Video Bitrate Guide: What Is Bitrate & How To Optimise It
When planning video content or sitting down to stream live to an audience, it’s easy to get caught up in how your setup looks on camera, but there are actually arguably more important technicalities to consider. Whether you’re using a hardware or software encoder, your settings need to be spot on to ensure your videos are displayed to all viewers at the optimum resolution and don’t take years to load.
Video bitrate is just one of the components to think about, that can make or break a live stream. Zidivo explains what your bitrate is, how it affects your video quality and outline the ideal settings for a successful live stream.
What is video bitrate?
In a nutshell, video bitrate refers to the size of your video file. It’s an overall measure of the quality of your audio and video image, which in turn determines the size of your overall output. So, the higher the quality of your video output, the higher your overall bitrate will be and the stronger your internet’s bandwidth will need to be to accommodate this.
How to check video bitrate:
Video bitrate is measured using the number of bits per second (bit/s), with a ‘bit’ being the smallest amount of data that can be processed by a computer and bitrate being the number of bits that can be transmitted per second.
As bits are such a small metric, they’re usually measured in Megabits per second (Mbps) for video output and Kilobits per second (Kbps) for audio.
Video bitrate formula (bps) = Target pixel count/resolution x frame rate x 1/2/4 (depending on how dynamic your video is) x 0.07.
Essentially, your resolutions need to match your bitrate (or be near enough). For example, a common bitrate for a full HD video with standard resolution would be 3500-5000 kbps or 4500-6000 kbps for the same video with a higher resolution.
How does bitrate affect video quality?
If your video bitrate isn’t high enough, the quality of your video image will be limited and even impeded in some cases. Because of this, if you are planning to stream or upload a high-resolution video in 1080p or 4k HD, you will need to make sure your bitrate and therefore hardware has the means to cope with the demand. There’s no good attempting to share a video online in 1080p HD if your internet network isn’t strong enough to support this; your bandwidth should overcompensate for the quality you want to offer your audience.
If you are confident in your internet network and have multiple sources of connection at hand, you might assume that using the highest video bitrate possible is the way to go to offer the ultimate viewing experience. Actually, though, this can have the opposite effect. Think about your audience in terms of the types of devices they will be using, the strength of their average internet connection and whether this will support your planned 4k HD live stream. If not, you risk your videos buffering, being slow to load or even failing to play altogether as your viewers’ devices will have to work extra hard. Aim to find a happy medium by offering a high-quality video that doesn’t have huge file size and demand too much from the devices of your audience.
Video bitrate for streaming:
If you’re planning to broadcast or upload a high-resolution video online, find your estimated bitrates and divide this by the length of your planned stream in seconds, this will give you the average video bitrate for streaming your file.
Standard bitrate settings for live streaming:
- Video resolution: 1080p or above
- Variable or adaptive bitrate: On
- Video bitrate: 4,500 to 6,000 kbps
- Audio bitrate: 128 Kbps stereo
When streaming with a hardware encoder, always set your encoder to use a variable bitrate (VBR) if your settings allow this to make sure the quality of your video isn’t limited. This way, your encoder won’t use a set bitrate for the entire stream and will instead allocate higher bitrates to the more dynamic sections of your video content. For example, if there are parts of your stream where the setting changes or the people in the video move positions, your encoder will recognise this movement and ensure there is enough bitrate to offer these parts of the video in their utmost quality.
Although hardware encoding equipment is more reliable and is best for larger-scale live streams that involve multiple cameras, cloud transcoders have their own benefits too, such as adaptive bitrate streaming (ABS). Adaptive streaming allows you to offer multiple versions of your live stream, allowing viewers to choose the optimum resolution that their device or internet bandwidth allows. Rather than every viewer that tunes in being offered the same lower resolution stream, you can ensure that those that do have strong internet connections can watch your videos in the highest resolution possible. The result is improved viewing experiences all round!
As you can see, the settings of your video encoding equipment are just as important to get right as the look and feel of your streams, if you want to keep viewers watching and engaged. Zidivo’s team are at hand to answer any queries regarding the setup of a live stream or the uploading of an on-demand video, to make sure your entire audience can access and enjoy your content with no technical issues. Get in touch with us today or sign up for a free 30-day trial of the video platform to benefit from our advice.