Video bitrate is an essential aspect of video content that influences its quality and efficiency. It’s similar to the volume of water flowing through a pipe. Just as a high water flow produces a fast and powerful stream, a high video bitrate ensures sharper and more detailed visuals. On the other hand, content that has a low video bitrate will have poor quality video quality with less detailed (or sometimes blurry) visuals. The amount of data that goes behind displaying one second of video is known as the bitrate, which in common language is known as bits per second (bps).
In this blog, we’ll explore the various aspects of video bitrate and how it makes a difference in video quality and efficiency.
Understanding Video Resolution & Why it’s Important
Video resolution refers to the number of pixels that compose an image (or a video still) displayed on the screen. It’s the video resolution of any content that determines how detailed or clear the video is. The resolution it’s basically the area covered inside width and height, and is represented as width x height; for example, 1920 x 1080 (Full HD) or 3840 x 2160 (4K Ultra HD).
Picture a grid, made up of many small squares. Each of these squares represents a pixel. Collectively, these pixels form an image. Just like how a picture is made up of small puzzle pieces, a video is composed of millions of such small pixels. Now, the video resolution is like the size of the grid; the higher the resolution, the more the pieces of the puzzle, meaning a sharper image, and vice versa.
Everything You Need to Know About Video Bitrates
1. How is Constant Bitrate (CBR) different from Variable Bitrate (VBR)?
There are two ways to carry out audio and live video call encoding. One is Bitrate Control Rate and the other is Variable Control Rate. As it’s apparent from the names, both of these methods control the bitrate, and consequently the file size.
While the function of both these approaches are similar to each other, there are significant differences between VBR and CBR. Let’s delve a little deeper into what these differences are.
|As the name suggests, BCR is used in audio and video encoding to maintain a constant bitrate throughout the entire encoded file. It strictly enforces a fixed bitrate, making sure that the output is consistent throughout and in the process, it may potentially sacrifice quality during complex segments.
|As opposed to CBR, VBR (as the name goes) allows bitrate to dynamically change based on the complexity of the content being encoded. That means, for more complex parts, VBR allocates more bits maintaining a higher quality and vice versa.
|BCR strictly enforces a fixed bitrate throughout the entire encoded file, ensuring a consistent file size.
|VBR allows the bitrate to vary dynamically depending on the complexity of the content.
|Constant vs. Variable Quality
|BCR provides a consistent quality throughout the entire file, as the bitrate remains constant. This may be helpful in circumstances when maintaining a certain standard of quality is important.
|VBR provides a variable quality level by allocating bitrates more efficiently in accordance with the complexity of the information, resulting in better quality for complex portions and lower quality for simpler ones.
|Since the bitrate is predetermined, BCR encoding can be completed more rapidly since it does not need a thorough study of the video.
|The time required for VBR encoding could increase since it entails analysing the video or audio information to find the right bitrate for each part.
2. Which Factors Influence Video Bitrate?
When choosing the right video bitrate for a particular video file, several criteria are taken into consideration. To strike the correct balance between video quality, file size, and streaming needs, these aspects must be taken into careful account as they interact and have an influence on one another.
2.1. Resolution: Higher resolutions, such as 4K or full HD, typically require higher bitrates to maintain quality.
2.2. Frame rate: Higher frame rates, like 60 frames per second (fps), require higher bitrates to capture smooth motion.
2.3. Complexity of content: Videos with more motion, detail, or fast-paced scenes may require higher bitrates to avoid compression artefacts.
2.4. Compression technology: Different video codecs and compression algorithms can affect the efficiency of bitrate utilisation.
2.5. Encoding settings: The choice of encoding settings, such as the type of encoding (CBR or VBR) and the target quality level, affects the required bitrate.
2.6. Audio quality: Higher bitrate settings for audio can increase overall video bitrate.
2.7. Platform or streaming requirements: Specific platforms or streaming services may have bitrate limitations or recommendations that need to be considered.
2.8. Target audience and device capabilities: Bitrate should align with the connection speeds and device capabilities of the intended viewers.
By understanding and optimising these factors, content creators and streaming platforms can ensure an optimal viewing experience for their target audience.
3. Understanding the Ideal Bitrates for Different Video Resolutions
When it comes to video resolutions, it’s important to consider the recommended bitrates for optimal quality and smooth playback. From standard definition to ultra HD, here are the suggested bitrates for various resolutions.
3.1. Standard Definition (480p)
Recommended bitrate: 2.5 Mbps – 4 Mbps
It needs at least 2.5 to 4 Mbps for a video quality that can be considered standard definition.
3.2. High Definition (720p)
Recommended bitrate: 5 Mbps – 8 Mbps
High definition videos need a bitrate between 5 to 8 Mbps to stream for a smooth viewing experience.
3.3. Full HD (1080p)
Recommended bitrate: 8 Mbps – 12 Mbps
Along with a good internet speed, you need 8 to 12 Mbps in order to have a seamless viewing experience.
3.4. Ultra HD / 4K (2160p)
Recommended bitrate: 15 Mbps – 25 Mbps
For incredible sharpness like in video games you need bitrate anywhere between 15 and 25 Mbps.
4. Techniques for Optimising Video Bitrates
Bitrate optimisation techniques are methods used to enhance the efficiency and quality of video streams by manipulating the bitrate. These techniques include:
4.1. Adaptive Bitrate Streaming (ABR)
Adaptive Bitrate Streaming (ABR) is a technique that alters the video bitrate in real time, like YouTube and Netflix, based on your internet connection or speed so you continue watching the content despite a slow or faulty internet connection.
4.2. Two-Pass Encoding
Two-pass encoding is a process where the video is encoded in two stages. In the first pass, the video analysis phase occurs, gathering information about the video’s characteristics and complexity. In the second pass, the actual encoding takes place using the gathered data. This process is like creating a detailed blueprint of a building before constructing it. By analysing the video beforehand, two-pass encoding optimises the compression process to achieve better video quality and smaller file sizes.
4.3. Codec Selection
The codec selection involves choosing the appropriate coding-decoding algorithm for video compression. Codecs are like language translators that convert video information into a compressed format. Choosing the right codec ensures efficient compression while maintaining video quality.
4.4. Constant Rate Factor (CRF) Encoding
Constant Rate Factor (CRF) encoding is a method that controls video quality while maintaining a consistent file size. It determines the compression level by adjusting the bitrate for different sections of the video automatically. CRF encoding ensures a balance between file size and video quality, resulting in efficient storage and streaming.
The Significance of Video Bitrate: Understanding Its Importance
Video bitrate, as mentioned earlier, is a critical aspect of video encoding and streaming that significantly impacts the quality and viewing experience. Understanding the importance of video bitrate is crucial for content creators, streaming platforms, and viewers alike. Let’s delve into the key reasons why video bitrate holds significant value in the realm of video content:
1. Video Quality and Viewing Experience:
Video bitrate directly influences the visual quality of a group video call. By utilising higher bitrates, video content creators can provide users with an engaging and immersive viewing experience that enhances the overall quality of the content.
2. Bandwidth Efficiency:
By managing the bitrate to match the available network conditions, content providers can ensure smooth video streaming without interruptions or buffering issues. This is particularly crucial for delivering a seamless viewing experience across various devices and network connections.
3. File Size and Storage Requirements:
Higher bit rates generally result in larger file sizes, requiring more storage space and longer transfer times. Video content can be stored, transferred, and managed more effectively when the bitrate is balanced, in order to reduce file size without compromising video quality.
4. Video Distribution and Streaming:
Different platforms and networks have specific requirements for video bitrate. Adhering to these requirements ensures compatibility and optimal video streaming performance across various platforms, whether it’s streaming services, social media platforms, or video conferencing applications.
5. Compatibility and Platform Requirements:
Video bitrate is an essential consideration to ensure compatibility across different platforms and devices. Each platform may have specific bitrate constraints. Adapting the video bitrate to meet platform requirements increases accessibility and ensures viewers can enjoy the content seamlessly.
6. Video Editing and Post-Production:
Bitrate is significant during video editing and post-production processes as well. Higher bitrates preserve more visual details and provide greater flexibility for editing, colour grading, and other enhancements. Having an ample bit rate during the production stage enables content creators to optimise the final output and deliver high-quality videos.
It is crucial to understand what video bitrate will work the best for your content and then optimise it accordingly to create high-quality content. This is important to provide users with an experience they are paying for. By considering factors, including resolutions, frame rate, complexity of the content and platform requirements, you can bring about the right balance between video quality, file size and bandwidth efficiency. And at last, implementing bitrate optimisation techniques can further enhance the efficiency and quality of video streams.