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 ownershipo no platform integration and testo 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

AppServers

MediaServer

App Servers

HM

P

HM

P

HM

P

HM

P

HM

P

Primary Features

• IVR Operationso Play prompt, record and play messages,

detect DTMF tones, ASR & TTS interface

• Audio processing operationso Automatic gain control, voice activity

detector, acoustic DTMF detector

• Enhanced media serviceso Transcoding (audio and video),

conferencing

• VoIP call connectionso RTP packetization, SIP signaling, encryption

Application Control Options

Application Server

Application Server

Application Server

Application Server

Application Server

Application Server

IP Media ServerIP Media ServerHMP Media Server

“Native” VOIP Application

“Native” VOIP Application

“Native” VOIP Application

IP Media ServerIP Media ServerHMP Media Server IP Media ServerIP Media ServerHMP Media Server

API

VoiceXML& CCXML

Control Protocol (SIP)

• MarkupLanguages

• API • ControlProtocol

Inside the HMP Media Server: Protocol Stacks

Host Ethernet Ports

Host IP Protocol Stack (QoS, Firewall)

UDP / SCTP TCP

RTP

HostMedia

Processing

HTTP

Scripting Engines

Media Control

Protocols

SIPMRCP

Speech Automation

Application InterfaceMedia Services

HMP StackExample Configuration for IVR

IP (QoS)

UDP

IP (Firewall)

UDP

RTPEgress IngressRTP

Packet Scheduler Jitter 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 Applicationso Reliable delivery

without error; timing is not critical

o Bursty, unpredictable bandwidth consumption

o Nonlinear performance degradation near bandwidth saturation

time

bandwidth

bandwidth

time

• Voice Applicationso 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

CoderTransmission

BandwidthDelayTime

Mean Opinion Score (1-5)

G.711 64 kbps 0.75 ms 4.4

G.726 16-32 kpbs 1.0 ms 4.2

G.729a 8 kbps 10 ms 4.2

G.723.1 6.3 kbps 30 ms 4.0

iLBC 15 kbps 20 ms 4.2

Voice Coder Resiliency

Mean Opinion Score

1.5

2.0

2.5

3.0

3.5

4.0

4.5

No Loss 5% Loss 10% Loss

Packet Loss

iLBC

G.711

G.723.1 G.729A

Native RTP File Recording

ContentStore

File Stream withEncapsulated RTP

• Improve the quality of recordings

• Reduce the cost of transcoding

VoIP CallersG.711 G.726 G.723 G.729

HMP

Application

Types of Attack or Misuse

Source: IDC, 2003 CSI/FBI Computer Crime and Security Survey

0 10 20 30 40 50 60 70 80 90

Percentage Responding to Survey

Active Wiretap

Telecom Eavesdropping

Telecom Fraud

Financial Fraud

Sabotage

Theft of Property Information

System Penetration

Denial of Service

Insider Unauthorized Access

Laptop

Insider Abuse of Network

Virus

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

• Kernel • User-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

0

500

1000

1500

2000

2500

3000

2003 2005 2007 2009

Nn

um

be

r o

f P

ort

s p

er

1U

Montecito (4-Way)

Tanglewood(16-Way)

Dual 2.4 GHz

Dual 64-Bit

Based on Intel CPU Roadmap

DSP vs. HMP ??

• DSPo Very high

densityo High

transcoding requirement

o Low power requirement

o PSTN interfaces and signaling

• HMPo Lower densityo Need to deploy

on generalized servers

o VOIP-only

Is HMP Inevitable ??

• New processing requirements that favor DSP economicso Security – encryptiono Wideband audio (conferencing)o Video transcoding, transrating,

resizing, and conferencingo …