Apple Compressor (4.0) - Manual (Page 124)

Chapter 5 Custom settings and output formats 124
Reducing the sample rate can shrink a media file by as much as 5:1. The audio quality will be
affected, but not as much as it would be if you used 8-bit sampling. The following table shows
common sample rates and the audio device quality to expect at each rate.
Sample rate Audio device quality
48 kHz DAT/DV/DVD
44 kHz CD
22 kHz FM radio
8 kHz Telephone
Sound sample size
The sound sample size determines the dynamic range of the sound. For example, 8-bit
sound provides for 256 possible values, whereas 16-bit sound allows for more than 65,000
possible values.
Choose 16-bit sound for music that has both soft and loud sections, such as orchestral music. For
spoken voice or music that has a more or less constant volume level, choosing 8-bit sound can
still yield good results.
If you need to shrink your media file, you can reduce the sample size from 16 bits to 8 bits. This
cuts the file size in half but also degrades the audio quality.
Create QuickTime media files
There are many QuickTime video and audio codecs that you can choose from in Compressor. You
access all codecs from the Compression Settings and Sound Settings dialogs, which you open
from the QuickTime Movie Encoder pane.
Stage 1: Open the QuickTime Movie Encoder pane and choose basic settings
1 In the Settings tab, select a setting or create a new setting by choosing QuickTime Movie from
the Create a New Setting (+) pop-up menu.
2 Click the Encoder button in the Inspector window.
The QuickTime Movie Encoder pane appears, containing the Video and Audio Settings buttons,
the Enabled pop-up menus, the Streaming pop-up menu, the Options button (dimmed), and the
Summary table.