CBR (constant bitrate) encoding holds a fixed number of bits per second regardless of how simple or complex the audio is at any moment. Its virtue is predictability: stream planners know the exact bandwidth, packets are uniform, and it is easy to fit into a fixed-rate channel or a streaming ladder rung. The cost is efficiency — quiet or simple passages waste bits they don't need while complex passages may get fewer than they'd like — so at a given average rate CBR is usually slightly worse quality than VBR. It remains common where the transport demands a steady rate, such as broadcast multiplexes and some real-time links.
The book · Volume 4 of 7
Audio for Video: A Complete Guide to Sound in Video Products: From PCM and Codecs to Loudness, Accessibility, and Real-Time Voice Processing
CBR makes bandwidth predictable, which streaming and broadcast need, but it wastes bits on silence and starves complex passages. Volume 4 covers CBR in detail within audio codecs: constant versus variable bitrate, AAC and Opus rate control, bitrate targets for voice and music and how delivery formats constrain the choice. Written by Nikolay Sapunov, CEO at Fora Soft.
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