Bitrate vs. Video Resolution
which is more important for streaming video?
Many people have this confusion because these two factors can have a profound effect on the encoder’s output.
How do you think it should be chosen?
Choose 1080p or 720p?
Choose 5mbps or 3mbps?
Choose 1080p@5mbps or 1080p@7mbps?
If you don’t know what to choose, great. That’s why I wrote this article: to explain the relationship between bitrate and resolution in simple terms, and to help you choose the right encoder settings.
Let’s start by understanding bitrate.
What is the bitrate of the video?
Video bitrate or bit rate refers to the number of bits transmitted per second of video information. The code rate unit is usually:
kbps or kilobits per second
mbps or megabits per second
When you are compressing video, you usually need to set the video compression software not to exceed a certain bit rate.
For example, if you set the video compression software’s bitrate to 3mbps, the software will compress the video at 3mb per second (on average) and stream it to the decoder or player. This is the code rate.
When you talk about bitrate, you’re really talking about: the relationship between video compression and video quality loss. The more you compress, the lower the quality of the video (and this is not always the case, as we will see later).
When compressing video, the following algorithms can be used for speed control, these are:
CBR (Constant Bitrate) – It is best to keep the bitrate constant if video quality is lost.
VBR (Variable Bitrate) – Maintains consistent video quality, allowing for bitrate fluctuations.
Capped VBR – Keep the video quality as constant as possible, allowing the bitrate to fluctuate within a set range.
This article will not discuss the above frequency control methods in detail. Friends who want to know more, welcome to read: Understanding Frequency Control Modes: What are CBR, VBR, CRF and Capped-CRF?
So when we talk about the bit rate, we should pay attention to the following points:
The quality of high bitrate video is usually higher than that of low bitrate video. I say generally, because the video quality reaches a certain point where it will no longer improve (no matter how much the bitrate increases).
The code rate refers to bits (bit) instead of bytes (byte).
The bit rate alone does not determine the quality of the video, you have to take into account factors like resolution, frame rate, screen size, etc.
Codecs for video compression: H.264/AVC, HEVC, VP9, AV1? If you change the video codec and its settings (or encoding tools), the same bitrate will provide a very different video quality.
