JP3073948B2 - Digital video decoding apparatus and digital video decoding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital moving picture decoding apparatus for decoding image data coded by using variable length coding for digital storage media or broadcasting and communication, and a digital moving picture decoding apparatus. More particularly, the present invention relates to a digital video decoding apparatus and a digital video decoding method for decoding and reproducing coded data that has become discontinuous during reproduction due to program switching or the like without error. It is.

[0002]

BACKGROUND OF THE INVENTION The demand for general-purpose encoding of moving images and associated sounds for a variety of applications, including digital storage media or television broadcasting and communications, has increased and the International Standards Organization (ISO) International Moving Picture Experts Group (MPE) of the Standards Council (IEC)
G), the international standardization of the moving picture coding system is promoted, and ISO / IEC 13818-2 (MPEG2 video) and the like are standardized.

[0003] As an example of the prior art, for example, an MPE as disclosed in Japanese Patent Application Laid-Open No. 8-32927 is disclosed.
A digital video decoding device that decodes data encoded by the G encoding method will be described with reference to FIG.
Reference numeral 900 denotes a conventional digital video decoding device,
Reference numeral 11 denotes an input of an encoded video stream corresponding to a plurality of encoded programs, and selects and encodes a bit stream corresponding to one of the plurality of programs according to a program selection signal input by a user. Channel selection means for outputting as coded image data 901 and at the same time, outputting a program switching signal. The output coded image data 901 passes through a code pattern detection unit 903 to be described later and passes through an input buffer memory 902.
Is accumulated in

[0004] The code pattern detecting means 903 uses the switching detection signal from the coded data switching detecting means 904 to add a GOP (Group of picture) of a predetermined code pattern to the coded image data 901. This block prohibits data passage to the input buffer memory 902 until a picture is detected, and is in a data passage permitted state during normal reproduction.

[0005] Decoding means 905 issues a data request to the input buffer memory 902, and the obtained data is subjected to decoding processing and sequentially stored in a predetermined reproduction image area in a reproduction image memory 907. You. The display image determining unit 906 determines the playback image to be displayed based on the time information of each playback image and the data area information in the playback image memory 907 from the time information management unit 908 and the playback image area management unit 909. , And output as reproduction image data 910 to realize reproduction display.

Next, a description will be given of the operation of the above-described configuration when the normal playback mode is shifted to the special playback mode in which the playback speed is changed to perform high-speed playback.
When a user requests high-speed reproduction, the encoded image data 9
01 is a format in which an intra-frame coded image (I picture) is converted from a bit stream recorded on a recording medium.
Only the I picture is taken out and sent to the code pattern detecting means 903. By detecting the continuous pattern of the I picture, the shift to the special reproduction mode is detected. Then, the transfer of data to the input buffer memory 902 is stopped, and the code pattern detecting means 903 is stopped.
Outputs a clear signal to the input buffer memory 902, and the data stored in the input buffer memory 902 at that time is erased.

[0007] When the normal pattern is detected again by the code pattern detecting means 903, it is recognized that the special reproduction mode has been released, the blue-back processing described later is released, and the data transfer to the input buffer memory 902 is stopped. Will be resumed.

Next, the operation of the above-described configuration in the case where the coded data being reproduced becomes discontinuous in the middle due to a program change or the like will be described. When the encoded data switching detection means 904 detects that the switching of the encoded data inputted by the program switching detection signal has been performed, it sends a clear signal to the input buffer memory 902 and at that time, the input buffer memory 902 At the same time as clearing all the stored data, a data passage prohibition signal is sent to the code pattern detecting means 903 until the start code (I picture) of the intra-frame coded image is detected by the code pattern detecting means 903. , The passage of data to the input buffer memory 902 is prohibited.

At this time, as shown in FIG. 6, after switching the coded data, a blank image (Bu picture) is inserted following the bidirectional predictive coded image (B picture) B3, and the entire screen becomes blue. Such a blue-back process is performed.

[0010] When the start code (I picture) of the intra-frame coded image is detected from the coded image data after switching by the code pattern detecting means 903, the data passes through the input buffer memory 902 again. The permission is granted, the blue-back processing is released, and the reproduction operation is restarted.

By performing the above-described processing, it is possible to prevent a reference image error due to the concatenation of different data strings before and after the switching of the encoded data, and to prevent the reference image from remaining in the buffer when the encoded image data is switched. It is configured not to decode the data that is being read.

[0012]

The conventional digital video decoding apparatus and digital video decoding method are constructed as described above, and different data strings are connected before and after switching of the encoded data. Has a configuration to prevent the reference image error due to the fact that when the coded data is switched to change the program, etc.
There is a problem that a viewer may feel uncomfortable, for example, a blue screen is displayed for a certain period of time.

In the case where the switching of the encoded data is not performed in units of one image data, and the input encoded data is switched while the decoding means 905 is decoding one image data, FIG. As shown in FIG. 8A, when a program switching operation occurs during the decryption processing, FIG.
As shown in (b), in the decoding processing by the decoding means, a state similar to that in which different data strings are concatenated and input is obtained, a decoding error occurs, and a remarkable display disturbance due to an error image occurs. There was a problem.

As shown in FIG. 5, the structure of encoded data encoded by a method using bidirectional encoding such as the MPEG method is based on the arrangement order of image data in the encoded data,
The display order is different from the display order at the time of reproducing the image. For this reason, at the time of the decoding processing of the bidirectional predictive coded image (B picture), the forward predictive coded image (P Picture), and the decoded data is stored in the playback image memory. For this reason,
As shown in FIG. 6, when the input coded image data is switched, the decoding processing has already been completed, but the display time has not yet been reached and the undisplayed reproduced image data (P6
) Is stored in the playback image memory 907,
In a configuration that only clears the input buffer memory in the previous stage, when the display time according to the time information of the reproduced image is reached, the reproduced image data is displayed,
When the display time interval between the reproduced images is long, it takes time until the unnecessary reproduced image data (P6) is displayed, and the switching processing time of the encoded image data being reproduced becomes longer. There is a problem in that the display time is prolonged, giving the viewer a sense of discomfort.

[0015] The present invention has been made to solve the above-described problems, and when a coded data is switched for a change of a program or the like, a blue-back screen is displayed or the like. It is an object of the present invention to provide a digital video decoding device and a digital video decoding method in which a person who does not feel uncomfortable.

Further, even if the input coded data is switched during the decoding process of one image data instead of switching the coded data in units of one image data, no decoding error occurs. It is an object of the present invention to provide a digital video decoding device and a digital video decoding method.

Further, at the time when the encoded image data is switched, decoding of one image data which has not yet reached the display time according to the time information determined in units of one display image has already been completed, and the reproduced image is reproduced. Even when the image data is stored in the image memory, it takes time to display the unnecessary reproduced image data, and the digital moving image decoding does not increase the switching time of the encoded image data being reproduced. It is an object to provide a decoding device and a digital video decoding method.

[0018]

According to a first aspect of the present invention, there is provided a digital moving picture decoding apparatus comprising: an input buffer memory for storing coded data before decoding; and a reproducing apparatus for storing image data after decoding and before display. In a digital moving picture decoding apparatus comprising an image memory and a display image determining means for determining a reproduced image to be output among the image data stored in the reproduced image memory, the type of the encoded data before decoding , A program switching detecting means for receiving the output of the program switching means and detecting that the type of coded data before decoding has been switched, and receiving the output of the program switching detecting means and When it is detected that the type of the coded data has changed and its time-series continuity has been lost, the current display is performed by the display image determining means. To hold the display state of that reproduction image is obtained by a display state maintaining means for controlling the output image data from the reproduced image memory.

According to a second aspect of the present invention, there is provided a digital video decoding apparatus according to the first aspect, wherein the program switching detecting means comprises: A difference between a normal reproduction state and a program switching state or a reproduction state at a speed different from the normal reproduction speed is detected.

According to a third aspect of the present invention, in the digital video decoding apparatus according to the first aspect, the data at the time of decoding is chronologically changed by the program switching detecting means. An input buffer memory erasing means for erasing coded data before decoding stored in the input buffer memory when it is detected that the data is not continuous.

According to a fourth aspect of the present invention, there is provided a digital video decoding apparatus comprising: an input buffer memory for storing encoded data before decoding; a reproduced image memory for storing image data before display after decoding; In a digital moving picture decoding apparatus having a display image determining means for determining a reproduced image to be output from image data stored in the reproduced image memory, program switching for switching the type of encoded data before decoding is performed. Means, program switching detecting means for receiving the output of the program switching means and detecting that the type of coded data before decoding has been switched, and receiving the output of the program switching detecting means for the coded data before decoding. Of the data stored in the reproduction image memory when it is detected that the type of Those having a reproduced image memory invalidation means for invalidating the data other than the corresponding data in the reproduced image that is currently displayed.

According to a fifth aspect of the present invention, there is provided the digital moving picture decoding apparatus according to the fourth aspect, wherein the image data decoded by the decoding means is stored in the reproduced picture memory. A reproduction image area management means for managing memory area information when writing in the reproduction image memory invalidating means is provided. In this case, memory area information corresponding to data other than the data corresponding to is deleted.

According to a sixth aspect of the present invention, in the digital moving picture decoding apparatus according to the fourth aspect, the reproduced picture memory invalidating means includes: The data other than the data corresponding to the currently displayed reproduced image is deleted.

According to a seventh aspect of the present invention, in the digital moving picture decoding apparatus according to the fourth aspect, the digital moving picture decoding apparatus further comprises: This is to write the decoded image data.

Further, a digital video decoding apparatus according to claim 8 of the present invention comprises: an input buffer memory for storing encoded data before decoding; a reproduced image memory for storing image data before display after decoding; In a digital moving picture decoding apparatus having a display image determining means for determining a reproduced image to be output from image data stored in the reproduced image memory, program switching for switching the type of encoded data before decoding is performed. Means, program switching detecting means for receiving the output of the program switching means and detecting that the type of coded data before decoding has been switched, and receiving the output of the program switching detecting means for the coded data before decoding. If it is detected that the type has changed and its chronological continuity has been lost, the decoding processing by the decoding means is stopped, and As decoded completed data the data in the middle of decoding have those having a decoding stop means for controlling the decoding means so as to write in the reproduced image memory.

A digital moving picture decoding method according to a ninth aspect of the present invention is a digital moving picture decoding method comprising: a first step of detecting whether data at the time of decoding is continuous in time series; A second step of maintaining the display state of the currently displayed reproduced image when it is determined that the data is not continuous in time series.

In a digital moving picture decoding method according to a tenth aspect of the present invention, a first step of detecting whether or not data at the time of decoding is continuous in time series, If it is determined that the data is not continuous in time series, the data other than the data corresponding to the currently displayed playback image is invalidated.
Step.

Further, in the digital moving picture decoding method according to the present invention, in the digital moving picture decoding method according to the tenth aspect, the data at the time of decoding in the first step is time-series. If it is determined that the data is not continuous, the decoding process is stopped, and a third step of processing data that is being decoded at that time as decoded data is included.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a digital video decoding apparatus and a digital video decoding method according to the present invention will be described with reference to the drawings. Embodiment 1 FIG. FIG. 1 shows a block diagram of a digital video decoding apparatus according to Embodiment 1 of the present invention. In the figure, reference numeral 100 denotes a digital moving picture decoding apparatus of the present invention, 104 denotes an input of an encoded video stream corresponding to a plurality of encoded programs, and a program selection input by a user through a control means (remote control) 111. This is a program switching detecting means for selecting a bit stream corresponding to one of the plurality of programs according to a signal and outputting the selected bit stream as encoded image data 101.

During a normal decoding operation, the input coded image data 101 passes through a code pattern detecting means 103, which will be described later, and is stored in an input buffer memory 102.

The input buffer memory 102 has, for example, 4
It has a relatively large size of about 00 Kb and outputs coded data stored in response to a request from the decoding means 105 described later.

The decoding means 105 manages the amount of data in the input buffer memory 102 based on the amount of data input to the means and the amount of data output, and calculates the amount of data stored in the input buffer memory 102. The input of data to itself is controlled accordingly. The decoding means 105 also has a reproduced image memory address management table for managing a free address when writing the decoded image data to a reproduced image memory 107 described later.

The code pattern detecting means 103 is a block for prohibiting data passing to the input buffer memory 102 until a predetermined code pattern is detected by the data passing prohibiting signal from the program switching detecting means 104. The inside is in a data passing permission state.

The reproduced image memory 107 is, for example, an SDRAM
And the like, and has regions M0 to M2 divided into a capacity (500 Kb × 3 = 1.5 Mb) for storing image data for three frames. The decoded coded image data is stored in one of the reproduced image areas M0 to M2 in the reproduced image memory 107 in units of one display image.

The display image determining means 106 includes a reference time counter that counts up with time accuracy equal to or higher than the time accuracy of time information determined in units of one frame image by the time information managing means 108 described later. The reference time counter manages the reference time for the reproducing operation. When a reference time information signal is inputted from the decoding means 105, the value of the reference time counter is updated to the reference time information. Then, the value of the reference time counter is compared with the value of the time information from the reproduced image area management means 109, which will be described later, and when it is determined that they match or approximate to each other, based on the accumulated information from the reproduced image area management means 109, hand,
The playback image area to be output is determined, and an output playback image area selection signal for outputting decoded data of the area is output to the playback image memory 107 and the playback image area management unit 109.

Reference numeral 109 denotes a reproduced image area management unit which stores the decoded image data in the reproduced image memory 107, respectively.
1 is associated with a display state flag fed back from the display image determining means 106, which will be described later.
It is managed using a table as shown in FIG.

In the above configuration, the control means (remote control) 111 implements a program switching means, and the program change detection means 104 detects that a program has been switched in response to a program selection signal from the control means (remote control) 111. Program switching detecting means to execute, and input buffer memory 1
02, an input buffer memory erasing means for erasing the data stored in the storage area 02, a display state holding means realized by the display image determining means 106 and the reproduced image area managing means 109, and the program switching detecting means 104 and the reproduced image area The management means 109 implements a reproduced image memory invalidating means and a decoding stopping means.

FIGS. 2 to 4 are flowcharts showing the processing of the digital video decoding apparatus.
Hereinafter, the operation will be described with reference to this flowchart. First, it is assumed that a predetermined program is currently selected by a user input and the image data stored in the reproduced image area M1 among the image data stored in the reproduced image memory 107 is being reproduced. .

Next, with reference to the block diagram of FIG. 1 and the flowchart of FIG. 2, the operation when the encoded data is switched during reproduction due to the program switching and the data sequence to be decoded is discontinuous in the middle. It will be explained while doing.

During reproduction, in step S1, the program to be reproduced is changed by the control means (remote controller) 111,
By outputting a program selection signal for switching the encoded data to be reproduced to the program switching detecting means 104, the program switching process during reproduction is started.

Then, in step S2, immediately after the program selection signal is inputted, the program switching detecting means 104 instructs the code pattern detecting means 103 to pass the data which inhibits the passage of the encoded data until a predetermined code is detected. Output a prohibition signal, and output a data clear signal to the input buffer memory 102 to clear all data currently stored in the input buffer memory 102;
A decoding process stop signal for stopping the decoding process currently being performed is output to the decoding unit 105, and the data of an area other than the currently displayed playback image area is output to the playback image area management unit 109. At the same time.

Thereafter, the program switching detecting means 104
From among a plurality of input program stream data strings, coded data of a program based on a program selection signal from the control means (remote control) 111 is selected, and the coded data is output to a code pattern detecting means 103. Start.

The code pattern detecting means 103 inhibits the input coded data from passing through the input buffer memory 102 by the input of the data passage prohibition signal.
It is in a state of waiting for input of a sequence header code in the EG format encoded data. Also, the input buffer memory 102
Is set to a state of waiting for data input from the code pattern detecting means 103 after clearing all accumulated data by input of a data clear signal.

The decoding means 105 stops the currently executing decoding processing in response to the input of the decoding stop signal, and waits for the input of a sequence header code. afterwards,
A data request signal for new encoded data is output to the input buffer memory 102.

In step S3, when data is input, it is checked whether the data is a sequence header code. If the data is other than the sequence header code, the data is discarded. In the same manner, whether or not it is a sequence header code is confirmed. The process of step S3 is repeated until a sequence header code is input.

As described above, when the program is switched, the decoding process is immediately stopped, so that in the digital video decoding apparatus having the conventional configuration, different data strings are connected to the decoding means and input. As a result, a decoding error occurs, and a significant display disturbance due to an error image display does not occur, so that the viewer does not feel discomfort.

The reproduction image area management means 109 clears data in the reproduction image memory 107 other than the reproduction image area currently used for display output in the reproduction image memory 107 by the flag erasure signal. Specifically, the flag is rewritten so that information other than the information corresponding to the reproduced image area M1 in the data stored information in the reproduced image memory 107 is set to "no data". By this processing, the unnecessary reproduced image data, which has been generated in the digital video decoding device having the conventional configuration, is displayed, and from the occurrence of switching of the input encoded image data to the switching of the reproduced image. The problem of longer time will be solved.

Further, at the same time as clearing the data in the reproduced image memory 107, the data storage information and the time information notification signal, which are the contents of the reproduced image area state table updated to the state after the data clear, are sent to the display image determining means 106. Is output.

The display image determining means 106 detects from the data storage information and the time information notification signal from the reproduction image area management means 109 that there is no data other than the reproduction image area currently used for display output. Even when it is time to display the next image, there is no data other than the playback image area currently used for output, so the playback playback image area selection signal that instructs to repeatedly output the data in the same playback image area is played. Output to the image memory 107. By this process, a blue-back display process (see Bu in FIG. 6) until a new image after switching (see I0 'in FIG. 6), which has occurred in the digital video decoding device having the conventional configuration, can be displayed. And so on, so that the problem that the display transition becomes extremely uncomfortable is solved.

Next, a description will be given of the operation at the time of processing for reproducing and displaying new encoded data after the program is switched.
In step S3, the code pattern detecting means 103
Analyzes the new encoded data from the program switching detection means 104, detects the sequence header code,
When the sequence header code is detected, the flow advances to step S4 to permit the passage of the encoded data to the input buffer memory 102 again.

Thereafter, the process proceeds to step S5, where the accumulation is resumed from the encoded data after the sequence header code in the input buffer memory 102, and the data is output according to the data request signal from the decoding means 105.

In step S6, the decoding means 105 determines whether the coded data contains the display order information of the image for each frame currently being decoded and the time information for displaying the image. , Extracts the information from the encoded data, and outputs an extracted information signal for notifying the time information management unit 108 of the information. At this time, if there is no time information in the encoded data at which the image of one frame unit currently being decoded is to be displayed, only the display order information is output to the time information management unit 108 as an extraction information signal. . Further, when reference time information is included in the encoded data, the decoding unit 105 extracts the information from the encoded data and outputs the information to the display image determination unit 106 as a reference time information signal.

Thereafter, the operation at the time of normal reproduction is performed.
As shown in the flowchart of FIG. 7, in step 7, the decoding means 105 determines whether or not the input coded data is data of the predictive coding method. A reference image data request signal for requesting image data;
9 is output. Here, when the input encoded data is not data of the predictive encoding method, the decoding process is performed only with the input encoded data.

In step S9, the reproduction image area management means 109 checks which reproduction image area in the reproduction image memory 107 has the requested reference image data, and in step S10, the reproduction image area management means 1
09 outputs a reference image data output control signal for instructing to output data of the determined area as reference image data.

Then, in step S11, the reproduced image memory 107 outputs the data of the designated area as reference image data according to the instruction of the reference image data output control signal.

Then, in step S12, the decoding means 105 starts decoding the coded data of the predictive coding method using the input reference image data.

Then, in step S12-1, the decoding means 105 outputs the decoded data after the decoding process to the reproduced image memory 107. At this time, the reproduced image area management means 109 outputs an address signal to the reproduced image memory 107 to indicate in which area the decoded data after decoding is to be stored.

If the encoded data currently being decoded contains reference time information, the information is output to the display image determining means 106 as reference time information. Also, the display order information of the one-frame image currently being decoded and the time information at which the image should be displayed are extracted from the encoded data, and the time information management means 1 extracts
08 is output. Here, when the time information is not included in the encoded data, only the display order information is extracted, and the time information management unit 1 is extracted as an extracted information signal.
08.

Next, when an extraction information signal is input in steps S13 to S15 of FIG. 4, the time information management means 108 determines whether or not the time information extracted from the encoded data has been input. However, when the time information is input, the time information is determined as the time information for displaying the one frame image currently being decoded by the decoding means 105, and the reproduced image area management means is output as the time information signal. When the time information is not input, the time information and display order information of another one-frame image previously input from the decoding means 105 and the current decoding means 105 input this time are output. From the display order information of the one-frame image undergoing the decoding process, time information to be displayed of the one-frame image currently undergoing the decoding process is calculated, and And it outputs the reproduced image area management unit 109 as information signal.

Next, in step S16, the reproduced image area management means 109 checks the contents of the managed reproduced image area state table, and clears the decoded data other than the reproduced image area (M1) currently being displayed and output. Decoding means 105 for the reproduced image area (M0, M2)
The new decoded data after the program switching from is output. At the same time, the contents of the reproduction image area state table are updated, and the data accumulation information and the time information notification signal are output to the display image determination means 106.

Next, in step S17, the display image determining means 106 detects that a new image is ready for output based on the data accumulation information and the time information notification signal, and when the time according to the time information of the image is reached, An output reproduction image area selection signal is output so as to output the decoded data in a reproduction image area having the image.

Then, in step S18, the reproduced image memory 107 outputs new decoded data after program switching according to the output reproduced image area selection signal as reproduced image data. By the above processing, the displayed image is switched to the content of the newly selected program.

As described above, according to the first embodiment, when program switching is detected, the input buffer memory 102
To the input buffer memory 1
02 is erased and the display image determination means 106 is controlled to hold the display image at that time. A simple screen is not displayed, and the user's discomfort can be reduced.

When a program change is detected, the area information other than the area currently used for display in the reproduced image memory 107 is cleared to make it a usable free area, so that the coded data change is detected. It is possible to prevent the display of an unnecessary image that is later in time than is performed, and the encoded data after the switching is quickly written to the reproduced image memory 107. In addition, it is possible to reduce the processing time required for displaying the reproduced image of the encoded data after the switching.

When a program change is detected, the decoding process by the decoding means 105 is stopped, and a one-image-data decoding end code is added to the image data being decoded, as shown in FIG. 8C. In addition, the subsequent data sequence of another program is not erroneously recognized as a continuous data sequence in the middle of decoding, so that a decoding error due to erroneous recognition and display of an error image can be prevented.

In the first embodiment described above, the operation in which the code pattern detecting means 103 and the decoding means 105 wait for the detection of the sequence header code after the occurrence of the program switching has been described. Is not limited to the function of detecting the sequence header code as long as it is a function of detecting a code pattern representing MPEG.
Other code patterns, such as a GOP header code of a format or a start code of an intra-frame coded image (I picture), can be used if the image can be reproduced only by the coded data after the detected data. It doesn't matter.

Further, in each of the above embodiments, the configuration in which the code pattern detecting means 103 is arranged at the preceding stage of the input buffer memory 102 has been described.
03 is disposed after the input buffer memory 102, and the input buffer memory 102
The same operation can be performed by a configuration in which data is output as needed in response to a data request from the third unit and data transfer to the subsequent decoding unit 105 is prohibited until the code pattern detection unit 103 detects a predetermined code pattern. Needless to say, there is.

Further, in each of the above-described embodiments, three reproduced image areas are shown in the reproduced image memory 107. However, the number is not limited to three, and the decoded reproduced image data is displayed in the display order. There may be any number of reproduced image areas as long as the number is more than the number that can be displayed according to

In each of the above embodiments, the reproduced image area in the reproduced image memory 107 is shown as a continuous area. However, the structure of the reproduced image memory 107 is not limited to this. A configuration may be adopted in which a memory having a configuration in which data of one reproduced image is divided and stored in a discontinuous area of the reproduced image memory.

Further, in each of the above embodiments, the case where the decoding processing target is the encoded data according to the MPEG system has been described. However, the encoding data to be decoded is the one encoded according to the MPEG system. The present invention is not limited to this, and any encoded data that has been encoded using the bidirectional predictive encoding method may be encoded using an encoding method other than the MPEG method.

The stream data input to the program switching detecting means 104 is not broadcast, and may be configured to read necessary program stream data from a storage medium such as a disk.

Further, in each of the above embodiments, the configuration has been described in which the value of the reference time counter is updated in accordance with the reference time information every time the reference time information is input to the display image determining means 106. It is configured to update for each data only when the first reference time information in the data is input to the display image determining means 106, or to update at any different timing by an external control signal or the like. Is also good.

Further, the reference time information is not updated by the data extracted from the encoded data by the decoding means 105, but an arbitrary value is set to the reference time counter directly from outside. It may be configured.

[0074]

As described above, according to the digital moving picture decoding apparatus and the digital moving picture decoding method of the present invention, when a program change is detected during reproduction, the passage of data to the input buffer memory is prevented. Inhibiting and simultaneously erasing all data in the input buffer memory and controlling the display image determination means to retain the display image at that point in time. There is an effect that an unnatural screen such as a screen is not displayed, and the user's discomfort can be reduced.

When the data in the input buffer memory is cleared when a program change is detected during reproduction, the current display state is held at the same time, and the end code of one image data is input simultaneously by the decoding means. The same processing as that described above is performed, and the decoding processing of one image data is terminated halfway.
By waiting in a state of waiting for detection of a predetermined code pattern, a data sequence before and after switching is not erroneously recognized as a continuous data sequence, thereby preventing a decoding error due to erroneous recognition and displaying an error image. There is an effect that can be realized.

When the data in the input buffer memory is cleared when a program change is detected during the reproduction, the data other than the area currently used for the current display in the reproduced image memory is cleared, and the time is cleared from the time. There is an effect that it is possible to not display the unnecessary image rearward and to shorten the processing time until displaying the reproduced image of the coded data after switching.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a digital video decoding device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a flowchart for explaining an operation at the time of program switching in the digital video decoding device according to the first embodiment.

FIG. 3 is a diagram showing a flowchart for explaining the operation of the decoding means at the time of program switching in the digital video decoding device according to the first embodiment.

FIG. 4 is a flowchart illustrating an operation of reproducing and displaying new encoded data after switching programs in the digital moving picture decoding apparatus according to the first embodiment.

FIG. 5 is a diagram illustrating a configuration example of a bit stream encoded by an encoding method using bidirectional prediction encoding such as the MPEG method.

FIG. 6 is a diagram illustrating an example of the configuration of a bit stream in the case where switching of encoded data input during playback has occurred, and an example of the operation of a digital video decoding device having a conventional configuration.

FIG. 7 is a diagram showing an operation example of the digital video decoding device of the present invention under the conditions shown in FIG. 5;

FIG. 8 is a diagram illustrating a state of a decoding unit when encoded data is switched during decoding of one image data.

FIG. 9 is a block diagram of a digital video decoding device having a conventional configuration.

FIG. 10 is a conceptual diagram of a reproduced image area state table included in the digital video decoding device according to the first embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Digital video decoding device 101 Encoded data 102 Input buffer memory 103 Code pattern detection means 104 Program switching detection means 105 Decoding means 106 Display image determination means 107 Reproduction image memory 108 Time information management means 109 Reproduction image area management means 110 Reproduction image data 111 Control means (remote control)

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/94-5/956 H04N ^7/ 24-7/68

Claims (11)

(57) [Claims] 1. An input buffer memory for storing encoded data before decoding, a reproduced image memory for storing image data before display after decoding, and an image data to be output among image data stored in the reproduced image memory. A digital video decoding device comprising a display image determining means for determining a reproduced image, a program switching means for switching a type of encoded data before decoding, and a code before decoding by receiving an output of the program switching means. Switching means for detecting that the type of the coded data has been switched, and the type of the coded data before decoding has been changed by receiving the output of the program switching detecting means, and the time-series continuity has been lost. Is detected, the output image from the reproduction image memory is held so that the display state of the reproduction image currently displayed by the display image determination means is maintained. A digital video decoding device comprising: a display state holding unit for controlling image data. 2. The digital video decoding apparatus according to claim 1, wherein said program switching detecting means detects a normal playback state and a program switching or a speed different from the normal playback speed based on an output of said program switching means. A digital moving picture decoding apparatus for detecting a difference from a reproduction state in a digital video. 3. The digital video decoding device according to claim 1, wherein when the program switching detection means detects that the data at the time of decoding is not continuous in time series, the data is stored in the input buffer memory. A digital video decoding apparatus comprising input buffer memory erasing means for erasing encoded data before decoding. 4. An input buffer memory for storing encoded data before decoding, a reproduced image memory for storing image data before display after decoding, and an image data to be output among image data stored in the reproduced image memory. A digital video decoding device comprising a display image determining means for determining a reproduced image, a program switching means for switching a type of encoded data before decoding, and a code before decoding by receiving an output of the program switching means. Switching means for detecting that the type of the coded data has been switched, and the type of the coded data before decoding has been changed by receiving the output of the program switching detecting means, and the time-series continuity has been lost. Is detected, invalidates data other than the data corresponding to the currently displayed playback image among the data stored in the playback image memory. A digital moving picture decoding apparatus comprising: a reproduced picture memory invalidating means for converting a moving picture into a decoded picture. 5. The digital moving picture decoding apparatus according to claim 4, wherein said reproduced picture area managing means for managing memory area information when said decoding means writes the decoded image data into said reproduced picture memory. Wherein the reproduced image memory invalidating means deletes memory area information corresponding to data other than the data corresponding to the currently displayed reproduced image stored in the reproduced image area management means. A digital video decoding device characterized by the above-mentioned. 6. A digital moving picture decoding apparatus according to claim 4, wherein said reproduced image memory invalidating means deletes data in said reproduced image memory other than data corresponding to a currently displayed reproduced image. A digital moving picture decoding apparatus characterized in that: 7. The digital moving picture decoding apparatus according to claim 4, wherein the next decoded picture data is written into the invalidated memory area of said reproduced picture memory. Decryption device. 8. An input buffer memory for storing encoded data before decoding, a reproduced image memory for storing decoded image data before display, and an image data to be output among image data stored in the reproduced image memory. A digital moving picture decoding apparatus comprising: a display image determining means for determining a reproduced image; a program switching means for switching a type of encoded data before decoding; Switching means for detecting that the type of the coded data has been switched, and the type of the coded data before decoding has been changed by receiving the output of the program switching detecting means, and the time-series continuity has been lost. Is detected, the decoding processing by the decoding means is stopped, and the data being decoded at the time is regarded as decoded completed data. A digital moving picture decoding apparatus, comprising: decoding stop means for controlling the decoding means so as to write to a reproduced picture memory. 9. The type of encoded data before decoding is switched.
A first step of detecting that the encoded data has not been decoded in the first step.
And a second step of maintaining the display state of the currently displayed reproduced image when detecting that the type has been switched . 10. The type of encoded data before decoding is switched.
A first step of detecting that the encoded data has not been decoded in the first step.
A second step of invalidating data other than the data corresponding to the currently displayed reproduced image when detecting that the type has been switched . 11. The digital moving picture decoding method according to claim 10, wherein when it is determined in the first step that the data at the time of decoding is not continuous in time series, the decoding process is stopped. And a third step of processing data in the middle of decoding at the time as decoded data.