Asterisk v1.6 & HDVoice

Demonstrating HDVoice In Asterisk Using Polycom’s Siren Codecs

Who Am I?

• Michael Graves, Pixel Power Inc– System Integration Manager– Oversee telecom for North America

• VoIP Blogger– Focused on SOHO/SMB space– Asterisk user since 2003

• VoIP Users Conference– Guest host & frequent contributor

A Few Simple Facts

• Polycom hardware is extremely popular with Asterisk installations

• Polycom offer high-quality SIP hard phones at prices from $ to $$$$*

• The SoundPoint IP series desktop models support G.722

• VVX-1500 & SoundStation conference phones support G.722, Siren7 & Siren14

Polycom Siren7 Basics

• HDVoice call quality at reduced bitrates– Modulated Lapped Transform (MLT) – Suitable for music & speech– 16 KHz sample rate– 50 – 7,000 Hz audio response– Three bitrates: 16*, 24 or 32 kbps – 40 ms algorithmic delay (20ms frames)– ITU-T Standard G.722.1 (9/1999)

Polycom Siren14 Basics

• Siren 14 – “Super-Wideband” calling– 32 KHz sample rate– Suitable for music & speech– 50 – 14,000 Hz audio response– Three bitrates: 24, 32 or 48 kbps– 40 ms algorithmic delay (20ms frames)– ITU-T Standard G.722.1 Annex C

Asterisk Development

• Access to Siren is in very recent code– Asterisk v1.6.20 trunk

– Progressed significantly over the past two weeks

• Polycom offers royalty free license – Siren 7&14 are not released under GPL

– The Siren codecs are not part of the normal Asterisk distribution

– Distribution is as a binary module

Using Siren In Asterisk

Canonical names used in sip.conf & iax.conf– Allow=siren7– Allow=siren14– Allow=g.722.1– Allow=g.722.1c

Using Siren In Asterisk

Current implementation supports:– Full rate only

• Siren7 @ 32 kbps

• Siren14 @ 48 kbps

– Asterisk is limited to 16 KHz sampling• Siren14 streams down-sampled (32 > 16/8 KHz)

• Support higher sample rates in future– CELT, Siren14, SILK

Using Siren In Asterisk

Current implementation supports:– Recording (ex voicemail)– Playback (ex IVR prompts)– Conferencing

• MeetMe application relies upon DAHDI for timing and does not support wideband conferencing

• Using ConfBridge app @ 16 KHz sample rate– Considered “a bit experimental”

Performance Considerations

• CPU requirement is asymmetrical– Encoding uses more CPU than decoding

• Siren playback/decoding is very cheap– Similar in complexity to GSM-FR

– Down-sampling is similarly easy• 16 > 8 KHz, 32 > 16 KHz, or 32 > 8 KHz

– Less processor intensive than the aged G.722!

• Encoding not especially processor intensive– Estimated <20% of the CPU load of a G.729a stream

Preparing Audio Samples

PC with soft phone & Vemotion

software plays the uncompressed wav

files into a call

Polycom VVX-1500

Records G.711,G.722 & G.722.1 calls to USB stick

Line out from VVX to Zoom H2 recorder for

G.722.1C

SIP call analog

Sample #1: The Female Voice

I asked Mrs Evelyne Resnick

the following question:

“What’s it like being married

to a VoIP geek?”

Sample #2: The Male Voice

Michael Iedema

Lead Developer

Askozia Project

http://www.askozia.com

Sample #3: The Male Voice

Ruben Olsen

VoIP blogger

http://www.open-voip.com

Norwegian

Name That Codec!

Languages:

• Chinese

• French

• German

• Russian

• Spanish

Sample encodings:

• Uncompressed

• Siren14

• Siren 7

• G.711

• Comparative

Name That Codec! Round #1

Languages:

• Chinese

• French

• German

• Russian

• Spanish

Sample encodings:

• Siren14

• Siren 7

• G.711

Name That Codec! Round #2

Languages:

• Chinese

• French

• German

• Russian

• Spanish

Sample encodings:

• Siren14

• Siren 7

• G.711

Name That Codec! Round #3

Languages:

• Chinese

• French

• German

• Russian

• Spanish

Sample encodings:

• Siren14

• Siren 7

• G.711

Name That Codec! Round #4

Languages:

• Chinese

• French

• German

• Russian

• Spanish

Sample encodings:

• Siren14

• Siren 7

• G.711

Name That Codec! Round #5

Languages:

• Chinese

• French

• German

• Russian

• Spanish

Sample encodings:

• Siren14

• Siren 7

• G.711

What Are The Advantages?

• Optimal wideband interop with the broad range of Polycom HDVoice hardware

What Are The Advantages?

• Superior voice quality at reduced bitrates for on-net calling– Internal calling– Inter-office calling– SIP trunking– IP Peering

What Are The Advantages?

• A more enjoyable call experience• Fewer misunderstandings• Reduced call fatigue & frustration• Happier customers• Better quality of life• World peace

Special Thanks

• Darrick Hartman, DJH Solutions– Help with Asterisk v1.6.20 trunk in Astlinux

• Plantronics– Savi Go: a truly wideband capable Bluetooth headset

• Michael Iedema, Askozia PBX– Chinese, English, German, Russian & Spanish

• Ruben Olsen– English & Norwegian

• Randy & Evelyne Resnick, Resmo– French & English