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Tuesday, August 30, 2011

DPP Solutions: Get Connected

A quick guide to the interfaces for video and audio that you’ll encounter as you get into working with motion



Connecting a DSLR to a peripheral used to be simple. You had a USB cable, a card reader—maybe USB or FireWire—and you were done. Images could move from camera to computer fast and easy. Times have changed, and now DSLRs can connect to TVs, projectors, computers and other devices. You’re shooting stills and HD video, and you may be recording sound to a separate recorder altogether. The number and variety of connectors that you encounter have grown exponentially. To help you get a handle on what’s what, here’s a short list of the types of audio and video connections encountered while using video-capable DSLRs and editing systems.

Analog Audio I/Os
XLR: A three-pin connector for balanced connections between microphones and mixing consoles/recorders, for example, or between system components at a nominal +4 dBu line operating level; capable of carrying phantom power to microphones; rugged connector format with cable-strain relief.

RCA/Phono: An unbalanced connector for consumer and semiprofessional audio equipment; levels normally referenced to a nominal -10 dBV operating level.
¼-inch Mono/Stereo: Used for various connections as plug-in links between system components; alternates are miniature 1⁄8-inch connectors.

Digital Audio I/Os
AES/EBU (AES3): Dual-channel digital interface capable of supporting 24-bit data transfers at variable sample frequencies; uses three-pin XLR or BNC connectors; self-synchronization feature eliminates the need for a separate word-clock connection.

MADI: A multichannel version of the AES/EBU format used in high-end studio systems.

S/PDIF: A consumer/semiprofessional version of the AES/EBU digital format; uses RCA/phono or optical links via short cable runs.

Toslink/Optical: For “Toshiba Link,” which carries digitized audio over an optical fiber using a rectangular connector at data rates up to 125 Mb/s.

Analog Video I/Os
Composite Video: Color and luminance signals are combined with audio and carried via RCA (short distances) or BNC connectors; modulated on a high-frequency carrier, such signals are carried via coaxial and similar cabling between antenna/cable/satellite outlets and set-top boxes, cable modems, receivers, etc.
Component Video (Y/Pb/Pr): Two separate color signals with a luminance/black-and-white signal carried via three RCA or BNC connectors.

S-Video (Y/C): Carries two video components, brightness and color, via multipin connectors; no audio channel.

VGA/Super VGA (Video Graphics Array/Super Video Graphics Array): A multipin format developed by IBM for PCs and similar devices with resolutions of 640x480 and 800x800 pixels, respectively; other formats up to QSXGA extend image size to 2560x2048 pixels.

Digital Video I/Os
DVI (Digital Visual Interface): Carries audio and video signals between a PC or workstation and displays; supports projectors and consumer receivers through DVI-to-HDMI converters; developed by Digital Display Working Group (DDWG) to replace analog VGA/S-VGA connections; partially compatible with HDMI in digital mode (DVI-D) and VGA in analog mode (DVI-A).
HDMI (High Definition Multimedia Interface): For set-top boxes, DVD/Blu-ray players, camcorders, game consoles and PCs; carries compressed/uncompressed video, multichannel audio and auxiliary/control data.

SDI (Serial Digital Interface): A series of SDIs standardized by SMPTE to define digital-video interfaces for high-end broadcast-grade material; SD-SDI operates at uncompressed data rates between 143 and 360 Mb/s over coaxial and fiber-optic connections; HD-SDI or 1.5G SDI, standardized in SMPTE 292M, provides a data rate of 1.485 Gb/s; dual-link HD-SDI is used for digital cinema or HDTV 1080P; 3G-SDI comprises a single 2.970 Gb/s rate to replace dual-link HD-SDI.

Mel Lambert has been intimately involved with AV production industries on both sides of the Atlantic for more years than he cares to remember. He's now principal of Content Creators, a Los Angeles-based editorial and photographic service. You can reach him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

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