QuickTime Pro: About Audio and Video Tracks

Video and audio tracks are the most common forms of QuickTime media tracks. Chances are you'll spend most of your time working with them.

Video tracks:
A QuickTime video track can be created from:

• Digital video (DV).
• Digitized analog video.
• A 2D or 3D animation program.
• Any other source capable of generating an image sequence in any of the many file formats importable into QuickTime.

Movies can have many video tracks, and the tracks can be edited, layered, and have effects and transitions applied to them. You have complete control over such properties as frame size, frame rate (frames per second), data rate, and video compression.

Video compression:
Video compression is necessary to make your movies play at full speed on most computers or to be small enough to view on the web. QuickTime supports a wide range of codecs (compressors-decompressors), both lossless (high quality, large files) and lossy (lower quality, small files).
To see your codec options:

1. Choose Export from the File menu.
2. Choose 'Movie to QuickTime Movie' from the Export pop-up menu.
3. Click Options
4. Click Settings under Video. The first pop-up menu under Compressor lists the codec options.

The Apple Sorenson codec is recommended as a high-quality lossy codec for video and rendered animation.


Special effects, transitions, and filters:
QuickTime includes fifteen video filters for such visual effects as blur, edge detection, emboss, film noise, HSL balance, RGB balance, and sharpen; thirteen basic video transitions, including cross-fade, explode, gradient wipe, implode, push, slide, and wipe, each with several variations, and ripple, fire, clouds, and glass effects. These are applied through the Fitlers Option to the selected range of frames. The QuickTime Effects Architecture is fully open and extensible, so that you can write your own filters.


Audio tracks:
A QuickTime audio track contains digitized sound samples. These can be an MP3, an audio CD track or sampled analog tape recording, or from any other audio source that can generate a sound file compatible with QuickTime (and most are). Audio quality ranges from high (16-bit, 44.1 kilohertz, uncompressed) to low (8-bit, 22 kilohertz, highly compressed). As with video tracks, you can edit audio tracks and layer one audio track on top of another to build a complex audio experience.

Music tracks:
QuickTime also supports a separate audio track type called a music track. This is actually a MIDI (Musical Instruments Digital Interface) track that contains, not digitized audio, but note information played with a virtual instrument. QuickTime includes its own selection of high-quality MIDI instruments. MIDI delivers long and complex pieces of music using small files and little bandwidth.

Audio compression:
QuickTime offers a variety of sound and music compressors. QDesign's Music Codec is recommended for its high quality and small-size files.