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.

  • Anyone has a clue what exactly is behind g711-HD as employed by AVM (Berlin)? My guess is that this either g711.1 or a modification of it, but that’s really nothing more than a pure guess…

  • I’ve not seen any AVM stuff in this part of the world, so I really can’t say. I see that http://www.sipro.com/ still has patent calls out re: G.711.1 and G.729.1. So they will be patent encumbered and likely commercially licensed. That could take them out of play in many cases.

    • The implication given here is that G.711-HD is actually G.711.1, with the addition of some marketechture. That page is from a German forum but Google translator did a good job making and English version for me. Here

      • From a recent thread on the Asterisk Users Mailing list it now appears that G.711-HD is a kind of AVM specific non-standard G.711 that is simply clocked at 16 KHz resulting in 8 KHz (ish) passband. It’s a non-standard encoding that they use between their own devices. They support G.722 for us in connection to other devices.