Microsoft clearly recommends using the ACELP codec by VoiceAge. This is the same codec RealNetworks uses to encode speech. "Indeed, when encoded at just 16 Kbps (one-fourth the size), the ACELP voice codec nearly matches MP3 quality at 64 Kbps!"
ACELP.net, like prestigious standards such as EFR GSM, IS-136, TETRA, G.723.1, G.729 and G.729 Annex A, is based on ACELP technology. This state-of-the-art technology has now been adapted to meet the needs of IP networks and the PC platform by using an improved, net-adapted packetization method that outperforms conventional approaches. In particular, it minimizes the impact of errors while significantly improving error correction possibilities in case of data-packet losses. Through frame concatenation and interlacing, the communication channel is made more robust.
The ACELP.net family includes a dual-rate codec (8.5/6.5 kbps), a fixed-rate codec (5.0 kbps) and a wideband codec (16 kbps). The dual-rate version of ACELP.net has the ability to switch bit rates on the fly to effectively handle network inconsistencies. ACELP.net provides toll-quality compression at 8.5 kbps and near-toll quality at lower rates.
The ACELP.net family has already gained broad recognition, with ACELP.net being the preferred low bit rate speech codec in RealAudio® and being included in both Microsoft MediaPlayer and Audible ready equipment. This technology can be rapidly harnessed for applications such as broadcast over Internet (multicasting), multimedia email and multimedia conferencing.
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