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Discussion Groups | Speech Coding | Re: what's the function of postfilter in G.729 decoder part?
Technical discussions related to Speech Coding (all itu and other vocoders, ACELP, CELP, AMR, etc)
what's the function of postfilter in G.729 decoder part? - ytjiang2002 - Feb 26 6:10:00 2002
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hi, I'm new to speech coding. I have read the recommedation of G.729 and I can't understand the postfilter in decoder part. And i cut the postfilter in decoder routine and the output speech is also clear. So i want to know what's the real function of postfilter in details. Thanks a lot in advance. Kevin Jiang |
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(RE) postfilter in G729 - Author Unknown - Feb 27 3:02:00 2002
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It's function is speech enhancement and is consist of three functions 1. long term postfilter : It adjusts frational pitch.. 2. short term postfilter : It enhance spectrum shape 3. tilt compansation : It adjusts tilt of spectrum generally postfilter makes speech smooth In case of G.729A(complexity reduced version), postfiler was simplified Dong won. *********************************************************** À̵¿¿ø() »ï¼ºÀüÀÚ Á¤º¸Åë½ÅÃÑ°ý / Åë½Å¿¬±¸¼Ò IMT2000´Ü¸»¿¬±¸ÆÀ Core±â¼ú¿¬±¸±×·ì GSM/SPRS L1 S/W ¿¬±¸¿ø Phone : 031-279-5451 H.P : 016-9530-5451 Dong-Won, Lee Core Tech Research Team/ Telecommunication R&D center Information and Communication Business SAMSUNG ECELTRONICS CO., LTD. *************************************************************** |
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Re: what's the function of postfilter in G.729 decoder part? - Vinay M K - Feb 27 3:53:00 2002
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Hi Kevin Jiang, Post filtering is done to improve the perceptual quality of speech. Most of the algorithms focus on emphasising the formants and pitch harmonics while attenuating spectral valleys. They also perform formant equalisation (reduction is spectral tilt to avoid muffling). For a detailed description of this block refer to the paper Adaptive Postfiltering for Quality Enhancement of Coded Speech -Juin -Hwey Chen and Allen resho IEEE Trans On Speech and Audio Proc, Vol 3, No1 Jan 1995 Can be downloaded from: http://scl.ece.ucsb.edu/pubs/pubs_E/e95_1.pdf regards Vinay 2/26/2002 11:40:02 AM, "ytjiang2002" <> wrote: >hi, >I'm new to speech coding. I have read the recommedation of G.729 and >I can't understand the postfilter in decoder part. And i cut the >postfilter in decoder routine and the output speech is also clear. So >i want to know what's the real function of postfilter in details. > >Thanks a lot in advance. >Kevin Jiang > > >_____________________________________ > -Vinay _________________________________________________________ ">http://mail.yahoo.com |
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