CN101072360A - Method for improving receiving performance of mobile multimedia broadcasting terminal - Google Patents

Abstract

The invention discloses a method for improving the receiving performance of a mobile multimedia broadcasting terminal, which is applied to the terminal to obtain a target multiplexing subframe according to the received multiplexing frame, comprising the steps of: when the multiplexing frame header performs a cyclic redundancy check error , determining the start position of multiplexed subframe 1 in the multiplexed frame according to the length of the multiplexed frame header of the last correctly parsed multiplexed frame, and parsing the subframe header of the multiplexed subframe 1, Obtain the length of the multiplexing subframe 1; obtain the starting position of the target multiplexing subframe header according to the starting position and length of the multiplexing subframe 1 and the sequence number of the target multiplexing subframe , and then acquire the target multiplexing subframe. The method of the invention prevents the receiving terminal from discarding the entire multiplexing frame data due to the CRC checking error of the multiplexing frame header when the CRC checking error of the multiplexing frame header is wrong, and improves the receiving performance of the terminal under the code error condition.

Description

A Method for Improving Receiving Performance of Mobile Multimedia Broadcasting Terminal

technical field

The invention relates to a method for improving the receiving performance of a terminal, in particular to a method for improving the receiving performance of a mobile multimedia broadcasting terminal.

Background technique

In recent years, digital mobile multimedia broadcasting technology and standards have developed rapidly, such as DVB-H (Digital Video Broadcast Handheld, digital video broadcasting handheld reception) in Europe, MediaFLO (Media Forward Link Only, media single forward link) in the United States and China's CMMB (China Mobile Multimedia Broadcasting, Mobile Multimedia Broadcasting), etc., provide its end users with many services, such as advertisements, weather forecasts, news, sports programs, variety shows, multimedia radio dramas, movies and other programs. Users can choose the service programs of mobile multimedia broadcasting according to their own preferences.

In China's CMMB standard, mobile multimedia broadcasting uses a time-division method to send multimedia broadcasting services. A broadcast channel frame has a duration of 1 second and consists of 40 time slots of 25 milliseconds. One or more time slots can carry data encapsulated in a multiplexing frame (Multiplexing Frame, MF for short). In the multiplexing frame structure of mobile multimedia broadcasting, the multiplexing frame is divided into three parts: the multiplexing frame header, the multiplexing frame payload and the padding, as shown in FIG. 1 .

FIG. 2 shows the relationship between multiplexed frames and multiplexed subframes. A broadcast channel frame, such as broadcast channel frame k in FIG. 2 , transmits information content divided into control information and service data. The control information is transmitted in the multiplexed frame 0, and the service data is transmitted in the multiplexed frame 1, the multiplexed frame 2, . . . , the multiplexed frame n, where n is less than 40. The multiplexed frame payload of each business data multiplexed frame consists of one or more multiplexed subframes, as shown in the figure, multiplexed subframe 1, multiplexed subframe 2, ..., multiplexed subframe p, but can only include 15 multiplexed subframes at most, that is, p is less than or equal to 15. Each multiplexing subframe carries a multimedia service.

The structure of the multiplexing frame header is shown in Figure 3, which includes parameters such as the length of the multiplexing subframe. The "next frame parameter indication" field indicates whether the key parameter of the next multiplexed frame with the same multiplexed frame identifier MF_ID is included in the multiplexed frame header, '0' means no, '1' means yes. If the value of the "Next Frame Parameter Indication" field is '1', the "Next Frame Parameter" includes the multiplexing frame header length, multiplexing subframe 1 ( The length of the first multiplex subframe) and the header length of multiplex subframe 1. The multiplexing frame header adopts 32-bit CRC (Cyclic Redundancy Check, Cyclic Redundancy Check) for checking.

The structure of the multiplexed subframe is shown in Figure 4, which consists of a subframe header, a video segment, an audio segment and a data segment. Wherein the subframe header includes the header length (occupies 8 bits), start playing time, video segment length, audio segment length, data segment length, extension area parameters, etc., and also adopts 32-bit CRC check.

As shown in Figure 5, after the mobile multimedia broadcast terminal in the CMMB system receives the multiplexing frame, it will perform the following demultiplexing process:

Step 501: Analyze the multiplexed frame header to obtain the length of the multiplexed frame header, the update sequence number of various control information tables and the length of each multiplexed subframe;

Step 502: According to the length of the multiplexing frame header and the length of each multiplexing subframe, the required multiplexing subframe is parsed from the payload of the multiplexing frame, which is called the target multiplexing subframe;

Step 503: Parsing out the video segment, audio segment and data segment from the target multiplexing subframe;

Step 504: Parse the payloads of the video unit, audio unit and data unit from the video segment, audio segment and data segment respectively, and send them to an upper-layer application (such as a player) for processing.

The CMMB system broadcasts multimedia through air channels. Because the wireless environment is very complex, even if channel coding with excellent performance is adopted during broadcasting, channel bit errors cannot be avoided. When the mobile multimedia broadcasting terminal demultiplexes the received data, it involves the CRC check of the multiplexing frame header. The current general method is to calculate the CRC check, and if a CRC error is detected, the terminal discards all data in the multiplexed frame.

Figure 6 shows the detailed flow steps of an embodiment of demultiplexing processing in the prior art, including:

Step 601: When the terminal processes the multiplexed frame, it first obtains the length of the multiplexed frame header;

Step 602: Obtain the data of the multiplexing frame header, and perform CRC_32 check;

Step 603: judging whether the multiplexed frame header CRC is correct, if correct then go to step 604, otherwise go to step 608;

Step 604: Perform operations such as updating and saving the data information in the multiplexing frame header, specifically including processing the update sequence number of the control information table, such as emergency broadcast instructions, saving the length of the multiplexing frame header, and caching if there is a next frame parameter This parameter; and obtain the length of each multiplexing subframe in the multiplexing frame;

Step 605: Obtain the start position of the target multiplexed subframe according to the sequence number of the target multiplexed subframe according to the offset value, read the data of the target multiplexed subframe, and obtain the length of the header of the multiplexed subframe; in bytes , where the offset value is the length of the multiplexing frame header + 4-byte CRC_32 code + the sum of the lengths of the subframes before the target subframe;

Step 606: Analyze the subframe header data of the target multiplexed subframe and perform CRC check to obtain the length of the subframe header of the target multiplexed subframe, the length of the video segment, audio segment and data segment in the subframe, and the start playing time and other information;

Step 607: Perform corresponding processing on the video segment, audio segment and data segment in the target multiplexing sub-frame;

Step 608: Since the CRC_32 check of the multiplexed frame header does not pass correctly, the current multiplexed frame data is discarded.

Since the multiplexed frame multiplexes services in units of one second, the terminal will directly discard the data of a multiplexed frame when it detects a CRC error in the multiplexed frame header. All video data and audio data are discarded, which directly causes severe interruption of the picture and sound of the terminal. Such a processing process makes the reception of the terminal very sensitive to the bit error rate of the channel, and the resistance to the bit error rate is poor, which seriously reduces the efficiency of data reception and affects the smoothness of the user's audio and video experience.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for improving the receiving performance of the mobile multimedia broadcasting terminal, which is applied to improve the receiving performance of the terminal when the terminal obtains the target multiplexing subframe according to the received multiplexing frame.

In order to solve the above technical problems, the present invention provides a method for improving the receiving performance of a mobile multimedia broadcast terminal, comprising the following steps:

(1) Obtain the multiplexing frame header length and the multiplexing frame header data of the multiplexing frame, carry out cyclic redundancy check to the multiplexing frame header, if correct, then analyze the multiplexing frame header, save The multiplexing frame header length of the multiplexing frame, and obtain the length of each multiplexing subframe in the multiplexing frame and the starting position of the target multiplexing subframe, and then obtain the target multiplexing subframe, otherwise turn to step (2);

(2) According to the length of the multiplexing frame header of the multiplexing frame correctly parsed last time, determine the starting position of the multiplexing subframe 1 in the multiplexing frame, and carry out the subframe header of the multiplexing subframe 1 Analyzing, obtaining the length of the multiplexing subframe 1;

(3) According to the starting position and length of the multiplexing subframe 1, and the sequence number of the target multiplexing subframe, obtain the starting position of the target multiplexing subframe header, and then obtain the target multiplexing subframe.

According to the method for improving the receiving performance of a mobile multimedia broadcasting terminal, when the multiplexing frame header cyclic redundancy check described in its step (1) is correct, the length of the multiplexing frame header can be calculated in units of bytes , the length of the cyclic redundancy check code, and the sum of the lengths of the multiplexed subframes before the target multiplexed subframe are used as the offset value to obtain the start position of the target multiplexed subframe.

According to a kind of above-mentioned method for improving the receiving performance of the mobile multimedia broadcasting terminal, when the cyclic redundancy check is carried out to the multiplexing frame header in its step (1), if it is correct, if the next frame parameter is included in the multiplexing frame header , then the next frame parameter can be further saved.

Further, the content of the next frame parameter may include the length of the multiplexed frame header and the length of the multiplexed subframe 1 of the multiplexed frame to be received next time.

Moreover, the step (2) may further include, judging whether the next frame parameter in the last correctly parsed multiplexing frame is stored, and if so, according to the information in the next frame parameter, obtain the The starting position of the multiplexing subframe 1 and the length of the multiplexing subframe 1 in the multiplexing frame. Furthermore, in step (2), the length of the multiplexing frame header of the multiplexing frame to be received next time in the next frame parameter and the length of the cyclic redundancy check code can be added to obtain the The start position of multiplexing subframe 1.

According to the above-mentioned method for improving the receiving performance of a mobile multimedia broadcasting terminal, the step (2) may include:

(21) According to the length of the multiplexing frame header of the multiplexing frame correctly parsed last time, the starting position of the multiplexing subframe 1 in the multiplexing frame is positioned;

(22) Perform a cyclic redundancy check on the subframe header corresponding to the starting position of the positioned multiplexed subframe 1, and if the cyclic redundancy check is correct, the start of the multiplexed subframe 1 is obtained position, then directly execute step (24), otherwise go to step (23);

(23) increasing or decreasing the length of the multiplexing frame header of the last correctly parsed multiplexing frame by an integer multiple of 3 bytes, and positioning the starting position of the multiplexing subframe 1 in the multiplexing frame again, Until the cyclic redundancy check of the subframe header corresponding to the positioned start position of the multiplexed subframe 1 is correct, the start position of the multiplexed subframe 1 is obtained;

(24) Analyzing the subframe header of the multiplexed subframe 1 whose starting position is determined, and obtaining the length of the multiplexed subframe 1 .

According to the above-mentioned method for improving the receiving performance of a mobile multimedia broadcasting terminal, the length of the multiplexing subframe 1 described in its step (2) can be equal to the length of the subframe header of the multiplexing subframe 1, the cyclic redundancy check length and the length of each information segment in the multiplexed subframe 1.

According to the above-mentioned method for improving the receiving performance of a mobile multimedia broadcasting terminal, the step (3) may include, according to the starting position and length of the multiplexing subframe 1, sequentially determine each multiplexing subframe before the target multiplexing subframe The start position and length of the multiplexed subframe are finally obtained to obtain the start position of the header of the target multiplexed subframe.

Further, step (3) may further include that the subframe header cyclic redundancy check of each multiplexed subframe before the target multiplexed subframe is wrong, then stop parsing the multiplexed frame received this time, and clear The multiplexing frame header length information retained in the buffer.

The method of the present invention fully utilizes the length information of the multiplexing frame header of the multiplexing frame received and correctly analyzed last time when the CRC check error of the multiplexing frame header is used to extract the target multiplexing subframe from the current multiplexing frame. Compared with the existing technology, it avoids the receiving terminal from discarding the entire multiplexed frame data due to the CRC check error of the multiplexed frame header, significantly improves the receiving performance of the terminal under the condition of bit error, and effectively improves the picture and sound of the terminal. intermittent situation.

Description of drawings

FIG. 1 is a schematic structural diagram of an embodiment of a multiplexing frame in the prior art;

FIG. 2 is a schematic structural diagram of an embodiment of a multiplexing frame and a multiplexing subframe in the prior art;

Fig. 3 is a schematic structural diagram of an embodiment of a multiplexing frame header in the prior art;

FIG. 4 is a schematic structural diagram of an embodiment of multiplexing subframes in the prior art;

Fig. 5 is a schematic flow chart of an embodiment of demultiplexing processing of a mobile multimedia broadcasting terminal in the prior art;

Fig. 6 is a detailed flowchart of an embodiment of demultiplexing processing in the prior art;

Fig. 7 is a schematic flow chart of a method embodiment of the present invention;

Fig. 8 is a schematic flowchart of an application embodiment of the method of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Analyzing the structure of the multiplexing frame, the following characteristics can be found:

(A) take byte as unit, the length of multiplexing frame=multiplexing frame header length+the length of each multiplexing subframe in the multiplexing frame+filling data length+4 byte CRC_32 data length;

(B) The length of the multiplexing frame headers of different multiplexing frames will only change when the number of multiplexing subframes in these multiplexing frames increases or decreases. And the change is regular, every time a multiplexing subframe is added or decreased, the frame header length of the multiplexing frame will increase or decrease by 3 bytes;

(C) For a multiplexed frame, besides obtaining the length of each multiplexed subframe in the multiplexed frame from the multiplexed frame header, there is another way to obtain it: when the subframe of the multiplexed subframe When the header is parsed correctly, in bytes, the length of the multiplexed subframe = the length of the subframe header + the CRC_32 code of 4 bytes + the length of each information segment.

From the above analysis of the multiplexing frame structure, we have come to such a conclusion: when the terminal does not switch services, when the CRC check error occurs in the multiplexing frame header, if the multiplexing frame in the multiplexing frame can be correctly found The receiving terminal can continue to analyze the multiplexed subframes in the multiplexed frame.

The idea of the present invention is: when the terminal detects that there is an error in the multiplexing frame header CRC in the current multiplexing frame, according to the next frame parameter information and the length of the multiplexing frame header provided in the last received multiplexing frame , performing positioning and demultiplexing of target multiplexing subframes in the current multiplexing frame, extracting relevant multiplexing subframes from the current multiplexing frame as much as possible, and improving the receiving performance of the terminal.

Fig. 7 shows the method for improving the receiving performance of the mobile multimedia broadcasting terminal proposed by the present invention, which mainly includes the following steps:

Step 701: When the receiving terminal is processing the multiplexed frame, it saves the length of the multiplexed frame header of the last correctly parsed multiplexed frame, and if the multiplexed frame also contains the next frame parameter, then the next frame parameter is also to save;

Step 702: When the frame header CRC of the received multiplexed frame is wrong, use the frame header length information of the last received and correctly parsed multiplexed frame to directly skip an offset value as the multiplexed subframe The starting position of frame 1, where the offset value is in bytes, which is equal to the buffered frame header length + 4-byte CRC code;

Step 703: According to the determined start position of the multiplexed subframe 1, perform subframe header analysis and subframe header CRC check on the multiplexed subframe 1, if the subframe header CRC check is wrong, stop parsing the current reception The received multiplexed frame, and clear the information such as the length of the multiplexed frame header retained in the buffer; otherwise, the length of the multiplexed subframe 1 can be obtained;

Step 704: According to the start position and length of the multiplexed subframe 1 and the sequence number of the target multiplexed subframe, the start position of the target multiplexed subframe can be obtained, and then the target multiplexed subframe can be obtained.

In step 704, if the subframe header CRC check error of a certain multiplexed subframe before the target multiplexed subframe, stop parsing the multiplexed frame received this time, and clear the multiplexed frame header retained in the buffer area length and other information.

Moreover, in the process of obtaining the start position of the target multiplexed subframe, the subframe headers of each multiplexed subframe before the target multiplexed subframe are parsed and CRC checked, and if the CRC check is wrong, stop parsing the received multiplexed frame, and clear the multiplexed frame header length and other information retained in the buffer. Specifically, according to the starting position of multiplexing subframe 1 and the length of multiplexing subframe 1, the starting position of multiplexing subframe 2 is obtained; the subframe header of multiplexing subframe 2 is analyzed and CRC checked, if The subframe header CRC check error, stop parsing the multiplexed frame received this time, and clear the information such as the length of the multiplexed frame header retained in the buffer area; otherwise, the multiplexed subframe can be obtained according to the length of the multiplexed subframe 2 3; similar to this, until the start position of the target multiplexing subframe is found.

Fig. 8 shows an application embodiment of the method of the present invention, comprises the following steps:

Step 801: When processing multiplexed frames, the terminal first acquires the length of the multiplexed frame header and the data of the multiplexed frame header.

Step 802: Perform CRC_32 check on the multiplexed frame header to determine whether the CRC of the multiplexed frame header is correct, if correct, go to step 803, otherwise go to step 804.

Step 803: After parsing the multiplexed frame header, the length of each multiplexed subframe is obtained, and the length of the multiplexed frame header is stored in the terminal's memory; the rest of the information in the multiplexed frame header is updated, Save and other operations; if there is a parameter for the next frame, the parameter is cached. Among them, operations such as updating and saving the rest of the information in the multiplexed frame header are respectively performed, specifically including processing the update sequence number of the control information table, such as emergency broadcast instructions. The next frame parameter includes the header length of the same MF-ID to be received next time, the length of the first multiplexing subframe (multiplexing subframe 1) and the header length of the multiplexing subframe 1. Then go to step 809 to continue execution.

Step 804: Judging whether the next frame parameter in the last correctly parsed multiplexing frame is stored in the buffer area, if yes, go to step 805, otherwise go to step 806.

Step 805: According to the length of the multiplexing frame header to be received next time in the saved next frame parameters, strip the multiplexing frame header from the multiplexing frame received this time, so as to obtain the multiplexing frame header received this time The start position of multiplexed subframe 1 in the frame. That is, the position of the multiplexing subframe 1 is determined according to the CRC_32 that will be added to the length of the multiplexing frame header received next time plus 4 bytes in the next frame parameter that was correctly parsed last time, specifically skipping the next frame parameter that will The start position of the multiplexing subframe 1 in the multiplexing frame received this time can be determined by adding 4 bytes of CRC_32 data to the length of the multiplexing frame header received next time. Then go to step 807 to continue execution.

Step 806: Considering that the length of the multiplexed frame header is relatively fixed during the normal broadcasting of the program, it is possible to refer to the length of the multiplexed frame header of the latest correctly parsed multiplexed Locate the starting position of the multiplexed subframe 1 in the multiplexed frame: If the CRC check of the subframe header corresponding to the positioned start position of the multiplexed subframe 1 is correct, the multiplexed subframe 1 is obtained. Starting position; if the CRC of the subframe header is incorrect, increase or decrease the length of the multiplexed frame header by 3 bytes, and locate the starting position of the multiplexed subframe 1 again, if it is not correct, then increase or decrease Reduce 3 bytes, locate the starting position of multiplexing subframe 1 again until the CRC check is correct; obtain the correct starting position of multiplexing subframe 1 and the length of multiplexing subframe 1 (multiplexing subframe length=subframe header length+the length of each information segment in the multiplexed subframe+the length of the CRC code) then go to step 807 and continue to execute.

Step 807: If the target multiplexing subframe is multiplexing subframe 1, go to step 809, otherwise go to step 808.

Step 808: After obtaining the start position of the multiplexed subframe 1, analyze the subframe header of the multiplexed subframe 1 to obtain the length of the multiplexed subframe 1; according to the start position and length of the multiplexed subframe 1 , you can get the starting position of the multiplexed subframe 2, and analyze the subframe header of the multiplexed subframe 2 to obtain the length of the multiplexed subframe 2; and so on, according to the sequence number of the target multiplexed subframe, The start position of the target multiplexed subframe header can be obtained by processing the subframe headers of the multiplexed subframes before the target multiplexed subframe to obtain the length of the corresponding multiplexed subframe. Specifically, the length of the multiplexed subframe 1 is added to the start position of the multiplexed subframe 1 to obtain the start position of the multiplexed subframe 2. According to the start position of the multiplexed subframe 2 and the multiplexed subframe 2 length, to obtain the starting position of the multiplexed subframe 3, and continue processing in this way until the starting position of the target multiplexed subframe is obtained; then go to step 809 to continue execution.

Step 809: After determining the starting position of the target multiplexed subframe, obtain the multiplexed subframe header of the target multiplexed subframe, and obtain the length of the target multiplexed subframe and the target multiplexed subframe The length and start playing time of each video, audio and data segment in the frame, so that the target multiplexing sub-frame can be analyzed. So far, the process of receiving and processing a multiplexed frame is completed.

In step 808, if the subframe header CRC check error of a certain multiplexing subframe before the target multiplexing subframe, then stop parsing the multiplexing frame received this time, and clear the multiplexing frame header length retained in the buffer area and other information. In step 809, if the CRC check of the subframe header of the target multiplexed subframe is incorrect, the parsing of the multiplexed frame received this time is also stopped, and information such as the length of the multiplexed frame header retained in the buffer area is cleared.

In the method of the present invention, when the CRC check error of the target multiplexing frame header is wrong, the next frame parameter information and the length information of the multiplexing frame header provided in the last correctly parsed multiplexing frame are fully utilized to locate and resolve the target multiplexing subframe. Multiplexing, extracting relevant video data and audio data from the target multiplexing frame, avoiding the terminal discarding the entire multiplexing frame data due to CRC errors in the multiplexing frame header and multiplexing sub-frame header, and significantly improving the terminal under bit error conditions. Excellent receiving performance, which improves the situation that the terminal discards the multiplexed frame data due to the error of the CRC check of the multiplexed frame header, which causes severe discontinuity in the picture and sound.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and All deformations should fall within the scope of protection of the appended claims of the present invention.

Claims (10)

1. A method for improving the receiving performance of a mobile multimedia broadcasting terminal, characterized in that, comprising the steps: (1) Obtain the multiplexing frame header length and the multiplexing frame header data of the multiplexing frame, carry out cyclic redundancy check to the multiplexing frame header, if correct, then analyze the multiplexing frame header, save The multiplexing frame header length of the multiplexing frame, and obtain the length of each multiplexing subframe in the multiplexing frame and the starting position of the target multiplexing subframe, and then obtain the target multiplexing subframe, otherwise turn to step (2); (2) According to the length of the multiplexing frame header of the multiplexing frame correctly parsed last time, determine the starting position of the multiplexing subframe 1 in the multiplexing frame, and carry out the subframe header of the multiplexing subframe 1 Analyzing, obtaining the length of the multiplexing subframe 1; (3) According to the starting position and length of the multiplexing subframe 1, and the sequence number of the target multiplexing subframe, obtain the starting position of the target multiplexing subframe header, and then obtain the target multiplexing subframe. 2. The method according to claim 1, wherein, when the multiplexing frame header cyclic redundancy check described in step (1) is correct, the multiplexing frame header length, cycle The sum of the length of the redundancy check code and the lengths of the multiplexed subframes before the target multiplexed subframe is used as an offset value to obtain the start position of the target multiplexed subframe. 3. The method according to claim 1, wherein, in step (1), when the cyclic redundancy check is correct for the multiplexing frame header, if the multiplexing frame header contains the next frame parameter, Then further save the next frame parameter. 4. The method according to claim 3, wherein the content of the next frame parameter includes the length of the multiplexed frame header and the length of the multiplexed subframe 1 of the multiplexed frame to be received next time. 5. The method according to claim 3, characterized in that said step (2) further comprises, judging whether there is a next frame parameter in the multiplexed frame correctly parsed last time, and if so, according to the following The information in one frame parameter obtains the start position of the multiplexed subframe 1 and the length of the multiplexed subframe 1 in the multiplexed frame received this time. 6. The method according to claim 5, characterized in that, in step (2), the length of the multiplexing frame header of the multiplexing frame to be received next time in the next frame parameter, plus the cyclic redundancy The length of the check code is used to obtain the start position of the multiplexed subframe 1. 7. The method according to claim 1, characterized in that said step (2) comprises: (21) According to the length of the multiplexing frame header of the multiplexing frame correctly parsed last time, the starting position of the multiplexing subframe 1 in the multiplexing frame is positioned; (22) Perform a cyclic redundancy check on the subframe header corresponding to the starting position of the positioned multiplexed subframe 1, and if the cyclic redundancy check is correct, the start of the multiplexed subframe 1 is obtained position, then directly execute step (24), otherwise go to step (23); (23) increasing or decreasing the length of the multiplexing frame header of the last correctly parsed multiplexing frame by an integer multiple of 3 bytes, and positioning the starting position of the multiplexing subframe 1 in the multiplexing frame again, Until the cyclic redundancy check of the subframe header corresponding to the positioned start position of the multiplexed subframe 1 is correct, the start position of the multiplexed subframe 1 is obtained; (24) Analyzing the subframe header of the multiplexed subframe 1 whose starting position is determined, and obtaining the length of the multiplexed subframe 1 . 8. The method according to claim 1, wherein the length of the multiplexed subframe 1 in step (2) is equal to the length of the subframe header of the multiplexed subframe 1, the length of the cyclic redundancy check, and the length of the multiplexed subframe 1. The length of each information segment in the multiplexing subframe 1. 9. The method according to claim 1, characterized in that step (3) comprises, according to the starting position and length of the multiplexing subframe 1, sequentially determine the multiplexing subframes before the target multiplexing subframe 1 The start position and length of the subframe finally obtain the start position of the header of the target multiplexed subframe. 10. The method according to claim 9, characterized in that step (3) further comprises, each multiplexing subframe before the target multiplexing subframe includes the target multiplexing subframe, if the subframe header If the cyclic redundancy check error occurs, stop parsing the multiplexed frame received this time, and clear the length information of the multiplexed frame header retained in the buffer.

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