How to Calculate the Optimal Bitrate for MPEG Encoding

First, you need to know:

File size is generally calculated in Megabytes (MB)
Data rate is generally calculated in Kilobits (Kb)

1 Byte = 8 Bit
1 KB = 1,024 Byte = 8,192 Bit
1 MB = 1,024 KB = 1,048,576 Byte = 8,388,608 Bit

The conversion is summarized in the table below:

Second, calculate how much data can fit on a CD:

If you used 74min CD-R, it will hold 650 MB of data

650 MB x 1,024 KB/MB x 8 bits/Byte = 5,324,800 kilobits (kbits)

If you used 80min CD-R, it will hold 700MB of date

700 MB x 1,024 Kb/MB x 8 bits/Byte = 5,734,400 kilobits (kbits)

Third, what data rate (kbits/sec) to use for encoding:

If you want to encode a 30-minute video on a 74min CD-R, then the optimal bitrate to fit on 1 CD is:

1. 30 min x 60 sec/min = 1,800 sec
2. 5,324,800 kbits / 1800 sec = 2,958 kbits/sec

If you want to encode a 30-minute video on a 80min CD-R, then the optimal bitrate to fit on 1 CD is:

1. 5,734,400 kbits / 1,800 sec = 3,185 kbits/sec

Remarks: if you are encoding the video for making a VCD/SVCD/DVD title, then you have to comply with the relevant standards and budget for non-video assets. Please refer to relevant sections for more information.