Developing Applications with Host Media Processing David Asher

Host Media Processing: What We’re Talking About Using a general-purpose computing platform To create a telephony application

Market Trend: Host Media Processing Lower acquisition costs, sometimes Lower provisioning and maintenance costs Eliminate special hardware associated costs More failure recovery options

HMP Reliability Economics 1 DSP platform with 480 ports 4 HMP platforms with 480 ports 1 Failure = 480 ports 1 Failure = 120 ports

HMP Application Economics ~ $4k for 1U Dual Xeon 120 application sessions rated capacity  ~ $33 per session HW cost Reduction in total cost of ownership o no platform integration and test o no special hardware inventory, tracking, failures, replacements, repairs, tech support

Distributed Media Processing Single large DSP media server Small media servers “built-in” to each application App Servers Media Server App Servers HMP

Primary Features IVR Operations o Play prompt, record and play messages, detect DTMF tones, ASR & TTS interface Audio processing operations o Automatic gain control, voice activity detector, acoustic DTMF detector Enhanced media services o Transcoding (audio and video), conferencing VoIP call connections o RTP packetization, SIP signaling, encryption

Application Control Options Application Server Application Server Application Server Application Server Application Server Application Server IP Media Server HMP Media Server “Native” VOIP Application “Native” VOIP Application “Native” VOIP Application IP Media Server HMP Media ServerIP Media Server HMP Media Server API VoiceXML & CCXML Control Protocol (SIP) Markup Languages API Control Protocol

Inside the HMP Media Server: Protocol Stacks Host Ethernet Ports Host IP Protocol Stack (QoS, Firewall) UDP / SCTPTCP RTP Host Media Processing HTTP Scripting Engines Media Control Protocols SIPMRCP Speech Automation Application InterfaceMedia Services

HMP Stack Example Configuration for IVR IP (QoS) UDP IP (Firewall) UDP RTP EgressIngress RTP Packet SchedulerJitter Buffer Auto Gain Control Voice Decoder Voice Activity Det. Tone Detector RTP Stream Switching Media Processing RecordPlay Application Interface Packet Processing Voice Activity Det. Tone Generator Voice Encoder Gain Control Operating System API / IVR

Quality of Service – Why? Data Applications o Reliable delivery without error; timing is not critical o Bursty, unpredictable bandwidth consumption o Nonlinear performance degradation near bandwidth saturation time bandwidth time Voice Applications o Timely delivery is critical; errors can be tolerated o Predictable bandwidth consumption o Linear, well distributed performance degradation near bandwidth saturation

Quality of Service – What? Jitter Increase or Packet Loss Events Available Bandwidth Voice Class Data Class time

Voice Coder Performance Coder Transmission Bandwidth Delay Time Mean Opinion Score (1-5) G kbps0.75 ms4.4 G kpbs1.0 ms4.2 G.729a8 kbps10 ms4.2 G kbps30 ms4.0 iLBC15 kbps20 ms4.2

Voice Coder Resiliency

Native RTP File Recording Content Store File Stream with Encapsulated RTP Improve the quality of recordings Reduce the cost of transcoding VoIP Callers G.711 G.726 G.723 G.729 HMP Application

Types of Attack or Misuse Source: IDC, 2003 CSI/FBI Computer Crime and Security Survey

SECURITY IS YOUR RESPONSIBILITY !!! An HMP platform is a computer like any other It is vulnerable to many Internet security threats The application developer is responsible for building secure applications!

Kernel vs. User-Space Implementation KernelUser-space o HMP exists in the same process space as the applications o A critical failure in the HMP stack can crash the server o Hard to isolate HMP problems from application problems o HMP exists in it’s own process space; the service can be stopped o A critical failure in the HMP stack won’t destabilize the server o HMP problems are isolated from application problems

HMP Density Roadmap Montecito (4-Way) Tanglewood (16-Way) Dual 2.4 GHz Dual 64-Bit Based on Intel CPU Roadmap

DSP vs. HMP ?? DSP o Very high density o High transcoding requirement o Low power requirement o PSTN interfaces and signaling HMP o Lower density o Need to deploy on generalized servers o VOIP-only

Is HMP Inevitable ?? New processing requirements that favor DSP economics o Security – encryption o Wideband audio (conferencing) o Video transcoding, transrating, resizing, and conferencing o …