Powerful servers and IP telephony have given rise to the host-media-processing (HMP) media server. The term “HMP” is loosely applied since not all HMP media servers actually process a call’s media stream. The IETF RFC2833, which specifies how in-band telephony tones can be transported in RTP packets, allows the signal processing needed to detect these tones to be outsourced to the media gateway. And messaging can be implemented by simply storing the RTP packet payload.
But what happens when real media processing is required? For example, often the requirements for in-band call-progress analysis for dial-and-deliver applications in messaging servers exceed the capabilities of media gateways. And what if voice messages are stored in G.711 or G.726, and the playback requires a different codec, perhaps a MIPS-hungry low-bit-rate vocoder? How about T.38 or G.711 pass-through fax termination?
That’s when you need HMPturbo.
HMPturbo Transcoding Subsystem (TSS) is available in two versions: one requires no additional hardware. It’s for the processing-challenged media server. Here, HMPturbo is needed to meet additional requirements, as described above. Packet buffers are sent to the HMPturbo subsystem through an easy-to-use API. The subsystem can handle, for example, in-band call-progress analysis, DTMF, real-time IP fax (G.711 or T.38) termination (and relay), and vocoder transcoding. The second version is functionally identical and exposes the same API, but uses Commetrex’ MSP-320 to really “turn on the turbo.” The same media-processing functions are available, but they are executed by the PCI board’s DSPs.
The MSP-320 includes two TI TMS320C6201 DSPs, each with the resources to process 20 G.729a/b streams or approximately the same number of V.17 fax-modem receivers.