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Discovering Your Systems Optimum Data Rate
A data rate limit prevents your computer from dropping frames when you capture or render digital video, which causes video to appear stuttered or jerky. The data rate you choose for video capture depends on the capabilities of your system and hardware configuration, while the data rate you choose for playing or previewing video depends on the target playback system.
If your movie will be played or previewed on your local hard drive, you should limit the data rate to the maximum video data rate of your local system and hardware configuration.
If your movie will be played on other systems, you should limit the data rate to the maximum video data rate of those playback systems. For example, a realistic data rate for CD-ROM movies is 90-100 K/sec for single-speed (1x) CD-ROM drives, 150-200 K/sec for double-speed (2x) drives, and 350-500 K/sec for quad-speed (4x) drives. Remember you may have a (24x) or (36x) CD-ROM, but most computers still have a quad-speed at most.
Choosing a Data Rate Limit for Capturing Video in Premiere
When capturing video, the amount of data you capture should not exceed the capacity of your capture drive and video capture card, otherwise your computer will drop frames. Because the amount of data you can capture is affected by your system and hardware configuration, the only way to determine an appropriate data rate is to test the system yourself.
To determine your system’s maximum data rate for video capture using Adobe Premiere:
1. Make sure you have followed your device manufacturer’s instructions for optimizing your system and hardware configuration. Adobe also provides optimization instructions for some capture cards.
2. In Premiere, choose File > Preferences > Scratch Disks.
3. Choose the hard drive you will use to capture video from the Temp/Captured Movies pop-up menu (Macintosh) or from the pop-up menu that appears (Windows), then click OK.
4. Choose File > Capture > Movie Capture to activate the Movie Capture menu.
5. Follow the instructions provided with your video capture card for entering a data rate limit. The procedure for most capture cards is as follows:
- In Premiere for the Macintosh, choose Movie Capture > Video Input. Select your hardware compressor from the pop-up menu in the upper left corner, enter a data rate limit, then click OK.
- In Premiere for Windows, choose Movie Capture > Recording Options, then click Compression. Enter a data rate limit, click OK to close the Video Compression dialog box, then click OK to close the Recording Options dialog box.
6. Disable audio input by making sure Sound Off is checked on the Movie Capture menu (Macintosh), or Record Audio is unchecked on the Movie Capture menu (Windows).
7. Click Record in the Movie Capture window, wait for a few seconds, then click the mouse to stop recording.
8. When the Clip window appears, choose File > Save. Name the file, specify a target location, then click Save.
9. Choose File > Tools > Movie Analysis. In the dialog box that appears, locate and select the movie you just saved, then click Analyze (Macintosh) or Open (Windows).
10. In the Analysis window, scroll to the Video section. If the first line reads “This movie appears to have dropped frames,” your capture data rate was too high, and you should repeat steps 4-9 using a lower data rate limit (try using the average data rate reported in the Movie Analysis window). If the Video section does not report dropped frames, repeat steps 4-9 using a higher data rate limit. Once you have found the highest data rate limit possible without dropping frames, use this data rate as the limit when capturing video. You may need to adjust this limit as your configuration or source video changes.
Choosing a Data Rate Limit for Hardware Compressed Premiere Projects
To set an appropriate data rate limit for hardware compressed Premiere projects that will be played on your computer:
1. Open your Premiere project, then choose Make > Compression.
2. In the Compression Settings dialog box, choose the compressor you will use for your final output from the Compressor pop-up menu (Macintosh) or Method pop-up menu (Windows).
3. Select Limit Data Rate To (if available), or click Configure to access the data rate limit option for your hardware compressor .
4. Enter the data rate that matches the average data rate reported by the Movie Analysis tool for the clips in your project, or enter your initial estimate of the highest data rate supported by your system.
5. Click OK to close the Compression Settings dialog box.
6. Choose Project > Preview.
7. Watch the preview and evaluate how smoothly it plays. If your movie stutters or jerks when played, repeat steps 1-6 using a lower data rate limit. If your entire movie plays smoothly, repeat steps 1-6 using a higher data rate limit. Once you have found the highest data rate limit possible without stuttered playback, set this data rate as your limit in the Compression Settings dialog box. You may need to adjust this limit as your configuration or source video changes.
Choosing a Data Rate Limit for Software Compressed Premiere Projects
To set an appropriate data rate limit for projects that are compressed with a software compressor in Premiere:
1. Open your Premiere project, then choose Make > Compression.
2. In the Compression Settings dialog box, choose the compressor you will use for your final output from the Compressor pop-up menu (Macintosh) or Method pop-up menu (Windows).
3. Select Limit Data Rate To, then enter your initial estimate of the highest data rate supported by your target playback system (e.g., 350-500 K/sec for quad-speed (4x) CD-ROM drives).
4. Click OK to close the Compression Settings dialog box.
5. Render a movie from your project using the compression settings you entered in steps 1-4.
6. Play the movie on your target playback system and evaluate how smoothly it plays. If your movie stutters or jerks when played, repeat steps 1-5 using a lower data rate limit. If your entire movie plays smoothly, repeat steps 1-5 using a higher data rate limit. Once you have found the highest data rate limit possible without stuttered playback, set this data rate as your limit in the Compression Settings dialog box. You may need to adjust this limit as your target playback system changes.
In the Compression Settings dialog box. You may need to adjust this limit as your configuration or source video changes.
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