CN117915162A - Real-time video transmission dynamic delay control system based on link state and time stamp - Google Patents
Real-time video transmission dynamic delay control system based on link state and time stamp Download PDFInfo
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- CN117915162A CN117915162A CN202311692750.5A CN202311692750A CN117915162A CN 117915162 A CN117915162 A CN 117915162A CN 202311692750 A CN202311692750 A CN 202311692750A CN 117915162 A CN117915162 A CN 117915162A
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Abstract
The invention discloses a real-time video transmission dynamic delay control system based on a multi-link state and a time stamp, which is used for a multi-link wireless network, and when the system receives a video data packet transmitted by a link L i, if the related video frame is judged to be received incompletely and the playing time of the data packet is not passed, the state of the link L i is judged in real time: if the number of lost packets of the link L i is within the q-th time periodIf the data packet is larger than or equal to the threshold value c, the sending speed of the data packet at the sending end of the link L i is slowed down, and meanwhile, the target delay of the data packet of the link L i is increased; if the link L i is in n consecutive time periods, the number of lost packetsAnd the data packet is smaller than the threshold d, the sending speed of the data packet at the sending end of the link L i is improved, and meanwhile, the target delay of the data packet of the link L i is reduced. The invention dynamically adjusts the balance of low delay and reliability of the system based on real-time judgment of the link state and the time stamp, and is beneficial to improving the quality of real-time video transmission of the system.
Description
Technical Field
The invention relates to the technical field of delay control strategy research of a real-time video transmission system under multiple links.
Background
In a conventional multilink real-time video transmission system, in order to ensure the smoothness of video receiving end play, a unified buffer area is usually set at the receiving end, and the transmitted video data packets are buffered in advance, so as to reduce the influence of network jitter. And after the video message received by each link is cached by the receiving end, video recombination is carried out, and the video message is submitted to the application layer for decoding and playing after the delay time is reached.
The state of each link is unstable due to the time-varying nature of the wireless network. Conventional fixed target delay strategies are not sufficiently resistant to the effects of the time-varying nature of wireless network links. The low-delay, high-reliability and large-code-rate real-time video service is the target pursued by the current scenes, the lower delay means better experience of users, but the too small end-to-end target delay of the video data packet can cause a large number of packet loss problems caused by the fact that the packet cannot arrive within the delay time, the reliability is reduced, and in a word, the low-delay and the high-reliability are difficult to balance.
Disclosure of Invention
The invention aims to provide a real-time video transmission dynamic delay control system based on a link state and a data packet time stamp, which adjusts the target delay of a video data packet in real time by judging the time stamp of the link data packet and the state of the link, realizes the dynamic balance of low delay and reliability and improves the quality of real-time video transmission.
The invention realizes the aim of the invention through the following technical scheme: a real-time video transmission dynamic delay control system based on link state and time stamp is used for a multi-link wireless network, the system sets a variable X for judging the integrity of a video frame, when the value is a, the system indicates that the video frame, namely all data packets in the video frame, are completely received, and when the value is b, the system indicates that the video frame is not completely received;
Setting a variable T wait for judging whether the data packet of the received video frame reaches the playing time or not, and T wait＝Tplay-Ti m;
A time stamp representing the recorded mth data packet of the received ith video frame, T play being a predetermined play time of the data packet;
When the system receives a video data packet transmitted by a link L i, judging whether a video Frame received in a buffer area is complete or not in real time, and judging whether the data packet of the video Frame reaches a playing time T play or not:
If the variable x=b and T wait is equal to or greater than 0, determining the state of the link L i in real time:
If the number of lost packets of the link L i is within the q-th time period If the data packet is larger than or equal to the threshold value c, the sending speed of the data packet at the sending end of the link L i is slowed down, and meanwhile, the target delay of the data packet of the link L i is increased; if the link L i is in n consecutive time periods, the packet loss number/>And the data packet is smaller than the threshold d, the sending speed of the data packet at the sending end of the link L i is improved, and meanwhile, the target delay of the data packet of the link L i is reduced.
When the link state is bad, the sending speed of the data packet of the link sending end is properly slowed down, so that more links with good slave states can send the data packet. However, if the rate of the sending end is reduced singly, the time-out of the data packet reaching the receiving end may be caused, and the risk of discarding the data packet is increased. For the link with good state, the sending rate of the data packet is properly improved, so that the link can be better utilized, and the burden of other links, particularly links with bad state, is balanced. However, if the rate of the sending end is singly increased, the problem of packet accumulation and even link breakdown may occur. The scheme of the invention combines two items, and avoids causing new problems while realizing dynamic balance of low delay and reliability of the system according to the link state and the time stamp.
As an improvement scheme: when the system receives the video data packet transmitted by the link L i, if the variable X=a and T wait is more than or equal to 0, the video frame is directly sent to the play queue, so that the waiting time of the video frame is reduced.
As a further improvement scheme: when the system receives the video data packet transmitted by the link L i, if the variable X=a and T wait is less than 0, the sequence number N of the video frame is recorded and compared with the sequence number M of the video frame to be played next, and if N is more than or equal to M, the video frame is sent to the play queue.
If the variable x=a and T wait <0, and N < M, or x=b and T wait <0, then the entire video frame is deleted.
L i in the above step represents any one link in the wireless transmission system.
The beneficial effects are that:
In the working process, the invention judges the state of the transmission link in real time according to the received data packet, improves the data transmission rate of the link with good state, reduces the target time delay of the link with bad state, reduces the data transmission rate of the link with bad state, increases the target time delay of the link with bad state, reasonably optimizes the end-to-end target time delay of the system according to the link state compromise, realizes the dynamic balance of low time delay and reliability of the system, avoids causing new problems, and is beneficial to improving the quality of real-time video transmission of the system.
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FIG. 1 is a general block diagram of the present invention;
Fig. 2 is a schematic diagram of a multi-link dynamic target delay strategy according to the present invention.
Detailed Description
In this embodiment, the real-time video transmission dynamic delay control system based on the link state and the time stamp under the multilink actually determines whether the Frame of the video Frame received in the buffer is complete or not, and whether the data packet of the Frame of the video Frame reaches the playing time T play or not.
In general, a video segment is transmitted by several video frames, one video frame includes several data packets, and the integrity of the video frame is determined, i.e. whether all the data packets of the video frame are received. In this embodiment, the integrity of the video frame is determined by the boolean variable B frame, where the boolean variable B frame has two values, "0" and "1", the value "1" indicates that the video frame is completely received, and "0" indicates that the video frame is incompletely received.
In this embodiment, whether the received data packet of the video frame reaches the playing time is determined by T wait, T wait＝Tplay-Ti m; Representing the recorded timestamp of the mth packet of the received ith video frame, T play is the predetermined play-out time of that packet. T wait represents the required waiting time, which should generally be greater than or equal to 0, and less than 0 occurs when the reception delay occurs.
A. If the video frame B frame＝1and Twait is more than or equal to 0, the video frame is directly sent into a play queue without waiting, so that the waiting time of the video frame is reduced. The operation can reduce the risk of freezing the video picture at the user side, and is beneficial to improving the visual experience of the user.
B. if the video frame B frame＝0and Twait is more than or equal to 0, the state of the current data packet transmission link is judged in real time, and the state of each transmission link is usually different due to the time-varying characteristic of the wireless network.
As shown in fig. 1, it is assumed that the real-time video transmission system has two links for simultaneously transmitting video data L 1 and L 2, if the number of dropped packets of link L 1 is within the qth periodThe sending speed of the data packet at the sending end of the link is slowed down, so that more links L 2 with good slave state of the data packet can be sent, and meanwhile, the target delay D 1 of the data packet of the link L 1 is properly increased, otherwise, if the state of a certain link such as L 2 is always good, the number of lost packets/>, is increased in n continuous time periodsIf the transmission delay is smaller than the set threshold, for example, 1, the target delay D 2 can be reduced appropriately, and the transmitting end of the link is notified to raise the transmission rate of the data packet appropriately. The scheme can reduce the overall time delay of the system, realize the dynamic balance of low time delay and reliability, simultaneously avoid the problem of data packet accumulation or overtime caused by single adjustment rate or time delay, and improve the quality of real-time video transmission of the system. The overall system strategy is shown in fig. 2.
As an improvement scheme of the system: when the video frame B frame＝1and Twait is smaller than 0, the system records the sequence number N of the video frame, compares the sequence number N with the sequence number M of the video frame to be played next, and sends the video frame into a play queue to wait for playing if N is larger than or equal to M, namely the video frame is not actually played currently (play delay), otherwise, deletes the whole video frame and ensures smooth playing of the subsequent video.
Claims (4)
1. A real-time video transmission dynamic delay control system based on a link state and a time stamp is used for a multi-link wireless network and is characterized in that a variable X is set for judging the integrity of a video frame, and when the value of the variable X is a, the variable X indicates that all data packets in the video frame are completely received, and when the value of the variable X is b, the variable X indicates that the video frame is not completely received;
Setting a variable T wait for judging whether the data packet of the received video frame reaches the playing time or not, and T wait＝Tplay-Ti m;
A time stamp representing the recorded mth data packet of the received ith video frame, T play being a predetermined play time of the data packet;
When the system receives a video data packet transmitted by a link L i, judging whether a video Frame received in a buffer area is complete or not in real time, and judging whether the data packet of the video Frame reaches a playing time T play or not:
If the variable x=b and T wait is equal to or greater than 0, determining the state of the link L i in real time:
If the number of lost packets of the link L i is within the q-th time period If the data packet is larger than or equal to the threshold value c, the sending speed of the data packet at the sending end of the link L i is slowed down, and meanwhile, the target delay of the data packet of the link L i is increased; if the link L i is in n consecutive time periods, the packet loss number/>And the data packet is smaller than the threshold d, the sending speed of the data packet at the sending end of the link L i is improved, and meanwhile, the target delay of the data packet of the link L i is reduced.
2. The system of claim 1, wherein when receiving a video packet transmitted by the link L i, the system directly sends the video frame to the play queue if the variable x=a and T wait is equal to or greater than 0.
3. The dynamic delay control system of claim 2 wherein when the system receives a video packet transmitted over link L i, if the variable x=a and T wait <0 is determined, the sequence number N of the video frame is recorded and compared to the sequence number M of the next video frame to be played, and if N is greater than or equal to M, the video frame is sent to the play queue.
4. The dynamic delay control system of claim 3 wherein, upon receipt of a video packet transmitted by link L i, if the variables x=a and T wait <0 and N < M, or x=b and T wait <0 are determined, then the entire video frame is deleted.
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| CN202311692750.5A CN117915162A (en) | 2023-12-11 | 2023-12-11 | Real-time video transmission dynamic delay control system based on link state and time stamp |
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| CN202311692750.5A CN117915162A (en) | 2023-12-11 | 2023-12-11 | Real-time video transmission dynamic delay control system based on link state and time stamp |
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