I wanted some conrete numbers on the sound quality loss of digital mp3
files in each of following steps:
1. When Digital MP3 is streamed as analog audio (i.e Digital to Analog conversion)
2. The analog audio is converted to a sub band codec (SBC) (i.e Analog -> SBC)

The quality of mp3 can be assumed to be between 128 and 256Kbps.

---

Clarification of Question by bha-ga on 05 Jan 2004 11:21 PST

By "loss" the dB scale is fine. Any quantification of "loss" in sounda
quality would be acceptable. More-over i'm thinking of the input
signal as mp3 audio of 128-196KBps.

thanks,
vaibhav

Hi, bha-ga:

It's not clear to me what "loss" you meant in the Digital to Analog
conversion.  In principle such a conversion can be done quickly and
with as little loss as desired.  You'd need to specify a
hardware/software CODEC if you wanted to discuss a particular
implementation.

Concrete measures of "quality loss" in sound are often expressed in
terms of signal-to-noise ratios, using decibels (dB).  These values
can vary with frequency.

Sub-Band Coding (SBC) is a technique which can produce acceptable
quality for voice transmission with high rates of compression, e.g.
for Voice over IP (VoIP).  How much "sound quality loss" occurs is
highly dependent on the nature of the signal, and one would almost
certainly find many applications (music) in which SBC disappoints:

http://www.nextgendc.com/?/seminar_voice_coding.htm

Quantification of the analog -> SBC "quality loss" would therefore
require some assumptions about both the compression rate acheived and
the nature of the signal.

regards, mathtalk-ga