Where I can find the introduction on speech coding?

Started by jin li in Speech Coding10 years ago 2 replies

Hi All, Is there any website or book that give a common intrroduction on speech coding algorithm and how to evaluate the audio quality? Is...

Hi All, Is there any website or book that give a common intrroduction on speech coding algorithm and how to evaluate the audio quality? Is there any standard defined for evaluating the audio quality? Thanks! jin


How to adjust timing of speech frame

Started by dbga...@gmail.com in Speech Coding10 years ago 6 replies

Hi, Anyone here know a method to adjust timing of 22.5ms speech frames to 20ms. I am working with different vocoders including AMBE (Advanced...

Hi, Anyone here know a method to adjust timing of 22.5ms speech frames to 20ms. I am working with different vocoders including AMBE (Advanced Multiband Excitation) versus CELP/VSELP. The generated vocoder frames are originally 22.5ms, but the vocoder DSP chip takes in 20ms. Basically, are there techniques that exist such as time compression, post-filtering/processing, duplicating speech fra...


Method of Finding LPC Coefficients for Digital Filter

Started by alexandra3753 in Speech Coding10 years ago

Hi, I'm doing some speech processing using Linear Predictive Coding, and I'm trying to use MATLAB to find the feedback coefficients, ai, for a...

Hi, I'm doing some speech processing using Linear Predictive Coding, and I'm trying to use MATLAB to find the feedback coefficients, ai, for a digital filter of the form y[n] = x[n] + Ʃ(ai * y[n-i]) (sum goes from i = 1 to i = N where N is the order of the filter) where n is the index of the sample point, y[n] is the output, x[n] is a pulse input with period equal to the pitch per


ITUT G729 preprocessing question

Started by hyee...@yahoo.com.cn in Speech Coding10 years ago 1 reply

About ITUT G729, I have two questions. 1. In the processing section of G729 spec, it says to apply a high pass filter with a cut-off frequency...

About ITUT G729, I have two questions. 1. In the processing section of G729 spec, it says to apply a high pass filter with a cut-off frequency of 140 Hz. As we know, the range of pitch is between 55 and 400 Hz. Then, how to search the pitch with frequency below 140Hz with such a preprocessing algo? It is as fetching the moon from sea. 2. G729 preprocessing section uses a second order pole/ze...


LPC spectra estimate

Started by hyee...@yahoo.com.cn in Speech Coding10 years ago 3 replies

LPC spectra should correspond with the envelope of DFT spectra. I plot LPC spectra with matlab. The LPC spectra keep the same shape with the...

LPC spectra should correspond with the envelope of DFT spectra. I plot LPC spectra with matlab. The LPC spectra keep the same shape with the envelope of DFT spectra. But it is larger with a offset than the DFT envelope. Why? Where it go wrong? Here is the matlab script which illustrate it. N = 2560; [x,fs] = wavread('lpc.wav',N); % any speech signal can be used p=12; a =...


MOS Score - G.726 ADPCM & G.729 CS-ACELP - Voice Quality issues?

Started by raju...@ngc.com in Speech Coding10 years ago

Hi DSP Related members, I am researching to find out information on the voice quality of codecs used for VoIP communication using networking...

Hi DSP Related members, I am researching to find out information on the voice quality of codecs used for VoIP communication using networking routers, switches and access devices. The main objective is that the MOS (Mean Opinion Score) should be greater than 3.82 on the scale of 1 (poor quality) and 5 (best quality). Is the Codec G.726 ADPCM (32 Kbps) with a MOS of 3.85 is used in the re...


GSM-FR CODEC

Started by amit...@vnl.in in Speech Coding10 years ago 1 reply

Hello I need GSM-FR codec (encoder and decoder) exe or source code for windows host machine, can anyone suggest where can i find it.

Hello I need GSM-FR codec (encoder and decoder) exe or source code for windows host machine, can anyone suggest where can i find it.


Adding Noise

Started by fara...@yahoo.co.uk in Speech Coding11 years ago

Hello, I am working on a filtering project, I am simulating the filter in Matlab. To see how it works in realnoise surroundings, I have...

Hello, I am working on a filtering project, I am simulating the filter in Matlab. To see how it works in realnoise surroundings, I have recorded noise (bus, street etc.) which I want to add over my speech signal. Now, my problem is that when I do so, the error is that the matrix dimensions don't agree. I list the code where I do the adding: realNoiseType=get(handles.noiseSource,'Value'); ...


about fractional pitch search of melp

Started by tms3...@yahoo.com.cn in Speech Coding11 years ago

hi all I'm learning MELP source code.I am not able to understand the fractional pitch search algorithm in function Shortword...

hi all I'm learning MELP source code.I am not able to understand the fractional pitch search algorithm in function Shortword frac_pch(Shortword sig_in[],Shortword *pcorr,Shortword fpitch, Shortword range,Shortword pmin,Shortword pmax, Shortword pmin_q7,Shortword pmax_q7,Shortword lmin); somebody can give me some hints about determining fractional pitch in Bandpass voicing analy...


residual redundancy breakdown

Started by eric...@yahoo.com in Speech Coding11 years ago 1 reply

Hi everyone! Residual redundancies that are extracted from the parameters of a particular source encoder output is said to be the result of (1)...

Hi everyone! Residual redundancies that are extracted from the parameters of a particular source encoder output is said to be the result of (1) the nonuniform distribution of values (quantized levels) and (2) the actual temporal correlation that exists (memory) between successive frames. Based on formula, I am able to compute for the entropy rate of any particular parameter in question. The r...


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