I am running some tests on audio compression and trying out Skype's Silk. In their test application I am seeing compression rates of 94%. This seems high, is this a typical rate on Silk? Is this comparable to other audio compression codecs?
+1
A:
Most speech/telephony codecs run at pretty low bit rates, so 94% does not sound unrealistic, particularly if you're starting with a fairly high sample rate. E.g. 22 kHz 8 bit audio compressed to a 9600 bps stream would be around 94% compression.
Paul R
2010-06-28 13:30:39
AFAIK VoIP uses only frequencies from ~200-2000Hz. This will give you a good compression due to the fact that you can lower the sample rate a lot (e.g. 8kHz).
InsertNickHere
2010-06-28 13:39:03
@InsertNickHere: yes, standard telephony bandwidth is only 3 kHz, but there is a lot more that can be done when you are compressing speech only. Modern speech codecs can get down to very low bit rates.
Paul R
2010-06-28 13:47:10