WO2009086658A1 - Method for receiving and playing back video data - Google Patents

Abstract

A method for receiving and playing back video data is provided. A video data buffer and a low threshold are set at the video data receiving side. When the timer that is periodically started expires, the storage amount of the video data in the video data buffer is inspected. If the storage amount of video data is smaller than the low threshold, the request for video data is sent and the video data received from the transmitting side is stored into the video data buffer. And the receiving side reads out the video data from the video data buffer to play back the video data. By the above method for receiving and playing back video data, when thestorage amount of the data in the buffer becomes smaller, the video data can be obtained in time through the transmission link to ensure the less response time of video data display. By inspecting the storage amount of the data in the local buffer when video data is received or the timer expires, it can be ensured that there is a certain amount of data stored in the local buffer, and the smooth playback of video data can be realized.

Description

 Method for receiving and playing video data

Technical field

 The invention relates to a method for receiving and playing video data. Background technique

 As a very important broadband application service, broadband video surveillance can conveniently monitor the status of various monitored locations in real time, record historical surveillance video, and enable users (monitoring personnel) to see in real time or non-real time through a broadband network. Monitor screen. The broadband video surveillance service is currently developing rapidly at home and abroad, and has gradually become an important means for fixed network operators to develop new services.

 FIG. 1 is a schematic diagram of a network structure of a distributed broadband video monitoring system. As shown in Figure 1, the broadband video surveillance system usually adopts a distributed deployment mode. The entire system can be divided into multiple video surveillance domains (A domain, B domain, and C domain). Each video surveillance domain includes: video surveillance management platform (PS_A, PS_B, PS_C), front-end monitoring devices (PU1 1 , PU12, PU21, PU31, PU32), and monitoring clients (CU1 1 , CU12, CU21, CU31).

 Generally, each video monitoring domain includes at least one video monitoring management platform, and the video monitoring management platform is mainly used to manage front-end monitoring devices in the video monitoring domain to which it belongs, and monitor the video monitoring domain and other video monitoring domains. The client provides the video file content of the front-end monitoring device and the IP (Internet Protocol) address, port number and other information.

 The video surveillance domain may include one or more front-end monitoring devices. The front-end monitoring device is mainly used for video surveillance data collection (recording), and is managed by the video surveillance management platform in the video surveillance domain to provide video surveillance data. The file name and other information, and provide the collected video surveillance data for the monitoring client of the video surveillance domain or other video surveillance domain.

 The monitoring client obtains file information such as the name of the video monitoring data from the video monitoring management platform of the video monitoring domain, and obtains service address information such as an IP address and a port number of the front-end monitoring device storing the video monitoring data; The file information and service address information acquire video surveillance data and play it.

Devices in each video surveillance domain and in each video surveillance domain can be connected through a network. In the domain system environment, the sharing of front-end monitoring devices is realized. For example, the monitoring client of the A domain obtains the IP address and port number of the front-end monitoring device of the video surveillance domain from the video surveillance management platform of the other video surveillance domain through the protocol interaction, and obtains the video recording corresponding to the front-end monitoring device.

 In the prior art, the monitoring client (receiver) generally acquires video data from the front-end monitoring device (sender) and plays the following method: The monitoring client periodically requests data from the front-end monitoring device, and saves the received video data in In the cache, the video data in the cache is played when it is full or almost full.

 The above method for receiving and playing video data usually causes the user to see that the picture is not smooth, and the waiting time is long (sometimes longer than 3 seconds).

 In addition, when the video data is received by the above method, the video data in the cache is often received when new video data is received; the processing of the processing resources and the network bandwidth resources by the transmitting end and the receiving end is wasteful; This waste increases the size of the cache, which increases the cost of the receiving end and does not effectively avoid the above problem.

Summary of the invention

 The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and propose a video data receiving and playing method for smoothing the playback effect.

 In order to solve the above problem, the present invention provides a method for receiving and playing video data, which sets a video data buffer and a low threshold threshold at a receiving end of the video data; and checks a video data buffer when the periodically started timer is full. Video data inventory, when the video data inventory is less than the low threshold threshold, initiate a video data request, and store the video data received from the sender into the video data buffer;

 And, the receiving end takes out video data from the video data buffer for playing.

 In addition, the receiving end checks the video data inventory in the video data buffer when receiving the video data, and initiates the video data request when the video data inventory is less than the low threshold threshold.

 In addition, a high threshold threshold is set at the receiving end, and the video data request is initiated only when the video data inventory is less than or equal to the high threshold threshold; the high threshold reading is greater than the low threshold threshold.

In addition, when receiving video data, and/or, when the timer is full, the receiving end is based on Setting the data growth identifier of the receiving end to the data growth identifier of the receiving end: if the current video data inventory is less than the low threshold threshold, setting the data growth identifier to insufficient inventory, and initiating a video data request; if the current video data inventory is greater than the a high threshold threshold, the data growth indicator is set to the inventory; and

 When the video data is received, and/or, when the timer is full, if the video data inventory is greater than or equal to the low threshold threshold and less than or equal to the high threshold threshold, the video data request is initiated if and only if the data growth identifier is insufficient. The high threshold threshold is greater than the low threshold threshold.

 In addition, the receiving end cancels the timer when receiving the video data, and restarts. In addition, the amount of video data that can be stored in the video data buffer is greater than the data length of the high threshold threshold of one key video frame.

 In addition, different processes at the receiving end, or different threads of the same process are completed: the task of initiating a video data request and storing the received video data into a video data buffer, the fetching from the video data buffer The task of playing video data.

 In addition, when the video data buffer contains 2 frames or more of video data, and at least 1 frame is a key video frame, the video data is taken out from the video data buffer for playing.

 In addition, the key video frame is an I frame.

 In addition, the sending end is a front-end monitoring device of the video monitoring network, and the receiving end is a monitoring client of the video monitoring network; the transmitting end and the receiving end are connected by a network.

By adopting the receiving and playing method of the video data of the invention, the video data can be acquired through the transmission link in time when the data storage in the buffer is small, and the response time of the display video data is guaranteed to be less; by receiving the video data or timing When the device is full, it checks the data inventory in the local buffer to ensure that a certain amount of buffered data is stored locally to achieve smooth playback of the video data. In addition, the local buffer can be effectively managed by the method of the present invention. In the case of setting a buffer of a reasonable size, there is no phenomenon that the buffer is full and the received video data has to be discarded. BRIEF abstract

1 is a schematic diagram of a network structure of a distributed broadband video surveillance system; 2 is a flow chart of a method for receiving and playing video data according to an embodiment of the present invention;

 Figure 3 is a schematic diagram showing the state transition of the data buffer of the data buffer when the data is received by the method of the present invention. Preferred embodiment of the invention

 The basic idea of the present invention is to effectively monitor and manage the buffer at the receiving end of the video data by setting two threshold values and data growth identifiers to achieve smooth playback of the video data.

 The invention will now be described in detail in conjunction with the drawings and embodiments.

2 is a flow chart of a method for receiving and playing video data according to an embodiment of the present invention. The method for receiving and playing video data of the present invention is divided into three sub-processes: an initialization process, a receiving process of video data, and a playback process of video data. Specifically, it includes the following steps:

 Initialize

 101: The monitoring client (hereinafter referred to as the receiving end) sets the local data buffer size, the high threshold threshold and the low threshold alarm value; the data inventory is monitored.

 The data threshold corresponding to the low threshold threshold must be at least equal to or greater than the data length of one key video frame.

 For video data in the MPEG (Moving Picture Experts Group) format, the above key video frames are I-frames (intra-coded frames).

The size of the local data buffer is greater than the high threshold threshold by at least 1 key video frame (I frame).

102: The receiving end performs a protocol interaction with the video monitoring management platform, and obtains identification information of the video data, and an IP address and a port number of the front-end monitoring device (hereinafter referred to as the sending end) that stores the video data; The above video data identification information is usually the name of the video recording file.

 103: The receiving end initiates a link transmission process (or thread) and a playback process (or thread);

Video data reception

 104: Set the data growth indicator on the receiving end, and initialize it to 1;

 The above data growth indicator is used to determine whether a data request needs to be initiated to obtain more video data. A data growth indicator of 1 means: New data is required (or indicates: insufficient stock), 0 means no new data is required for the time being (or: stock is sufficient).

 For ease of reading and writing, the above data growth indicator is usually a local or global variable of the link transmission process (or thread).

 105: The link transmission process/thread initiates a data request to the sender to acquire new video data; the link transmission process/thread may initiate the data request by using the identification information of the video data and the IP address and port number of the sender.

 106: link transmission process / thread start timer;

 The main function of the above timer is to periodically start the data inventory check in the data buffer when the video data sent by the sender is not received for a period of time, and judge whether it is necessary to send a data request according to the check result.

 107: The link transmission process/thread determines whether to receive the stop playing message;

 When receiving the stop play message, the link transfer process/thread needs to cancel the timer and close the process/thread (107A), and the process ends; otherwise, the next step is executed.

 108: The link transmission process/thread listens for video data packets on the receiving port and determines whether the timer expires:

 If it times out and does not receive the video data, then jump to step 1 1 1;

 If the timeout period is not received and the video data is received (that is, the video data message is heard before the timer expires), the next step is performed;

Otherwise, loop this step (ie wait for the timer to time out and continue to listen for video data messages on the receiving port). 109: link transmission process / thread cancellation timer (ie stop timer timing);

 110: The link transmission process/thread saves the received video data in a local data buffer;

 111: Link transfer process / thread to check the data inventory in the data buffer:

 If the video data inventory in the data buffer is greater than the high threshold threshold, perform the next step; if the video data inventory in the data buffer is less than the low threshold threshold, then jump to step 113; if in the data buffer If the video data inventory is greater than or equal to the low threshold threshold and less than or equal to the high threshold value, then the process proceeds to step 114.

 112: Set the data growth indicator to 0, and go to step 116;

 113: Set the data growth indicator to 1;

 114: judge the data growth identifier, if it is 1, perform the next step; otherwise, jump to step 116;

 115: Initiating a data request to obtain new video data;

 116: Reset and start the timer, restart timing, and skip to step 107.

Playback of video data (not shown)

 117: The playback process/thread determines whether the stop play message is received, and if the stop play message is received, the process/thread is closed, and the process ends; otherwise, the next step is performed;

 118: The playback process/thread checks the local data buffer. If the data buffer contains 2 frames or more of data, and at least 1 frame is a key video frame (I frame), the data buffer is taken out. The video data is played quickly and jumps to step 117.

Since the playback process/thread checks the data buffer timing, when the data buffer contains 2 frames or more of data, and contains key video frames (I frames), it plays in time instead of waiting for buffering. The area starts to play and the response time is very short. FIG. 3 is a schematic diagram showing state transition of a data buffer of a data buffer when data is received by the method of the present invention.

 A method of receiving video data of the present invention will be described below with reference to Figs. 1, 3, and a specific example.

 In this example, the receiving end is the monitoring client CU12 in the A domain, the transmitting end is the front-end monitoring device PU21 in the B domain; the A domain and the B domain are connected through the Internet (Internet).

 For 2MB/S wideband video recording, the video keyframe I frame size is generally less than 100KB, CU12 sets the local data buffer size to 400KB, the low threshold threshold is 128KB, and the high threshold threshold is 256KB (guarantee to reach the high threshold threshold) The video data buffer can be played for 1 second).

 The CU12 performs a video file query on the PU21 through the video surveillance management platform PS-A in the A domain, and obtains the IP address of the PU21, the port number of the UDP (User Datagram Protocol), and the video file VIDE01 to be played through the protocol exchange.

 The CU12 initiates the link transmission process and the playback process; the link transmission process sends a data request to the server PU21, and sets a timer T1 (1 second timing) to initialize the data growth indicator to 1.

 As the link transmission process acquires video data from the PU 21 and saves it in the data buffer; at the same time, the playback process retrieves the video frame data from the data buffer for playback, and the local data buffer sequentially performs the following state transitions:

 State ( a ) : initial state

 In this state, there is no data in the data buffer; at this time, the data growth identifier is 1, and the link transmission process listens for data packets on the receiving port of CU12.

 State (b): growth period

 The link transmission process receives the data packet sent by the PU21, cancels the timer T1, and stores the received video data into the local data buffer.

 At this time, the video data inventory in the current data buffer is less than 128 KB, and the local data buffer is in the growth period; the link transmission process sets the data growth identifier to 1 (insufficient inventory), initiates a data request to PU21, resets and starts timing. T1 ;

State (c): high threshold The link transmission process receives the data packet sent by the PU21, cancels the timer T1, and stores the received video data into the local data buffer.

 At this time, the video data stock in the current data buffer is greater than or equal to 256 KB, and the local data buffer is in a high threshold state; the link transmission process sets the data growth identifier to 0, does not send a data request, and resets and starts the timer T1;

 State (d) : reduction period

 As the playback process continuously consumes video data in the local data buffer, the video data inventory in the data buffer is less than 256 KB, but is greater than 128 KB, which is in a reduced period;

 Since the data growth indicator is 0 at this time, the link transmission process does not send a data request when receiving the video data sent by the PU21, or the timer is full, and only resets and starts the timer T1;

 State (e) : low threshold

 As the playback process further consumes video data in the local data buffer, the video data inventory in the data buffer is less than 128 KB, which is in a low threshold state;

 At this time, when the link transmission process receives the video data sent by the PU21, or the timer expires, the following operations are performed:

 (1) Set the data growth indicator to 1;

 (2) initiating a data request to the PU 21;

 (3) Reset and start the timer Tl.

 State (f) : growth period

 When the video data acquired by the link transmission process from the PU21 is larger than the consumption of the playback process, the video data inventory in the data buffer is greater than 128 KB, but less than the growth period of 256 KB.

 Since the data growth indicator is 1 at this time, the link transmission process performs the following operations when receiving the video data sent by the PU21, or when the timer is full:

 (1) initiating a data request to the PU 21;

( 2 ) Reset and start the timer Tl. In this way, under normal circumstances, the video data stock of the local data buffer will be between 128KB (low threshold threshold) and 256KB (high threshold threshold) for most of the time, ensuring smooth playback of wideband video recording.

Based on the principles of the present invention, various changes can be made to the above embodiments, such as:

 (1) It is possible to use only the low threshold threshold to determine whether a data request needs to be initiated. That is, a data request is initiated when the video data inventory is less than the low threshold threshold. Of course, in this case, it is necessary to set the low threshold threshold higher to avoid frequent shortage of video data in the data buffer. Of course, using only the low threshold threshold cannot effectively avoid the problem of discarding the received video data when the data buffer is full.

 (2) In the above embodiment, the timer is canceled when the video data is received, and is restarted; that is, the timer is started/stopped in a non-fixed cycle;

 In another embodiment, the timer may not be cancelled when the video data is received; that is, the timer is started/stopped at a fixed cycle.

 (3) The video data stock in the video data buffer may be checked only when the timer that is periodically started is full to determine whether a data request needs to be initiated; and the above check is not performed when the video data is received.

Industrial applicability

 By adopting the receiving and playing method of the video data of the invention, the video data can be acquired through the transmission link in time when the data storage in the buffer is small, and the response time of the display video data is guaranteed to be less; by receiving the video data or timing When the device is full, it checks the data inventory in the local buffer to ensure that a certain amount of buffered data is stored locally to achieve smooth playback of the video data. In addition, the local buffer can be effectively managed by the method of the present invention. In the case of setting a buffer of a reasonable size, there is no phenomenon that the buffer is full and the received video data has to be discarded.

Claims

Claim  A method for receiving and playing video data, characterized in that  Setting a video data buffer and a low threshold threshold at the receiving end of the video data; checking the video data inventory in the video data buffer when the periodically started timer is full, and starting the video when the video data inventory is less than the low threshold threshold Data request, and store the video data received from the sender into the video data buffer;  And, the receiving end takes out video data from the video data buffer for playing.  2. The method according to claim 1, wherein the receiving end checks the video data stock in the video data buffer when receiving the video data, and initiates the video data request when the video data stock is less than the low threshold threshold.  The method of claim 2, wherein a high threshold is set at the receiving end, and a video data request is initiated only when the video data inventory is less than or equal to a high threshold; the high threshold is greater than Describe the low threshold threshold.  4. A method according to any one of claims 1 to 3, characterized in that  When the video data is received, and/or, when the timer is full, the receiving end sets the data growth identifier of the receiving end according to the video data inventory: if the current video data inventory is less than the low threshold threshold, Setting the data growth indicator to insufficient inventory and initiating a video data request; if the current video data inventory is greater than the high threshold alarm value, setting the data growth indicator to the inventory amount;  When the video data is received, and/or, when the timer is full, if the video data inventory is greater than or equal to the low threshold threshold and less than or equal to the high threshold threshold, the video data request is initiated if and only if the data growth identifier is insufficient. The high threshold threshold is greater than the low threshold threshold.  The method according to claim 2, wherein the receiving end cancels the timer when receiving the video data, and restarts.  The method of claim 3, wherein the amount of video data that can be stored in the video data buffer is greater than the data length of the high threshold threshold of one key video frame. 7. The method according to claim 1, wherein: different processes at the receiving end, or different threads of the same process are completed: the initiating video data request and the received video The task of storing data into a video data buffer, the task of taking out video data from a video data buffer for playback.  8. The method according to claim 1, wherein when the video data buffer contains 2 or more frames of video data, and at least one of the frames is a key video frame, the video data buffer is buffered. Take out the video data for playback.  9. The method according to claim 6, wherein the key video frame is an I frame.  The method according to claim 1, wherein the transmitting end is a front end monitoring device of a video monitoring network, and the receiving end is a monitoring client of a video monitoring network; between the transmitting end and the receiving end Connected to the network.