How to mix AMR files ?

Started by horiaciu in Speech Coding12 years ago 1 reply

Hello, I am implementing a simple mixing program (i.e. create a new sound file combinig two initial files - all the same format). I have...

Hello, I am implementing a simple mixing program (i.e. create a new sound file combinig two initial files - all the same format). I have implemented this for WAV files (PCM) and now I want to support AMR. I can do this in 2 ways: 1. convert to PCM and reuse the mixing code - I cannot find any documentation on how to convert an AMR frame to PCM samples. What happens after I reorder ...


Input for G729 and G723 from U/A law PCM code.

Started by zhang_zhh in Speech Coding16 years ago 4 replies

Hi all, I have a simple question: according to the G729/G723 spec, the input buffer should be 16bit linear PCM code, but the...

Hi all, I have a simple question: according to the G729/G723 spec, the input buffer should be 16bit linear PCM code, but the decode of U/A law PCM is 14/13 bit linear code, do I just need shift 2/3 bit before call the G729/G723 codec? What is the standard method to handle this


Query: 13 bit PCM ?

Started by jay_coep in Speech Coding15 years ago 1 reply

Hello, Can anybody please help explaining why GSM speech codecs (atleast HR,AMR) prefer 13 bit uniform PCM encoding ? I...

Hello, Can anybody please help explaining why GSM speech codecs (atleast HR,AMR) prefer 13 bit uniform PCM encoding ? I mean what is so special about '13' (Anything to do with SNR for speech signal?) Thanks in anticipation. Regards, Jayd


data format of PCM 16bit signed mono-channel and alignment(line-up) two PCM-16bit .wav files.

Started by nangergong in Speech Coding9 years ago 2 replies

Hi, all: I have some .wav files with format of PCM 16bit signed mono-channel from this...

Hi, all: I have some .wav files with format of PCM 16bit signed mono-channel from this link: https://ccrma.stanford.edu/courses/422/projects/WaveFormat/ I know each sample of these .wav files(except the header) can be converted to value -32768 to 32767 I want to time-align two .wav files with the format mentioned above. My steps are: 1) convert .wav files...


Samples in 16 bit PCM

Started by bine...@gmail.com in Speech Coding13 years ago 2 replies

Hai, I am a new member of this group.I am a 6th sem MCA student.Now I am trying to implement G729 codec.Till now i didn't get a clearcut idea...

Hai, I am a new member of this group.I am a 6th sem MCA student.Now I am trying to implement G729 codec.Till now i didn't get a clearcut idea about 16 bit linear PCM file format.What is samples init? Please give response. Thanks in advance Bineesh Jose


Reg G726 test vector verification

Started by Aditi Akula in Speech Coding10 years ago

Hi everyone, I am working on G726. I have the source code in C (from Sun Microsystems). I am trying to test the algorithm using the ITU test...

Hi everyone, I am working on G726. I have the source code in C (from Sun Microsystems). I am trying to test the algorithm using the ITU test vectors. I have converted the NRM.M and OVR.M hex files to binary files using the cvt_h_b.c (code from ITU site). My code takes in linear PCM and outputs linear PCM so I have converted the mu-law and a-law binary files into linear PCM files. I...


How to mix pcm sample?

Started by galip0986 in Speech Coding11 years ago 5 replies

Hello, I am implementing a voice conferencing program. I am using tms320vc5416 dsp.I have a distortion problem. I have A-law expanded(13...

Hello, I am implementing a voice conferencing program. I am using tms320vc5416 dsp.I have a distortion problem. I have A-law expanded(13 bit) pcm samples. These samples are stored as unsigned short in buffers. I convert this samples signed int and then I simply add these samples together. I abstract users own voice from the sum. At the and I scale the conclusion(shift right 2 bits). T...


[ TONE Generation ] PCM - ADPCM

Started by Dhiraviam Natarajan in Speech Coding16 years ago

Hi ppl, I working on tone generation for an Access Network ( of a telephone exchange ). Can some one throw light on PCM to...

Hi ppl, I working on tone generation for an Access Network ( of a telephone exchange ). Can some one throw light on PCM to ADPCM conversion algorithm , point me some useful web tutorials / links. Can ADPCM samples be generated directly by any means ? Genera


ITU G726 code not working for speech files

Started by Aditi Akula in Speech Coding10 years ago 3 replies

Hi Everyone, I am using the G726 code from ITU (g726.c, g726.h, cvt_h_b.c, etc) for 16 kbps an using it as a Visual C++ project. I have tested...

Hi Everyone, I am using the G726 code from ITU (g726.c, g726.h, cvt_h_b.c, etc) for 16 kbps an using it as a Visual C++ project. I have tested the code using the test vectors from ITU and found them to be bit exact (sent in the 16-bit A-law/ Mu-law output from the cvt_h_b.c code). I have also modified the code to accept 16-bit linear PCM data and send out linear PCM data and tested with t...


About PESQ scores(audio quality evaluation)

Started by nang...@gmail.com in Speech Coding9 years ago 2 replies

I have a question on PESQ If I want to verify the PESQ score of G711 and G729 codec, what procedures should I take? my idea is: 1)...

I have a question on PESQ If I want to verify the PESQ score of G711 and G729 codec, what procedures should I take? my idea is: 1) prepare a audio .wav file, whose format is PCM 8000Hz, signed 16 bit, let me name it ori.wav 2) encode it into G711 or G729 format and get enc.wav 3) convert enc.wav into PCM 8000Hz, signed 16 bit format, and I get deg.wav 4) run PESQ alg...


linear to mu conv??

Started by simha j in Speech Coding17 years ago

hi all, I was going through the c-codes for linear pcm to u-law conversion, available on the web. one of the sources use...

hi all, I was going through the c-codes for linear pcm to u-law conversion, available on the web. one of the sources use lookup tabel method and another uses direct implementation (without LUT). I tested both by giving 16bit linear value (0X0100),


Number of ADPCM channels in E1 ??

Started by saha...@yahoo.com in Speech Coding14 years ago

Hi fellow Im new comer . could anyone please help me out . 1 . how many channels are transmitted if we have compressed the voice...

Hi fellow Im new comer . could anyone please help me out . 1 . how many channels are transmitted if we have compressed the voice channels in E1 with ADPCM with 40kbps, 32kbps, 24kbps, 16kbps bitrate. 2. Is their any specific frame structure like that for Pcm channels transmitted in E1 . 3. If possible please refer me some site or document.


G729A CODEC application.

Started by raghu kisore in Speech Coding18 years ago 1 reply

hi, Description of the problem: ----------------------- i have got the ITU standatrd G.729A CODEC application written in...

hi, Description of the problem: ----------------------- i have got the ITU standatrd G.729A CODEC application written in c.along with the code i have got a test file named TEST.INP the TEST.INP has a 1.77 seconds raw speech data and has 16 bit PCM value corre


File Size

Started by than...@askcalea.net in Speech Coding12 years ago 1 reply

I got the G 729 ITU-T C code compiled and running. I'm confused about two issues though. 1) Why is the file size of the encoder output the...

I got the G 729 ITU-T C code compiled and running. I'm confused about two issues though. 1) Why is the file size of the encoder output the same/or about same as the input. (I used a PCM 8000Mhz file for input) Shouldn't this file come out quite smaller, to the order of 1/8 th the size? 2) I have a sample encoded file from a vendor that does not decode even though I know it to be valid 729 A...


I/O File Size In G729

Started by bine...@gmail.com in Speech Coding13 years ago 4 replies

Hi, Now I am working with ITU-T's G729 recommendation.The size of the input I given to this coder was 586 KB(16 bit PCM mono)and I got the...

Hi, Now I am working with ITU-T's G729 recommendation.The size of the input I given to this coder was 586 KB(16 bit PCM mono)and I got the output as 600 KB. Is this output's size is right or not? I think that, as an encoder it's output size should be less than input size( That is why we are encoding). The output is right,then What is the reson? Please clear my doubts immediately. Thanks in ...


[ PCM -ADPCM conversion & vice versa ]

Started by Dhiraviam Natarajan in Speech Coding16 years ago

Hi All, I'm abt to implement ADPCM decoding/encoding in ADSP 2191.With a minimum background in Communication Systems, I find it...

Hi All, I'm abt to implement ADPCM decoding/encoding in ADSP 2191.With a minimum background in Communication Systems, I find it difficult to understand the ADPCM encoding/decoding algo explained in ADSP Application Manuals. Can any one suggest/point me some good links t


how to find the no of samples for a GSM file format, to put in the fact chunk ??

Started by ashwinimanjunath in Speech Coding14 years ago

hey, can anyone give some information on how to find the no of samples for a GSM file format.in case of GSM610 (or any other compression...

hey, can anyone give some information on how to find the no of samples for a GSM file format.in case of GSM610 (or any other compression format other than PCM) an additionsl chunck called the 'fact chunk'needs to added while creating the .wav file. this chunk contains the number of samples . buti do not understand how to calculate this?? can anyone pl


Regarding float to fixed point conversion

Started by anu prabhu in Speech Coding14 years ago 3 replies

  Hello !! I am working on float to fixed point conversion of a Speech Codec. The input to the speech codec (floating one)...

  Hello !! I am working on float to fixed point conversion of a Speech Codec. The input to the speech codec (floating one) is 16 bit PCM. Fixed point representation has its own limitations of hadling the dynamic range (which is not there in floating point