I am developing a voice application, I have 2 options speex and nellymoser .Why should I use speex instead of nellymoser in flex application.
this should make it clear , Comparison of both codecs for flex:
http://askmeflash.com/article/2/speex-vs-nellymoser
Speex is open source, optimized for speech and seems to have lower bandwidth requirements. However, in Flash/AIR, Speex is always 16 kHz, which is not quite the Skype-like crispness of the sound. Because of that, we're currently contemplating switching to the "old" Nellymoser where we have an option of 22 and even 44 kHz.
来源：https://stackoverflow.com/questions/750824/speex-or-nellymoser