Michael Stanford On Wideband At TMC

snom_820_links_hoch_perspektive_200pxMichael Stanford of Wirevolution has an article called Better Sounding Calls in the March issue of Internet Telephony that was today published on TMCs HDVoice Community site. While very general it’s nevertheless a nice article. He cites Speex developer Jean-Marc Valin referencing the fact that wideband is the principle means of VoIP surpassing the PSTN in terms of end-user call quality.

He notes that transcoding between wideband codecs, or worse wideband and narrowband, is generally a bad idea. He further makes an assertion based upon Polycom’s release of the Siren7 and Siren14 codecs under a royalty free licensing scheme;

There are now three high quality wideband voice codecs that phone vendors can use without paying royalties: Speex and two from Polycom. There is no reason why any phone or soft phone should ship without all three of them.

I whole-heartedly agree, and further assert that Skype’s SILK should be thrown into that mix. Of course, G.722 is royalty free as well, although not nearly as sophisticated as the others mentioned.

It’s also interesting to note that Speex adoption in hardware remains extremely limited. I wonder if that might change as wideband continues to gain momentum? Or does it get left behind in the face of newer royalty free, if not open source, codec offerings? The open source community has also moved on to offer CELT, which is a very new but extremely low-latency, very flexible wideband codec.

Codec Wars vs Serving The Common Good

There has been for many years a subtle conflict ongoing in telecom space. Various vendors have created digital encoding techniques (codecs) that target common network issues. Since various network realities exist so too do various approaches to the problems faced. So a range of codecs exist in the marketplace.  Typically a high-quality solution comes with an associated cost, reflecting the very fact that the solution has merit.

The poster-child for this is the G.729a codec. Over time this patented codec has become the industry standard low-bitrate codec for voice applications. Who can argue. It works well. It squeezes reasonable voice quality down to under 30 kbps and it’s compute overhead is acceptable on available hardware.

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Wideband Voice And Free World Dialup

For the past few weeks I’ve been hunting for a soft phone with specific wideband voice capabilities. I’ve found a couple but there arises complications.

Wideband-capable hard phones usually support G.722, G.722.1 or G.722.2 (aka AMR-WB) codecs. There are other codecs out there that support wideband voice coding. Speex is the one most often cited. However, Speex support in hardware is extremely limited. So Speex implemented in a soft phone is not going to help me evaluate interoperability with hard phones.

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