NVIDIA nForce Computex 2001 Preview

Media and Communications Processor (MCP) & Audio Processing Unit (APU)

The nForce MCP provides all the standard south bridge features, including support for Ultra ATA 100, 6 USB ports, 10/100 Ethernet, 1/10 HomePNA, 56k modem and AC'97 sound. Unlike the integrated Ethernet found in recent Intel and VIA south bridges, it looks like most motherboard manufacturers will actually be taking advantage of this nForce feature.

What differentiates the nForce MCP from other south bridges is the Audio Processing Unit (APU) NVIDIA has integrated into the chip. This will be the first fully DirectX 8 compliant audio part when it hits the market. The APU supports 64 3D voices or 256 2D voices in hardware, 32 hardware submixers, and is EAX 2 and I3DL2 compatible.

There are two versions of the MCP, with the difference being support for real time Dolby Digital AC-3 (5.1) encoding. This is by no means a trivial accomplishment and is the feature that distinguishes the MCP-D from the standard MCP. As such, the MCP-D is virtually identical to the MCPX found in the XBOX, but adds the PCI bus that a console has no need for. It seems that NVIDIA licensed the Parthus MediaStream DSP in order to integrate such a complex feature quickly enough to meet Microsoft's XBOX deadlines.

Dolby Digital AC-3 encoding means that you'll be able to digitally connect your computer to a home theater (or any other sound system) with a Dolby Digital Decoder and get sound quality that rivals a DVD movie - if done properly. If you choose not to use an AC-3 out, the APU can work with 2, 4, or 6 speaker configurations using standard analog interfaces.

The 4 billion operations per second of the MCP's DSP aren't used just to encode Dolby Digital on the fly, but also calculates occlusions, reflections, and HRTF functions, offloading these functions from the CPU. Thus, enabling 3D audio in games on an nForce-based system should not result in any slow down over standard stereo audio - at least in theory.

Right now, it's not clear whether or not the standard MCP will include fully hardware accelerated sound or if this will only come with MCP-D, but early indications are positive. It is clear, however, that Dolby Digital encoding will be limited to the MCP-D parts. So far, it seems that most of the motherboard manufacturers intend to include MCP-D on their initial boards, although this may change depending on the pricing of the chipset. Chipsets including MCP-D will have a "D" appended to their name, such as nForce 420D.