Chapter 8: Encoding
192
Frame Rate versus Frame Size
A few different factors can limit the frame rate and frame size that you can effectively use on a
project.
The most common limitation is the image quality. Larger frame sizes and higher frame rates
require more data to maintain acceptable image quality. If the data rate of the movie is not high
enough to accommodate the frame size and rate, the image quality suffers.
The other common limitation of frame size and rate is the codec you are using and the CPU of
the target computer. Some CPU-intensive codecs can produce high-quality images at larger
frame sizes and higher frame rates with reasonable data rates. However, these movies may
require very high-end computers to play properly, so testing is critical.
Frame Size
Like frame rate, choosing an appropriate frame size for the movie has an important effect on
video quality. The larger the image size is at a given data rate, the lower the resulting image
quality.
The best size for the video depends on your data rate, frame rate, codec, source material and
personal preferences. All of these factors are interrelated, so experimentation is the best way to
find the optimal setting for your project.
Use the following list as a rough guideline. Experiment to find the best setting for your project
and make sure to test your final movies to ensure they play on the minimum target computer.
Display Size
Some formats, such as QuickTime, enable you to create movies at one image size and display
them at a different size. For example, you can create a movie at 160x120 pixels, but display the
movie at 320x240 pixels. Because fewer pixels are stored, the codec can concentrate its limited
bitrate on fewer pixels, which results in a better-quality compression and may improve the final
image quality of low-bitrate movies.
Doubling is commonly used to display full-screen video from 320x240 sources. However, when
used on movies displayed larger than 320x240, a faster computer or hardware acceleration may
be required to play the video properly. Run tests to determine if this feature meets the
requirements for your minimum target computer.
Modem
160x120
Dual ISDN
192x144
T1/DSL/Cable
320x240
CD-ROM
480x360
DVD-ROM
640x480
Содержание 64006-051108-9001 - Discreet Cleaner - Mac
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