Apple Compressor (4.1.2) User Manual
Page 26
Chapter 4
Advanced adjustments
26
Audio properties
•
Channel layout: Use the pop-up menu to manually set the type of audio channel layout. For
more information about audio channel layouts, including the surround sound channel layout,
see
on page 65.
•
Sample rate: Use this pop-up menu to set the number of times per second that music
waveforms (samples) are captured digitally. The higher the sample rate, the higher the audio
quality and the larger the file size.
Note: All files intended for video and audio DVD authoring must have a 48 kHz sample rate as
required by the DVD specification.
•
Target system: Use this pop-up menu to identify the system on which you are going to play the
output file. Compressor limits options in other related properties to those appropriate for the
target system.
•
DVD Video: Choose this option if you’re encoding for use in a DVD video authoring application.
•
DVD Audio: Choose this option if you’re encoding for use in a DVD audio authoring application.
•
Generic AC-3: Choose this option to remove the target system setting limit (the most
generic choice).
•
Data rate: Use this pop-up menu to set the number of kilobits per second (kbps) required to
deliver your audio file. Using a higher rate will produce a higher-quality audio file.
Tip: For stereo encoding, rates of 192 kbps and 224 kbps are typical and will produce good
results. For Dolby Digital 5.1 encoding, a rate of 384 kbps is recommended. For 5.1 Dolby Digital
Plus encoding, a rate of 192 kbps is recommended.
•
Bit stream mode: Use this pop-up menu to define the audio service contained within the Dolby
Digital or Dolby Digital Plus bitstream.
•
Surround mode: When using a Mono or Stereo (L R) channel layout, this property tells the
playback device whether the two-channel encoded bitstream contains a Dolby Surround (Lt/
Rt) program that requires Dolby Pro Logic decoding. There are three menu options:
•
Not Indicated: Does not send the playback device information about whether the bitstream
was encoded in Dolby Surround.
•
Not Encoded: Tells the playback device that the bitstream contains information not encoded
in Dolby Surround.
•
Surround Encoded: Tells the playback device that the bitstream contains information encoded
in Dolby Surround.
•
Surround EX Mode: When using a 5.1 (L R C LFE Ls Rs), 5.0 (L R C Ls Rs), 4.1 (L R LFE Ls Rs), or 4.0
(L R Ls Rs) layout, this property tells the playback device whether the audio has been encoded
in Dolby Digital Surround EX. There are three menu options:
•
Not Indicated: Does not send the playback device information about whether the bitstream
was encoded in Dolby Digital Surround EX.
•
Not Encoded: Tells the playback device that the bitstream was not encoded in Dolby Digital
Surround EX.
•
Surround Encoded: Tells the playback device that the bitstream was encoded in Dolby Digital
Surround EX.
•
Stereo downmix: Use this pop-up menu to set how to downmix a surround signal to a stereo
signal. For more information, see
on page 65.
Important:
The LFE signal may be discarded by the Dolby Digital downmix process.
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