Autodesk 64006-051108-9001 User Guide - Page 200

192 Chapter 8: Encoding 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. Modem Dual ISDN T1/DSL/Cable CD-ROM DVD-ROM 160x120 192x144 320x240 480x360 640x480 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.