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DeltaChrome As Is

We managed to get our hands on the graphics adapter based on DeltaChrome S8 chip, which is the second fastest VPU from S3G positioned as a direct competitor to mass solutions of the 3D market leaders, namely ATI Technologies and NVIDIA Corporation. As a result we decided to compare it with graphics solutions based on RV350/360 and NV31/36 respectively. If we approach this comparison from a theoretical point of view, DeltaChrome will look not any worse than the solutions from the two largest graphics processor developers.

Moreover, S3G newcomer boasts a number of interesting technologies. The most remarkable one, which we should mention separately is the Chromotion engine. Starting with R300, ATI’s VPUs are known to support real time video streams processing with the help of pixel shaders unit. S3 Graphics engineers have significantly enhanced the idea about involving pixel shaders into video processing. Having implemented this idea in real silicon they called it Chromotion. What can this wonder-technology actually do? In fact, it can do quite a lot of things: the use of pixel shaders allows performing the following with the video streams:

  • Per-pixel adaptive deinterlacing;
  • 4x4 programmable kernel filter video scaling;
  • Real-time post processing;
  • Real-time video effects.

All in all, DeltaChrome is very rich in video processing features and boasts the following additional things:

  • Hardware MPEG-2/4 acceleration;
  • Hardware IDCT and motion compensation support;
  • Hardware Windows Media Video acceleration;
  • HDTV support (component output);
  • 4:4:4 conversion with 10 bit DAC
  • 2/3 tap flicker filter with programmable coefficients;
  • Vertical over/underscan compensation;
  • 2x Oversampling for premium image quality;
  • Full range RGB to YUV color space conversion with Hue, Saturation and Contrast adjustment.

S3 has definitely outperformed all its competitors here, although it still failed to become the first in the field of pixel shaders for video streams processing. The leadership here surely belongs to ATI Technologies with its VideoShader, which has hardly been used by the software developers at all (except DiVX Player). We hope that the arrival of the new VPU featuring such wide range of options for video processing will manage to stimulate the developers’ interest and we will finally see the whole bunch of software products using brilliant opportunities offered by VideoShader and Chromotion technologies.

We can’t help mentioning the support of vertex and pixel shaders with the parameters beyond DirectX 9.0 specifications: this is where S3 developers did a really great job. Just take a look at the comparative spec table for NVIDIA, ATI and S3 graphics processors:

 

ATI RADEON 9800

S3 DeltaChrome S8

NVIDIA GeForce FX 5950

Manufacturing technology

0.15micron

0.13 micron

0.13micron

Number of transistors

110-115mln

80mln

135mln

Chip frequency

412MHz

300MHz

475MHz

Graphics memory controller

256bit
DDR SDRAM

128bit DDR SDRAM

256bit
DDR SDRAM

Graphics memory frequency

730MHz
(365MHz DDR)

650MHz
(325MHz DDR)

950MHz
(475MHz DDR)

Peak memory bus bandwidth

23.4GB/s

10.4GB/s

30.4GB/s

Max graphics memory size

256MB

256MB

256MB

AGP interface

AGP 3.0 4x/8x

AGP 3.0 4x/8x

AGP 3.0 4x/8x

Pixel Pipelines, Pixel Shaders

Pixel pipelines

8

8

4, 8

Texturing unites per pipeline

1

1

2, 0

Max number of textures during multi-texturing

8

8

8

Texture filtering types

bi-linear
anisotropic
tri-linear
tri-linear + anisotropic

bi-linear
anisotropic
tri-linear
tri-linear + anisotropic

bi-linear
anisotropic
tri-linear
tri-linear + anisotropic

Max anisotropy level

16

16

8

Pixel shaders version

v.2.0 (f-buffer, v2.0+)

v2.0+

v.2.0+

Branching, subroutines and loops

none

n/a

none

Max number of textures per shader

16

16

16

Max number of texture instructions

32

n/a

1024

Max number of arithmetic instructions

64 (+64)

n/a

1024

Max number of instructions per shader

96 (+64)

n/a

1024

Registers

2 color registers,
32 constant registers,
8 texture coordinates registers,
16 TMU identification registers,
12 temporary registers,

4 resulting color registers,
1 resulting Z register

n/a

2 color registers,
512 (1024) constant registers,
8 texture coordinates registers,
16 TMU identification registers,
16 (32) temporary registers,

4 resulting color registers,
1 resulting Z register

Data representation formats

Fixed point,
16bit floating point,
32bit floating point

Fixed point,
16bit floating point,
32bit floating point

Fixed point,
16bit floating point,
32bit floating point

Internal Pixel Shader Pipeline Precision

96bit pixel precision/24bit floating point precision

96bit pixel precision/24bit floating point precision

128bit pixel precision/32bit floating point precision, 16bit floating point precision

Vertex pipelines, vertex shaders

Vertex pipelines

4

4

3

Vertex shaders version

v.2.0

v.2.0+

v.2.0+

Branching, subroutines and loops

Static

Dynamic, 16x16 maximum loops

Dynamic

Max number of instructions per shader

256

n/a

256

Max number of instructions with loops extension

65536

65536

65536

Registers

16 input registers,
12 temporary registers,
256 constant floating-point registers,
16 constant integer registers,
16 Boolean registers,
1 address register,
1 loops counter register,

8 output registers for texture coordinates,
1 fog color output register,
1 vertex position output register,
1 pixel size output register,
2 output registers for diffuse/mirror color component

16 input registers,
16 temporary registers, etc…

16 input registers,
16 temporary registers,
256 constant floating-point registers,
256 constant integer registers,
256 Boolean registers,
1 address register,
1 loops counter register,

8 output registers for texture coordinates,
1 fog color output register,
1 vertex position output register,
1 pixel size output register,
2 output registers for diffuse/mirror color component

Data representation formats

32bit floating-point

 

32bit floating-point

Full-Scene Anti-Aliasing

FSAA methods

Rotated grid multi-sampling
(RGMS)

Supersampling, Multisampling

Supersampling,
Ordered grid multi-sampling
(OGSS, OGMS)

Number of samples

2, 4, 6

2

2 (OGSS, OGMS),
Quincunx,
4 (OGSS, OGMS, OGSS+OGMS),
6 (OGSS+OGMS),
8 (OGSS+OGMS)

Technologies aimed at higher memory bandwidth efficiency

Hidden Surfaces Removal (HSR)

Yes

Yes

Yes

Frame-buffer compression

Yes

n/a

Yes

Z-buffer compression

Yes

n/a

Yes

Other techniques

Yes

Yes

Yes

As you see, the abilities of DeltaChrome solution in terms of shader processing is far beyond the DirectX 9.0 minimal requirements. Will the game developers really take advantage of it? It is hard to answer this question, actually. But if this is ever destined to happen we will have to wait for quite a long time, maybe until these features become a widely spread standard.

Besides that, DeltaChrome features bi-directional color and Z buffers, supports hardware GDI+ acceleration, can lay up to 16 textures per single pass and perform 2x supersampling and up to 16x anisotropic filtering. Unfortunately, the current driver version doesn’t support multi-sampling, which the company also claims as one of the features.

Theoretically, DeltaChrome looks like a very successful solution: the chip boasts a lot of interesting features and strikes as pretty competitive. However, it is high time we shifted from beautiful and promising but “theoretical” tables to the real graphics accelerator and find out what the new S3 baby is actually capable of.

 
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