Apple DVD Studio Pro 4 - Manual (Page 62)

Choosing a Bit Rate for SD Projects
Bit rate directly determines file size, and thus how many minutes of material you can fit
onto a DVD disc. SD-based DVD players support combined bit rates of up to 10.08 megabits
per second (Mbps), but this must include the audio and subtitles as well. The maximum
video bit rate is 9.8 Mbps.
Note: Some DVD players have trouble playing video that uses sustained high bit rates.
On such players, you may see dropped frames during playback.
Typical maximum bit rates used for video are around 8 Mbps. The maximum MPEG-1 bit
rate is 1.856 Mbps, while 1.15 Mbps is most typical.
The actual video content determines how low a bit rate you can use and still get acceptable
quality. Video with little movement works well at lower bit rates, while higher bit rates
are best at handling video with a lot of movement (a quick camera pan, for example).
For more information on choosing a bit rate that ensures all the content in your project
will fit on a DVD, see
Making Sure Your Content Will Fit .
Choosing a Bit Rate for HD Projects
Choosing a bit rate for use in HD projects is similar to doing so for SD projects, but there
are some differences.
The maximum overall bit rate for HD projects is 30.24 Mbps. While an HD project can use
both SD and HD video assets, the maximum bit rate you can use is different for each:
• HD assets: 29.4 Mbps
Note: HD assets include the 480p and 576p resolutions.
• SD assets: 15.0 Mbps
MPEG Encoding Methods
There are three common methods of encoding video: CBR (constant bit rate, also known
as one-pass), one-pass VBR (variable bit rate), and two-pass VBR.
• CBR (one-pass) method: You choose a bit rate and it is used for the entire video,
regardless of its content. The advantage of this method is that you can reliably predict
the final encoded file size. By adjusting the bit rate, you can ensure the video will fit
on the DVD. The disadvantage is that the same bit rate gets applied to all of the video,
regardless of the motion content. You must choose a high enough bit rate to provide
acceptable results for the scenes with motion, even if they are only a small part of the
movie.
62 Chapter 4 Preparing Video Assets