Apple Compressor (4.0) - Manual (Page 114)

Chapter 5 Custom settings and output formats 114
Audio tab
You use the Audio tab to make settings related to the audio format.
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Enabled: Make sure this checkbox is selected if you want the MPEG-1 output format to include
the Audio tab settings.
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Sample Rate: Choose the sample rate of the output audio.
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48 kHz: Required for use on DVDs.
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44.1 kHz: Used on audio CDs. This is the most commonly supported sample rate.
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Channels: Select the channel valence (stereo or mono) for the output media file.
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Stereo: Select this option to create a stereo output audio file.
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Mono: Select this option to create a mono output audio file.
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Bit Rate: Set the bit rate to use for the output audio (64 kbps, 128 kbps, 192 kbps, 224 kbps,
or 384 kbps). Higher bit rates produce higher-quality audio, but they also produce larger
output files.
Note: The 224 kbps and 384 kbps settings are not available when Channels is set to Mono.
MPEG-4 files
MPEG-4 Part 2 overview
Compressor provides the tools you need to create exceptional MPEG-4 transcoded files.
MPEG-4 Part 2 (known as MPEG-4 video in QuickTime 6) plays an important role in the evolution of
standards for the Internet and wireless multimedia industries, where it has been widely adopted.
Use MPEG-4 Part 2 if your output files should be compatible with MPEG-4 Part 2 devices or
players, such as the millions of smartphones and digital still cameras that capture and play back
MPEG-4 Part 2 video.