JP2004328391A - Moving image decoding method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the price of a device becomes high since an image memory becomes necessary for an OSD image separately from an image memory for main video to be used for decoding for performing on-screen display such as a caption in the reproduction method of a digital moving image. <P>SOLUTION: The image memory 140 of a B frame not to be used for prediction is made to also serve as the image memory for the OSD image among image memories to be used for decoding of the main video. OSD data are overwritten by making a special value as 0, instead of the pixel value of the B frame. In the case of display, the value is detected, converted into desired luminance and color data, superimposed on the main video, and displayed. Restriction is imposed so that no special value is used as the decoded value of the B frame. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a moving picture decoding method and apparatus, and more particularly to a moving picture decoding reproduction method and apparatus used when decoding and reproducing an encoded moving picture.
[0002]
[Prior art]
In recent years, with the era of full-scale commercialization of digital technology, moving images can be recorded and played back by devices such as recording and playback devices, personal computers, and home servers, and transmitted over long distances using the Internet and other communication networks. Is becoming possible. A digital mobile communication device such as a mobile phone is also provided with a means for capturing a moving image on the spot and immediately transmitting the moving image to another person. Also, in the field of broadcasting, transmission and coding using digital technology are adopted for moving images such as television.
[0003]
Digital video signals and audio signals can be processed more flexibly than analog signals, so they have the advantages of high quality and high reliability. , Widely used.
[0004]
As a method of reproducing a moving image, a so-called on-screen display (hereinafter, referred to as an OSD) such as a guide character, captions such as dialogue, and an operation icon on a screen is provided in addition to decoding and presenting the moving image. ).
In a conventional moving picture decoding apparatus, a dedicated picture memory is used for OSD data (for example, see Patent Document 1).
[0005]
Hereinafter, a moving image reproducing method used in these conventional apparatuses and the apparatus will be described with reference to FIGS.
FIG. 15 is a block diagram of a reproducing apparatus using a conventional moving image reproducing method.
15, reference numeral 410 denotes a stream input terminal, 510 denotes a decoding unit, 520 denotes a control unit, 530 denotes a reference image memory, 540 denotes an output image memory, 550 denotes an OSD image memory, 450 denotes a host controller, and 570 denotes a host controller. A switch 590 is a superimposing means, and 420 is a video output terminal.
[0006]
First, the moving image stream provided to the input terminal 410 is decoded by the subsequent decoding unit 510, and the restored image is stored in the reference image memory 530 or the output image memory 540. As an example, this decoding method is called "Information Technology Generic Coding of Moving Pictures and Associated Audio Information" (MPEG2 (Moving Picture Experts Group Phase2)) which is an international standard. Information technology—Generic coding of moving pictures and associated audio information ”). A moving image obtained by decoding in this manner is called a main video.
[0007]
Here, an outline of an image encoding method according to the MPEG2 standard will be described.
As shown in FIG. 17, a continuous image group is decoded using an I-frame (Intra-coded frame) that can be completely decoded only by the data of the frame, and another single frame (I or P frame). P-frames (Predictive-coded frames) and B-frames (Bi-directionally predictive-coded frames) decoded using up to two other frames (I or P frames), and are usually regular patterns. Assigned by. In the case of FIG. 17, the order of decoding is IO, P3, B1, B2, P6, B4, B5,. . It becomes order of. Here, the creation of the P3 frame requires an IO frame, and the creation of a B1 or B2 frame requires the I0 and P3 frames. Therefore, the I or P frame is temporarily created for the subsequent image frame. It should be noted that even after the output from the video output is completed, it must be stored on the image memory. These will be referred to as reference frames.
[0008]
On the other hand, once a B frame is created, it is not referred to at all when other frames are created, and only the image is output thereafter.
[0009]
In the example of FIG. 17, the I frame and the P frame are stored in the reference image memory 530, and the B frame is stored in the output image memory 540. The switch 570 appropriately selects the images in the reference image memory 530 or the output image memory 540 so that the images are output in the order in which the original images are output (display order).
[0010]
The control unit 520 appropriately controls the decoding unit 510 and the switch 570 in accordance with a reproduction instruction from the user given from the host controller 450, and performs overwriting of an image that must be held until it is originally displayed. The switch 570 is controlled so as to prevent such a situation, to continue the decoding operation so that the completed image for display does not run out, or to output images in an appropriate order as described above. Further, the control unit 520 has a function of generating an OSD pattern in accordance with an instruction from the host controller 450 and drawing the OSD pattern on the OSD image memory 550.
[0011]
Next, the operation of the superimposing means 590 will be described with reference to FIG.
Here, the OSD image 610 stored in the OSD image memory 550 is superimposed on the main video image 600 input to the superimposing unit 590, and the superimposed image 620 is obtained. FIG. 16 shows the case of subtitle data as OSD data, and shows a state in which the OSD data is overwritten on the main video.
[0012]
Next, the image memory will be described.
First, a video to be handled is a 4: 2: 0 image represented by luminance Y and two color difference signals Cb and Cr as shown in FIG. In the case of the standard television signal, Y is composed of 720 horizontal pixels and 8 bits of data per 480 vertical pixels, and each of Cb / Cr has half the number of vertical and horizontal Y samples.
A typical example of an image memory for storing these is, as shown in FIG. 18B, continuously divided into three areas of Y, Cb, and Cr on the image memory.
[0013]
As described above, in order to superimpose and display the OSD on the main video, the OSD data read from the OSD image memory 550 and the main video data read from the reference image memory 530 or the output image memory 540 are superimposed. The video output is obtained by the combination by means 590.
[0014]
[Patent Document 1]
JP-A-10-340077
[0015]
[Problems to be solved by the invention]
However, in the above configuration, it is necessary to separately provide an image memory for OSD data in addition to the memory used for decoding the main video, and there has been a problem that the price of the apparatus is increased.
The present invention has been proposed in view of the above-described conventional problems, and has as its object to provide a moving image decoding method and an apparatus therefor that do not require the provision of an OSD-specific image memory.
[0016]
[Means for Solving the Problems]
In order to solve the above problem, a moving picture decoding method according to claim 1 of the present invention, wherein a stream obtained by predictively encoding a moving picture is input, and the decoding method for decoding the stream, A reference image memory for storing a reference image used when performing decoding, and an output image memory for storing an output image decoded with reference to the reference image memory, comprising: At the time of decoding, the decoded output image data is corrected to an approximate value so as not to take this value as a special value for at least one gradation value, and stored in the output image memory. The on-screen display data is stored as the special value in the output image memory.
[0017]
A moving picture decoding method according to claim 2 of the present invention is the moving picture decoding method according to claim 1, wherein the special value is one of 0 or a maximum expressible value. It was done.
[0018]
A video decoding method according to a third aspect of the present invention is the video decoding method according to the first aspect, wherein the special value is 0 and a maximum expressible value. .
[0019]
A moving picture decoding method according to a fourth aspect of the present invention is the moving picture decoding method according to any one of the first to third aspects, wherein the predictive coding method is an MPEG method. It is.
[0020]
According to a fifth aspect of the present invention, there is provided a moving picture decoding apparatus which receives a stream obtained by predictively encoding a digital moving picture, decodes the stream, and decodes the first stream obtained by the decoding. A reference image memory for storing the decoded image of the above as a reference image, an output image memory for storing the second decoded image obtained at the time of the decoding as an output image, an output of the output image memory, The output of the decoding means is input and the second decoded image data output by the decoding means is corrected to an approximate value so that at least one gradation value is not taken as a special value group. And combining the output of the output image memory with the output of the decoding means, and outputting the combined image data to the output image memory; and outputting the on-screen display data to the output image memory. Image And a superimposing means for superimposing the special value on the output image memory before storing the second decoded image. For the image area where the group is detected, the special value group is stored as it is, and for the image area where the special value group is not detected, the read value is stored, so that the on-screen display data is stored in the special value. It is stored in the output image memory as a group.
[0021]
In a moving picture decoding method according to a sixth aspect of the present invention, in the moving picture decoding apparatus according to the fifth aspect, the superimposing means outputs the output of the output image memory and the output of the reference image memory. As an input, when outputting the contents of the output image memory, or the reference image memory, the contents of the output image memory, only for the image area in which the special value group is detected, brightness previously set, The color data is replaced and output.
[0022]
The video decoding device according to claim 7 of the present invention is the video decoding device according to claim 5, wherein the superimposing means includes an output of the output image memory, an output of the reference image memory, When external video data is input and one of the output of the output image memory or the output of the reference image memory is output as the selected video, the content of the output image memory is a special value Only for an image region in which a group has been detected, the selected image and the external image are mixed and generated with predetermined transparency to generate and output video data. For an image region in which the special value group is not detected, the selected image is Is output as it is.
[0023]
In the moving picture decoding method according to claim 8 of the present invention, in the moving picture decoding device according to claim 5, the superimposing means includes an output of the output image memory, an output of the reference image memory, When the external video data is input and one of the output of the output image memory or the output of the reference image memory is output as the selected video, the content of the output image memory is changed to the For an image region in which the first special value group is detected, video data in which the selected video and the external video are mixed with a preset transparency is output. For an image region in which the first special value group is not detected, The selected video is output as it is, and the image area in which the second special value group has been detected is output after replacing it with luminance and color data set in advance.
[0024]
A moving picture decoding method according to a ninth aspect of the present invention is the moving picture decoding method according to any one of the fifth to eighth aspects, wherein the predictive coding method is an MPEG method. It is.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a configuration diagram of a video decoding method and an image reproducing apparatus according to Embodiment 1 of the present invention.
In FIG. 1, reference numeral 10 denotes a stream input terminal, 110 denotes a decoding unit, 120 denotes a control unit, 130 denotes a reference image memory, 140 denotes an output image memory, 160 denotes a synthesizing unit, 50 denotes a host controller, 170 denotes a switch, 190 is a superimposing means, and 20 is a video output terminal.
[0026]
Next, the operation of the playback device according to the first embodiment will be described.
First, the moving image stream provided to the input terminal 10 is decoded by the subsequent decoding means 110, and the restored image is stored in the reference image memory 130 or the output image memory 140. This decoding method uses a method according to MPEG2 as an example.
[0027]
As a result of decoding by a method according to MPEG2, the I frame and the P frame are stored in the reference image memory 130, and the B frame is stored in the output image memory 140.
[0028]
The switch 170 appropriately selects the images in the reference image memory 130 or the output image memory 140 so that the images are output in the order in which the images are originally output (display order).
[0029]
The control means 120 appropriately controls the decoding means 110 and the switch 170 in accordance with a reproduction instruction from the user given from the host controller 50, and controls the decoding of the image which must be held until it is originally displayed. The switch 170 is controlled so as to prevent overwriting, to continue the decoding operation so that the completed image for display does not run out, or to output images in an appropriate order as described above.
[0030]
Further, the control unit 120 has a function of generating an OSD pattern such as a caption in accordance with an instruction from the host controller 50 and drawing the OSD pattern in the output image memory 140. This explanatory diagram is shown in FIG. 3 and FIG.
[0031]
FIG. 3 shows how values are used in the output image memory 140. The image data for B frame is stored in the output image memory 140. Since each pixel data is 8 bits, the range that can be originally expressed is from 0 to 255 as shown in FIG. It is. As described above, when the control unit 120 performs the drawing operation on the output image memory 140, the value of 0 among these 256 gradations is defined as a marker that specifically indicates the OSD area, and the character or icon of the character or icon is defined. The OSD pattern is overwritten with 0 data. The remaining 1 to 255 are data of the main video as before. Creating a new pixel value by overwriting the OSD pattern with special value 0 data on the main video data is hereinafter referred to as synthesis.
[0032]
However, in place of the above, it is prohibited to take the value 0 as the decoded image data of the original B frame. That is, the image data of the B frame decoded as 0 is corrected, for example, by clipping it to 1 which is close to the image data, and storing it in the output image memory 140. If the value is corrected to such a degree, the difference cannot be identified due to human visual characteristics, so that a change in the appearance of the image cannot be felt.
[0033]
FIG. 4 shows how the OSD data is drawn on the output image memory 140. FIG. 4 is an enlarged view of a part of the output image memory 140, in which cells represent pixels, and pixels 30b of OSD data are mixed together with pixels 30a of main video data of the original B frame. It shows the situation. It is important to immediately discriminate between the two values, that is, the main video data and the OSD data, depending on whether the value is 0 or not.
[0034]
In the above description, a value that has a special meaning, such as a value of 0, which is not the main video data but OSD data and is not an original tone, is called a special value. To
[0035]
Next, the operation of the superimposing means 190 will be described. Here, it is detected whether or not the input image data has the above-described special value. If the input image data has the special value, predetermined luminance and color data are superimposed as OSD data. As an example, the OSD data is superimposed on the main video data by superimposing a special value of 0 as white caption data.
[0036]
Hereinafter, how the superimposing operation is performed will be described.
FIG. 5 shows the state of the video output from (a) the reference image memory 130, (b) the output image memory 140, and (c) the video output terminal at each time.
[0037]
The reference image memory 130 internally has two screens of FM0 and FM1, and stores image data of an I or P frame. When one is created, the other is referenced and updated alternately. On the other hand, the output image memory 140 is equivalent to one screen of FM2, and stores image data of a B frame.
[0038]
First, at time T1, it is assumed that the image data of the currently displayed main video is stored in FM0 of the reference image memory 130, which is an I or P frame. Then, referring to FM0, a new P frame is created and stored in FM1. In the FM0 and FM1, the OSD data is not overwritten with the special value 0 and stored at any time. However, the main video data of the output image memory 140 is also read out in parallel, the area of the special value 0 included therein is detected, and the OSD is located at the corresponding position on the screen in the area where the special value 0 is detected. Data is superimposed.
[0039]
That is, an image in which the main video data of FM0 and the area of special value 0 of FM2 are replaced with desired luminance and color is output as a video output.
[0040]
Next, at time T2, a state in which the B frame is decoded and output is shown. The image data of the B frame that the decoding unit 110 predicts from the reference images of FM0 and FM1 is generated in FM2. Although it is stored, it is not stored as it is, and the special value area which is read out before being stored is left as the special value 0 as it is.
[0041]
On the other hand, when the obtained image data of the B frame takes the value of the special value 0, the clipping is corrected to the value 1 as an example so as not to become the special value 0 as described above. . The corrected data is stored again in FM2.
[0042]
By this operation, only the main video data is updated to the latest decoded image without changing the OSD data. As described above, in the FM2, the main video data and the special value 0 are mixedly stored in the same image memory.
[0043]
Next, at the time T3, as in the case of the time T2, a state in which the B frame is decoded and output is shown. The operation is the same as that at time T2, and a description thereof will be omitted.
[0044]
The reading, the storage of the area of the special value 0, and the clipping processing performed at time T2 and T3 prior to the update of FM2 are performed by the synthesizing unit 160, and the configuration is shown in FIG. In FIG. 2, reference numeral 200 denotes a detecting unit, and 210 denotes a replacing unit.
[0045]
The B frame data obtained by reading out the output image memory 140 is input to the detection unit 200, which detects the OSD area in the image and notifies the replacement unit 210. The replacement unit 210 receives the decoded value obtained by decoding by the decoding unit 110 as an input, and when it finds video data that matches the special value 0, as an example, corrects it to an approximate value 1 by clipping, and outputs it. Get data. Further, the replacement means 210 outputs the special value 0 in the notified OSD area, and otherwise outputs the video data, and stores the video data in the output image memory 140.
[0046]
Next, at time T4, a state in which the P frame is decoded is shown. Referring to FM1 on the opposite side to time T1, a new P frame is created and stored in FM0.
Also at this time, similarly to time T1, FM2 is read out in parallel, and an image in which the special value 0 is replaced with a desired luminance and color is output as a video output.
[0047]
The above operation is repeatedly and continuously performed by the superimposing means 190. As a result, the OSD data of desired luminance and color data is superimposed on the main video regardless of the type of the I, P, and B frames. Can be done.
In the above embodiment, 0 is selected as the special value. However, the special value is not limited to 0, and may be 255 or any other value.
[0048]
In the moving picture decoding method according to the first embodiment as described above, in the decoding method for decoding a stream obtained by predictively coding a moving picture, the reference method for storing a reference picture used when decoding is performed. Image memory, and an output image memory that stores an output image with reference to the reference image memory, and when decoding a stream, the output image data stored in the output image memory The at least one gradation value is set as a special value, the value is limited to an approximate value so as not to be taken, and the on-screen display data is stored as the special value in the output image memory. The memory 140 is used to store OSD display data. As described above, among the image memories used for decoding the main video, the image memory of the B frame that is not used for prediction is also used as the image memory for the OSD image. There is no need to provide an image memory dedicated to OSD data, and there is an effect that a low-cost image reproducing apparatus can be obtained.
[0049]
(Embodiment 2)
Next, a video decoding method and an image reproducing apparatus according to Embodiment 2 of the present invention will be described with reference to FIG.
The second embodiment shown in FIG. 6 differs from the first embodiment shown in FIG. 1 in that the combining means 160 is replaced by the combining means 160a, the superimposing means 190 is replaced by the superimposing means 190a, and the special value setting is performed. Means 180 is added, and the special value set thereby is supplied to both the synthesizing means 160a and the superimposing means 190a. The other components denoted by the same reference numerals are the same as those in FIG.
[0050]
In the first embodiment, the only special value of 0 is used as a marker indicating the OSD area. However, in the second embodiment, as shown in FIG. It is assumed that values are provided and converted into luminance and color data defined in an LUT (lookup table).
[0051]
The LUT is a conversion table table in which one special value x is associated with a set of values of Y, Cb, and Cr. An example is shown in FIG. 9C. In this example, the special value x = 1 appearing in the output image memory is interpreted as pixel data of Y = 188, Cb = 156, Cr = 100, replaced by the superimposing means 190a, and output as a video output. .
[0052]
In FIG. 6, a special value setting means 180 gives a tone value to which the special value is set, and the setting of the special value is supplied to the synthesizing means 160a and the superimposing means 190a.
[0053]
FIG. 7 shows the configuration of the synthesizing means 160a.
In FIG. 7, reference numeral 200a denotes a detecting unit, and 210a denotes a replacing unit. The B frame data obtained by reading the output image memory 140 is input to the detection unit 200a, which detects the OSD area in the image and notifies the replacement unit 210a. The replacement unit 210a receives the decoded value obtained by decoding by the decoding unit 110 as input, and when it finds video data that matches the special value, as an example, corrects it to an approximate value by clipping and converts the output data. obtain.
[0054]
As an example, when using the LUT of FIG. 9, the pixel data from 0 to 15 is clipped to 16. When the LUT of FIG. 10 is used, in addition, the pixel data of 0 to 15 is clipped to 16 and the pixel data of 236 to 255 is clipped to 235.
[0055]
The replacement means 210a outputs a special value in the notified OSD area, and otherwise outputs the video data, and stores it in the output image memory 140. The replacement means shown in FIG. Same as 210.
[0056]
FIG. 8 shows the configuration of the superimposing means 190a shown in FIG.
In FIG. 8, 230 is a detecting means, 240 is a replacing means, and 250 is a look-up table.
[0057]
The main video data output from the selecting means 170 together with the image data read from the output image memory 140 in parallel is input to the replacing means 240 as a read value, and the detecting means 230 stores the special value in the former. Is found, the look-up table 250 is drawn, the image data is replaced with the value obtained and output, and the OSD data is superimposed on the corresponding position on the screen of the detected area. Here, the look-up table 250 gives a result as shown in FIG.
[0058]
In such a moving picture decoding method according to the second embodiment, special values from 0 to 15 are provided as special values which are OSD display data output from the output image memory 140. Two or more luminance and color representations can be performed by OSD display, and the combination of the luminance and color can be arbitrarily changed, so that an effect of enabling OSD display with a high degree of freedom can be obtained.
[0059]
In the above embodiment, the special value is selected from 0 to 15, but is not limited to 16 tones and can be arbitrarily selected. In particular, as shown in FIG. 10, a special value may be selected not only at the lower end of the gradation value but also at the upper end such as 236 to 255 as an example. Further, a special value may be selected only for the upper end.
[0060]
(Embodiment 3)
Next, a video decoding method and an image reproducing apparatus according to Embodiment 3 of the present invention will be described with reference to FIG.
The third embodiment shown in FIG. 11 is different from the above-described second embodiment shown in FIG. 6 in that the superimposing means 190a is replaced by the superimposing means 190b, and the input image from the external video input terminal 30 is superimposed. Input to the means 190b.
The other components denoted by the same reference numerals are the same as those in FIG.
[0061]
In the third embodiment, the special value is set by the special value setting means 180a, and is replaced with the final color and luminance by the look-up table 250a and output as in the second embodiment. However, in the third embodiment, as shown in FIG. 13B, as an example, the special values of the gradation values 0 to 15 are converted to the luminance and color data defined in the LUT (lookup table). And the gradation values 236 to 255 represent the transparency when the external video input from the external video input terminal 30 and the main video are mixed and displayed.
[0062]
Here, the transparency is an index called α, and as an example, as shown in FIG. 13B, 20 levels of α [x] (x = 0.1,..., 19) can be set.
Specifically, as an example, the state from the state in which the external video is completely transparent and only the main video is visible (α = 0) to the state in which the external video is completely opaque and the main video is hidden (α = 1) are equal. 20 steps can be set. That is, the result obtained by mixing the external video with the weight α and the main video with the weight (1−α) is output as a video output.
[0063]
FIG. 14 shows the state of the screen when this is used. FIG. 14 shows that a mixed image 670 is obtained when an external image 660 is given to a main image 650. This is, for example, the case where the gradation value 255 is set to α [19] = 1, and the gradation value 255 is set only in the portion corresponding to the area 665 of the external video 660 in the output image memory 140. It is a state.
[0064]
FIG. 12 shows the configuration of the superimposing means 190a. In FIG. 12, 230 is a detecting means, 250a is a look-up table, and 260 is an image processing means.
The image data read from the output image memory 140 in parallel and the main video data output by the selection means 170 are input to the image processing means 260 as read values. An external video is also input to this. When a special value is found in the image data by the detection means 230, the lookup table 25a is drawn, and the image data is replaced with the value thus drawn and output. The OSD data is superimposed on the position as in the second embodiment.
[0065]
However, the difference is that when the special value is transparency, the main video data and the external video are mixed according to the specified transparency.
In the moving picture decoding method according to the third embodiment, as in the second embodiment, the output image memory 140 is used to store the OSD display data, and the special value 0 To 15 are used, so that not only can two or more brightness and color expressions be displayed as OSD, but also the main video data and the external video are mixed at a specified ratio. The effect that the OSD display with a higher degree of freedom becomes possible is obtained.
[0066]
In the above embodiment, the special value is selected from 0 to 15; however, the present invention is not limited to 16 gradations and can be arbitrarily selected. In particular, as shown in FIG. 10, not only the lower end of the gradation value but also, as an example, the upper end such as 236 to 255 may be selected as a special value. Further, a special value may be selected only for the upper end. Further, the assignment of the transparency and the LUT in the gradation value is not limited to that shown in FIG. 13 and may be arbitrarily selected.
[0067]
In all of the above-described embodiments, the data of the moving image stream is not limited to the data coded according to the MPEG2 standard. Of course, it can be applied to an image reproducing method.
[0068]
Further, in all of the above embodiments, the data of the moving image stream is not limited to only the image data, and can be applied to a method of reproducing a moving image accompanied by audio data. is there.
[0069]
【The invention's effect】
As described above, according to the moving picture decoding method and the apparatus according to the present invention, the output picture memory is also used as the storage location of the OSD data. There is no need to provide a memory, and the effect that the price of the device can be reduced can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a moving image reproducing device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of a synthesizing unit 160 according to Embodiment 1 of the present invention.
FIG. 3 is an explanatory diagram of pixel values of an output image memory 140 according to the first embodiment of the present invention.
FIG. 4 is an enlarged view of an output image memory 140 according to the first embodiment of the present invention.
FIG. 5 is an explanatory diagram of a reference image memory, an output image memory, and a video output according to the first embodiment of the present invention.
FIG. 6 is an explanatory diagram of a moving image reproducing device according to a second embodiment of the present invention.
FIG. 7 is an explanatory diagram of a synthesizing unit 160a according to the second embodiment of the present invention.
FIG. 8 is an explanatory diagram of a superimposing unit 190a according to the second embodiment of the present invention.
FIG. 9 is an explanatory diagram of pixel values of an output image memory 140 according to Embodiment 2 of the present invention.
FIG. 10 is an explanatory diagram of pixel values of an output image memory 140 according to Embodiment 2 of the present invention.
FIG. 11 is an explanatory diagram of a moving image reproducing device according to a third embodiment of the present invention.
FIG. 12 is an explanatory diagram of a superimposing unit 190b according to the third embodiment of the present invention.
FIG. 13 is an explanatory diagram of pixel values of an output image memory 140 according to Embodiment 3 of the present invention.
FIG. 14 is an explanatory diagram of video output in Embodiment 3 of the present invention.
FIG. 15 is an explanatory diagram of a conventional moving image reproducing apparatus.
FIG. 16 is an explanatory diagram of video output of a conventional moving image reproducing apparatus.
FIG. 17 is an explanatory diagram of the MPEG2 standard.
FIG. 18 is an explanatory diagram relating to image data and arrangement of an image memory of a conventional moving image reproducing apparatus.
[Explanation of symbols]
10, 30, 410 input terminals
20, 420 output terminal
30a, 30b pixels
50, 450 Host controller
110, 510 decoding means
120, 520 control means
130, 530 Reference image memory
140, 540 Output image memory
550 OSD image memory
160, 160a Synthesizing means
170, 570 selection means
180, 180a Special value setting means
190, 190a, 190b, 590 Superposition means
200, 200a, 230 detecting means
210, 210a, 240 replacement means
250, 250a lookup table
260 image processing means
600, 650 Main video
610 OSD image
620 Image after superimposition
660 External input image
665 Specific area of external input image
670 Mixed image

Claims (9)

In a decoding method for inputting a stream obtained by predictively encoding a moving image and decoding the stream,
A reference image memory for storing a reference image used when performing the decoding,
An output image memory that stores an output image decoded with reference to the reference image memory,
When decoding the stream,
The decoded output image data is used as a special value for at least one gradation value, corrected to an approximate value so as not to take the value, and stored in the output image memory.
On-screen display data is stored in the output image memory as the special value,
A moving picture decoding method characterized by the above-mentioned. The moving picture decoding method according to claim 1,
The special value is either 0 or the maximum representable value.
A moving picture decoding method characterized by the above-mentioned. The moving picture decoding method according to claim 1,
The special value is 0 and a maximum representable value.
A moving picture decoding method characterized by the above-mentioned. The moving picture decoding method according to any one of claims 1 to 3,
The prediction encoding method is the MPEG method.
A moving picture decoding method characterized by the above-mentioned. Decoding means for receiving a stream obtained by predictively encoding a digital moving image and decoding the stream,
A reference image memory for storing the first decoded image obtained at the time of decoding as a reference image,
An output image memory for storing a second decoded image obtained at the time of decoding as an output image,
The output of the output image memory and the output of the decoding unit are input, and the second decoded image data output by the decoding unit is converted into a special value group for at least one gradation value. Synthesizing means for correcting the output value to an approximate value so as not to take the value, synthesizing the output of the output image memory and the output of the decoding means, and outputting the synthesized image data to the output image memory When,
Superimposing means for superimposing on-screen display data on the output image data, a digital video decoding device comprising:
The combining means includes:
Prior to storing the second decoded image, the output image memory is read out, and for an image region in which the special value group is detected, the special value group is stored as it is, and the image in which the special value group is not detected is stored. For an area, by storing the read value, the on-screen display data is stored in the output image memory as the special value group,
A moving picture decoding apparatus characterized in that: The moving picture decoding apparatus according to claim 5,
The superimposing means receives an output of the output image memory and an output of the reference image memory as inputs,
When outputting the content of the output image memory, or the content of the reference image memory, the content of the output image memory, only for an image area in which a special value group is detected, brightness and color data set in advance. Output
A moving picture decoding apparatus characterized in that: The moving picture decoding apparatus according to claim 5,
The superimposing means receives an output of the output image memory, an output of the reference image memory, and external video data as inputs,
When outputting either the output of the output image memory, or the output of the reference image memory as a selected video, the contents of the output image memory, only for the image area in which the special value group is detected, Generate and output video data in which the selected video and the external video are mixed with a preset transparency, and for an image region in which the special value group is not detected, output the selected video as it is.
A moving picture decoding apparatus characterized in that: The moving picture decoding apparatus according to claim 5,
The superimposing means receives the output of the output image memory, the output of the reference image memory, and the external video data as inputs,
When one of the output of the output image memory and the output of the reference image memory is output as a selected video, the contents of the output image memory are displayed in an image area in which a first special value group is detected. For, generating and outputting video data in which the selected video and the external video are mixed with a preset transparency,
For an image area in which the first special value group is not detected, the selected video is output as it is,
For the image area in which the second special value group has been detected, the image data is replaced with a preset luminance and color data and output.
A moving picture decoding apparatus characterized in that: The moving picture decoding method according to any one of claims 5 to 8,
The prediction encoding method is the MPEG method.
A moving picture decoding method characterized by the above-mentioned.

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