CN100548048C - A method and device for testing and analyzing AVS video elementary streams - Google Patents

Abstract

The invention discloses an AVS video elementary stream test and analysis method, comprising: inputting the AVS code stream to be analyzed and the corresponding original YUV code stream; if the AVS code stream is a transmission stream, decomplexing the input AVS code stream Use to extract the video elementary stream, if the input is an AVS video elementary stream, analyze it directly; analyze the video elementary stream in the AVS code stream, and display the motion information of the decoded image and macroblock in real time, as well as the video elementary stream Sequence summary information, frame summary information and macroblock summary information in the video stream, and at the same time perform standard conformance check on the video elementary stream; check the log of the video elementary stream. The method also includes a batch-mode test analysis of several video elementary streams. The invention realizes the test analysis analysis method for the AVS video code stream, so that the test work of the AVS video code stream becomes simple and standardized.

Description

A method and device for testing and analyzing AVS video elementary streams

technical field

The invention relates to the field of monitoring and analyzing AVS video compressed code streams, in particular to a method and device for analyzing and monitoring AVS video elementary streams.

Background technique

AVS is the abbreviation of Advanced Video and Audio Standard (Advanced Video and Audio Standard), which is the second-generation source coding standard with China's independent intellectual property rights. AVS is a set of technical standards with a wide range of adaptability, and its advantages are manifested in the following aspects: (1) AVS is an independent standard based on my country's independent innovation technology and international open technology, which properly solves the intellectual property issues; (2) High coding efficiency, 2-3 times higher than MPEG-2 international standard (high-definition TV can reach 3 times or more); (3) low computational complexity, low hardware implementation cost; (4) AVS can save half The above wireless spectrum and wired channel resources significantly reduce the economic investment of transmission, storage equipment and systems. The AVS standard includes four main technical standards of system, video, audio, and digital rights management, as well as supporting standards such as conformance testing. On December 29, 2004, the National Information Technology Standardization Technical Committee organized a review and passed the AVS standard video draft. On March 30, 2005, the Ministry of Information Industry approved the initial review, and the video part of the draft standard entered the publicity period. A draft of Part III (audio) was completed in August 2005.

The AVS standard is the product of China's independent intellectual property rights, and has huge industrial demand. It is widely used in radio and television live broadcast satellite, high-definition digital TV, high-density optical disc industry, 3G video communication, broadband network streaming media, video conferencing and video surveillance, etc. With major industrial opportunities, the AVS standard provides a rare opportunity for my country to build an industrial chain of "technology→patent→standard→chip and software→machine and system manufacturing→digital media operation and cultural industry".

The industrialization of the AVS standard involves various participants in the field of digital TV, including program broadcasters, network operators, equipment manufacturers and system integrators. When program broadcasters, network operators, equipment manufacturers, and system integrators use the AVS standard, they all need test and measurement equipment that conforms to the AVS standard as a basic tool to check whether the equipment is qualified, whether the network is running well, and whether the program broadcast and Whether the transmission is normal. The bit stream generated by the AVS video encoder is generated according to the AVS standard, but whether it fully complies with the AVS standard requires a completeness test and analysis of the bit stream generated by the encoder, and the performance of the encoder also needs to be objectively evaluated. At present, there is no complete set of test analysis and detection tools for AVS video elementary streams.

Contents of the invention

An object of the present invention is to overcome the low efficiency and error-prone defects in the prior art that the AVS code stream test is realized by manual analysis, and provides a kind of AVS video elementary stream test and analysis equipment to realize comprehensive testing and analysis of the AVS code stream .

Another object of the present invention is to verify whether the syntax and semantics of AVS video code stream compression meet the standard, and evaluate the quality of the corresponding coder, thereby providing a kind of AVS video elementary stream test applied to the AVS video elementary stream test analysis equipment Analytical method.

In order to achieve the above object, the present invention provides a kind of AVS video basic flow test analysis method, comprises the following steps:

1), input the AVS code stream to be analyzed and the corresponding original YUV code stream, if the AVS code stream is a transport stream, demultiplex the input AVS code stream, and extract the video elementary stream, if the input is AVS The video elementary stream is analyzed directly;

2) Analyze the video elementary stream in the AVS code stream, display the decoded image in real time, and the sequence summary information, frame summary information and macroblock summary information in the video elementary stream, and at the same time perform standard consistency check on the video elementary stream ; Wherein, analyzing the video elementary stream in the AVS code stream includes:

2-1), read the AVS video elementary stream data, judge whether the current data is the end point of the code stream, if yes, exit the analysis, if not, execute the next step;

2-2), determine whether the current data is the start code of the sequence, if yes, analyze the sequence summary, and select each parameter in the sequence summary field and the sequence, and perform steps 2-9), if not, perform the next step;

2-3), judge whether the current data is a frame header, if yes, analyze the summary information of the frame, and perform steps 2-9), if not, perform the next step;

2-4), determine whether the current data is a strip header, if yes, then parse the strip header, and perform steps 2-9), realize the consistency verification of the strip header summary information, if it passes the verification, then perform the next step, if If the current data is not a stripe header, execute steps 2-8);

2-5), decoding the macroblocks in the current slice, and counting the macroblocks, then updating the macroblock summary and motion information, and obtaining the motion compensation or motion estimation information of the macroblocks;

2-6), judging whether all macroblocks in the current slice have been decoded, if so, then perform the next step, otherwise, repeat steps 2-5);

2-7), determine whether all macroblocks in the current frame have been decoded, if so, update the frame summary information to be output to the user, then find the corresponding frame of the original YUV file, calculate the peak signal-to-noise ratio of the current frame, and Perform statistics on the corresponding content, save the statistical information, and return to step 2-1) to continue analysis; if not, directly return to step 2-1), continue to read data to decode the next band;

2-8), judge whether the current data is sequence termination information, if yes, then end the analysis process, if not, then continue to judge whether the current data is other extended header information, if yes, then skip this section of code stream and return to the step 2-1) Continue to read in the information, if it is not the extended header information, make a legality judgment on the read in information, if it is illegal information, send an alarm, let the user judge whether the analysis process is over, if it is not illegal information, then end the sequence analysis ;

2-9) Verify the standard conformance of the input summary information, check whether the test code stream format and the values of each field conform to the AVS standard specification, if it meets the AVS standard, output the summary information to the user and update the user's summary display information, and then re-execute step 2-1). If the AVS standard is not met, an alarm will be sent to remind the user. The user decides whether to terminate the analysis according to the actual situation. If the analysis is terminated, the analysis process will be exited. If the analysis is not terminated, this section will be skipped. The code stream returns to step 2-1) to read the data and continue to analyze;

3) Check the log of the video elementary stream.

In the above technical solution, in the step 1), the transport stream is a multiplexed stream of a video elementary stream and an audio elementary stream, and the demultiplexing is performed by searching for the video stream in the corresponding program stream in the transport stream Based on the PID value of the data packet, the corresponding video stream data packet is extracted and combined into a video elementary stream.

In the above-mentioned technical scheme, in described step 3) in, described log comprises the TRACE log file that has recorded decoding process in detail, has recorded the error log file of all mistakes encountered in the analysis process and to log file Statistics.

In the above technical solution, the sequence abstract information includes: the total size of the video sequence file, the total number of frames, the total play time, the total number of bits, the average code rate, the average frame rate, the pixel size of the video image, the encoding structure, the code stream formats and their grades and levels.

In the above technical solution, the frame summary information includes: current frame number, current frame playback time, frame pixel size, frame type, coding mode, location of the current frame start code in the code stream, and bits occupied by the current frame number.

In the above technical solution, the macroblock summary information includes: the frame number where the current macroblock is located, the slice number where the current macroblock is located, the relative macroblock sequence number in the frame, macroblock unit positioning, pixel unit positioning, macroblock coding mode , sub-macroblock (8×8 block) coding mode, sub-macroblock (8×8 block) forward/backward motion vector value, quantization step size, number of bits occupied by coding.

The macroblock specific motion compensation/motion estimation information includes: macroblock type and forward/backward motion vector.

In the above technical solution, the batch processing analysis can be performed on the video elementary stream, and the batch processing analysis refers to that several different elementary stream files can be analyzed simultaneously at one time, and then the analysis results are displayed in a list, including each Summary information for each frame in the elementary stream file and statistics for each elementary stream sequence.

A kind of AVS video elementary stream test analysis equipment corresponding to AVS video elementary stream test analysis method, this equipment comprises input unit 100, log checks analysis unit 120, batch processing analysis unit 130 and output unit 140, also includes real-time viewing analysis unit 110, of which,

The input unit 100 inputs the AVS code stream to be analyzed and the original YUV code stream, and demultiplexes the transport stream to extract the video elementary stream to be analyzed;

The real-time viewing and analysis unit 110 obtains the AVS video elementary stream from the input unit 100, and analyzes the data of the video elementary stream to obtain information of sequences, frames, slices, macroblocks and decoded images in the code stream, and Outputting the sequence summary information, frame summary information and macroblock summary information displayed in real time to the output unit 140;

Described log check analysis unit 120 obtains the log file in the analysis process from real-time check analysis unit 110, and log check analysis unit 120 analyzes the content of log file, checks original stream information, summarizes the result of statistical analysis, and finally outputs the result to The output unit 140 displays to the user;

The batch processing analysis unit 130 inputs a plurality of video elementary streams and original YUV files from the input unit 100, and outputs to the output unit 140 in log file form after analysis;

The output unit 140 uses a liquid crystal display to display and output the results of the test and analysis of the AVS video elementary stream in real time or in the form of a disk file.

The invention can reduce the cumbersome manual test and analysis work of the AVS video code stream, so that the test work of the AVS video code stream becomes simple and standardized.

Description of drawings

Fig. 1 is AVS video elementary stream test and analysis frame diagram of the present invention;

Fig. 2 is the real-time test and analysis flowchart of the AVS video elementary stream in the AVS video elementary stream test analysis method of the present invention;

Fig. 3 is the AVS video elementary stream analysis equipment structural diagram of the present invention;

Fig. 4 is a schematic diagram of the code stream structure in the video elementary stream;

FIG. 5 is a flow chart of the AVS video elementary stream test and analysis method of the present invention.

Illustration

100 input unit 110 real-time view analysis unit 120 log view analysis unit 130 batch analysis unit 140 output unit

Detailed ways

The method and corresponding equipment of the present invention will be described below with reference to the accompanying drawings and specific embodiments.

AVS video elementary flow test analysis method of the present invention comprises the following steps:

Step 10, input the AVS code stream to be analyzed and the corresponding original YUV code stream, if the input AVS code stream is a transport stream, demultiplex the input AVS code stream, and extract the video elementary stream, if the input If it is an AVS video elementary stream, analyze it directly. Transport stream is the multiplexing stream of video elementary stream and audio elementary stream, and the method of the present invention will test and analyze video elementary stream, therefore, before AVS bit stream is analyzed, if input bit stream is transport stream, Then it needs to be extracted from the input code stream by demultiplexing. Demultiplexing is to search the PID value of the video stream data packet in the corresponding program stream in the transport stream, extract the corresponding video stream data packet, and combine it into a video stream.

Step 20, analyzing the video elementary stream in the AVS code stream and displaying it in real time. In this step, the analysis process to the AVS video elementary stream mainly includes the following steps:

Step 21, read the AVS video elementary stream data, judge whether the current data is the end point of the code stream, if yes, exit the analysis, if not, perform the next step;

Step 22, determine whether the current data is the start code of the sequence, if yes, analyze the sequence summary, and select the sequence summary field and each parameter in the sequence, perform step 29, if not, perform the next step;

In this step, the obtained video sequence summary mainly includes the following contents:

·Video sequence file total size

·Total number of frames

· Total play time

·Total number of words

·Average code rate bits/s

· Average frame rate frames/s

·Video image pixel size: QCIF(176×144)/CIF(352×288)/ITU_601(720×576)/720P(1280×720)/1080i(1920×1080)

Coding structure (frame/field, progressive/interlaced)

· Stream format (AVS) and its grade/level

Step 23, judging whether the current data is a frame header, if yes, analyzing the summary information of the frame, and performing step 29, if not, performing the next step;

In this step, the frame summary information includes the following:

·Current frame number frame_num

·Current frame playback time

·Frame pixel size (QCIF176×144/CIF352×288/SD720×576/HD1280×720)

·Frame type (I/B/P)

Coding mode (field/frame)

The positioning of the current frame start code in the code stream

· Number of bits occupied by this frame

Step 24. Determine whether the current data is a slice header. If yes, parse the slice header, and perform step 29 to realize the consistency verification of the summary information of the slice header. If the verification is passed, perform the next step. If the current data is not a slice header , then perform step 28;

Step 25, decoding the macroblocks in the current slice, and counting the macroblocks, then updating the macroblock summary and motion information, and obtaining the specific motion compensation/motion estimation information of the macroblock;

In this step, the obtained macroblock summary information includes:

·(pointed by the mouse) the frame number frame_num where the current macroblock is located

The slice number slice_num where the current macroblock is located

· Intra-frame relative macroblock number MB_num

·Macroblock unit positioning (MB_x, MB_y)

· Pixel unit positioning (pixel_x, pixel_y)

·Positioning in the bitstream

· Macroblock coding mode

· Sub-macroblock (8×8 block) coding mode

Sub-macroblock (8×8 block) forward/backward motion vector value

· Quantization step size

· Number of bits occupied by encoding

In addition to the summary information of the macroblock, this step can also obtain the motion compensation/motion estimation information of the macroblock, specifically including:

·Macroblock type (marked with different colors)

·Motion vector (marked by arrow)

Step 26, judging whether all the macroblocks in the current slice have been decoded, if so, perform the next step, otherwise, repeat step 25;

Step 27, judge whether all macroblocks in the current frame have been decoded, if so, update the frame summary information to be output to the user, find the corresponding frame of the original YUV file, calculate the peak signal-to-noise ratio (PSNR) of the current frame, and Perform statistics on the corresponding content, save the statistical information, and return to step 21 to continue analysis; if not, directly return to step 21, and continue to read data to decode the next band;

The statistical information to be saved in this step includes:

The average number of bits of the same macroblock position in different frames

The average number of bits used to encode a macroblock in the same frame

・Average Quantized Value

The frequency at which macroblocks are coded as intra types

Step 28, judge whether the current data is sequence termination information, if yes, then end the analysis process, if not, then continue to judge whether the current data is other extended header information, such as sequence display extension, camera parameter extension, copyright extension, etc., if yes , then skip this segment of code stream and return to step 21 to continue reading in information. If the read-in information is not extended header information, the read-in information will be judged legally, if it is illegal information, an alarm will be issued, and the user will judge whether the analysis process is over, if it is not illegal information, then end the sequence analysis.

Step 29. Perform AVS consistency verification on the input summary information, check whether the format of the test code stream and the values of each field comply with the AVS standard specification, and if it meets the AVS standard, then output the summary information to the user and update the user's summary display information, If it does not meet the AVS standard, an alarm will be sent to remind the user. The user can judge whether to terminate the analysis according to the actual situation. If the analysis is terminated, the analysis process will be exited. If the analysis is not terminated, the code stream will be skipped and returned to step 21 to read the data and continue. analyze.

In this step, sequence summary information, frame summary information and macroblock summary information may be displayed in real time.

Step 30, check the log of the video elementary stream. During the analysis process in step 20, all the obtained information cannot be displayed in real time, and it is necessary to check the logs obtained during the analysis process. The logs viewed can include various aspects,

Step 31, check the TRACE log file, which records the decoding process in detail.

Step 32, check the error log file, which records all errors encountered during the analysis process.

Step 33, check the original information code stream. It can be viewed in the form of hexadecimal and ASCII codes, and the corresponding location data can be searched according to the absolute and relative addresses specified by the user. Users can also choose the number of bytes displayed in each line (4/8/16/32bytes) according to personal preferences.

Step 34, check statistical information. Open and view the analysis log file, and calculate the statistical results according to the statistical range (N~M frames) and statistical content (quantization coefficient, peak signal-to-noise ratio, number of intra blocks per frame, coding bits per frame, etc.) selected by the user.

The method of the present invention can also perform batch processing analysis on video elementary streams. The batch processing analysis refers to that several different elementary stream files can be analyzed simultaneously at one time, and then the analysis results are displayed in a list, and each elementary stream file is included in the table. Summary information of each frame in the frame, such as encoding type, quantization coefficient, peak signal-to-noise ratio, number of bits used for encoding, etc.; and statistical information of each elementary stream sequence, such as average code rate, average peak signal-to-noise ratio, etc.

The present invention also provides a set of AVS video elementary stream test and analysis equipment corresponding to the AVS video elementary stream test and analysis method of the present invention, this set of test equipment adopts a portable high-performance computing platform (such as ACME850 computer), and is divided into according to functions: An input unit 100 , a real-time view analysis unit 110 , a log view analysis unit 120 , a batch analysis unit 130 and an output unit 140 .

The function of the input unit 100 is to input the AVS code stream and the original YUV code stream to be analyzed. If the input AVS code stream is a transport stream, the transport stream needs to be demultiplexed in this unit to extract the video elementary stream to be analyzed. The input unit 100 sends the AVS video elementary stream to the real-time view analysis unit 110, and the real-time view analysis unit 110 analyzes the data of the video elementary stream to obtain the information of the sequence, frame, slice, and macroblock in the code stream and the information after decoding. , and output sequence summary information, frame summary information and macroblock summary information that can be displayed in real time to the output unit 140 for real-time display. The real-time viewing analysis unit 110 also records corresponding log files while analyzing.

The real-time viewing and analysis unit 110 transmits the log files obtained in the analysis process to the log viewing and analyzing unit 120, and the log viewing and analyzing unit 120 analyzes the contents of the log files, checks the original stream information, summarizes the results of statistical analysis, and finally passes the results through The output unit 140 displays to the user. .

The batch processing analysis unit 130 inputs a plurality of video elementary streams and original YUV files from the input unit 100, and outputs them to the client in the form of log files after analysis.

The output unit 140 uses a liquid crystal display to display and output the results of the test and analysis of the AVS video elementary stream in real time or in the form of a disk file.

The actual analysis process of the present invention will be described below in conjunction with an example of actual analysis.

First, the AVS code stream example.avs or example.ts. is input into the input unit 100, and the original code stream exaple.yuv is input at the same time. Among them, example.avs is the AVS video elementary stream file, example.ts is the video transport stream file, and example.yuv is the original YUV code stream. If the input is example.ts, you need to demultiplex example.ts to extract example.avs.

The code stream enters the real-time viewing analysis unit 110:

Example.avs stream structure analysis is shown in Figure 4. Open example.avs and read data into the buffer. Read the code stream data from the buffer, and judge whether the code stream is over. If there is no end, search for the start code of the sequence, find the sequence header and parse the output to the user, and then search for the next start code is the start code of the extension and user data, so skip this segment of the code stream and continue to search A start code, find the start code of the frame header. After parsing the frame header data, continue to search for the start code, and find the next start code is the start code of the extension and user data information, so skip this segment of code stream, continue to search for the next start code, and find the start code of the strip header. Start code, analyze the summary data of the slice, and decode the macroblock data in the slice, cyclically decode each macroblock data, analyze the motion information and summary information of the macroblock at the same time, display the motion vector and macroblock type (including INTRA, INTER, DIREC, COPY, P8x8, marked with different colors). After cyclically decoding all the macroblocks in the current slice, continue to read in the information to find the start code of the next slice. If all the slices are cyclically analyzed, continue to read in the information, find the start code of the next frame, and loop through the analysis After finishing all frames in the sequence, continue to read in information to determine whether the sequence is over.

In each step of parsing the code stream above, standard consistency verification must be carried out to check whether the syntax and semantics of the standard are met. Alerts are issued if standards are not met. Record TRACE logs, error logs and statistics logs while analyzing above.

The code stream enters the log viewing and analyzing unit 120 , respectively checks the detailed log output by the viewing and analyzing unit 110 and the original code stream information, performs statistical analysis, and outputs the result to the output unit 140 .

For multiple repeated tests and comparative analysis of multiple code streams, the batch analysis unit 130 can be used. Multiple video elementary streams and original YUV files are input from the input unit 100, or repeated files of an elementary stream are analyzed in batch mode and output to clients in the form of files.

Claims (8)

1, a kind of AVS video-frequency basic flow method for testing and analyzing may further comprise the steps:

1), input AVS code stream and the corresponding original YUV code stream that will analyze, if the AVS code stream is a transport stream, then the AVS code stream of being imported is carried out demultiplexing, extract video-frequency basic flow, if input is the AVS video-frequency basic flow, then directly analyze;

2), the video-frequency basic flow in the AVS code stream is analyzed, show decoded image in real time, and the sequence summary info in the video-frequency basic flow, frame summary info and macro block summary info, simultaneously video-frequency basic flow is done the standard consistency check; Wherein, described video-frequency basic flow analysis in the AVS code stream is comprised:

2-1), read AVS video-frequency basic flow data, judge whether current data is the end point of code stream, if, withdraw from analysis, if not, carry out next step;

2-2), judge whether current data are initial codes of sequence, if resolve the sequence summary, and choose each parameter in sequence abstract fields and the sequence, execution in step 2-9), if not, carry out next step;

2-3), judge whether current data is frame head, if, the summary info of parse for frame, and execution in step 2-9), if not, carry out next step;

2-4), judge whether current data is slice header, if then resolve slice header, and execution in step 2-9), realizes consistency checking, if by checking to the slice header summary info, then carrying out next step, is not slice header as if current data, then execution in step 2-8);

2-5), the macro block of decoding in the current band, and macro block counted, upgrade macro block summary and movable information then, and obtain the motion compensation or the motion estimation information of macro block;

2-6), judge whether all macro blocks have all been finished decoding in the current band, if, then carry out next step, otherwise, repeated execution of steps 2-5);

2-7), judge whether all macro blocks have all been finished decoding in the present frame, if, then upgrade the frame summary info that to export to the user, find the respective frame of original YUV file then, calculate the Y-PSNR of present frame, corresponding contents is added up, is preserved statistical information, and return step 2-1) continue to analyze; If not, directly return step 2-1), continue reading of data with next band of decoding;

2-8), judge whether current data is the sequence termination message, if then finish analytic process, if not, then continue to judge whether current data is other extension header information, if, then skip this segment encode stream, return step 2-1) continue the information of reading in, if not extension header information, then the information of reading in being made legitimacy judges, be illegal information, give the alarm whether finish by user's discriminatory analysis process, not illegal information, then finish this sequence analysis;

2-9), the summary info to input carries out the standard consistency checking, whether verification test code stream form and each field value meet the AVS standard criterion, if meet the AVS standard, then summary info is exported to the user and upgraded user's summary display message, re-execute step 2-1 then), if do not meet the AVS standard, then give the alarm and remind the user, whether the user determines termination analysis according to actual conditions, if termination analysis, then withdraw from analytic process, termination analysis is not then skipped this segment encode stream and is returned step 2-1) reading of data proceeds to analyze;

3), video-frequency basic flow being carried out daily record checks.

2, AVS video-frequency basic flow method for testing and analyzing according to claim 1, it is characterized in that, in described step 1), described transport stream is the multiplex stream that video-frequency basic flow and audio frequency flow substantially, described demultiplexing is by searching the pid value of the video streaming data packet in the respective program stream in the transport stream, extract corresponding video streaming data packet, be combined into video-frequency basic flow.

3, AVS video-frequency basic flow method for testing and analyzing according to claim 1, it is characterized in that, in described step 3), described daily record the has comprised detail record TRACE journal file of decoding process, write down in analytic process to be run into wrong error log file and to the statistical information of journal file.

4, AVS video-frequency basic flow method for testing and analyzing according to claim 1, it is characterized in that, described sequence summary info comprises: video sequence file is size always, totalframes, total reproduction time, total bit number, average bit rate, average frame per second, video image size, coding structure, code stream form and class thereof and rank.

5, AVS video-frequency basic flow method for testing and analyzing according to claim 1 is characterized in that, described frame summary info comprises: current frame number, the present frame reproduction time, frame pixel size, frame type, coding mode, the location of present frame initial code in code stream, the bit number that present frame takies.

6, AVS video-frequency basic flow method for testing and analyzing according to claim 1, it is characterized in that, described macro block summary info comprises: the frame number of current macro place frame, relative macro block sequence number in the bar reel number of current macro place band, frame, macro block unit location, pixel unit location, macro-block coding pattern, sub-macro-block coding pattern, quantization step, coding takies bit number.

7, AVS video-frequency basic flow method for testing and analyzing according to claim 1 is characterized in that, motion compensation that described macro block is concrete or motion estimation information comprise that macro block (mb) type and front and back are to motion vector.

8, AVS video-frequency basic flow method for testing and analyzing according to claim 1, it is characterized in that, described video-frequency basic flow can be done the batch processing analysis, described batch processing analysis is meant once can analyze the basic stream file of several differences simultaneously, then analysis result tabulation is shown, comprise that in table the summary info of each frame in each basic stream file and each flow the statistical information of sequence substantially.

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