Understanding Video Files and Logic


If a movie will play in QuickTime Player, it'll play in Logic. The movie itself can use any codec (compression/decompression algorithm) that QuickTime understands, and there's no limitation on the movie's dimensions or data rate. Logic is equally adept at scoring standard definition NTSC videos at 720 by 480 pixels as it is at scoring a banner ad movie at 90 by 700 pixels for a Web site. However, there is one important fact to keep in mind: Logic has to read the movie off your hard disk as it plays it. Logic also has to read your audio off the hard disk. Consequently, if you're scoring a video that uses a high-bandwidth codec such as the Animation codec, resources that could be devoted to reading audio off the hard disk will instead be devoted to reading the movie. The result is that Logic will react slower, and you won't be able to work with as many tracks of audio as you would be able to if the movie used a low-bandwidth codec such as Sorenson 3 or MPEG-4.

Because of this, it is common to score to a proxy movie. A proxy movie is a low-resolution and tightly compressed version of a high-resolution movie. As long as the frame rate remains unaltered, a proxy movie provides enough of a visual reference that you can still score the video, and you will not place as high a strain on your computer as you would using the uncompressed full-bandwidth version.

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You can create proxy movies using QuickTime Pro Player's export option (Movie to QuickTime Movie). For the codec, use Sorenson 3 or MPEG-4. Both provide exceptional image quality at an extremely reduced data rate, and with a little practice, you may not be able to tell the proxy movie from the original without first looking at its file size.

To reduce a video's file size even further, halve its dimensions. For example, when creating a proxy movie of a 720-by-480-pixel NTSC video, it's very common to reduce the dimensions to 360 by 240 pixels. Your proxy movie will be one-fourth the file size ofand thus use one-fourth of the system resources required bya full-size version encoded using the same codec.


The "Turtles" movie we'll use in this lesson is just such a proxy movie. (For reference, the uncompressed high-resolution version is included along with the proxy movie so you can open it up and see our turtles in all their swimming glory.) Let's open the proxy movie in QuickTime Player and see what it looks like.

1.

Navigate to the APTS_Logic_7 > Song Files > Lesson 13 Project Files > Movie Files folder, and double-click the movie named Turtles.mp4.

2.

The movie opens in QuickTime Player.

3.

Press Cmd-I (Window > Show Movie Info).

QuickTime Player's Movie Info window opens. This window displays several important movie properties, including frame rate, video and audio formats (codec), dimensions, and duration.

4.

Play the movie and familiarize yourself with its content.

As the movie plays, watch the Info window. Notice that the movie uses MPEG-4 video compression, it is 320 by180 pixels, and it plays at 29.97 frames per second.

5.

Quit QuickTime Player.



    Apple Pro Training Series Logic Pro 7 and Logic Express 7
    Apple Pro Training Series: Logic Pro 7 and Logic Express 7
    ISBN: 032125614X
    EAN: 2147483647
    Year: 2005
    Pages: 197
    Authors: Martin Sitter

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