Using Software Voice Engines Instead of External DSPs
Due to the reduction in hardware cost, a softDSP design is ideal for cost-reduced voice products which provide one to four telephony channels. This includes mobile handsets, which are increasingly providing VoIP services through WiFi. The break-even cost is at over four channels, where the tradeoff between SoC processing power available for softDSP can’t compete with a highly efficient external DSP.
The softDSP approach also works for designs with more than eight channels, where heat, board space, and the need for additional power supplies can become an issue for external DSPs. Such designs typically employ multi-core SoCs. A single core of the SoC can be dedicated to running the softDSP, or the MHz-heavy voice components can be distributed across multiple cores.