Audio Performance

DirectSound 2D

DirectSound 2D

	Audigy 2	nForce2 MCP SoundStorm with 2-channel Sensaura HRTF mode	nForce2 MCP SoundStorm in 6-channel AC-3 mode
Static 22kHz, 8-bit, 8 voices	0.0346	2.11	0.958
Streaming 22kHz, 8-bit, 32 voices	1.66	4.21	5.08
Static 22kHz, 8-bit, 8 voices	0	2.83	1.01
Streaming 22kHz, 8-bit, 32 voices	1.68	5.62	4.32
Static 44.1kHz, 16-bit, 8 voices	0.241	2.85	0.954
Streaming 44.1kHz, 16-bit, 32 voices	2.83	5.01	5.34
Static 44.1kHz, 16-bit, 8 voices	0.37	2.35	0.936
Streaming 44.1kHz, 16-bit, 32 voices	2.83	4.97	5.8

DirectSound 3D

	Audigy 2	nForce2 MCP SoundStorm with 2-channel Sensaura HRTF mode	nForce2 MCP SoundStorm in 6-channel AC-3 mode
Static 22kHz, 8-bit, 8 voices	0.804	3.29	3.09
Streaming 22kHz, 8-bit, 32 voices	2.83	6.64	5.34
Static 22kHz, 8-bit, 8 voices	0.633	3.21	2.98
Streaming 22kHz, 8-bit, 32 voices	2.66	6.99	5.2
Static 44.1kHz, 16-bit, 8 voices	1.06	3.39	2.28
Streaming 44.1kHz, 16-bit, 32 voices	3.21	7.31	6.27
Static 44.1kHz, 16-bit, 8 voices	1.03	3.72	3.22
Streaming 44.1kHz, 16-bit, 32 voices	3.47	7.31	6.25

The Audigy 2 offers superior performance. This is interesting to us given the fact that the nForce2 was supposed to have support for more 2D audio streams. We fired up a DirectX test application and began to play back multiple streams of “chimes.wav.” Each time we added a stream, two buffers appeared to be used on the Audigy while only one was used on the nForce2. After 24 streams, the Audigy 2 only reported having 14 hardware-accelerated buffers. The nForce still had over 200 buffers available. We re-ran the DirectSound benchmarks and the Audigy 2 still had the lead.

DirectSound 2D benchmark with 24 streams in the background

	Audigy 2	nForce2 MCP SoundStorm in 6-channel AC-3 mode
Static 44.1kHz, 16-bit, 8 voices	1.63	4.5
Streaming 44.1kHz, 16-bit, 32 voices	6.77	9.15
Static 44.1kHz, 16-bit, 8 voices	1.9	4.57
Streaming 44.1kHz, 16-bit, 32 voices	6.61	8.66

When you compare the two sets of numbers, it seems that the nForce2 has about 3% CPU usage overhead (recall that this is on a Duron 950). As the number of streams increase, however, the nForce2 starts to catch up. This is akin to the “faster at high resolutions and high color depths” phenomenon. Since the nForce2 drivers are still in their earliest stages, we believe that there remains room for improvement. Even though more speakers can offset the need for high-quality HRTFs, clearly more speakers *and* high quality HRTFs will be better. We expect newer nForce2 drivers to incorporate Sensaura's 5.1 algorithms. There's no additional license fee, only addition engineering work -- that engineering work has been one on the Xbox MCP"