Digidesign TDM technology

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Digidesign TDM is a proprietary technology of the company Digidesign , during the data transfer between the products manufactured by Digidesign Pro Tools - Sound cards , the thereon digital signal processors (DSP) and the computer architecture ( CPU and bus ) is used. The technology is based on a single 24- bit high-speed data connection (24-bit bus architecture). The simultaneous transmission of different signals on the TDM bus with a time-division realized, thus the name TDM (abbreviation for Time Division Multiplex , Engl. Declared time-division multiplexing).

TDM bus structure

Different channels that are assigned to different output signals (audio tracks, buses, sends etc.) of the Pro Tools mixer are managed by the Pro Tools audio cards and then combined on the existing TDM bus. This means that all signals can be forwarded simultaneously by assigning a single time slot on the multiplex bus to each individual audio signal or data stream . A single time slot is able to distribute the data stream bidirectionally to several destinations at the same time.

TDM I and TDM II

TDM I bus structure

There are two TDM versions. TDM-I technology was developed in conjunction with the Digidesign 24Mix systems. TDM II represents the direct further development of TDM technology and is used in the current HD systems.

TDM I

TDM I is equipped with only one bus. In the TDM-I system, 256 time slots are globally available for the entire system. If one of the time slots is now used to forward a signal internally, it will not be available for the rest of the system for playback. This reduces the total capacity on the TDM bus.

TDM II

TDM II bus structure

With the TDM-II system there is a separate TDM bus between the individual DSP processors, which can provide up to 512 bidirectional time slots at a sampling rate of maximum 48 kHz. In addition, another 512 time slots are available between the DSP processors and the global TDM bus. This structure enables several Pro Tools mixers (summing stages) which are calculated on different DSPs to be connected directly to one another. The DSP processors are arranged one after the other. With a TDM-II connection, only time slots are required between the two DSPs to be connected, with the data throughput remaining constant on the global TDM bus. This means that a total of around 5000 time slots are available per DSP card. If the sampling frequency is doubled , the number of maximum possible time slots is halved.

literature

  • Markus Ammer, Christian W. Huber: Music production with Pro Tools 7. Wizoo, Bremen 2006, ISBN 3-934903-55-X .
  • Mike E. Collins: Pro Tools LE and M-Powered. The Complete Guide. Focal, Amsterdam a. a. 2006, ISBN 0-240-51999-X .
  • Heiner Kruse: Tutorial Beat Design with Pro Tools . Wizoobooks, 2008.
  • Digidesign (Ed.): Pro Tools 201: Pro Tools Production Essentials . 2nd edition. Digidesign Training & Education Program, 2004, PN: 910216758-00 REV. B.
  • Digidesign (Ed.): Pro Tools 210M: Music Production Techniques . 2nd edition. Digidesign Training & Education Program, 2003, PN: 910612760-00 REV. A.
  • Digidesign (Ed.): Pro Tools 210P: Post Production Techniques . 2nd edition. Digidesign Training & Education Program, 2002, PT 210P REV B 020627.
  • David Leathers: Pro Tools Bible. (Covers up to Pro Tools 6.1 and Pro Tools HD. Software. Hardware. Plug-ins. Midi. Pro Tools 6.1 and beyond). McGraw-Hill Publishing, New York NY et al. a. 2004, ISBN 0-07-141234-4 .
  • Ken C. Pohlmann: Principles of Digital Sound. 4th edition. McGraw-Hill Professional, New York NY a. a. 2000, ISBN 0-07-134819-0 .
  • José Valenzuela: The Complete Pro Tools Handbook. Pro Tools / HD, Pro Tools / 24 mix, Pro Tools LE for home, project, and professional studios. Backbeat Books, San Francisco CA 2003, ISBN 0-87930-733-1 .

Web links