What is Variable Bitrate (VBR) Encoding?
VBR is an encoding method that ensures consistently high audio quality throughout an encoded file by making intelligent bit-allocation decisions during the encoding process based on a scale you set in the Encoder Preferences dialog. VBR encoding produces an overall higher and more consistent quality level than Constant bitrate (CBR) encoding.
How does Variable Bitrate (VBR) Encoding Work?
When the Encoder encounters difficult passages in the audio source (for example, sections containing a relatively wide stereo separation), it allocates additional bits to that section, ensuring the audio quality. When the Encoder encounters easy passages (for example, sections containing silence or a relatively narrow stereo separation), it allocates fewer bits to that passage, reducing unused bits. As a result, your MP3 file consists of variable bitrates throughout the file because the Encoder allocates the bits where they are most needed.
When to Use Variable Bitrate (VBR) Encoding
VBR encoding was developed for use when consistent audio quality is the top priority and constant or predictable encoded MP3 file size is not critical.
Variable Bitrate (VBR) Encoding Restrictions