JP2016146571A - Error correction function verification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately verify the error correction function of a video receiver, while achieving a suppressed processing load and a reduced verification cost.SOLUTION: An error correction function verification device 1 includes a packet loss detection unit 20, a decoded video error detection unit 40 and an FEC performance determination unit 50. The packet loss detection unit 20 detects whether or not a packet loss which occurred in a test stream can be restored by a video receiver 200. The decoded video error detection unit 40 detects a point in the test stream in which the packet loss which the video receiver 200 has failed to restore occurred. The FEC performance determination unit 50 determines whether or not the error correction function works as expected, on the basis of the detection result of the packet loss detection unit 20 and the decoded video error detection unit 40.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an error correction function verification device.

  In the consumer video distribution service, video distribution via a communication line such as an IP line is performed. Generally, with a public IP line, complete quality assurance is difficult and packet loss is unavoidable. In order to cope with this packet loss, an error correction function (for example, see Non-Patent Document 1) may be provided in the video reception apparatus. In this case, a certain amount of packet loss can be corrected by the video receiving apparatus to restore the video. For this reason, in order to realize a high-quality video distribution service, it is important to correctly realize the error correction function in the video reception device.

  Non-Patent Document 1 discloses FEC (Forward Error Correction) as an error correction function of a video receiver. Non-Patent Document 2 discloses a method for verifying an error correction function in a video receiving device development process. In the technique disclosed in Non-Patent Document 2, a video stream in which packet loss is appropriately controlled using a configuration such as a network emulator is generated, and it is determined whether or not the video stream can be restored by the video receiving device. Verify the error correction function of the receiving device.

“Content Delivery Error Recovery for IPTV service,” ITU-T H.701 “Conformance Testing Specification for H.701,” ITU-T HSTP.CONF-H701

  In the technique disclosed in Non-Patent Document 2, it is necessary to leave information indicating whether or not the video receiving apparatus has been restored as a history. For this reason, when the operation check of the video receiving apparatus in the development process is performed for a long time, it is necessary to leave the above-mentioned information for a long time as a history, and the data amount of the history information becomes enormous, and the verification cost Will increase. In addition, it is necessary to newly add a function for verifying the error correction function, such as a process for leaving a history or a process for confirming the remaining history, to further increase the verification cost. . Furthermore, the process of leaving a history leads to an increase in processing load on the video receiving apparatus, and there is a possibility that other real-time processing such as decoding processing performed on the video receiving apparatus may be adversely affected.

  Therefore, a video stream in which packet loss is appropriately controlled is input to the video receiving device, and the decoded video output from the video receiving device is displayed on the display and visually confirmed to verify the error correction function of the video receiving device. The method of, can be considered. However, with this method, as the time for checking the operation of the image receiving device in the development process becomes longer, the verification cost increases and a verification error occurs due to a decrease in the concentration of the inspector who visually confirms. The possibility becomes high.

  In recent years, higher resolution and higher frame rate of video have been promoted. However, as the video resolution increases, the bit rate increases and the number of packets increases. Therefore, in the method described in Non-Patent Document 2 described above, the verification cost increases due to an increase in the data amount of history information. The problem becomes noticeable. In addition, as the video resolution and frame rate increase, the effect of quality degradation due to packet loss becomes smaller on the entire video, so the above-mentioned visual confirmation method may further cause a verification error. It will be high.

  Therefore, the present invention has been made in view of the above-described problems, and an object thereof is to appropriately verify the error correction function of a video reception device while realizing reduction in processing load and reduction in verification cost. And

The present invention proposes the following matters in order to solve the above problems.
(1) The present invention is an error correction function verification device (for example, equivalent to the error correction function verification device 1 in FIG. 1) for verifying an error correction function of a video reception device (for example, the video reception device 200 in FIG. 1). A counter measurement unit (e.g., corresponding to the counter measurement unit 10 in FIG. 1) that captures a test stream input to the video reception device and obtains counter information of the test stream; and the counter measurement unit Whether or not the video reception device can restore the detected location of the packet loss detected in the test stream input to the video reception device based on the counter information acquired by the A packet loss detecting means (for example, corresponding to the packet loss detecting unit 20 in FIG. 1), and a test channel to which the video receiving apparatus is input. Output video storage means (for example, corresponding to the output video memory 30 in FIG. 1) for storing the decoded video obtained by decoding the stream as an error correction decoded video, and the error correction stored in the output video storage means The decoded video is compared with the lossless decoded video obtained by decoding the test stream in which no packet loss has occurred, and the test stream input to the video receiving device is subjected to packet loss. Decoded video error detection means (for example, corresponding to the decoded video error detection unit 40 in FIG. 1), a detection result by the packet loss detection means, and the decoded video error detection means for detecting a portion that could not be restored by the video reception device And whether the error correction function is operating as expected based on the detection result Error correction performance determining means (e.g., corresponding to FEC performance determination unit 50 of FIG. 1) that has proposed an error correction function verification device characterized by comprising a, a.

  According to the present invention, the counter measurement means captures the test stream input to the video receiving apparatus and acquires the counter information of the test stream. In addition, the packet loss detection unit detects packet loss in the test stream input to the video reception device based on the counter information acquired by the counter measurement unit, and receives the video where the detected packet loss has occurred. It was decided whether or not the device could be restored. For this reason, if the error correction function is operating as expected in the part where the packet loss has occurred in the test stream input to the video receiving device, it can be theoretically restored.

  According to the invention, the output video storage means stores the decoded video obtained by decoding the test stream input by the video receiver as an error correction decoded video. Further, the decoded video error detection means compares the error correction decoded video stored in the output video storage means with the lossless decoded video obtained by decoding the test stream in which no packet loss occurs, In the test stream input to the video reception device, a portion that could not be restored by the video reception device due to packet loss was detected. For this reason, in the test stream input to the video reception device, it is possible to know the location where the packet loss that the video reception device could not actually restore has occurred.

  Further, according to the present invention, whether or not the error correction function is operating as expected based on the detection result by the packet loss detection unit and the detection result by the decoded video error detection unit by the error correction performance determination unit. It was decided to judge. For this reason, if the error correction function is operating as expected, it is theoretically possible to determine whether or not there is a packet loss that can be recovered, and whether the packet loss that the video receiver cannot actually recover It is possible to determine whether or not the error correction function is operating as expected by comparing the generated location.

  According to the above, it is possible to verify the error correction function of the video reception device in the error correction function verification device, that is, outside the video reception device. For this reason, it is not necessary to add a new function to the video receiving apparatus, and visual confirmation by the inspector is unnecessary, so that the verification cost can be reduced. Further, since visual inspection by the inspector is unnecessary, the possibility of a verification error occurring can be reduced, and the error correction function of the video reception device can be verified appropriately. Furthermore, since the process for verifying the error correction function of the video receiving apparatus is performed outside the video receiving apparatus, the processing load on the video receiving apparatus can be suppressed.

  (2) According to the present invention, the error correction function verification device of (1) generates the test stream by drawing identification information for identifying each frame as an image on the image of each frame. We have proposed an error correction function verification device.

  According to the present invention, in the error correction function verification device of (1), the identification information for identifying each frame is drawn on the image of each frame as an image to generate a test stream. Therefore, if the identification information drawn on the error correction decoded video is compared with the identification information drawn on the lossless decoded video, the frame of the error correction decoded video on which the same identification information is drawn and the lossless Decoded video frames can be detected. Therefore, the decoded video error detection means can compare the frame of the error-corrected decoded video on which the same identification information is drawn with the frame of the lossless decoded video.

  (3) According to the present invention, in the error correction function verification device of (2), any one of a serial number and time information of each frame is used as the identification information. A device is proposed.

  According to the present invention, in the error correction function verification device of (2), the serial number and the time information of each frame can be used as the identification information.

  (4) According to this invention, in the error correction function verification device according to any one of (1) to (3), the counter measurement means is described in the header of the RTP packet as counter information of the test stream. An error correction function verification apparatus using an RTP counter is proposed.

  According to the present invention, in the error correction function verification device of any one of (1) to (3), the counter measurement means uses the RTP counter described in the header of the RTP packet as the counter information of the test stream. Can do.

  (5) According to this invention, in the error correction function verification device according to any one of (1) to (4), the decoded video error detection means is configured to store the error correction decoded video stored in the output video storage means. The pixel value is obtained for each frame, the pixel value of the lossless decoded video is obtained for each frame, and the pixel value of each frame of the error-corrected decoded video and the error-corrected decoded video frame of the lossless decoded video are supported. The error correction is characterized in that a pixel value of a frame to be compared is compared, and a portion of the test stream input to the video reception device that cannot be restored by the video reception device due to packet loss is detected. A function verification device is proposed.

  According to this invention, in the error correction function verification device according to any one of (1) to (4), the decoded video error detection unit converts the pixel value of the error correction decoded video stored in the output video storage unit for each frame. In addition, the pixel value of the lossless decoded video is obtained for each frame. The decoded video error detection means compares the pixel value of each frame of the error-corrected decoded video with the pixel value of the frame corresponding to the frame of the error-corrected decoded video among the lossless decoded video, and In the input test stream, a portion that could not be restored by the video reception device due to packet loss was detected. For this reason, the pixel value of the error correction decoded video and the pixel value of the lossless decoded video are compared for each frame, and in the test stream input to the video receiving device, the packet loss that the video receiving device cannot restore is The occurring location can be detected.

  (6) According to the present invention, the error correction function verification device according to any one of (1) to (4) generates a reduced test stream by reducing the resolution of the test stream in which no packet loss has occurred. A reduced stream generation unit (e.g., corresponding to the reduced stream generation unit 80 in FIG. 4), and the decoded video error detection unit is configured to generate the reduced test stream generated by the reduced stream generation unit instead of the lossless decoded video. Has proposed an error correction function verification device characterized by using reduced lossless decoded video obtained by decoding.

  According to the present invention, in the error correction function verification device of any one of (1) to (4), the reduced stream generation means reduces the resolution of a test stream in which no packet loss has occurred, and generates a reduced test stream. It was decided to generate. In addition, the reduced lossless decoded video obtained by decoding the reduced test stream generated by the reduced stream generating means is used instead of the lossless decoded video by the decoded video error detecting means. Therefore, the decoded video error detection unit compares the error correction decoded video stored in the output video storage unit with the reduced lossless decoded video instead of the lossless decoded video. Therefore, since the resolution of the video to be compared with the error correction decoded video is lowered, the processing load on the decoded video error detecting means can be suppressed.

  (7) According to the present invention, in the error correction function verification device of (6), the decoded video error detection means obtains the feature quantity of the error correction decoded video stored in the output video storage means for each frame. In addition, a feature amount of the reduced lossless decoded video is obtained for each frame, a feature amount of each frame of the error correction decoded video, and a feature amount of a frame corresponding to the frame of the error corrected decoded video among the reduced lossless decoded video And an error correction function verification device that detects a portion of the test stream input to the video reception device that could not be restored by the video reception device due to packet loss. doing.

  According to the present invention, in the error correction function verification device of (6), the decoded video error detection means obtains the feature amount of the error correction decoded video stored in the output video storage means for each frame and reduces the lossless decoding. The feature amount of the video is determined for each frame. In addition, the decoded video error detection means compares the feature amount of each frame of the error-corrected decoded video with the feature amount of the frame corresponding to the frame of the error-corrected decoded video among the reduced lossless decoded video. In the test stream input to, a portion that could not be restored by the video reception device due to packet loss was detected. For this reason, for each frame, the feature amount of the error-corrected decoded video is compared with the feature amount of the reduced lossless decoded video, and the packet that the video receiver cannot restore in the test stream input to the video receiver. It is possible to detect the location where the loss occurs.

  (8) According to this invention, in the error correction function verification device according to (7), the decoded video error detection means uses an average value of pixel values in a frame as a feature quantity. A verification device is proposed.

  According to the present invention, in the error correction function verification device of (7), the average value of the pixel values in the frame can be used as the feature amount by the decoded video error detection means.

  (9) According to this invention, in the error correction function verification device of any one of (1) to (8), after a test stream for a processing frame is input to the video receiving device, the processing frame for the processing frame A processing delay detection unit (e.g., corresponding to the processing delay detection unit 70 in FIG. 3) for detecting a time until detection by the decoded video error detection unit is completed, and the error correction performance determination unit includes the processing delay detection unit; The frame from which the detection result by the packet loss detection means is obtained and the frame from which the detection result by the decoded video error detection means is matched based on the time detected by Based on the detection results of the loss detection means and the decoded video error detection means, the error correction function is It proposes an error correction function verification apparatus and judging whether or not work as.

  According to this invention, in the error correction function verification device according to any one of (1) to (8), after the test stream for the processing frame is input to the video reception device by the processing delay detection means, The time until the detection by the decoded video error detection means is completed is detected. Further, the error correction performance determining means, based on the time detected by the processing delay detecting means, the frame from which the detection result by the packet loss detecting means is obtained, and the frame from which the detection result by the decoded video error detecting means is obtained. , And based on the detection results of the packet loss detection means and the decoded video error detection means for the same frame, it is determined whether or not the error correction function is operating as expected. For this reason, the detection results of the packet loss detection means and the decoded video error detection means are compared with each other for the same frame in consideration of the difference in processing time in each configuration provided in the error correction function verification device and the video reception device. Can be matched.

  (10) According to this invention, in the error correction function verification device of (9), the processing delay detection means is stored in the output video storage means and the information related to the picture order described in the test stream. The identification information that can be read from each frame of the error-corrected decoded video, and the n-th information among the information relating to the picture order arranged in the order of the frames (where n is an arbitrary value satisfying n ≧ 1) Integer) and the nth identification information among the arranged identification information, the test stream for the nth frame, and the error correction decoded video of the nth frame stored in the output video storage means And an error correction function verifying device characterized by synchronizing these with each other.

  According to the present invention, in the error correction function verification device of (9), the processing delay detection means causes the information related to the picture order described in the test stream and the error correction decoded video stored in the output video storage means to Each of the identification information that can be read from each frame is arranged in the order of the frames. Further, the processing delay detection means associates the nth information in the information about the arranged picture order with the nth identification information in the arranged identification information, and outputs a test stream for the nth frame, and an output The error correction decoded video of the nth frame stored in the video storage means is synchronized. For this reason, the processing delay detection unit appropriately detects the time from when the test stream for the processing frame is input to the video receiving apparatus until the detection by the decoded video error detection unit for the processing frame is completed. Can do.

  (11) According to this invention, in the error correction function verification device according to any one of (1) to (10), the location where the error correction performance determination means is detected as recoverable by the packet loss detection means When the decoded video error detection means does not detect that the video receiving device cannot restore the location, it is determined that the error correction function is operating as expected for the location. When the portion detected as unrecoverable by the packet loss detection means is detected by the decoded video error detection means as a portion that could not be restored by the video receiver, the error correction is performed for the portion. An error correction function verification apparatus characterized by determining that a function is operating as expected has been proposed.

  According to the present invention, in the error correction function verification device according to any one of (1) to (10), a decoded video error is detected for a portion detected by the error correction performance determination unit as recoverable by the packet loss detection unit. When it is detected by the detection means that the location cannot be restored by the video reception device, it can be determined that the error correction function is operating as expected for this location. Further, when it is detected by the error correction performance determination means that it is impossible to restore by the packet loss detection means, it is detected by the decoded video error detection means that the video reception device cannot restore, It can be determined that the error correction function is operating as expected at this location.

  According to the present invention, it is possible to appropriately verify the error correction function of the video reception device while realizing reduction in processing load and reduction in verification cost.

1 is a block diagram of an error correction function verification system according to a first embodiment of the present invention. It is a figure which shows an example of a test image | video. It is a block diagram of the error correction function verification system which concerns on 2nd Embodiment of this invention. It is a block diagram of the error correction function verification system which concerns on 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the constituent elements in the following embodiments can be appropriately replaced with existing constituent elements, and various variations including combinations with other existing constituent elements are possible. Accordingly, the description of the following embodiments does not limit the contents of the invention described in the claims.

<First Embodiment>
[Configuration and operation of error correction function verification system AA]
FIG. 1 is a block diagram of an error correction function verification system AA according to the first embodiment of the present invention. The error correction function verification system AA includes a video transmission device 100, a video reception device 200, a network 300, and an error correction function verification device 1.

[Operation of Video Sending Device 100]
The video transmission device 100 is connected to the video reception device 200 via the network 300 and transmits a test stream to the network 300 according to a predetermined network protocol. It is assumed that the test stream is a file conforming to a protocol such as MPEG2-TS. Further, as a predetermined network protocol, a protocol such as TS over RTP can be applied.

  The test stream is generated outside the video transmission device 100 by compressing the test video using a video compression technique, and is input to the video transmission device 100. It is assumed that identification information, which is information for uniquely identifying each frame, is drawn as an image on each frame image constituting the test video. As the identification information, for example, a serial number or time information (time code) of each frame of the test video can be used.

  FIG. 2 is a diagram showing an image of each frame constituting the test video. FIG. 2 shows a case where a serial number is used as identification information. The number “1” is drawn on the first frame image of the test video, the number “2” is drawn on the second frame image of the test video, and the third frame image of the test video is displayed. , "3" is drawn.

[Operation of Video Reception Device 200]
Returning to FIG. 1, the video receiving apparatus 200 receives the test stream sent from the video sending apparatus 100, decodes the test stream, and outputs it as a decoded video. The video reception device 200 is equipped with an error correction function, and the video reception device 200 performs error correction as necessary when packet loss occurs in the received test stream.

[Configuration and operation of error correction function verification apparatus 1]
The error correction function verification device 1 verifies an error correction (FEC) function installed in the video reception device 200. The error correction function verification apparatus 1 includes a counter measurement unit 10, a packet loss detection unit 20, an output video memory 30, a decoded video error detection unit 40, and an FEC performance determination unit 50.

  The counter measurement unit 10 receives a test stream input to the video receiving apparatus 200, that is, a test stream that may have a packet loss. The counter measurement unit 10 captures a test stream packet input to the video reception device 200, acquires test stream counter information described in the packet, and outputs the acquired test stream counter information.

  Note that the counter information of the test stream is expressed by a finite bit length. For this reason, the counter information of the test stream generally circulates at a constant cycle. Therefore, in this embodiment, it is necessary to use the test stream counter information having a sufficiently long cyclic cycle. As the test stream counter information, for example, an RTP counter described in the header of the RTP packet can be used.

  The packet loss detection unit 20 receives the counter information of the test stream output from the counter measurement unit 10 as an input. The packet loss detection unit 20 detects packet loss in the test stream input to the video reception device 200 based on the test stream counter information output from the counter measurement unit 10, and generates the detected packet loss. It is detected whether or not the video receiving apparatus 200 can restore the existing frame.

  Specifically, the packet loss detection unit 20 first detects a packet loss in the test stream input to the video reception device 200 based on the test stream counter information output from the counter measurement unit 10. As for packet loss detection, it is determined that packet loss has occurred when the value of the counter information of the test stream output from the counter measurement unit 10 is inappropriately skipped. Hereinafter, a packet immediately before a packet in which a packet loss has occurred is referred to as a previous packet.

  Next, the packet loss detection unit 20 specifies in which frame of the test stream the packet loss has occurred, based on the test stream count information in the immediately preceding packet. As specific counter information, for example, a picture order count (POC) in a slice header of a video stream can be used to identify a frame in which a packet loss has occurred. When using POC, it is determined whether packet loss has occurred between adjacent POCs in the test stream. For example, packet loss has occurred in the test stream between POC = 1 and POC = 2. For example, it is determined that a packet loss has occurred in the frame of POC = 1.

  Next, the packet loss detection unit 20 determines whether or not the detected packet loss is within the range of the performance of the error correction function installed in the video reception device 200. Specifically, the packet loss detection unit 20 recognizes in advance the performance of the error correction function implemented in the video receiving device 200, and the number of packet losses within a predetermined time recognizes the performance. It is determined whether or not the number is less than the upper limit of the number of packet losses that can be corrected by. If it is determined that the packet loss is less than or equal to the upper limit, the detected packet loss is within the range of the performance of the error correction function implemented in the video receiving apparatus 200, and the frame in which the detected packet loss has occurred is received by video reception. This means that the device 200 can be restored. On the other hand, if it is determined that there is more than the upper limit, the detected packet loss exceeds the range of the performance of the error correction function implemented in the video receiving device 200, and the frame in which the detected packet loss has occurred is detected. This means that the video receiving device 200 cannot be restored.

  Next, the packet loss detection unit 20 performs frame counter information, information indicating whether or not the video receiving device 200 can recover the packet loss, for each frame identified as having undergone packet loss, Generate a list by linking and output the generated list.

  The output video memory 30 receives the decoded video output from the video receiving device 200. The output video memory 30 captures and stores the input decoded video and outputs the stored decoded video as appropriate.

  The decoded video error detection unit 40 receives the decoded video output from the output video memory 30 (hereinafter referred to as an error-corrected decoded video for convenience) and sends it to the network 300 from the video transmission device 100. A previous test stream, that is, a test stream in which no packet loss has occurred is held in advance. The decoded video error detection unit 40 decodes the error-corrected decoded video and a decoded video obtained by decoding a test stream that has been stored in advance and has no packet loss (hereinafter referred to as lossless decoded video for convenience). In the test stream input to the video receiving device 200, a frame that cannot be restored by the video receiving device 200 due to packet loss is detected.

  There are two possible causes for the packet loss that cannot be restored by the video reception device 200 due to packet loss. The first cause is that the generated packet loss exceeds the performance of the error correction function of the video reception device 200. The second cause is that the generated packet loss is within the range of the performance of the error correction function of the video reception device 200, but the error correction function of the video reception device 200 is not operating normally. The error correction function of the receiving apparatus 200 is not operating as expected (as designed). For this reason, a frame that cannot be restored by the video receiving apparatus 200 with respect to packet loss can also be expressed as a frame that cannot be restored by the video receiving apparatus 200 due to packet loss.

  Specifically, the decoded video error detection unit 40 first decodes a test stream that has been stored in advance and has no packet loss, and generates a lossless decoded video. According to this, in the lossless decoded video generated by the decoded video error detection unit 40, video deterioration due to packet loss does not occur.

  Next, the decoded video error detection unit 40 compares the identification information drawn on the error correction decoded video with the identification information drawn on the lossless decoded video, and the same identification information is drawn. Error correction decoded video frames and lossless decoded video frames are detected.

  Next, the decoded video error detection unit 40 calculates the pixel value of the error-corrected decoded video for each frame, calculates the average value of the pixel values of the lossless decoded video for each frame, and the same identification information is drawn. The difference of the average value of the pixel values between the detected frames is calculated.

  Next, the decoded video error detection unit 40 does not cause video degradation (noise or the like) due to packet loss for frames in which the difference between the calculated pixel values is less than or equal to a threshold value (for example, “0”). It is determined that the video receiving apparatus 200 has been restored. On the other hand, for a frame in which the difference between the calculated pixel values is larger than the threshold, it is determined that video degradation due to packet loss has occurred, that is, the video receiver 200 could not restore.

  Next, the decoded video error detection unit 40 determines the frame of the error-corrected decoded video that has been determined to have deteriorated due to packet loss, that is, the frame of the error-corrected decoded video that has been determined to be unrecoverable by the video receiving device 200. Is generated, and the generated list is output.

  The FEC performance determination unit 50 receives the list output from the packet loss detection unit 20 and the list output from the decoded video error detection unit 40 as inputs. The FEC performance determination unit 50 determines whether or not the error correction function of the video reception device 200 is operating as expected based on the lists output from the packet loss detection unit 20 and the decoded video error detection unit 40. . The FEC performance determination unit 50 will be described in detail below.

  First, a case where the error correction function of the video reception device 200 operates as expected will be described below. In this case, if the error correction function is operating as expected, the video receiving apparatus 200 should be able to restore frames that can be restored. Further, if the error correction function is operating as expected, the video receiving apparatus 200 should not be able to restore frames that cannot be restored. That is, when the error correction function of the video reception device 200 is operating as expected, the video reception device 200 can restore frames that should be recoverable and cannot restore frames that should not be recoverable. It will be.

  Next, a case where the error correction function of the video reception device 200 is not operating as expected will be described below. In this case, there may be a case where the video receiving apparatus 200 cannot restore a frame that can be restored if the error correction function is operating as expected. In addition, there may be a case where the video receiving apparatus 200 can restore a frame that cannot be restored if the error correction function is operating as expected. That is, when the error correction function of the video receiving apparatus 200 is not operating as expected, the video receiving apparatus 200 cannot restore a frame that should be recoverable or can restore a frame that should not be recoverable. There is a possibility that it will be lost.

  Therefore, the FEC performance determination unit 50 first recognizes from the list output from the packet loss detection unit 20 whether or not it can be theoretically restored if the error correction function operates as expected for each frame. To do. In addition, the FEC performance determination unit 50 recognizes from the list output from the decoded video error detection unit 40 whether or not the video reception device 200 has actually been restored for each frame.

  Next, for each frame, the FEC performance determination unit 50 compares the recognition result as to whether or not the restoration is theoretically possible with the recognition result as to whether or not the video reception device 200 has actually been restored. It is determined whether or not the error correction function of the video reception device 200 is operating as expected.

  According to the error correction function verification apparatus 1 described above, the following effects can be obtained.

  The error correction function verification device 1 can verify the error correction function of the video reception device 200 outside the video reception device 200. For this reason, it is not necessary to add a new function to the video receiving apparatus 200, and visual confirmation by an inspector is unnecessary, so that the verification cost can be reduced. In addition, since visual inspection by the inspector is unnecessary, the possibility of a verification error occurring can be reduced, and the error correction function of the video reception device 200 can be verified appropriately. Furthermore, since the process for verifying the error correction function of the video receiving apparatus 200 is performed outside the video receiving apparatus 200, the processing load on the video receiving apparatus 200 can be suppressed.

  In the error correction function verification apparatus 1, identification information, which is information for uniquely identifying each frame, is drawn as an image on each frame image constituting the test video. Therefore, the decoded video error detection unit 40 can compare the frame of the error correction decoded video on which the same identification information is drawn with the frame of the lossless decoded video.

  In addition, the error correction function verification apparatus 1 can use a serial number or time information of each frame of the test video as identification information for each frame image constituting the test video.

  Further, the error correction function verification apparatus 1 can use the RTP counter described in the header of the RTP packet as the counter information of the test stream in the counter measurement unit 10.

  In addition, the error correction function verification device 1 determines the pixel value of the error correction decoded video, the pixel value of the lossless decoded video, and the pixel value of the lossless decoded video for each frame detected by the decoded video error detection unit 40 that the same identification information is drawn. In the test stream input to the video receiving apparatus 200, it is possible to detect a frame in which a packet loss has occurred that the video receiving apparatus 200 cannot restore.

Second Embodiment
[Configuration and operation of error correction function verification system BB]
FIG. 3 is a block diagram of an error correction function verification system BB according to the second embodiment of the present invention. The error correction function verification system BB is different from the error correction function verification system AA according to the first embodiment of the present invention shown in FIG. 1 in that an error correction function verification apparatus 1A is provided instead of the error correction function verification apparatus 1. Different. In the error correction function verification system BB, the same components as those in the error correction function verification system AA are denoted by the same reference numerals, and the description thereof is omitted.

[Configuration and operation of error correction function verification apparatus 1A]
Similar to the error correction function verification apparatus 1, the error correction function verification apparatus 1 </ b> A verifies the error correction function installed in the video reception apparatus 200. This error correction function verification device 1A is different from the error correction function verification device 1 in that it includes a video decoding unit 60 and a processing delay detection unit 70, and includes a decoded video error detection unit 40A instead of the decoded video error detection unit 40. This is different from the above point in that an FEC performance determination unit 50A is provided instead of the FEC performance determination unit 50.

  The video decoding unit 60 receives a test stream input to the video receiving apparatus 200, that is, a test stream in which packet loss may occur. The video decoding unit 60 obtains a processing time required for decoding a test stream input to the video receiving device 200 for each processing frame.

  Specifically, the video decoding unit 60 first decodes a test stream input to the video receiving device 200 to obtain a decoded video.

  Next, the video decoding unit 60 acquires counter information corresponding to each frame of the acquired decoded video, and sets the processing time from the start to the end of the above-described test stream decoding processing as the acquired counter information. Ask based. If a packet loss has occurred in the test stream, the video decoding unit 60 can perform decoding by skipping processing to the next GOP (Group of Picture) without performing error correction processing. Only the frame is decoded.

  Next, the video decoding unit 60 outputs the acquired decoded video and the counter information indicating the above processing time.

  The decoded video error detection unit 40A receives the error-corrected decoded video output from the output video memory 30, and a test stream before being sent from the video sending device 100 to the network 300, that is, no packet loss has occurred. A test stream is stored in advance. Similar to the decoded video error detection unit 40, the decoded video error detection unit 40A generates a list of information indicating frames of error-corrected decoded video determined to be unrecoverable by the video reception device 200, and outputs the generated list To do. Furthermore, the decoded video error detection unit 40A sequentially outputs the video of the frame for which the above determination has been completed among the input error correction decoded video at the timing at which the above determination has been completed.

  The processing delay detection unit 70 receives the decoded video output from the video decoding unit 60 and counter information representing the processing time, and the error correction decoded video output from the decoded video error detection unit 40A. This processing delay detection unit 70 is from when the test stream for the processing frame in the processing delay detection unit 70 is input to the video receiving device 200 until the output from the decoded video error detection unit 40A for this processing frame is completed. Detect time.

  Specifically, the processing delay detection unit 70 first performs frame matching between the decoded video output from the video decoding unit 60 and the error correction decoded video output from the decoded video error detection unit 40A. A search is made for a matching frame between the decoded video and the error correction decoded video.

  In the frame matching described above, the processing delay detection unit 70 first acquires information (for example, POC) related to the picture order described in the test stream from the decoded video output from the video decoding unit 60. Next, identification information for identifying each frame is acquired from each frame of the error-corrected decoded video output from the decoded video error detection unit 40A. Next, information relating to the picture order and identification information are arranged in the order of frames, and the nth information (where n is an arbitrary integer satisfying n ≧ 1) among the information relating to the arranged picture order, The nth identification information among the identification information is associated with each other, and the test stream for the nth frame and the error correction decoded video for the nth frame are synchronized. According to this, a matching frame between the decoded video and the error correction decoded video is searched.

  Next, when a matching frame is found, the processing delay detection unit 70 acquires a time difference in which each frame is input to the processing delay detection unit 70 in units of counters. For example, a case where the first frame of the decoded video output from the video decoding unit 60 matches the second frame of the error correction decoded video will be described below. In this case, the processing delay detection unit 70 calculates a time difference from the input of the first frame of the decoded video output from the video decoding unit 60 to the input of the second frame of the error correction decoded video. Obtained based on the counter information corresponding to one frame and the counter information corresponding to the second frame, the counter information representing the above time difference is acquired.

  Next, the processing delay detection unit 70 adds the counter information indicating the processing time output from the video decoding unit 60 to the acquired counter information indicating the time difference, and outputs the addition result as an error detection processing time. According to this, for each processing frame in the processing delay detection unit 70, a test stream for this processing frame is input to the video receiving apparatus 200, and then the output from the decoded video error detection unit 40A for this processing frame is completed. The time until this is output from the processing delay detection unit 70 as the error detection processing time.

  The FEC performance determination unit 50A receives the list output from the packet loss detection unit 20, the list output from the decoded video error detection unit 40A, and the error detection processing time output from the processing delay detection unit 70. To do. Similar to the FEC performance determination unit 50, the FEC performance determination unit 50A determines whether or not the error correction function of the video reception device 200 is operating as expected. However, the FEC performance determination unit 50A is different from the FEC performance determination unit 50 in that the error detection processing time is taken into consideration in the determination. The fact that the FEC performance determination unit 50A considers the error detection processing time in the determination will be described in detail below.

  Although not considered in the first embodiment of the present invention, in each configuration provided in the video reception device 200 and the error correction function verification device 1A, the processing time from when a signal is input to when the signal is output is shown. Occurs. Furthermore, compared with the processing time in the counter measurement unit 10 and the processing time in the packet loss detection unit 20, the processing time for decoding and error correction in the video reception device 200 becomes longer. For this reason, when the error correction function is operating as expected, the timing at which a list for recognizing whether the frame is theoretically recoverable is input from the packet loss detection unit 20 to the FEC performance determination unit 50A. There is a possibility that there is a time difference between the timing at which the list for recognizing whether or not the video receiving apparatus 200 can actually restore the frame is input from the decoded video error detection unit 40 to the FEC performance determination unit 50A. There is. According to this, in the FEC performance determination unit 50A, if the error correction function is operating as expected, it is theoretically possible to restore the frame and whether or not the video reception device 200 has actually been restored. There is a risk that a difference between the frame and the recognized frame may occur.

  Therefore, the FEC performance determination unit 50A recognizes whether or not the frame can be theoretically restored if the error correction function is operating as expected, and whether or not the video reception device 200 has actually been restored. The above-described determination is performed after matching the frame with the error detection processing time output from the processing delay detection unit 70.

  According to the error correction function verification apparatus 1A described above, in addition to the above-described effects that can be achieved by the error correction function verification apparatus 1, the following effects can be achieved.

  The error correction function verification device 1A theoretically takes into account the difference in processing time between the components provided in the error correction function verification device 1 and the video reception device 200, as long as the error correction function is operating as expected. The information on whether or not it is a frame that can be restored and the information on whether or not the frame can be actually restored by the video receiving apparatus 200 can be compared with each other for the same frame.

<Third Embodiment>
[Configuration and operation of error correction function verification system CC]
FIG. 4 is a block diagram of an error correction function verification system CC according to the third embodiment of the present invention. The error correction function verification system CC is different from the error correction function verification system BB according to the second embodiment of the present invention shown in FIG. 3 in that an error correction function verification apparatus 1B is provided instead of the error correction function verification apparatus 1A. Different. In the error correction function verification system CC, the same components as those in the error correction function verification system AA and the error correction function verification system BB are denoted by the same reference numerals, and the description thereof is omitted.

[Configuration and operation of error correction function verification apparatus 1B]
Similar to the error correction function verification apparatuses 1 and 1A, the error correction function verification apparatus 1B verifies the error correction function installed in the video reception apparatus 200. This error correction function verification device 1B differs from the error correction function verification device 1A in that it includes a reduced stream generation unit 80 and a decoding video error detection unit 40B instead of the decoded video error detection unit 40A. .

  The reduced stream generation unit 80 holds in advance a test stream before being transmitted from the video transmission apparatus 100 to the network 300, that is, a test stream in which no packet loss has occurred. The reduced stream generation unit 80 reduces the resolution of a test stream in which no packet loss has occurred, and generates a reduced test stream. Specifically, the reduced stream generation unit 80 performs resolution reduction processing after decoding a test stream in which no packet loss occurs, and then encodes and outputs the result as a reduced test stream.

  The decoded video error detector 40B receives the error-corrected decoded video output from the output video memory 30 and the reduced test stream output from the reduced stream generator 80. Similar to the decoded video error detection units 40 and 40A, the decoded video error detection unit 40B generates a list of information indicating frames of error-corrected decoded video determined to be unrecoverable by the video reception device 200, and the generated list Is output. Similarly to the decoded video error detection unit 40A, the decoded video error detection unit 40B sequentially outputs the video of the frame for which the above determination is completed among the input error correction decoded video at the timing when the above determination is completed. To do. However, the decoded video error detection unit 40B is different from the decoded video error detection units 40 and 40A in that a reduced test stream is used instead of a test stream in which no packet loss occurs when the above list is generated. Different. The following describes in detail how the decoded video error detection unit 40B generates the above list using the reduced test stream.

  The decoded video error detection unit 40B first decodes the reduced test stream to generate a reduced lossless decoded video. According to this, video degradation due to packet loss does not occur in the reduced lossless decoded video generated by the decoded video error detection unit 40B.

  Next, the decoded video error detection unit 40B compares the identification information drawn in the error correction decoded video with the identification information drawn in the reduced lossless decoded video, and the same identification information is drawn. The error-corrected decoded video frame and the reduced lossless decoded video frame are detected.

  Next, the decoded video error detection unit 40B calculates the feature amount of the error-corrected decoded video for each frame, calculates the feature amount of the reduced lossless decoded video for each frame, and the same identification information is drawn. The difference in the feature amount between the detected frames is calculated. As the feature amount, for example, an average value or a variance value of pixel values can be used.

  Next, the decoded video error detection unit 40B does not cause video degradation (noise or the like) due to packet loss for frames whose calculated feature difference is equal to or less than the threshold value, that is, can be restored by the video receiving device 200. It is determined that On the other hand, for a frame in which the difference between the calculated feature amounts is larger than the threshold, it is determined that video degradation due to packet loss has occurred, that is, the video reception device 200 could not restore.

  Next, the decoded video error detection unit 40B determines the frame of the error-corrected decoded video that has been determined to have undergone video degradation due to packet loss, that is, the frame of the error-corrected decoded video that has been determined to be unrecoverable by the video receiver 200 Is generated, and the generated list is output.

  According to the error correction function verification apparatus 1B described above, in addition to the above-described effects that the error correction function verification apparatus 1A can achieve, the following effects can be achieved.

  In the error correction function verification device 1B, the decoded video error detection unit 40B compares the error correction decoded video stored in the output video memory 30 with the reduced lossless decoded video having a resolution lower than that of the lossless decoded video. For this reason, since the resolution of the video to be compared with the error correction decoded video is lowered, the processing load on the decoded video error detection unit 40B can be suppressed.

  The processing of the error correction function verification device 1, 1A, 1B of the present invention is recorded on a computer-readable non-transitory recording medium, and the program recorded on this recording medium is stored in the error correction function verification device 1, 1A. 1B can be read and executed to implement the present invention.

  Here, for example, a nonvolatile memory such as an EPROM or a flash memory, a magnetic disk such as a hard disk, a CD-ROM, or the like can be applied to the above-described recording medium. Further, reading and execution of the program recorded on the recording medium is performed by a processor provided in the error correction function verification device 1, 1A, 1B.

  The above-described program is transmitted from the error correction function verification apparatus 1, 1A, 1B storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. May be. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.

  Further, the above-described program may be for realizing a part of the above-described function. Furthermore, what can implement | achieve the above-mentioned function in combination with the program already recorded on the error correction function verification apparatus 1, 1A, 1B, what is called a difference file (difference program) may be sufficient.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes a design that does not depart from the gist of the present invention.

AA, BB, CC ... error correction function verification system 1, 1A, 1B ... error correction function verification device 10 ... counter measurement unit 20 ... packet loss detection unit 30 ... output video memory 40, 40A, 40B ... Decoded video error detection unit 50, 50A ... FEC performance determination unit 60 ... Video decoding unit 70 ... Processing delay detection unit 80 ... Reduced stream generation unit 100 ... Video transmission Device 200 ... Video receiving device 300 ... Network

Claims (11)

An error correction function verification device for verifying an error correction function of a video reception device,
Counter measurement means for capturing a test stream input to the video receiver and obtaining counter information of the test stream;
Based on the counter information acquired by the counter measurement means, the packet loss can be detected in the test stream input to the video reception device, and the video reception device can restore the location where the detected packet loss has occurred. Packet loss detection means for detecting whether or not there is,
Output video storage means for storing the decoded video obtained by decoding the test stream input by the video receiver as an error-corrected decoded video;
The error correction decoded video stored in the output video storage means and the lossless decoded video obtained by decoding the test stream without packet loss are compared and input to the video receiving device. Decoded video error detection means for detecting a portion of the test stream that could not be restored by the video reception device for packet loss,
Error correction performance determination means for determining whether or not the error correction function is operating as expected based on the detection result by the packet loss detection means and the detection result by the decoded video error detection means; An error correction function verification device comprising:   2. The error correction function verification device according to claim 1, wherein the test stream is generated by drawing identification information for identifying each frame as an image on an image of each frame.   The error correction function verification apparatus according to claim 2, wherein any one of a serial number and time information of each frame is used as the identification information.   4. The error correction function verification device according to claim 1, wherein the counter measurement unit uses an RTP counter described in a header of an RTP packet as counter information of the test stream. The decoded video error detection means includes
The pixel value of the error correction decoded video stored in the output video storage means is determined for each frame, and the pixel value of the lossless decoded video is determined for each frame,
The test stream input to the video receiver by comparing the pixel value of each frame of the error-corrected decoded video with the pixel value of the frame corresponding to the frame of the error-corrected decoded video of the lossless decoded video 5. The error correction function verification device according to claim 1, wherein a portion that cannot be restored by the video reception device is detected for packet loss. A reduced stream generating means for reducing the resolution of the test stream in which no packet loss occurs and generating a reduced test stream;
2. The decoded video error detecting unit uses a reduced lossless decoded video obtained by decoding the reduced test stream generated by the reduced stream generating unit, instead of the lossless decoded video. To 4. The error correction function verification device according to any one of 4 to 4. The decoded video error detection means includes
Obtaining the feature quantity of the error-corrected decoded video stored in the output video storage means for each frame, and obtaining the feature quantity of the reduced lossless decoded video for each frame;
The feature amount of each frame of the error-corrected decoded video is compared with the feature amount of the frame corresponding to the frame of the error-corrected decoded video in the reduced lossless decoded video, and the test input to the video receiving device The error correction function verification device according to claim 6, wherein a portion of the stream that cannot be restored by the video reception device due to packet loss is detected.   8. The error correction function verification apparatus according to claim 7, wherein the decoded video error detection unit uses an average value of pixel values in a frame as a feature amount. A processing delay detection unit for detecting a time from when a test stream for a processing frame is input to the video reception device until detection by the decoded video error detection unit for the processing frame is completed;
The error correction performance determination means has obtained the detection result by the packet loss detection means and the detection result by the decoded video error detection means based on the time detected by the processing delay detection means. And determining whether or not the error correction function is operating as expected based on the detection results of the packet loss detection means and the decoded video error detection means for the same frame. The error correction function verification device according to claim 1. The processing delay detection means includes
Each of the information related to the picture order described in the test stream and the identification information that can be read from each frame of the error correction decoded video stored in the output video storage means are arranged in the order of the frames,
The n-th information (where n is an arbitrary integer satisfying n ≧ 1) in the information relating to the arranged picture order is associated with the n-th identification information in the arranged identification information, and n 10. The error correction function verification apparatus according to claim 9, wherein a test stream for the frame and an error correction decoded video of the nth frame stored in the output video storage means are synchronized. The error correction performance determination means includes
When the portion detected as recoverable by the packet loss detection means is detected by the decoded video error detection means as not being a portion that could not be restored by the video reception device, the error correction function for the location is detected. Is working as expected,
When the portion detected as unrecoverable by the packet loss detection means is detected by the decoded video error detection means as a portion that could not be restored by the video receiver, the error correction is performed for the portion. The error correction function verification apparatus according to claim 1, wherein the function is determined to be operating as expected.

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