Ulead MEDIASTUDIO PRO 7, User Manual

Page: 399 / 436

APPENDIX 399
Understanding the frame rate
The frame rate determines how many images get displayed during every
second of a video. The higher the frame rate, the smoother your playback
can be because motion can be shown in smaller increments and at a faster
rate. But higher frame rates require more memory as a greater number of
images must be stored and shown each second. So, if you are producing
fast motion video, such as recording a sporting event, you probably need
to retain as high a frame rate as possible. But if you are working on a
project where there is little or slow movement, you might be able to save
some space by using a slower frame rate.
Understanding the frame size
The frame size determines how big the video image appears on screen.
By using a larger frame size, your image can be bigger and assuming your
source material is of sufficient quality, you can include more detail in your
video. But larger frame sizes carry two distinct problems. First, each
frame requires more data to store the information. For example, an
uncompressed frame with a size of 320 x 240 might require about 250KB
of memory. A 640 x 480 frame (twice the size) would require about 1MB,
(four times as much memory!). The frame size also affects how well the
video plays back for another reason. Larger frames require more informa-
tion to be redrawn. Some displays cannot refresh themselves fast enough
to show each change smoothly.
Understanding data types
The data type of a frame refers to how many bits (memory) are allocated
for displaying colors. For example, 8-bit (1 byte) data types can show a
maximum of 256 colors, while 24-bit can show over 16 million colors
(256x256x256). Obviously, the greater the data type the larger the file size
for the video. While this may be true in most cases, you will find that a
24-bit video can often be compressed to rates equivalent to 8-bit video as
compression schemes can easily reduce the thousands of colors present to