Compression by the method of encryption of lengths of reiterations




Contents

 

 

1 Calculation-graphic work №1  
1.1 Compression by the method of encryption of lengths of reiterations  
2 Calculation-graphic work №2  
2.1 Choice of the shortest way in a network on the method of Dijkstra  
List of reductions  
Список литературы  
Appendix A  
Appendix B  
An appendix is V  
Appendix of G  
List of literature  

 

 


Calculation-graphic work №1

 

 

Compression by the method of encryption of lengths of reiterations

 

1.1.1 Task №1.1:

- using these initial images driven to the appendix A, it is necessary to code binary-coded (two-color) representation measuring 8 elements in a line and 8 elements in a column. Thus an empty cage designates white color, and cage in that the letter of "CH" is filled in designates a black;

- the choice of variant of tasks comes true on the list of magazine of teacher;

- about scan a two-color image on lines (to two colors dark-and-light will correspond 0 and 1). As a result will get the binary vector of data.

1.1.2 Task №1.2:

Using original data contained in Annex B necessary- Using original data contained in Annex B necessary to describe the scenario setting (complete, registration, cancellation of registration, etc.). Communication between paragraphs IP-telephony network. Options are described in Annex B.

1.1.3 Guidelines for the assignment 1.1.1. The encoding of messages may be performed to reduce the amount of information and improve its transmission speed or reduce the bandwidth required for transmission. Such coding is called economical, or effective coding and data compression.

The goal of data compression is to provide a compact representation of the data produced by the source, for their more economical preservation and transmission channels. Data compression system consists of a source encoder and decoder. The encoder converts the data source in the compressed data, and a decoder for restoring the source data from the compressed data. The recovered data is generated by the decoder can either be exactly the same as the original data source, or slightly away from them.

In this paper we consider the compression method length coding regions (or repetitions). This method is quite effective in compression of binary data, such as black and white facsimile images, black and white images comprising a plurality of straight lines and uniform portions, circuits, etc. Length encoding is part of the well-known image compression algorithm JPEG (Joint Photographic Experts Group). The idea of ​​data compression based on length coding repetitions is that instead of coding the actual data were coded numbers corresponding to long sections on which data is stored fixed value.

Suppose we want to encode a binary (two-color) image size of 8 elements in the row and column elements 8, shown in Figure 1.1. After scanning the image along the lines get binary data vector X [1]. to describe the scenario setting (complete, registration, cancellation of registration, etc.). Communication between paragraphs IP-telephony network. Options are described in Annex B.

1.1.3 Guidelines for the assignment 1.1.1. The encoding of messages may be performed to reduce the amount of information and improve its transmission speed or reduce the bandwidth required for transmission. Such coding is called economical, bezizbytochnym, or effective coding and data compression.

The goal of data compression is to provide a compact representation of the data produced by the source, for their more economical preservation and transmission channels.

Data compression system consists of a source encoder and decoder. The encoder converts the data source in the compressed data, and a decoder for restoring the source data from the compressed data. The recovered data is generated by the decoder can either be exactly the same as the original data source, or slightly away from them.

In this paper we consider the compression method length coding regions (or repetitions). This method is quite effective in compression of binary data, such as black and white facsimile images, black and white images comprising a plurality of straight lines and uniform portions, circuits, etc. Length encoding is part of the well-known image compression algorithm JPEG (Joint Photographic Experts Group). The idea of ​​data compression based on length coding repetitions is that instead of coding the actual data were coded numbers corresponding to long sections on which data is stored fixed value.

Suppose we want to encode a binary (two-color) image size of 8 elements in the row and column elements 8, shown in Figure 1.1. After scanning the image along the lines get binary data vector X [1].Figure 1.1 - A two-color image

 

 

Рисунок 1.1 – Двухцветное изображение

 

Х=(01111111 11000000 11111101 11111111 00000000 01000000 10000001 11111111) length of 64 bits (the speed of the source code is 1 bit per pixel).

Isolate vector X plots on which data is stored fixed value, and define their length. The resulting sequence of lengths of - positive integers corresponding to the original data vector X - has the form r = (1, 9, 6, 6, 1, 9, 9, 1, 6, 1, 6, 9). In this sequence noticeable definite repeatability that can be coded in any static code (Table 1.1).

 

Table 1.1 - Encoder

The length of

Codeword

Table 1.1 –Codeword

The length of Codeword
   
   
   

 

In order to indicate that the encoded sequence starts with zero, to add at the beginning of the codeword prefix character 0.

The result is a code word length of 25 bits, that is, the resultant code rate R will be 25/64, or a little more than 0.39 bits per pixel. When compressing images larger and contain many repetitive elements the compression efficiency can be substantial.

 

B(r) =(0 110 0 10 10 110 0 0 110 10 110 10 0)

 

1.1.4 Guidelines for the assignment of work 1.1.2.

IP-telephony - telephony over IP.

Under IP-telephony means a set of communication protocols, technologies and methods, providing traditional telephony dialing, dialing, and two-way voice communication, as well as video calling over the Internet or any other IP-based networks. The signal is transmitted over a communication channel in digital form and are usually converted before transmission (compressed) in order to remove the excess information and reduce the load on the data network.

Consider the scenario of the steps of establishing a connection between two H.323 terminals (Figure 1.2):

 

 

Figure 1.2 - Scenario establishing a connection between terminals H.323

 

- End point A (the caller) is connected to a terminal point B (the called party) and sends a Setup (installation), which includes a call type (eg, audio signals only), number of the called and calling party address;

- Endpoint B responds notification message (Alerting). Endpoint A shall take this message before elapsed time allotted for the installation;

- When a user at the terminal station B answers the call (off-hook), the message Connect (Connect) is transferred to the end point A;

- Both terminals transmit information about their capabilities (media type, codec selection and information on multiplexing) reported Terminal Capability Set (installation of terminal capabilities);

- Each terminal responds Terminal Capability Set Ack (confirmation install terminal capabilities). If the remote endpoint does not have some features, a message will be sent TerminalCapabilitySetReject (deviation setting terminal capabilities), and terminals will continue to send these messages until they determine that the installed features are supported by both endpoints;

- Each terminal transmits H.245 OpenLogicalChannel (open logical channel), allows you to open a logical channel to the remote endpoint to adjust the voice channels, which will be exchanged media streams;

- In the case of readiness for acceptance of each terminal transmits data OpenLogicalChannelAck (confirmation of the opening of the logical channel) to the remote endpoint, specifying the port number on which the remote endpoint must transmit data to RTP, and the port number to which to transmit data to the remote endpoint RTCP;

- Endpoints exchange information in packets RTP. During this exchange RTCP packets are transmitted for the quality control data;

- When the endpoint A hangs up (hangs up), it shall send a message H.245 CloseLogicalChannel (close logical channel) for each channel open at a terminal point B;

- Endpoint B responds CloseLogicalChannelAck (confirmation of the closing of a logical channel);

- Endpoint A sends H.245 EndSessionCommand (logout), and closes the channel after receiving a similar message from the terminal point B;

- Send a message to both terminals H.225.0 ReleaseComplete (complete exemption) for call signaling channel, which closes the channel and terminates the connection.

 

 


 



Поделиться:




Поиск по сайту

©2015-2024 poisk-ru.ru
Все права принадлежать их авторам. Данный сайт не претендует на авторства, а предоставляет бесплатное использование.
Дата создания страницы: 2016-02-13 Нарушение авторских прав и Нарушение персональных данных


Поиск по сайту: