User Guide

The Bit Budget 53
The Bit Budget
To determine the bit rates you will use when encoding video and audio, you can calculate
the Bit Budget.
There are two factors that constrain your choice of bit rates. One factor is the type of disc
you will use and, therefore, how many bits are available for each second of the content. The
other factor is the maximum bit rate allowed by the DVD-Video format. This is 9.8 MBps
(millions of bits per second), which must be divided between the video and audio streams.
This section includes the following topics:
• “Calculating the Bit Budget” on page 53
• “Media Capacities” on page 55
• “Sample Bit Budget Calculation” on page 57
Calculating the Bit Budget
The bit budget calculation produces two values that you must use when encoding video:
• Maximum video bit rate
• Average video bit rate
Since video usually requires the largest bandwidth, the best way to calculate a bit budget is
to subtract the audio requirements from the available bandwidth to get the maximum and
average video bit rates. The bit rate for audio depends on the number of audio channels and
the type of audio.