Hi all,I am working on G.729 and when going thru' the C code I came across the folowing: In perceptual weighting filter to find the value of gamma2(weighting parameter) the formula used is gamma2=1-6.0*pi*dmin whereas in the G.729 code it is given as gamma2=1-6.0*dmin I would like to know which is the correct equation? 2)If a detailed description of the preselection procedure for gain quantisation is available online can someone help out with the web site? Thanks a lot Thenral |

# On G.729 Perceptual weighting and Gain Quantisation

Started by ●November 9, 2001

Reply by ●November 10, 20012001-11-10

From: "Thenral p" <> wrote: >I am working on G.729 and when going thru' the C code I came across the >folowing: >In perceptual weighting filter to find the value of gamma2(weighting >parameter) the formula used is >gamma2=1-6.0*pi*dmin > >whereas in the G.729 code it is given as gamma2=1-6.0*dmin > >I would like to know which is the correct equation? This rings a faint bell (from quite a few years back). The value dmin is derived from line-spectrum frequencies. I remember that when I wrote a floating-point g729 and compared it with the official fixed-point code, there were confusions to do with whether the LSF are considered to run from -1 to 1 or -pi to pi. Probably you will find that both the equation and code are correct, but use a different definition. In any case, if you want to write a g729 the C code is definitive, however silly. >2)If a detailed description of the preselection procedure for gain >quantisation is available online can someone help out with the web site? Not that I know of, I'm afraid. Tim. ------------------------ Tim Thorpe Tel: +44 1223 240366 Fax: +44 1223 414402 ------------------------ |