dtmf meaning

Pjsip source code is relatively powerful. Let's talk about what DTMF is? Dual-Tone Multi-frequency DTMF (Dual Tone Multi frequency), dual-Tone Multi-frequency, composed of high frequency groups and low frequency groups, each of which contains four frequencies. A high-frequency signal and a low-frequency signal are combined to form a combined signal, representing a number. The

This item is the starting point for accurate identification of DTMF signals. After detecting this item, the DTMF decoder is triggered to decode the received data and wait until the corresponding dial key value is reached.1. analysis of input signal features: the signal is the circuit noise in the DTMF signal plus the channel. Now, preliminary analysis shows that

DTMF encoding transmitted by rfc2833 in Voice Transmission 2007-03-23 11:13:48 The class is defined as follows: # If! Defined (afx_head_2833_h000093b5c358_6f19_475b_a49f_13bfcc9dfe1c00000000ded _)# DefineAfx_head_2833_h000093b5c358_6f19_475b_a49f_13bfcc9dfe1c00000000ded _ # If _ msc_ver> 1000# Pragma once# Endif // _ msc_ver> 1000 Class chead_2833{Public:Bool dispelhead (char *Cvalue );Int btodd (char * cvalue );Char * dtob (intNvalue );Che

This article from csdn ucser, http://blog.csdn.net/perfectpdl reprinted to indicate the source, thank you! DTMF is called multi-tone dual-join, also called secondary dialing. There are three methods for VoIP to carry DTMF: inband, RFC 2833 (the latest RFC is 4733, which is referenced in IMS), and SIP info. The inband mode transfers the buffer generated by keys to the audio RTP stream, instead of definin

The meaning of directory and file permissions in Linux The meaning of file permission R: You can read the specific contents of this document; W: You can edit the contents of this file, including adding the details of the deleted file; X: The file has executable permissions-------Note: Here and window is not the same, in win, the file executable permissions are expressed through the extension, such as EX

What is the definition in C language? What is the meaning of the statement? What is the difference between them ?, Meaning difference In the C language, we may be very familiar with definitions and declarations, but we may not really understand them! Definition meaning: the so-called definition is to create (compiler) an object, allocate a memory space for this

String formatting symbolic meaning Symbol Description %c Formatting characters and their ASCII code %s formatting strings %d formatting integers %o Formatting an unsigned octal number %x formatting unsigned hexadecimal numbers %x Format unsigned hexadecimal number (uppercase) %f Format fixed-point numb

String formatting symbolic meaning Symbol Description %c Formatting characters and their ASCII code %s formatting strings %d formatting integers %o Formatting an unsigned octal number %x formatting unsigned hexadecimal numbers %x Format unsigned hexadecimal number (uppercase) %f Format fixed-point numb

A lot of friends in the tuning with MySQL will certainly use the explain to see the execution of the SELECT statement, here is a brief introduction to the results of the meaning of the two columns.1 Type column The official saying that this column represents the "type of access", and more commonly, the way MySQL finds the data rows needed. One is to introduce the worst from the most efficient to the best: all this is called a full-table scan, and no i

A lot of friends in the tuning with MySQL will certainly use the explain to see the execution of the SELECT statement, here is a brief introduction to the results of the meaning of the two columns.1 Type column The official saying that this column represents the "type of access", and more commonly, the way MySQL finds the data rows needed. One is to introduce the worst from the most efficient to the best: all this is called a full-table scan, and no i

Meaning of DBUnitdb, or decibel, is a very common unit in the field of electronics. This unit is characterized by the use of logarithms to represent the original data. 1 shell = 10 db = 10dB = 10 times times PowerFor an amplifier,power Magnification Ap = ten lg (PO/PI)voltage Magnification Au = LG (UO/UI)current Magnification Ai = LG (IO/II)For example: amplifier magnification of 40dB, indicating that its voltage amplification is 100 times times, curr

Option meaning of info. plist, meaning of info. plist 1. application does not run in background (container name: UIApplicationExistsOnSuspend) from the end of iOS4.0, when you apply the program line, press Home terminal, the application does not parse the current line, but hides in the background. Therefore, if you want to download the current program line after you press Home then, check this option. 2. A

This may be used in the shell, including DOS.Null is something called a null bucket, and the benefit of redirecting the output to it is that the file size is not constantly increasing due to too much content in the output. In fact, you think that null is nothing, that is, the output of the command is discarded.1 indicates standard output, 2 indicates standard error output, 2>1 indicates the standard error output is redirected to standard output, so that the normal output and error output of the

The meaning of the forest root domain in the domain tree, and the meaning of the domain forest root domain Contoso has many IT resources in the company's IT environment, and these IT resources are all in a state of decentralized management, which virtually increases the management cost of contoso, moreover, the management system cannot be implemented in the actual production environment. So how can we solv

When the search engine grasps the lifeblood of the Internet economy, the typical application of the Internet, which is created by the search behavior, will affect all the people and things related to it. For the moment, we call the economic model of the related behavior a search economy. In this section we discuss one of the most basic elements of a search economy – search keywords. What are the key words? It can be any word in any language, mainly in the form of words. The essence of writing i