Apple Logic Pro 9 (TDM Guide) - Manual (Page 13)

Logic Pro allows you to use the TDM functions of Pro Tools HD systems. TDM is an
abbreviation for Time Division Multiplexing—the time-interlaced transmission of multiple
digital audio signals (or streams) through a single data bus. This bus system is physically
isolated from the computer system bus, and runs between the individual TDM-capable
(PCI or PCIe) cards.
Up to 512 digital audio channels, each with 24-bit resolution, can be transmitted on the
TDM bus. These streams form the signal paths within a virtual mixer. These signal paths
are necessary for the insertion of plug-ins, which are calculated on the DSP hardware,
and routed into the individual channels, or are selected through auxiliary busses.
Logic Pro allows you to use both your TDM system DSPs and the computer’s native CPU
processing resources. The link between the DSP world of your TDM system, and your
computer’s native CPU processing resources is ESB TDM. See
ESB TDM and EXS24 TDM .
Note: It should be noted that the TDM channel count is sample-rate dependent, so if a
rate of 88.2 or 96 kHz is used, the 512 channels available to a Pro Tools HD system will be
halved to 256. At a sample rate of 192 kHz, this will again be halved to 128.
This chapter covers the following:
• How TDM Differs from Native Processing (p. 13)
• TDM Plug-ins (p. 14)
• Using TDM-Specific Functions (p. 15)
• Simultaneous Use of TDM and Other Hardware (p. 15)
How TDM Differs from Native Processing
Using Logic Pro with a TDM or native processing system is quite similar. Here is an overview
of the main differences between the two systems:
• In a TDM system, all audio processing is done by the DSP chips of the TDM hardware.
This means that “native” Logic Studio or Audio Units plug-ins cannot run on the
TDM DSPs. TDM plug-ins, however, can be fully used and automated.
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About TDM 2