Michael 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…
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.
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.