What is VBR?
VBR—or Variable Bitrate, is an encoding technique that enables the transmission of large video and audio files at variable bitrates. VBR leverages a dynamic bit rate that varies throughout playback based on the desired level of detail required. This makes it possible to transmit large files at a higher bit rate.
How does VBR work?
VBR leverages quality-based encoding, unconstrained encoding, and constrained encoding to achieve specific goals of quality, bandwidth, and optimization. Segments of audio and video data are packaged flexibly and accurately according to their size and complexity to optimize transmission. For instance, slower scenes require lesser bits when compared to fast-action scenes.
VBR Use-cases
The variable aspect of VBR encoding makes it ideal for on-demand video transcoding since it requires a longer time to process data. However, VBR is not suitable for live streams.
VBR vs. CBR
CBR—or Constant Bitrate, is an encoding technique that leverages a constant bitrate to transmit data. It doesn't depend on the size or complexity of the processed files. Regardless of the variables, the output will remain constant.
CBR
- It is best suited for time-sensitive video streaming.
- It generates consistent results despite the bitrate. For instance, if you set the speed to 1100 kbps, CBR will still maintain a bitrate of 1100 kbps.
- It is widely supported because it is historically popular and has been an industry-standard in the video streaming landscape for quite some time.
- CBR is ideal for multimedia and live stream encoding.
VBR
- VBR generates higher-quality streams.
- It is not limited by time constraints.
- VBR doesn't reduce video quality
- VBR is not as widely supported as CBR.
- It is ideal for VOD transcoding.
- VBR is more complicated and takes longer to process data, making it more prone to errors.