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Discussion Groups | Speech Coding | look-ahead in AMR why?
Technical discussions related to Speech Coding (all itu and other vocoders, ACELP, CELP, AMR, etc)
look-ahead in AMR why? - manoj garg - Mar 11 13:38:00 2002
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Dear friends, > i am learning AMR-NB. In the specifications i found > that the look-ahead is used in all modes except 12.2k > mode. my doubts are: > 1- What is the adavantage of using 5 ms look-ahead > while there is no look-ahead in 12.2k mode. what is > the necessity of just adding additional delay of 5ms > > 2- Why auto-correlation computation is done twice in > 12.2k > > 3- why not use the look-ahead in 12.2k also. > > could anyone give me the reasons for the above ones. > > thanks in adavance > regards > manoj |
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DTMF Decoder - shahram heidari - Mar 12 1:10:00 2002
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Dear Friends I am working to simulation and implementation of multichannel dtmf encoder/decoder on ADSPs. I have found many documents and codes, which among them, TI's application notes is more completed. But in DTMF decoding stage before Goertzel Block the design should have a gain and amplitude control of input for preventation of variable in Goertzel algorithm. I converted this part of the TI's TMSC54x code to c++ but it is not sufficient and some overflow will happen. If each of you have any experince or idea, I will appreciate to propose me. shahram heidari Field Application Engineer BBS Electronics Pte Ltd Singapore |
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