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What is the Video Bitrate?

What is the video bitrate

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When we watch TV shows, play games, or stream online videos, we definitely want good-quality videos. Poor video quality can be annoying and unenjoyable.

When we talk about video quality, we usually just focus on resolutions, such as 1080p, 4k, or even 8K. right? However, that does mean you’re overlooking nearly half the issue.  you are right, it’s bitrate. 

Some people are familiar with the term “bitrate,” However, they don’t realize how important this metric actually is to video quality. The term “bitrate” might sound like it belongs in a technical discussion about video compression algorithms. But it actually refers to something very important to you, So what exactly is bitrate? And why does it matter? Let’s take a look.

What is Video Bitrate?

Bitrate (bitrate or as a variable R) is the number of bits that are conveyed or processed per unit of time. When we talk about bitrate, we’re referring to how much information is stored in each individual frame of a digital video file. Each video frame contains hundreds of thousands of pixels. For example, when you record video, those pixels are converted into electrical impulses that are sent along wires to a recorder, where they are turned into bits of information that are saved onto a hard drive. Those information are called bitrate. 

We can set up different bitrates for the same video for different applications. A higher bit rate usually indicates a better quality, which is commonly used for sports broadcasts, games, and other applications where there’s a strict need for high quality, while for most online video streaming services, lower bitrates are usually preferred. 

What is Video Bitrate?

Bitrate is the number of bits that are conveyed or processed per unit of time.

How is Video Bitrate Measured?

Bitrate (bitrate or as a variable R) is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), which is commonly abbreviated as bps.

Normally, we have different measurements to describe the bitrate for audio and video files.

Audio bitrate is measured in kilobits per second (kbps), whereas the same value doesn’t apply to videos because their sizes are significantly larger; video bitrate are measured using megabits per second(Mbps).

kilo (1 kbit/s = 1,000 bit/s), mega (1 Mbit/s = 1,000 kbit/s), giga (1 Gbit/s = 1,000 Mbit/s) or tera (1 Tbit/s = 1,000 Gbit/s).

For example, a 1080p60fps HD movie has a bitrate of around 8 Mbps. This means 8 million bits of data are sent across the wire to play the video every second, 1 Mbps is used to mean one million bits per second.

Sometimes people confuse megabits per second (Mbps) and megabytes per second (MBps).

Megabits per second (Mbps) refer to the speed at which internet traffic travels through the network, while megabytes per second (MBps) define the size of the file that has been transferred.

How is Video Bitrate Measured

Megabits per second (Mbps) refer to the speed at which internet traffic travels through the network.
Megabytes per second (MBps) define the size of the file that has been transferred.

Variable Bitrate vs Constant Bitrate

Video Bitrate can be divided into constant bit rate (CBR) and variable bit rate (VBR).

Constant Bit Rate (CBR) encodes are used for streaming video because it does not vary in size based on how much data there is in a given frame. By contrast, Variable Bit Rate (VBR) encodes do compress frames differently depending on how many bits there are in each frame. VBR encodes tend to use more bandwidth, but give you better quality overall.

Variable bitrate (VBR) encoding is one of the most common types of video codecs used today. In fact, it’s the default option for almost all popular video editing software. However, VBR isn’t always the best choice for everyone. If you want to make sure that the quality of your videos doesn’t suffer, you might want to consider changing your setting to constant bitrate (CBR).

Unlike CBR, VBR takes into account how much data is needed for each single frame. So while CBR allocates the same amount of bits per second for every frame, VBR does exactly what its name suggests – it varies the bitrate depending on how many frames are encoded. For example, if there are 10 frames in a 30-second clip, the VBR encoder will allocate 2.5 Mbps for the first frame, 3.0 Mbps for the second, 5.0 Mbps for the third, 8.3 Mbps for the fourth, 12.3 Mbps for the fifth, 16.7 Mbps for the sixth, 25.1 Mbps for the seventh, 33.9 Mbps for the eighth, 50.2 Mbps for the ninth and 67.8 Mbps for the tenth.

The difference between CBR and VBR becomes obvious once you watch a movie or play a game where the camera moves around a lot. You won’t notice any problems with VBR because the bitrates change dynamically based on the scene. But if you use CBR, you’ll see some stuttering during fast movements.

Video Bitrate vs Video Quality

Bitrate refers to the number of bits per second used to compress a file. A higher video bitrate always means higher video quality. Bitrates, resolution, and frame rates all contribute to the high-quality video.

High-resolution video requires a high bit­­­­­­­­­­­rate ­to maintain smooth playback.

Increasing the bitrates of videos will improve their quality, but only up to some extend, however, if the video resolution is very low, it will look poor no matter how high the bitrate is.

To achieve the highest possible video quality, bitrate, resolutions, and frame rates must all be well-adjusted.

When the resolution keeps the same, If you’re looking for a way to improve the quality of your videos, increasing the video bitrate is often the best solution.

So a higher resolution is always better, right? Well, not necessarily. Higher resolutions means sharper images, but they also mean bigger data requirements. The larger the image, the more bandwidth it takes to transmit it across the internet, if the internet speed is not enough, the larger of the videos, the more buffering problems it might cause.

A higher video bitrate also means that a video takes up more space. This could affect both the size of your files and the amount of storage space needed to store those files. In addition, higher bitrates mean that your streams take longer to download.

Bitrate vs Bandwidth

As we stated above, a higher video bitrate normally means higher video quality, but a higher bitrate also requires high bandwidth. That means the bitrate has to meet the bandwidth requirement. If the bitrate exceeds the bandwidth, there will be buffering problems.

So is any chance to lower the video bitrate but keep the same video quality?

Yes, that’ the magic of compressed video. Compression is the process of converting digital files into smaller ones so they take up less space.

Compression offers several benefits, including:

  • Smaller file sizes
  • Lower storage requirements
  • Lower bandwidth requirements for transmission

For video compression, most commonly used formats include H.264 and H.265. H.265 is a newer video codec than H.264. It provides better quality at lower bit rates. HEVC (H.265) enables greater compression than HV4P3 (H.264), meaning that fewer bits need be stored to represent the same number of images.

Resolution H.264/AVC H.265/HEVC
Bandwidth required Bandwidth required
480p 1.5 Mbps 0.75 Mbps
720p 3 Mbps 1.5 Mbps
1080p 6 Mbps 3 Mbps
4K 32 Mbps 15 Mbps

Let’s take Youtube as an example.

Both Upload speed and download speed can be measured by bitrate.

Uploading is the act of transferring data from your device to the internet. Downloading is the process of getting data from the internet to your device.

Higher bitrates mean more information and better video quality.

For example, as we stated in the above table, a video bitrate of 6Mbps for 1080P resolution means good video quality if we use H.264 compression standard. However, if we use H.265 compression standard, 3Mbps is enough for the same video quality, which has a much lower requirement about the bandwidth.

What is the best Video bitrate?

As mentioned above, there are different types of bitrates, which range from 10 Mbps to over 200 Mbps.

However there is no best bitrate, which are determined by your application, chipset performance and budget. If you want to know what type of bitrate you should use, here’s a quick guide:

• If you want to upload your video to YouTube, Facebook, Instagram, Vimeo, etc., you’ll want to keep the video bitrate around 2-4 Mbps.

• If you’re planning on making a DVD copy of your video, you’ll want the video bitrate to go up to 5-8 Mbps.

For more information about bitrate, please refer https://en.wikipedia.org/wiki/Bit_rate

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