JP5833890B2 - Video encoding system converter - Google Patents

Description

  The present invention relates to a video encoding system conversion apparatus that converts a video signal encoded by a certain encoding system into a video signal encoded by another encoding system, and has a function of detecting a deterioration level at that time. Is.

  If the video signal is stored and transmitted as it is, the amount of information is large and costly. Therefore, it is common to reduce the number of information bits using a compression technique. At this time, different compression encoding methods (hereinafter simply referred to as encoding methods) are often adopted depending on the purpose of use of the video and the environment at the time of creation, and when used in a situation different from the situation at the time of creation. May not be used due to differences in encoding schemes. For this reason, it is necessary to reconvert a video signal compressed by a certain encoding method using another encoding method. However, since the video signal often deteriorates with the change of the encoding method, a video encoding method conversion system having a function of detecting the degree of deterioration is known. For example, Non-Patent Document 1 discloses a method for detecting the degree of deterioration.

  In general, in order to convert a first video signal compressed and encoded by the first encoding method (hereinafter simply referred to as encoding) into a second video signal encoded by the second encoding method. Therefore, it is necessary to decode the first video signal into an uncompressed first video signal, and re-encode it using the second encoding method. When trying to measure the degradation of the video accompanying this re-encoding, the conventional video encoding system conversion system can reproduce the first video signal and the second video signal after re-encoding in synchronization with each other. Each of the first encoding system decoding apparatus and the second encoding system decoding apparatus was compared while simultaneously decoding, and the degree of difference due to re-encoding was measured.

  A conventional video coding system conversion system used when converting a video signal of one coding system into a video signal of another coding system and inspecting image degradation due to the conversion is shown in FIG. Will be described with reference to FIG. FIG. 2 is a block diagram showing a schematic configuration of a conventional video coding system conversion system. As shown in FIG. 2, the conventional video coding system conversion system 2 includes a first coding system decoding apparatus 201, a second coding system coding apparatus 202, a second video signal storage apparatus 203, and the like. A first video signal storage device 204, a second encoding scheme decoding device 205, a first encoding scheme decoding device 206, and a video inspection device 207.

  The first encoding method decoding apparatus 201 receives the first video signal A compressed by the first encoding method and decodes it to generate an uncompressed first video signal A ′. The encoding device 202 of the second encoding method encodes the uncompressed first video signal A ′ generated by the decoding device 201 of the first encoding method by the second encoding method and generates the second video signal B. It is generated and stored in the storage device 203 for the second video signal. The first video signal storage device 204 stores the first video signal A input to the first encoding decoding device 201.

  The decoding device 205 of the second encoding method reads out the second video signal B from the video signal B storage device 203 after the encoding process by the encoding device 202 of the second encoding method is completed, and executes the decoding process To do. The first encoding decoding device 206 reads the first video signal A from the first video signal storage device 204 and executes a decoding process. At this time, the decoding apparatus 205 of the second encoding scheme outputs a synchronization signal to the decoding apparatus 206 of the first encoding scheme. In order for the first encoding scheme decoding device 206 and the second encoding scheme decoding device 205 to always decode the same temporally frame, the first encoding scheme decoding device 206 is synchronized. The frame specifying signal is sent to the first video signal storage device 204 based on the signal, and the second encoding decoding device 205 sends the frame specifying signal to the second video signal storage device 203 based on the synchronization signal.

  The uncompressed first video signal A ′ decoded by the first encoding scheme decoding device 206 and the uncompressed second video signal B ′ decoded by the second encoding scheme decoding device 205 are synchronized. The state is input to the video inspection apparatus 207. The video inspection device 207 compares the uncompressed first video signal A ′ and the uncompressed second video signal B ′ input in synchronization, inspects the degree of deterioration, and outputs a test numerical value.

"Objective perceptual multimedia video quality measurement in the presence of a full reference", Recommendation ITU-T J.247, p.11-20

  As described above, in the conventional method, the first video signal encoded by the first encoding method is converted into the second video signal encoded by the second encoding method, and further, the degree of deterioration of the video due to the conversion is converted. When the second video signal once generated is decoded by a decoding device of the second encoding method, the difference from the video obtained by decoding the first video signal is measured. For this reason, the time required for the conversion of the compression method and the time required for the inspection of the difference due to deterioration are required.

  An object of the present invention made in view of such circumstances is video coding system conversion capable of speeding up detection of the degree of deterioration due to conversion when converting an encoded video signal to another coding system. To provide an apparatus.

  In order to solve the above-described problem, the video coding method conversion apparatus according to the present invention also performs sequential decoding processing according to the progress of the coding processing by the second coding method, and the difference between the video before conversion and the video after conversion. Is calculated in parallel with the conversion process. In addition, in order to compensate for the delay caused by the decoding process and the encoding process, the storage unit temporarily stores the decoded video, and compares the frame images at the same time before and after the conversion.

That is, the video coding method conversion apparatus according to the present invention converts a video signal encoded by a first encoding method into a video signal encoded by another second encoding method. A decoding device that decodes a first video signal encoded by a first encoding method to generate an uncompressed first video signal, and the first encoding An uncompressed video signal temporary storage unit that stores the uncompressed first video signal generated by the decoding unit of the system, and the uncompressed first video signal generated by the decoding unit of the first encoding system. A second encoding method encoding unit that generates a second video signal by encoding with the second encoding method without going through the uncompressed video signal temporary storage unit; and an encoding unit of the second encoding method Decodes the second video signal generated by the above and generates an uncompressed second video signal A second encoding scheme decoding unit, the uncompressed first video signal stored in the non-compressed video signal temporary storage unit, and the uncompressed first video signal generated by the second encoding scheme decoding unit. A differential video generation unit that generates a differential video with the second video signal; and a degradation level detection unit that calculates a degradation level due to conversion of a coding scheme from the differential video, and a decoding unit of the second coding scheme Is characterized in that when the second video signal for a predetermined frame is generated by the encoding unit of the second encoding method, the second video signal for the predetermined frame is decoded.

  Furthermore, in the video coding system conversion device according to the present invention, the decoding unit of the first coding system generates a frame specifying signal that identifies a frame of the uncompressed first video signal, and the uncompressed video The temporary signal storage unit stores the uncompressed first video signal and the frame specifying signal in association with each other.

  Further, in the video coding system conversion device according to the present invention, the difference video generation unit includes a frame image of the uncompressed second video signal generated by the decoding unit of the second encoding system, and the non-compression Obtaining a frame image corresponding to the frame image of the uncompressed second video signal, which is stored in the video signal temporary storage unit and specified by the frame specifying signal, and generating a difference image between the two frame images. Features.

  Furthermore, in the video coding method conversion apparatus according to the present invention, the deterioration level detection unit calculates the deterioration level by statistically calculating the difference video.

  According to the present invention, since it is possible to sequentially detect the deterioration of the image being converted in parallel with the conversion process, it is possible to greatly reduce the time taken to detect the conversion process and the deterioration. .

It is a block diagram which shows schematic structure of the video coding system converter which concerns on this invention. It is a block diagram which shows schematic structure of the conventional video coding system converter.

  Hereinafter, an embodiment of a video encoding system conversion apparatus according to the present invention will be described in detail with reference to FIG.

  FIG. 1 is a block diagram showing a schematic configuration of a video encoding system conversion apparatus according to the present invention. As shown in FIG. 1, the video encoding scheme conversion apparatus 1 includes a first encoding scheme decoding unit 101, a second encoding scheme encoding unit 102, an uncompressed video signal temporary storage unit 103, A decoding unit 104 of a two-encoding method, a difference video generation unit 105, and a deterioration level detection unit 106 are provided. The video encoding method conversion apparatus 1 converts the first video signal A encoded by the first encoding method into the second video signal B encoded by the second encoding method. Then, almost simultaneously with the generation of the second video signal B, an inspection numerical value indicating the degree of deterioration of the video accompanying the conversion of the encoding method is output. The first encoding method is, for example, the MPEG-2 method, and the second encoding method is, for example, MPEG-4 AVC / H. H.264 system.

  The first encoding scheme decoding unit 101 decodes the first video signal A encoded by the first encoding scheme to generate an uncompressed first video signal A ′, and the second encoding scheme encoding Output to the conversion unit 102 and the uncompressed video signal temporary storage unit 103. The first encoding scheme decoding unit 101 outputs the frame specifying signal extracted from the first video signal A to the second encoding scheme encoding unit 102 and the uncompressed video signal temporary storage unit 103. The frame specifying signal is a signal for specifying the frame of the video signal being output based on the time code, the number of frames from the head, and the like, and is output in synchronization with the video signal.

  The uncompressed video signal temporary storage unit 103 temporarily stores the uncompressed first video signal A ′ generated by the decoding unit 101 of the first encoding method and the frame specific signal in association with each other. By designating the frame specifying signal to the uncompressed video signal temporary storage unit 103, it is possible to take out the uncompressed first video signal A 'for one frame corresponding to the designated frame.

  The encoding unit 102 of the second encoding method encodes the uncompressed first video signal A ′ generated by the decoding unit 101 of the first encoding method using the second encoding method and generates the second video signal B. The generated and encoded portions are sequentially output to the decoding unit 104 of the second encoding method. Further, the encoding unit 102 of the second encoding method also uses the second encoding method to specify a frame specifying signal for specifying the frame of the second video signal B that is currently sent to the decoding unit 104 of the second encoding method. Is output to the decoding unit 104. Accordingly, the decoding unit 104 of the second encoding method can specify which frame is currently being decoded.

  The decoding unit 104 of the second encoding method decodes the second video signal B generated by the encoding unit 102 of the second encoding method to generate an uncompressed second video signal B ′, and generates a difference video Output to the unit 105. The decoding unit 104 of the second encoding scheme decodes the second video signal for the predetermined frame at the time when the second video signal B for the predetermined frame is generated by the encoding unit 102 of the second encoding scheme. Here, in order to speed up the detection of the degree of deterioration, it is preferable that the predetermined frame is one frame. In addition, the decoding unit 104 of the second encoding method outputs a frame specifying signal that specifies a frame of the uncompressed second video signal B ′ that is sent to the differential video generation unit 105 at that time as a differential video generation unit 105, And output to the uncompressed video signal temporary storage unit 103.

  The uncompressed video signal temporary storage unit 103 performs the first encoding in order to compensate for delays caused by the decoding process of the encoding unit 102 of the second encoding method and the encoding process of the decoding unit 104 of the second encoding method. The uncompressed first video signal A ′ generated by the system decoding unit 101 is temporarily stored. The non-compressed video signal temporary storage unit 103 is sent from the second encoding scheme decoding unit 104 to the differential video generation unit 105 at that time when the frame specifying signal is input from the second encoding scheme decoding unit 104. The image of the frame of the uncompressed first video signal A ′ corresponding to the current frame is output to the differential video generation unit 105.

  The difference video generation unit 105 performs, for each frame, the uncompressed first video signal A ′ stored in the uncompressed video signal temporary storage unit 103 and the uncompressed first video signal generated by the second encoding method decoding unit 104. A difference image from the two video signals B ′ is generated and output to the deterioration level detection unit 106. That is, the difference video generation unit 105 acquires the latest one frame image of the uncompressed second video signal B ′ generated by the decoding unit 104 of the second encoding method, and temporarily stores the uncompressed video signal. The image of the frame corresponding to the frame of the acquired uncompressed second video signal B ′ among the uncompressed first video signal A ′ temporarily stored in the unit 103 is acquired, and the difference between the frame images for each frame Generate an image. Further, the difference video generation unit 105 outputs the frame specifying signal to the deterioration level detection unit 106. The difference image input to the deterioration level detection unit 106 represents a deterioration component of the video generated due to the encoding method conversion.

  The deterioration level detection unit 106 calculates the deterioration level due to the conversion of the encoding method from the difference image input from the difference video generation unit 105, and outputs the calculation result to the outside together with the frame specifying signal as a check value. The degree of deterioration (inspection numerical value) can be obtained by statistical calculation of a difference image. For example, when the inspection numerical value is the maximum absolute value of the difference image, it indicates the error value of the most deteriorated portion of the frame. When the inspection numerical value is the average value of the absolute values of the difference image, the average error value of the frame is indicated. When the inspection numerical value is an average value of the square values of the difference images, the average error energy value of the frame is indicated. In addition, various statistical calculations can be considered. Which inspection numerical value is used is determined depending on what kind of deterioration needs to be extracted depending on the application.

  The inspection numerical value generated by the deterioration level detection unit 106 represents how much each frame specified by the frame specifying signal has deteriorated due to the conversion of the encoding method from the first encoding method to the second encoding method. . For example, when the inspection numerical value exceeds a certain threshold value, a warning can be notified that the frame is recognized to have an unacceptable deterioration from the viewpoint of video quality. Since this warning can be output without waiting for completion of conversion of the encoding method or completion of the subsequent comparative inspection, it is possible to expedite the subsequent work.

  In this way, when the video coding method conversion apparatus 1 generates the second video signal for a predetermined frame by the encoding unit 102 of the second encoding method, the decoding unit 104 of the second encoding method causes the predetermined frame to be generated. Minutes of the second video signal is decoded. Assuming that the predetermined frame is one frame, each frame image of the uncompressed second video signal B ′ is generated, and at the same time, the difference video generation unit 105 and the corresponding frame image of the uncompressed first video signal A ′ It is possible to calculate the difference between the two. Thus, the video encoding system conversion apparatus 1 starts the inspection for degradation of video quality without waiting until the generation of the second video signal B is completed, and almost completes the generation of the uncompressed second video signal B ′. At the same time, the inspection for deterioration of video quality can be completed.

  Although the above embodiments have been described as representative examples, it will be apparent to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims.

  For example, in the above-described embodiment, the deterioration degree detection unit 106 calculates the deterioration degree by statistical calculation. However, the deterioration degree may be calculated by image analysis such as Fourier transform. When the difference image is subjected to frequency analysis by Fourier transform or the like, it is possible to show the frequency characteristic of the degree of deterioration, and it is also possible to show how much the error is distributed in a frequency region that is conspicuous for humans.

  INDUSTRIAL APPLICABILITY The present invention is useful for any application for inspecting deterioration of video quality associated with conversion of an encoding method when encoding a video signal for the purpose of storage or transmission.

DESCRIPTION OF SYMBOLS 1 Video coding system converter 101 Decoding part of 1st coding system 102 Coding part of 2nd coding system 103 Uncompressed video signal temporary storage part 104 Decoding part of 2nd coding system 105 Difference video production | generation part 106 Degradation Degree detection unit

Claims (4)

A video encoding method conversion device that converts a video signal encoded by a first encoding method into a video signal encoded by another second encoding method,
Decoding a first video signal encoded by the first encoding method to generate an uncompressed first video signal;
An uncompressed video signal temporary storage unit for storing the uncompressed first video signal generated by the decoding unit of the first encoding method;
The uncompressed first video signal generated by the decoding unit of the first encoding method is encoded by the second encoding method without the non-compressed video signal temporary storage unit to generate a second video signal. An encoding unit of the second encoding method,
A second encoding method decoding unit that decodes the second video signal generated by the second encoding method encoding unit and generates an uncompressed second video signal;
A differential image between the uncompressed first video signal stored in the uncompressed video signal temporary storage unit and the uncompressed second video signal generated by the decoding unit of the second encoding method is generated. A difference video generation unit;
A degradation level detection unit that calculates a degradation level due to conversion of an encoding method from the difference video,
The decoding unit of the second encoding method decodes the second video signal for the predetermined frame when the second video signal for the predetermined frame is generated by the encoding unit of the second encoding method. A video encoding system conversion device characterized by the above. The decoding unit of the first encoding method generates a frame specifying signal that specifies a frame of the uncompressed first video signal,
The video encoding method conversion apparatus according to claim 1, wherein the uncompressed video signal temporary storage unit stores the uncompressed first video signal and the frame specifying signal in association with each other.   The difference video generation unit is stored in a frame image of the uncompressed second video signal generated by the decoding unit of the second encoding method and the uncompressed video signal temporary storage unit, and is generated by the frame specifying signal. 3. The video encoding method according to claim 2, wherein a frame image corresponding to a frame image of the uncompressed second video signal that is specified is acquired, and a difference image between the two frame images is generated. 4. Conversion device.   The video coding method conversion apparatus according to any one of claims 1 to 3, wherein the deterioration level detection unit calculates the deterioration level by statistically calculating the difference video.

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