As the major telecom players (including Portuguese PT and Vodafone) and other carriers start to push HD voice in the mobile and fixed world, advocates are lining up behind their favorite bits of codes for delivering higher quality sound. There are three different battles shaping up among the codec-heads.
Battle #1 - G.722 vs. AMR-WB (G722.2) – Wireline vs. wireless
is the granddaddy of wideband HD voice codec, codified as a standard
back in 198xx by the ITU. Designed in the days the era of single core
CPUs running at Mhz speeds, it doesn’t use a lot of cycles and requires
64 kbit/s for a call – a lot of bandwidth back in the day, but
practically noise on any sort of broadband pipe these days.
phone guys have lined up behind G.722 because it’s easy to implement and
there’s no licensing fees since the patents have expired. It’s the de
facto standard for businesses and is also found in a lot of consumer
gear. Aastra, Allworx, AudioCodes, Avaya, Cisco, Panasonic, Polycom, ShoreTel, Thomson, Siemens, Snom and practically every no-name on the planet have put it in their phones.
Designed by the cellular crowd and build on the GSM
AMR narrowband standard, AMR-WB uses more CPU – and hence more power --
to deliver a HD voice session in 24 kbit/s. Cellular guys want to
squeeze every last Hz of RF bandwidth they can get, but heavier
compression means shorter battery life.
Getting AMR-WB into wide
circulation has been an uphill battle because it is a complicated piece
of work with several different profiles to implement and test.
Further, the underlying technology has a bunch of patents on top of it.
Patent holders include France Telecom and Ericsson – no big surprise the two are among the biggest advocates of the technology.
Telecom and other carriers would like to see the HD voice world move to
end-to-end AMR-WB because they then wouldn't have to worry about
transcoding between cellular and broadband worlds. VoiceAge, holder of
the AMR-WB patent pool, has tweaked its royalty schedule to encourage
incorporation of the codec into core network boxes and desktop IP
Creeping up behind AMR-WB is the threat of over-the-top (OTT) softphone clients running on 4G
networks. Global IP Solutions (GIPS) has provided its proprietary iSAC
codec to a number of softclients and D2 Technologies has added G.722
support to Android, so there's a lot of room for both G.722 and AMR-WB to proliferate.
Sampling comparing: http://www.voiceage.com/amrwb.php
Bloggers note: Future of HD Voice in fixed IP communications is soon to be a reality although there are some challenges regarding the full support of AMR-WB, like support for deployed IP Phone models and special licensing (eg: http://wiki.snom.com/Category:Codec)
Battle #2 - Skype's SILK vs. world
stirred up a lot of people around this time last year when it announced
its SILK superwideband codec. The tech-geeks love the fact that SILK
is a "superwideband" codec, that it's an adaptive bit-rate codec,
adjusting quality based upon available CPU and network resources, and
that it's available on a royalty-free basis.
At least one vendor -
AudioCodes - has hinted it will roll SILK into its IP desktop handsets.
However, some developers speaking off-the-record have been less than
enthusiastic with the process of working with Skype; more than one
person indicated it's not clear who is calling the shots between
Estonia, the UK, and California with a "non-linear" business evaluation
process when it comes time for decisions.
Battle #3 - Large number of HD voice codecs vs. limited enthusiasm for supporting all
is one of the biggest myths on the planet. While a codec may be
royalty-free, each codec put into a software program or phone requires
space in the code/firmware, programming and integration support into a
product, and another check-box on the testing laundry list before a
product is finalized.
One you plunk through G.722, AMR-WB, and
SILK, plus legacy codecs for narrowband, each additional codec starts
adding expense to the end-product for implementation and testing. At
some point, you have to stop and get the phone out the door.
you really want to muck things up, start throwing around phrases like
"software indemnification" and start mumbling things about patents.
You're safe with code like G.722, where all the patents have expired and
AMR-WB, since you pay royalties to use it.
Finally, carriers want to avoid transcoding between formats -
especially between HD voice formats. Having to support a large number of
codecs is not something to make a service provider of any size happy.
Edited by the blogger