Hi,

I would like to encode an audio book and listen on a pocket pc.
I gather my options are:

Using realproducer in voice only mode and playing with realplayer for pocket pc
Using windows media encoder for wma voice and playing with betaplayer on pocket pc
Using speex and playing with resco audio recorder on pocket pc

Does anyone have any opinions / comparisons of the quality of these codecs at around the 20k encoding level.

Thanks for any help.

I suggest you have a look at the Speex Samples page. You'll most likely want to use wideband if you target 20 kbps.

OK. Have come to the following conclusions. The most acceptable level to me for voice only codecs is around 30k.

Wideband vbr quality 8-10 speex is very good but the resco audio recorder used to play it on the pocket pc doesnt seem to be able to skip through the spx file it is playing - not good on a 15 minute spoken word track.

wma voice is playable on lots of pocket pc apps but i seem to be limited to 20k bitrate - is this correct ?

real audio appears to sound the best and have the best filesize at 34k bitrate but the player is so bad for playlist and file management on pocket pc that i am refusing to use it for the moment.

So where does that leave me. I have started looking at 64k with non-voice only codecs. Ogg seems quite good here and plays on lots of things. Can anyone point me to any tests on voice samples at 64k ?

Also, I am a little confused about frequency - I understand basically what it is but cant quite see the sensible process when converting from a frequency (ie 44000) to another. For example if i have a spoken word encoded as normal wma at 192k 44000 what are the effects of converting that frequency into say 16000 ?

Thanks for any help.