Gear & Now: A/D Converters
Posted Sep 16, 2005

The market for bridge devices between legacy analog equipment and digital computer-based video systems continues to grow. In fact, according to industry analyst InStat, worldwide media adapter shipments will see a compound growth rate of some 76% over the next few years. That's remarkable growth, especially given the trend toward integrating adapter technology directly into many electronic devices.

Because analog-to-digital converters have an important role to play in the edit suite, at the dubbing station, and even on location, we'll take a look at some popular and functional outboard hardware devices (there are many fine software solutions, as well as devices specifically for audio or video, not covered here) for converting analog video into digital data.

Devices from under $100 to nearly $3,000 are available; the higher-end models distinguish themselves from the consumer products by the connectivity options (supporting one device or many; one format or many), the conversion quality (dependent on internal codec and sampling algorithms), and overall features and functions (some devices are continually upgraded via software downloads; others are fixed in their features and performance).

Some converters do much more than just convert: there are products with image processing and enhancement tools, TV tuners, scan converters, frame stores, and more.

The more moderately priced A/D converter products include offerings from ADS Technologies, Dazzle/Pinnacle, Formac, LaCie, Miglia, and TV One. The higher-end conversion set includes the AJA I/O lineup, the Blackmagic Design Multibridge family, and Miranda's DVBridge products. Canopus offers A/D converters at almost every price point and feature set.

Datavideo
I've had occasion to work with three different models recently: the Datavideo DAC-100, Sony's DVMC-DA2, and the ProMax Pro Media Converter (Convergent Design SD-Connect).

The DAC-100 (about $180) is a simple and straightforward device for transferring video back and forth from DV to analog tape. Compatible with Mac or PC workstations, the unit has two 6-pin FireWire ports, along with Y/C and composite (RCA jacks) video and stereo audio I/O. Two control buttons are available: one for switching between A-to-D and D-to-A conversion, the other for switching between 16-bit and 12-bit audio.

Its DV output is ready for many NLEs (Apple, for example, recently qualified its output for Final Cut Pro 5, along with other units from DataVideo), and its video quality is quite good for the price. The audio is locked regardless of sampling rate.

Datavideo has other converters in its lineup; the newer DAC-30, for example, adds support for component video, balanced audio, and RS-422 connectivity. The unit has a built-in time-base corrector for image correction and stabilization, and the company's new software upgrade, called Smart DV, which helps eliminate system conflicts (such as when a computer senses both a DV tape source and a DV converter, in the same data stream). The DAC-30 lists at $2,499.

Sony
Sony's A/D converter, the DVMC-DA2, is an older unit (shipments of this configuration were stopped a while ago, but used and stockpiled units are still available online for around $450) but still a good one. It, too, converts back and forth between analog and digital video, and the video quality is very good. DV, S-Video, and RCA audio and video I/O connectors are available.

It's with this unit that we first encountered A/D audio sync issues, however. By default, when going analog to DV, the DA2 encodes audio in 12-bit mode. Most video editing systems prefer 16-bit (even though they can be switched). Because of the rate mismatch, the audio can drift out of sync. It's not locked audio anyway, so longer clips can pose real problems.

But, by holding the Analog In button down on the DA2, the unit will switch to 16-bit. Interestingly, for those who need it, the DA2 will retain closed-caption information during video conversion.

ProMax
The ProMax Pro Media Converter (aka Convergent Design SD) is a powerful A/D converter, with added features and functions always coming, thanks to its software upgradability.

The PMC is a much larger unit than the others mentioned so far; it features an LED screen that displays unit functions and settings, and it has an array of input and output connections on the back of the unit.

Component, S-Video, and composite machines all can remain connected to the converter, regardless of desired function. That's very handy in a multi-format editing environment (or any edit suite where getting to the cables is a nuisance); we have Betacam, S-Video, and VHS decks that remain connected all the time due to our workload.

Menu controls allow the user to select devices, conversion paths, and other settings quickly and easily, with just the twist of a dial. Current software (updates are downloaded off the Web) supports DV compatibility with Apple, Avid Xpress, Adobe, and Sony editing software, as well as some SDI devices. The unit converts analog audio to 48kHz audio; 32kHz support is coming (along with audio meter display, and audio/video test pattern generation), according to ProMax. The Pro Media Converter has an MSRP of $1,495.

Convergent Design, by the way, recently announced even more new software, new features, and new capabilities for the SD Connect converter box, including support for uncompressed (1:1) 10/8 bit video and audio over FireWire (beta drivers for uncompressed 10/8 bit video and 24-bit audio with Final Cut Pro had just become available at press time; uncompressed drivers for Premiere were expected within a month). The no-charge software adds 4-channel audio level meters, gen-lock delay control, SMPTE bars, and RS-422 to 1394 device control, among other features.

Canopus
Canopus, as mentioned, offers several external conversion devices; all are real-time, compatible with both PC and Macs, and feature Canopus' proprietary DV codec, delivering some of the best quality video conversions. Included are one-way (analog to DV-only) solutions like the ADVC 55 (about $230), and the more sophisticated multifunction TwinPact100 (around $550), which acts as a two-way video converter, image enhancer, and scan converter.

TwinPact100 converts on-screen graphics to analog and digital video, supporting resolutions up to 1600x1200. It has controller software, which allows the user to pan, scan, and zoom into an area for conversion. It has brightness, contrast, saturation, and sharpness controls to further enhance output.

Blackmagic Design
Conversion between analog and digital is one thing, but more and more videographers now are looking for standard to high-definition conversion, as well.

Blackmagic Design's Multibridge is a bi-directional analog converter that also switches between HDTV and SD video. The breakout box features just about connection you'll need for high-end video applications, along with selectable audio/video sampling rates and color space conversion ratios.

The HD Multibridge is $1,995 (a standard def-only version lists for $1,495). The company also offers PCI Express-based Multibridge models, priced up to $3,495.

Miranda
Miranda's DV-Bridge Pro converts analog component or composite video to DV and vice-versa. It has balanced audio inputs as well as unbalanced line inputs, and it preserves linear and vertical interval timecode during conversion. It has bi-directional VTR control capability, and operates in several different modes, including analog-to-DV (encoder), DV-to-analog (decoder), or analog-to-analog (pass-through).

It also converts between 4:3 and 16:9 aspect ratios, and uses audio sampling rates of 32, 44.1, and 48 kHz. The desktop package comes with universal built-in power supply, and is priced around $2,000. Miranda also offers a DV-to-SDI converter, for broadcast applications, that sits in between a camera and its tripod for field use and convenience.

AJA
According to many users (and Mac enthusiasts), the AJA Io family delivers some of the highest-quality 10-bit uncompressed video and multi-channel audio around. Video inputs include composite, component and S-video connections; analog audio uses XLR and TRS connections. Digital SDI and AES/EBU are also supported.

The Io line's various outputs are available all the time, allowing for easy conversion, tape deck recording and real-time monitoring. Io devices also feature RS-422 machine control, an audio word clock for perfect sync, and a professional video genlock. Pricing starts at $2,300.

Edirol
Finally, a quick word about a unique converter from Edirol. The VMC-1 breakout box features not only a bi-directional analog-to-DV converter (with 10-bit encoding and selectable 48 kHz/16 bits or 32 kHz/12 bits audio), but adds what Edirol calls a "Video Restorer and Optimizer." It's a built-in Time Base Corrector (TBC) and Frame Synchronizer offering four real-time color correction parameters, motion adaptive 3D Y/C separation for color fidelity, and gain controls to adjust exposure. Audio manipulation is not forgotten: the box boasts built-in audio level controls and separate clip/signal indicators as well.

While DV/1394 connections are featured, naturally, the other audio and video connections are RCA-type, one obvious drawback in an otherwise function-packed product.

Suggested Resources

ADS Technologies www.adstech.com

AJA
www.aja.com

Blackmagic Design
www.blackmagic-design.com

Data Video
www.datavideo.us

Edirol
www.edirol.com

Formac Electronic
www.formac.com

LaCie
www.lacie.com

Miglia
www.miglia.com

Miranda Technologies
www.miranda.com

Pinnacle Systems
www.pinnaclesys.com

ProMax Systems
www.promax.com

Sony Electronics
www.sonystyle.com

TV One
www.tvone.com