Remember that video quality will not improve beyond a certain point (however high the bitrate). A higher bitrate video is *generally* of higher quality than a lower-quality video.Wrapping up, when we talk about bitrate, there are a few things to be aware of – This allows encoders to compress cartoons efficiently and produce great quality at low bitrates. This is because the motion is very low in cartoon videos, and flat surfaces are easy to compress. We can see that the images look quite similar to each other. Let’s look at the output for both bitrates. We take the popular Simpsons Trailer (1080p) for the next experiment and compress it at 2.5 mbps and 1 mbps using H.264/AVC (in FFmpeg) without changing the rest of the encoder configurations. When we use a bitrate of 5 mbps 1080p, the quality is excellent for the same video, when we use a bitrate of 1.5 mbps, the quality is quite bad for CrowdRun video.īut does a low bitrate always produce a poor-quality video? Let’s run a quick experiment to answer this question! It is obvious that the upper one is the lower bitrate, and the second image is the higher bitrate. From the screenshots of the videos below, can you tell me which is taken from the higher and lower bitrate videos? We’ve compressed a sample video (CrowdRun) using FFmpeg at 1.5 mbps and 5 mbps. What does the “rate-distortion tradeoff” mean? This is called the rate-distortion tradeoff in video compression. If you compress a video lightly, the file size is big, but the quality is great.If you compress a video heavily, you lose a lot of information, and the visual quality reduces.So, when you compress a video, you throw away some information at the expense of visual quality. But throwing away coefficients results in a loss of information and video quality – so you must carefully decide how many coefficients you want to discard.Throwing away coefficients reduces the amount of data needed to carry the video.Next, the transcoder discards many coefficients using a process called “Quantization.”.Click here to read an intuitive explanation of the DCT. So, a block of video is converted to a block of frequency coefficients. Several other transforms can be used, but for the sake of this article, let’s stick to the DCT. It converts blocks of video from the “pixel domain” to the “frequency domain” using the Discrete Cosine Transform or DCT.Video transcoding or compression does two important things – Understanding how bitrate affects video quality is important to understand how video compression or transcoding works. HEVC: Detailed Results Showing 50% Gains For Varying Content VVC, EVC, LCEVC – MPEG’s New Video Codecs.Discrete Cosine Transform in Video Compression – Explain Like I’m 5.What is Essential Video Coding (EVC) MPEG-5 Part-1?.Explanation of the Block-based Transforms in VVC (Versatile Video Coding).To learn more about video codecs, here is a list of transcoding-related articles on OTTVerse. If you are new to video transcoding, read this article to understand the basics of video transcoding. Capped VBR or Capped Variable Bitrate: the video quality is kept constant while allowing the bitrate to fluctuate within a limit or cap.Ī detailed discussion of these rate control methods can be found here, here, and here (using FFmpeg) on OTTVerse.VBR or Variable Bitrate: the video quality is kept constant while allowing the bitrate to fluctuate.CBR or Constant Bitrate: the bitrate is kept constant while sacrificing video quality.If your video has a frame rate of 60 fps, and a bitrate of 3 mbps, then a Rate Control Algorithm in the transcoder decides how to distribute the 3 megabits between 60 frames of video. Bitrate and Rate Control AlgorithmsĪ transcoder uses a specialized algorithm called a “rate control algorithm” to decide how the bit-budget (or bitrate) is distributed between the frames of a video. We’ll discuss more about this in the later sections. Conversely, a low bitrate video suffers from poor video quality but requires less CDN bandwidth or storage space. If your video has a bitrate of 3 mbps, we can assume that three megabits of video will be transmitted to the player every second.Ī higher bitrate generally results in better video quality but also requires more bandwidth to transmit or more storage space to save the video file. The units of bitrate are typically kbps (or kilobits per second) or mbps (or megabits per second).Īnother way to look at it is bitrate defines how much data is transmitted to the user or video player in one second. Video Bitrate or (bitrate) is the number of bits used to deliver one second of video. Bitrate or Resolution – Which Is More Important?.What is Resolution or Video Resolution?.What does the “rate-distortion tradeoff” mean?.
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