Wired's MediaPress MPEG-2/DVD real-time encoder - Evaluation

Emedia Professional, May, 1999 by Jan Ozer

at $4,999, Wired Inc.'s MediaPress for Windows 95/98 is one of the cheapest real-time hardware MPEG-2/DVD encoders around, with good output quality that ultimately proved compatible with both of our test DVD authoring systems (Daikin Scenarist and Minerva Impression). However, the card doesn't support professional-quality input formats and lacks automation tools like machine control and batch encoding, as well as Windows NT compatibility. Though Wired has aggressive plans to add these features, MediaPress is currently best-suited for low-volume production for corporate or small multimedia developers.

MediaPress is a single-board encoder based on the Sony MPEG-2 encoder, with S-Video and composite video and stereo audio inputs. On the Wintel platform, MediaPress currently only runs under Windows 95/98--a frustrating limitation given that most DVD authoring programs, including those from Daikin and Minerva, only support NT.

The system used in testing included Wired's MasonX MPEG-2 decoder, which can preview encoded MPEG-2 audio/video streams from the MediaPress after a short delay. This decode-while-encode combination lets users instantly preview adjustments made to the video, a helpful feature. However, MasonX won't display on your computer monitor, and requires a separate NTSC monitor.

software functionality: the hard truth

Like many Mac programs ported over to Windows, the MediaPress Application software bundled with the encoder is minimalist in nature. To encode, first establish a target file name; then choose to encode audio, video, or both in either multiplexed or standalone format. Since most DVD authoring programs work with separate audio/video files, we encoded in this fashion.

With MediaPress, users can encode in either MPEG-1 or MPEG-2 formats at data rates ranging from 768kbps to 15mbps, in thumbnail-sized resolutions of 48 x 32 to full MPEG-2 720 x 480. The board also supports half-height D-1 (720 x 240) and Super Video CD (480 x 480) resolutions, but not square-pixel MPEG-1 (320 x 240)--an important limitation for producers of MPEG-1 CDs.

On the audio front, you can encode in either MPEG (layer 1 or 2) or Linear PCM formats, at data rates ranging from 64 to 384KB/sec in either variable or constant bit rate. AC-3 audio is not supported, so if your authoring program doesn't provide AC-3 compression, you'll need a third-party encoder, which starts at around $695 for a software-only system. DVD authors should keep this in mind when comparing price with other MPEG-2 encoding systems.

Unfortunately, MediaPress doesn't offer device control over source video decks, a feature that promotes capture precision and enables batch encoding and two-pass variable bit rate encoding. However, incoming media adjustments are extensive. For video, you can modify the incoming brightness, contrast, saturation, and hue, as well as enable or disable a low-pass filter, and multiple levels of noise reduction, smoothing, and sharpening. The board offers an inverse telecine mode for film-based assets, which we didn't test.

MediaPress also allows users to adjust the G0P size, pattern, or structure, but you can't insert an I-frame to clean up a dramatic scene change. The Sony encoder chip, on the other hand, automatically inserts I-frames during scene changes, but caused problems during testing. Also lacking are equalization controls that shift the video image in the capture window to eliminate misalignments. Our DV source camera was slightly misaligned with MediaPress, causing a two- or three-pixel border on top of all captured video.

MediaPress also provides control over other encoding minutiae like quantization scale, intra VLC format, and concealment MV, and several similarly enigmatic commands for audio encoding. Though you can preview all these adjustments in real-time with the MasonX decoder, most are beyond even the expert user, and few improve quality significantly.

According to Wired's developers, the company is shifting away from selling to Macintosh technophiles in favor of Windows users who, in general, are more concerned about DVD compatibility and ease-of-use. In this regard, during the latter stages of our review, we received a software update with presets for standard data types like DVD, Video CD, and CD-i. Each preset sets all critical encoding parameters for the target medium, vastly simplifying operation for less technical users.

As long as Wired's developers are open to changes, I'd suggest still image capture at 720 x 280 resolution to simplify capturing background screens for menus. Also on the wish list is online help, especially given the obscurity of certain configuration options and the equally minimalist 11-page manual. Overall, however, if you use the presets, you'll find MediaPress very easy to use.

Since MediaPress doesn't offer device control over source decks, the user must capture by rolling tape, pressing start to begin capture, and hitting stop at the end. Though real-time preview helps, this method inevitably results in "heads" and "tails"--unwanted frames--at the start and end of the clip.