate being too far off.