Picture This: TV-Output Comparison

Contrary to popular belief, there are only a few TV output chips that are widely used by graphics card manufacturers. The four main solutions being compared in this article are the Brooktree BT869, the Chrontel CH7002D-V, the Matrox MGA TVO, and the ATI ImpacTV2.

This proprietary controller is used on the ATI Rage 128 and provides the same basic functionality that the Chrontel and Brooktree solutions offer.

Brooktree BT869

The Brooktree BT869 is a very popular TV output controller and is featured on all TNT/TNT2 cards that support TV out (except for the Canopus Spectra 2500 and ASUS TNT/TNT2 cards) as well as Savage4 cards with TV out support, and the Voodoo3 3000. The supported resolutions are 640 x 480, 800 x 600, and 1024 x 768.

The benefit of the higher resolutions is not necessarily for better TV display, rather for support for higher desktop resolutions while running with TV output enabled. The BT869 is capable of outputting both to your monitor and an external TV, however they both must be at the same resolution.

This chip was primarily used by Canopus, and features the same functionality as the BT869.

The MGA TVO is used on the Matrox G400 line of video cards and supports resolutions up to 1024 x 768. What makes the TVO unique is that it is the driving force behind Matrox?s DualHead (see AnandTech?s review of the Matrox Millennium G400) technology, and essentially treats the TV output as a second monitor. This allows your desktop resolution/refresh rate to remain independent of your outputted TV resolution/refresh rate.

The four cards were tested at all supported resolutions, using three different tests, however due to the relative similarities between all tested resolutions and download constraints, only 800 x 600 (when possible otherwise 640 x 480) was used for the screen captures.

The first test is a screen capture from Rage Software?s Expendable. The original capture was performed at 1024 x 768 x 32-bit color, and demonstrates gaming image quality and resolution limitations.

The second test is Microsoft Wordpad displaying script.doc, a document file included with every Windows 9x installation. The capture was performed at all supported resolutions.

The third test is a DVD playback test using Zoran?s SoftDVD and a Phillips DVD drive displaying two scenes in the movie Ronin. The two scenes are designed to illustrate any banding or other visual artifacts created by the TV output.

The video card?s output was first tested on a Sony television (NTSC) for visible signs of flicker, image quality loss, and other noticeable artifacts produced by the TV output controller. The screen captures were performed using a S-Video cable from the video card directly to the input port on a test bed equipped with a Matrox Marvel G200, this was done to eliminate the influence of the test TV as an image degrading factor.