KR101236231B1 - Rtp packet transmitting and receiving method and system - Google Patents

Abstract

The present invention relates to a method and system for transmitting and receiving RTP packets, and more particularly, to a method and system for transmitting and receiving RTP packets that can easily process reading and writing RTP packets to and from the queue.
According to an embodiment of the present invention, a method for transmitting and receiving an RTP packet includes converting real-time data into the RTP packet at a transmitting end; Checking a sequence number of the RTP packet and updating a write pointer value of a transmission queue with the sequence number of the RTP packet; Storing the RTP packet in a transmission queue corresponding to the write pointer value; Updating a read pointer value of the transmission queue in order of sequence numbers of the RTP packets stored in the transmission queue each time a transmission of the RTP packets stored in the transmission queue is requested from a receiving end; Transmitting an RTP packet stored in a transmission queue corresponding to the read pointer value to the receiving end; Checking the sequence number of the RTP packet each time the RTP packet is received by the receiving end, and updating a write pointer value of the reception queue with the sequence number of the RTP packet; And storing the RTP packet in a receive queue corresponding to a record pointer value of the receive queue.

Description

RTP packet transmitting and receiving method and system

The present invention relates to a method and system for transmitting and receiving RTP packets, and more particularly, to a method and system for transmitting and receiving RTP packets that can easily process reading and writing RTP packets to and from the queue.

A service that provides multimedia content including broadcast programs through Voice over Internet Protocol (VoIP) or Internet Protocol (IP) network, a technology that implements voice calls through packets based on the Internet Protocol (IP) network. For real-time data services such as Internet Protocol TV (IPTV), a Real-time Transport Protocol / Real-time Transport Control Protocol (RTP / RTCP) based on User Datagram Protocol (UDP) is widely used.

UDP is a communication protocol that transmits data unilaterally at the transmitting end without going through a signal for transmitting data or a signal procedure for receiving data when exchanging data with each other on the Internet. In the transmitting end, it means that the receiving end can not confirm whether or not the data has been received. The concept is opposed to TCP (transmission control protocol), which is a communication protocol designed to communicate with a central computer server and simultaneously send and receive data by pressing an Internet icon. For example, when sending and receiving e-mails, 'receipt confirmation' shows whether the other party has read or not read the e-mail because the transmitting and receiving end can exchange data with each other. As such, the method of transmitting and receiving data to and from each other is TCP, and the method of transmitting data only from the transmitting end is UDP regardless of whether the receiving end sees data. In other words, UDP is a method of sending data unilaterally from the transmitting end without going through the receiving procedure.

Thus, unlike TCP, UDP is not responsible for the reception of data. This means that the sender sent the information, but the sender does not need to care about whether the information arrived at the receiver in time or the information contents were reversed. It's also less reliable than TCP, but much faster. In general, if a process wants to send a small message and not worry about reliability, use UDP rather than TCP.

RTP is a transport layer communication protocol for transmitting and receiving data in real time, and is defined together with RTCP in RFC 1889. Unlike RSVP (Resource Reservation Protocol), it is executed between terminals without relying on communication network devices such as routers. RTP is usually used as a higher communication protocol of UDP.

RTCP is a protocol for controlling RTP, a protocol for streaming video or voice over the Internet. It is specified in conjunction with RTP in RFC 1889 and is an Internet Engineering Task Force (IETF) standard. It checks for transmission delays and makes this information available to applications using RTP.

1 is a diagram for explaining the flow of voice data in a VoIP network using RTP / RTCP based on UDP.

As shown in FIG. 1, analog voice data input through a voice input device such as a microphone is converted into digital voice data by a codec. The converted digital voice data is compressed, and the compressed voice data is converted into RTP packets and transmitted to the receiver through the Internet. The receiving end stores the RTP packet transmitted through the Internet network in a buffer, restores the RTP packet stored in the buffer, and outputs analog voice data through a voice output device such as a speaker.

In this way, the RTP packet is read from the queue and written to the queue in the process of transmitting and receiving the RTP packet. However, there is a need for a method for simpler processing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described prior art, and an object thereof is to provide a method and a system for transmitting / receiving an RTP packet that can easily process reading and writing an RTP packet to a queue.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the RTP packet transmission and reception method according to an embodiment of the present invention comprises the steps of converting the real-time data to the RTP packet at the transmitting end; Checking a sequence number of the RTP packet and updating a write pointer value of a transmission queue with the sequence number of the RTP packet; Storing the RTP packet in a transmission queue corresponding to the write pointer value; Updating a read pointer value of the transmission queue in order of sequence numbers of the RTP packets stored in the transmission queue each time a transmission of the RTP packets stored in the transmission queue is requested from a receiving end; Transmitting an RTP packet stored in a transmission queue corresponding to the read pointer value to the receiving end; Checking the sequence number of the RTP packet each time the RTP packet is received by the receiving end, and updating a write pointer value of the reception queue with the sequence number of the RTP packet; And storing the RTP packet in a receive queue corresponding to a record pointer value of the receive queue.

And each time a read request of the RTP packet stored in the receive queue is requested, updating the read pointer value of the receive queue in the sequence number of the RTP packet stored in the receive queue; And outputting an RTP packet stored in a reception queue corresponding to a read pointer value of the reception queue.

The method may further include detecting an error of the RTP packet while receiving the RTP packet at the receiving end; Error processing if the error is detected and requesting the transmitting end to retransmit the detected RTP packet; Updating a read pointer value of the transmission queue with a sequence number of the RTP packet in which the error is detected, at the transmitting end receiving the retransmission request; And retransmitting an RTP packet stored in a transmission queue corresponding to a read pointer value of the transmission queue.

In order to achieve the above object, the RTP packet transmission and reception system according to an embodiment of the present invention, a transmitting end for transmitting the RTP packet; And a receiving end for receiving the RTP packet from the transmitting end, wherein the transmitting end includes an RTP packet generation unit for converting real time data into the RTP packet, a transmission queue for storing the RTP packet to be transmitted to the receiving end, and the RTP packet. Checks the sequence number of the packet, updates the write pointer value of the transmission queue with the sequence number of the RTP packet, stores the RTP packet in a transmission queue corresponding to the write pointer value, and transmits the transmission queue from the receiving end. Whenever the transmission of the RTP packet stored in the RTP packet is requested, the read pointer value of the transmission queue is updated in the sequence number of the RTP packet stored in the transmission queue, and the RTP packet stored in the transmission queue corresponding to the read pointer value is updated. And a transmission processing unit for transmitting the RTP packet received from the transmitting end. A check queue and a sequence number of the RTP packet each time the RTP packet is received, update the write pointer value of the receive queue with the sequence number of the RTP packet, And a receiving processor for storing the RTP packet in a corresponding receiving queue.

The reception processing unit updates the read pointer value of the reception queue in sequence of the sequence number of the RTP packet stored in the reception queue whenever a read request for the RTP packet stored in the reception queue is requested, and the read pointer value of the reception queue is updated. It is preferable to output the RTP packet stored in the reception queue corresponding to the.

The reception processor detects whether the RTP packet is in error while receiving the RTP packet, processes the error if the error is detected, and requests retransmission of the RTP packet in which the error is detected. Preferably, the read pointer value of the transmission queue is updated with the sequence number of the RTP packet in which the error is detected, and the RTP packet stored in the transmission queue corresponding to the read pointer value of the transmission queue is retransmitted.

As described above, according to the method and system for transmitting and receiving an RTP packet according to the present invention, there is an effect that the RTP packet can be easily read from the queue and written to the queue.

1 is a diagram for explaining the flow of voice data in a VoIP network using RTP / RTCP based on UDP.
2 is a block diagram of a system for transmitting and receiving an RTP packet according to an embodiment of the present invention.
3 is a diagram illustrating a format of an RTP packet header.
4 is a diagram illustrating a format of data encapsulated in UDP.
5 and 6 are flowcharts illustrating a method of transmitting and receiving an RTP packet according to an embodiment of the present invention.

Specific details of other embodiments are included in the detailed description and drawings, and the advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a method and a system for transmitting / receiving an RTP packet according to an embodiment of the present invention will be described with reference to the accompanying block diagrams or drawings.

At this point, it will be understood that each block of the flowchart illustrations and combinations of flowchart illustrations may be performed by computer program instructions.

Since these computer program instructions may be mounted on a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, those instructions executed through the processor of the computer or other programmable data processing equipment may be described in flow chart block (s). It creates a means to perform the functions.

These computer program instructions may be stored in a computer usable or computer readable memory that can be directed to a computer or other programmable data processing equipment to implement functionality in a particular manner, and thus the computer usable or computer readable memory. It is also possible for the instructions stored in to produce an article of manufacture containing instruction means for performing the functions described in the flowchart block (s). The computer program instructions It is also possible to mount on a computer or other programmable data processing equipment, so that a series of operating steps may be performed on a computer or other programmable data processing equipment to create a computer-executed process to perform a computer or other programmable data processing equipment May also provide steps for performing the functions described in the flowchart block (s).

In addition, each block may represent a portion of a module, segment, or code that includes one or more executable instructions for executing a specified logical function (s). It should also be noted that in some alternative implementations, the functions mentioned in the blocks may occur out of order. For example, the two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the corresponding function.

2 is a block diagram of a system for transmitting and receiving an RTP packet according to an embodiment of the present invention, FIG. 3 is a diagram illustrating a format of an RTP packet header, and FIG. 4 is a diagram showing a format of data encapsulated by UDP.

As shown in FIG. 2, an RTP packet transmission / reception system according to an embodiment of the present invention includes a transmitter 100 transmitting an RTP packet and a receiver 200 receiving an RTP packet.

The transmitter 100 may include an RTP packet generator 110 for converting real-time data into an RTP packet, a transmission queue 120 for storing an RTP packet to be transmitted to the receiver 200, and a transmission processor 130 for processing the RTP packet. ), And a connection unit 140 for connecting to the receiving terminal 200 by wireless or wired.

Referring to FIG. 3, the header of the RTP packet generated by the RTP packet generator 110 has a fixed size, followed by specific information and data.

Briefly describing each field of the RTP packet header, the V (Version) field is a version field, and the P (Padding) field is used to construct a packet in units of 32 bits. The X (Header Extention) field indicates whether the header is extended. The CC (CSRC Count) field indicates the number of CSRC Contributing Source Identifiers. The M (Marker) field represents a frame area for multimedia data. That is, it is used to distinguish between audio and video data in the packet. The PT (RTP Payload Type) field indicates the form of the RTP payload of the profile defined in RFC 1890 and is interpreted by the application. The Sequence Number field indicates the order of the RTP packets. The initial value is randomly selected and incremented by one each time the RTP packet is transmitted. Therefore, the receiver 200 can detect packet loss or reversal of order based on the sequence number. The Time Stamp field indicates the point in time when the first octet of the RTP packet is sampled. The Synchronization Source Identifier (SSRC) field means an identifier of a data source such as a camera or a microphone. A CSRC Contributing Source Identifier field indicates an identifier that can distinguish the sources when the RTP packets are mixed in the intermediate system.

Behind the header of the RTP packet is data formatted as a UDP packet. 4 shows the format of data encapsulated in UDP. Referring to FIG. 4, a UDP packet is composed of an IP header, a UDP header, and UDP data. In the IP header, the data source and destination addresses, higher layer protocols, checksums, and the like are recorded. In the UDP header, the port number of the source and destination, the size of the UDP header and data, and the UDP checksum are recorded. UDP data is data to be transmitted. The UDP header and UDP data are called UDP datagrams, and the IP header and UDP datagrams are called IP datagrams. Thus, an RTP packet consists of an RTP header and an IP datagram.

A queue is a data structure like an ordered list that allocates contiguous space in main memory in a computer so that data can be stored, retrieved, and used when needed. It happens at the other end.

The transmit queue 120 may be a circular queue to which the beginning and end of the arrangement are connected. The RTP packet is stored in the transmission queue 120 at the same address as the sequence number of the RTP packet. For example, an RTP packet of sequence number # 1 is stored at address # 1 of transmission queue 120, and an RTP packet of sequence number # 2 is stored at address # 2 of transmission queue 120.

The transmission processor 130 checks the sequence number of the RTP packet whenever the RTP packet is generated from the RTP packet generator 110 and updates the write pointer value of the transmission queue 120 with the sequence number of the generated RTP packet. . The transmission processor 130 stores the RTP packet in the transmission queue 120 corresponding to the record pointer value of the transmission queue 120. That is, as described above, the RTP packet is stored in the transmission queue 120 at the same address as the sequence number of the RTP packet.

Whenever the transmission of the RTP packet stored in the transmission queue 120 is requested from the receiving end 200, the transmission processing unit 130 sends a read pointer value of the transmission queue 120 to the RTP packet stored in the transmission queue 120. The sequence number is updated in order, and the RTP packet stored in the transmission queue 120 of the read pointer value is transmitted to the receiver 200 through the connection unit 140.

When retransmission of the RTP packet is requested from the receiver 200, the transmission processor 130 updates the read pointer value of the transmission queue 120 with the sequence number of the retransmission requested RTP packet. The transmission processor 130 retransmits the RTP packet stored in the transmission queue 120 corresponding to the read pointer value of the transmission queue 120.

The receiving end 200 includes a connection unit 210 for wirelessly or wired connection with the transmitting end 100, a receiving queue 220 storing an RTP packet received from the transmitting end 100, and a receiving processing unit which processes the RTP packet ( 230).

Receive queue 220 may be a circular queue is connected to the beginning and end of the array. The reception queue 220 stores the RTP packet received through the connection unit 210. At this time, the RTP packet is stored in the reception queue 220 having the same address as the sequence number of the RTP packet. For example, the RTP packet of sequence number # 1 is stored at address # 1 of receive queue 220, and the RTP packet of sequence number # 2 is stored at address # 2 of receive queue 220.

The reception processor 230 checks the sequence number of the RTP packet whenever the RTP packet is received through the access unit 210, and updates the write pointer value of the reception queue 220 with the sequence number of the received RTP packet. The reception processor 230 stores the RTP packet in the reception queue 220 corresponding to the recording pointer value of the reception queue 220. That is, as described above, the RTP packet is stored in the reception queue 220 at the same address as the sequence number of the RTP packet.

On the other hand, the arrival of the RTP packet is often delayed, lost in the middle, or out of order frequently arrive.

To solve this problem, the reception processor 230 detects whether an RTP packet is in error while receiving the RTP packet. Here, the detection of the error of the RTP packet is made based on the sequence number of the RTP packet. If an error of the RTP packet is detected, the reception processor 230 processes the error and requests the transmitter 100 to retransmit the corresponding RTP packet. For example, if you received 200 RTP packets starting with # 1001 and the sequence number was checked, the numbers appear in the order of # 1020, # 1021, # 1026, # 1027, and # 1028. , # 1024, # 1025, that is, 4 packets lost. Therefore, the receiver 200 requests retransmission to the transmitter 100 for the four lost packets # 1022, # 1023, # 1024, and # 1025.

The reception processor 230 updates the read pointer value of the reception queue 220 in the order of the sequence number of the RTP packets stored in the reception queue 220 each time a reading of the RTP packets stored in the reception queue 220 is requested. The RTP packet stored in the reception queue 220 corresponding to the read pointer value of the queue 220 is output. Here, the time point at which the read of the RTP packet stored in the reception queue 220 is requested depends on the relative timing indicated in the time stamp of the RTP packet.

5 and 6 are flowcharts illustrating a method of transmitting and receiving an RTP packet according to an embodiment of the present invention.

First, the RTP packet generation unit 110 converts real time data into an RTP packet (S110).

The transmission processor 130 checks the sequence number of the RTP packet whenever the RTP packet is generated from the RTP packet generator 110 and updates the write pointer value of the transmission queue 120 with the sequence number of the generated RTP packet. (S120).

The transmission processor 130 stores the RTP packet in the transmission queue 120 corresponding to the recording pointer value of the transmission queue 120 (S130).

Thereafter, whenever a transmission of the RTP packet stored in the transmission queue 120 is requested from the reception terminal 200 (S140), the transmission processing unit 130 transmits the read pointer value of the transmission queue 120 to the transmission queue 120. The sequence number of the stored RTP packet is updated in order (S150). The transmission processor 130 transmits the RTP packet stored in the transmission queue 120 of the read pointer value to the receiving terminal 200 through the connection unit 140 (S160).

The reception processor 230 checks the sequence number of the RTP packet each time an RTP packet is received through the access unit 210 and updates the write pointer value of the reception queue 220 with the sequence number of the received RTP packet (S170). ).

If the receiving processor 230 does not detect an error of the RTP packet based on the sequence number of the RTP packet while the receiving terminal 200 receives the RTP packet, the receiving processor 230 writes a record pointer value of the receiving queue 220. The RTP packet is stored in the reception queue 220 corresponding to the received queues (S180 and S190).

If the receiver 200 detects an error of the RTP packet based on the sequence number of the RTP packet while receiving the RTP packet, the receiver 200 processes the error and requests the transmitter 100 to retransmit the corresponding RTP packet. (S180, S200). Here, 0xFF can be written to the reception queue 220 as an error process. In addition, since a case in which the retransmission request is not received by the transmitter 100 within a transmission latency may occur, the retransmission request may be made a predetermined number of times.

The transmission processor 130 receiving the request for retransmission of the RTP packet from the receiver 200 updates the read pointer value of the transmission queue 120 with the sequence number of the RTP packet requested for retransmission (S210). Then, the transmission processor 130 retransmits the RTP packet stored in the transmission queue 120 corresponding to the read pointer value of the transmission queue 120 (S160).

On the other hand, the receiver 200 processes an error when the RTP packet cannot be re-received within the transmission latency, and releases an error indication when it receives again.

The reception processor 230 stores the read pointer value of the reception queue 220 in the reception queue 220 whenever a read of the RTP packet stored in the reception queue 220 is requested according to the relative timing indicated in the time stamp of the RTP packet. The sequence numbers of the RTP packets are updated in order (S220 and S230). The RTP packet stored in the reception queue 220 corresponding to the read pointer value of the reception queue 220 is output (S240).

Meanwhile, in the above-described embodiment, the transmission queue 120 and the reception queue 220 may be variably operated with an RTP packet size.

As described above, the present invention can easily process reading the RTP packet from the queue and writing the queue by setting the write / read pointer values of the transmission queue and the reception queue equal to the sequence numbers of the RTP packets.

Although the method and system for transmitting and receiving an RTP packet according to the present invention have been described with reference to the drawings illustrated as above, the present invention is not limited to the embodiments and drawings disclosed herein, and the technical scope of the present invention. Of course, various modifications can be made by those skilled in the art.

100: transmitting end 200: receiving end
110: RTP packet generation unit 120: transmission queue
130: transmission processing unit 140, 210: connection unit
220: reception queue 230: reception processing unit

Claims (6)

In the method of transmitting and receiving the RTP packet,
Converting real-time data into the RTP packet at a transmitting end;
Checking a sequence number of the RTP packet and updating a write pointer value of a transmission queue with the sequence number of the RTP packet;
Storing the RTP packet in a transmission queue corresponding to the write pointer value;
Updating a read pointer value of the transmission queue in order of sequence numbers of the RTP packets stored in the transmission queue each time a transmission of the RTP packets stored in the transmission queue is requested from a receiving end;
Transmitting an RTP packet stored in a transmission queue corresponding to the read pointer value to the receiving end;
Checking the sequence number of the RTP packet each time the RTP packet is received by the receiving end, and updating a write pointer value of the reception queue with the sequence number of the RTP packet; And
And storing the RTP packet in a receive queue corresponding to a record pointer value of the receive queue.
The method of claim 1,
Updating the read pointer value of the receive queue in sequence order of the RTP packet stored in the receive queue whenever a read of the RTP packet stored in the receive queue is requested; And
And outputting an RTP packet stored in a reception queue corresponding to a read pointer value of the reception queue.
The method of claim 2,
Detecting whether the RTP packet is error while receiving the RTP packet at the receiving end;
Error processing if the error is detected and requesting the transmitting end to retransmit the detected RTP packet;
Updating a read pointer value of the transmission queue with a sequence number of the RTP packet in which the error is detected, at the transmitting end receiving the retransmission request; And
Retransmitting the RTP packet stored in the transmission queue corresponding to the read pointer value of the transmission queue.
In a system for transmitting and receiving RTP packets,
A transmitter for transmitting the RTP packet; And
A receiving end receiving the RTP packet from the transmitting end,
The transmitting end checks a RTP packet generation unit for converting real time data into the RTP packet, a transmission queue storing the RTP packet to be transmitted to the receiving end, a sequence number of the RTP packet, and a write pointer value of the transmission queue. Is updated with the sequence number of the RTP packet, the RTP packet is stored in a transmission queue corresponding to the record pointer value, and each time a transmission of the RTP packet stored in the transmission queue is requested from the receiving end, A transmission processor for updating a read pointer value in sequence of the sequence numbers of the RTP packets stored in the transmission queue, and transmitting the RTP packet stored in the transmission queue corresponding to the read pointer value to the receiving end;
The receiving end checks a receiving queue storing an RTP packet received from the transmitting end, a sequence number of the RTP packet each time the RTP packet is received, and writes a write pointer value of the receiving queue to the sequence number of the RTP packet. And a reception processing unit for updating and storing the RTP packet in a reception queue corresponding to a record pointer value of the reception queue.
5. The method of claim 4,
The reception processing unit updates the read pointer value of the reception queue in sequence of the sequence number of the RTP packet stored in the reception queue whenever a read of the RTP packet stored in the reception queue is requested, and corresponds to the read pointer value of the reception queue. RTP packet transmission and reception system for outputting the RTP packet stored in the reception queue.
The method of claim 5,
The receiving processor detects whether the RTP packet is an error while receiving the RTP packet, processes the error if the error is detected, and requests the transmitting end to retransmit the detected RTP packet,
The transmission processing unit transmits and receives an RTP packet transmitting / receiving system that updates the read pointer value of the transmission queue with the sequence number of the RTP packet in which the error is detected, and retransmits the RTP packet stored in the transmission queue corresponding to the read pointer value of the transmission queue. .

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