DigiDesign Pro Tools, Справочное руководство

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Chapter 31: Mixdown 749
MXF (Material Exchange Format)
(Pro Tools with DigiTranslator Only)
MXF is a media file format that includes both
video and audio files, and is designed for the in-
terchange of audio-visual material with associ-
ated data and metadata. It was designed for im-
proving file-based interoperability between
servers, workstations, and other content cre-
ation devices.
AAF and OMF sequence format files can refer to
MXF media files, or have MXF media files em-
bedded within them. Pro Tools with DigiTrans-
lator supports AAF embedded sequences.
MPEG-1 Layer 3 (MP3)
The MPEG-1 Layer 3 compression format (MP3)
is used for streaming and downloading audio
over the Internet, and for playback on portable
devices. The MP3 Option is required to use this
file type.
The MP3 encoder provided as an install option
with Pro Tools is a fully functional 30-day demo
version. To purchase the full version of the MP3
encoder, visit Digidesign’s website (www.digide-
sign.com).
When you select this format, the Resolution
pop-up menu in the Pro Tools Output Options
dialog is unavailable. The resolution is set by the
encoder.
The sample rate chosen is given to the codec as
a base sample rate for operations. The actual
sample rate of the resulting file is determined in
the MP3 Encoder Options dialog. For example,
if a base sample rate of 48000 Hz is chosen, the
MP3 Encoder Options dialog will allow output
streams in 48, 24, or 12 kHz, depending on en-
coding quality.
When you export or bounce to MP3 format, you
can set the following options:
Encoder Settings
Encoder Speed Determines the audio quality of
the bounced file. There are two options: Highest
Quality and Fastest Encoding Time.
The Highest Quality setting can take up to five
times longer to process audio than the Fastest
Encoding setting, so you should use it only
when the highest fidelity is essential and you
have a considerable amount of time to devote to
the encoding process.
Constant Bit Rate (CBR) Encodes the file at a
single bit rate that you choose from the CBR
pop-up menu. Because the bit rate is fixed, the
quality of the encoded audio will vary depend-
ing on the nature of the material being com-
pressed. This option is best for streaming over
the Internet, since it has predictable bandwidth
requirements.
See the DigiTranslator Guide for more in-
formation.
The MP3 Export Option is available for pur-
chase from the online DigiStore at the Digi-
design website (www.digidesign.com).
MP3 Export Options