Ulead 1.0 - Manual (Page 82)

4—10 SpruceUp User’s Guide
“.pcm”, “.wav”, or “.aiff” extensions.
Multiplexed MPEG files, also known as “system” or “program” files, have the video and audio
combined into a single file, typically with an “.mpg” extension. A complication is that there
can be several video and audio streams within a multiplexed file. SpruceUp supports
multiplexed MPEG files with one video and one audio mono or stereo stream.
MPEG-1 and MPEG-2
The DVD Specification allows for the use of either MPEG-1 or MPEG-2 encoded video. In
general, MPEG-1 provides for smaller file sizes but with reduced picture quality (using a half
screen image scaled to full screen), while MPEG-2 provides for better quality but with larger
file sizes. There are many technical aspects to these two standards that are not covered
here.
Generally, MPEG-1 is used for titles where file size is critical (such as with DVDonCD titles
using 650MB disc vs. a typical DVD with 4.7GB), and playback will be on a computer as
opposed to a set-top DVD player.
MPEG-2 is the normal video format for DVD titles on DVD media.
SpruceUp works with both MPEG-1 and MPEG-2 video assets, as long as they are DVD
compliant. See the MPEG Settings Summary topic for a quick overview of SpruceUp
requirements.
Bit-Rates
The bit-rate directly determines the file sizes, and thus how many minutes you can fit onto
a CD or DVD. DVD players support combined bit-rates up to 10.08mbps, but this must
include the audio and other overhead as well. The maximum video bit-rate is 9.8mbps.
Typical maximum bit-rates used for video are around 8mbps. The maximum MPEG-1 bit-
rate is 1.856mbps with 1.15mbps typical.
The actual video content determines how low a bit-rate you can get by with and still have
acceptable quality. Video with little movement works well at lower bit-rates, while lots of
movement (a quick camera pan for example) shows the artifacts that higher bit-rates are
best at handling.
There are three common methods of encoding video - CBR (Constant Bit-Rate), 1-pass VBR
(Variable Bit-Rate), and 2-pass VBR. With CBR, you choose a bit-rate and it is used for the
entire video movie, regardless of its content. The VBR modes monitor the video content and
adjust the bit-rate to best fit the amount of motion occurring. 2-pass VBR provides more
efficient encodes since it uses one pass to first examine the video and then encodes it on
the second pass, with rates adjusted in anticipation of the video. SpruceUp supports video
encoded with any of these methods.
Video Resolution
The resolution determines the number of pixels processed within a frame. More pixels lead
to sharper details in the image. When you need to encode at a low bit-rate however, lower
resolutions will show fewer noticeable encode errors, since the bit-rate is being used for
fewer pixels, effectively resulting in a higher bit-rate (with the trade-off of reduced detail,
which is typically a less noticeable artifact). Depending on video content, it can be a good
idea to use MPEG-2 1/2 D-1 (which halves the horizontal resolution and leaves the vertical
at full) when you must use bit-rates less than 3mbps. Better MPEG encoders provide more
options with regards the video resolution. Note that regardless of the resolution picked,
most DVD players plays back at full screen. Following is a list of common resolutions used
with SpruceUp.
MPEG-1
• SIF (Standard Interface Format): 352x240 NTSC, 352x288 PAL