JP3879219B2 - Digital video transfer system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital moving image transfer method, and more particularly to a transfer method capable of displaying an interlaced digital moving image.
[0002]
[Prior art]
When displaying interlaced digital moving images, when transferring data from a data storage device (memory, hard disk, etc.) to the display memory, the processing method is also used in the normal procedure. If not changed, the following problems may occur.
The image used for display and the image to be transferred are overtaken as addresses in the memory, and as a result, the actually visible image is cut off halfway. This occurs when the content of the upper half is a new image and the lower half is an old image in one field screen, which is the basic unit of an interlaced image.
[0003]
In order to prevent overtaking in odd and even fields, if the process of waiting for transfer timing is performed, the display order of the paired fields will change, and it will be displayed at the same time as the other pair of one field old For this reason, the time axis advances only by one field, and the blurring increases when an object with intense movement is displayed.
[0004]
[Problems to be solved by the invention]
As mentioned above, when the data transfer speed cannot keep up with the display speed of the interlaced digital moving image display means, the image may be cut off in the middle, or the field combination may change and blurring may occur. Inconvenience is born.
[0005]
The present invention solves this problem, and prevents digital images in a single field screen from being cut off in the middle or an error in the combination of fields in a relatively simple manner. An object is to provide an image transfer method.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention transfers digital moving image data to be displayed from an auxiliary storage device to a frame memory for display means for displaying moving images in an interlaced manner in which one frame consists of two fields. in the transfer method of the digital video having a transfer means for the digital video data transfer means 1 field, longer than the scanning duration of one field of the display means, and the scanning time length of one field of the display means Is transferred to the frame memory in a time shorter than 1.5 times, and the transfer of the first field of this time is started at the display start timing of the second field of the previous transfer, and the display end timing of the second field of the previous transfer is started. If the first field transfer of this time has not been completed by this time, the second field of this time will be continued following the end of this first field transfer. Begins forwarding Rudo, starts the transfer of the next first field in the timing of the display start of the first second field after the transfer completion of the second field of the current frame memory is digital video for two fields It has a data storage capacity, and holds the digital moving image data of the current first field even after the transfer of the current second field .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a digital moving image transfer method according to the present invention will be described in detail with reference to the accompanying drawings.
Consider a case in which digital data of an interlaced moving image is transferred from a memory or a hard disk to a display frame memory in real time and displayed as a moving image as shown in FIG.
[0008]
FIG. 1 is a block diagram showing a configuration in this case. 1 is a CPU, 2 is a memory, 3 is an auxiliary storage device such as a hard disk, 4 is a graphic chip for performing image processing, and 5 is a frame memory for image display. A graphic memory, 6 is a monitor device for displaying, and 7 is a system bus.
If the memory 2, CPU 1, hard disk 3, and bus 7 have speeds sufficient to transfer moving image data, they can be transferred and displayed at the timing shown in FIG. 2.
In this figure, a rough shaded area represents an image of a 1st (first) field, and a fine shaded area represents an image of a 2nd (second) field.
The display memory is a single buffer (having an amount enough to store data for one screen necessary for display).
[0009]
In the interlaced image, one screen is composed of two screens of 1st field, 2nd field, and scanning twice. In this drawing method, it is necessary to avoid overtaking so that the addresses for accessing the transferred data and the data used for drawing do not coincide with each other in the display memory 5 as much as possible. This is because if the image is transferred and written in the vicinity of the address used for display, the image displayed on the monitor device 6 is cut before and after the address.
[0010]
In order to prevent this, in many cases, the transfer of the 1st field image is performed while the 2nd field is displayed, and the transfer of the 2nd field image is performed when the 1st field is displayed. In addition, the transfer and display are processed at opposite times so that the transfer operation is not visible on the monitor TV.
[0011]
FIG. 2 is a time chart showing the state of this transfer process. For the V synchronization signal (a), the 1st and 2nd fields are alternately displayed as shown in FIG. In the time zone opposite to this display timing, digital data is transferred from the storage device as shown in FIG. That is, the transfer of the 1st field is started at the display start timing of the 2nd field. Therefore, the transferred data is actually displayed at a time one field later.
In FIG. 2, since the transfer time is sufficiently faster than the display, the transfer timing of each field can be sequentially performed after the display start of the opposite field.
[0012]
Here, consider a case in which the amount of data to be transferred is large as shown in FIG. 3 and the transfer for one field exceeds the time for one field.
In such a case, as in FIG. 2, if the transfer timing is waited for the display of the reverse field, the result is as shown in FIG. At this time, until the paired 1st and 2nd images have been stored in the memory, an image one field old remains in the portion indicated by (B) in FIG. 3D, and as a result, the pair collapses. . In the case of an interlaced image, if the image moves rapidly, such a state will be greatly blurred when viewed on a monitor. This is because an old image is displayed even though the position is originally advanced in time.
[0013]
Therefore, in the present invention, a transfer method as shown in FIG. 4 has been developed. The following discussion is effective when the transfer time of one field of image data is longer than the scanning time length (field period) of one field and is at most 150% of the scanning time length of one field. is there.
In this method, the display field timing is read immediately after the transfer of the 1st field image. By checking the read timing, it is possible to know whether or not the transfer was possible in the field.
[0014]
In the case of FIG. 4, at the time point (C) in FIG. 4 (c) immediately after the transfer of the image of the 1st field, the display timing of the odd number (1st) has already been reached in FIG. Therefore, it can be seen that the next field has been consumed. Therefore, when it is determined that the time has not been met, the transfer of the paired 2nd field is started immediately without waiting for the start of the next field. By doing so, an old image is not displayed as shown in FIG. 3, so that the fields are continued in correct pairs.
At this time, the field to be transferred and the field to be displayed coincide with each other, but since the drawing time and the point to be transferred are deviated, problems such as overtaking will not occur. be able to.
[0015]
Details of the timing at point A in FIG. 4 are shown in FIG. Since a new image has already been written with respect to the scanning timing of time point A on the screen, there is no overtaking problem that an old image appears. Since all of the image data to be transferred has been transferred before the 2nd field is displayed, it is not caught up with the display timing, and it can be seen that a new 2nd field image is always displayed on the monitor.
[0016]
When such a method is adopted, two drawing methods can be considered in consideration of the transfer order of data from the storage device (memory, hard disk, etc.).
Assume that image data is stored as shown in FIG. When the transfer is not in time as shown in FIG. 4 and the method of skipping stored data every other frame (2 fields) as shown in FIG. 6B, the prepared image is skipped. The image is reproduced at the same time as when it was recorded.
On the other hand, if all the data is transferred in the order of the stored data as shown in FIG. 6C, it takes twice as long as the recorded time and is displayed at 1/2 speed.
[0017]
It should be possible for the user to select which method to use depending on the nature of the image.
For example, when data such as voice is accompanied, it is better to adopt the method of FIG. 6B in order to synchronize the data. In addition, it is considered that it is preferable to perform drawing by the method shown in FIG. 6C in which all data is displayed for the purpose of research and analysis using images.
[0018]
Such a method is particularly effective when drawing a frame-rendered work in computer graphics (CG). The frame-rendered image has a fixed movement in the frame, and there is no position shift between the 1st field and the 2nd field image, so even if it is a still image, there is no blurring peculiar to interlaced images. Is possible.
When this method is used to connect a CG animation that uses this rendering method with a bus or device with a slow transfer speed, it is possible to display a movie animation of a quality that can withstand practical use, even though frames are dropped. .
[0019]
Also, as shown in FIG. 6C, a CG moving image displayed at a half speed is recorded on the VTR, and is reproduced at a double speed by a VTR having a DT (dynamic tracking) function. It is also possible to display in time.
[0020]
Currently, in order to reproduce full-size animations and moving images stored in a hard disk with high image quality, high transfer specifications are required for the hard disk, transfer bus, CPU, memory, and the like used.
However, using the method of the present invention, it is considered that a high-quality image can be obtained even with a low-performance processing apparatus.
[0021]
【The invention's effect】
As described above, according to the first aspect of the present invention, the digital moving image data to be displayed is transferred from the auxiliary storage device to the display means for displaying the moving image by the interlace method in which one frame is composed of two fields. In a digital moving image transfer system comprising transfer means for transferring to a frame memory, the transfer means has one field of digital moving image data longer than the scanning time length of one field of the display means and one field of the display means. Is transferred to the frame memory in a time shorter than 1.5 times the scanning time length, and the transfer of the first field of this time is started at the display start timing of the second field of the previous transfer. If the current first field transfer is not completed by the display end timing, the current first field transfer will be The second starts field transfer, starts the transfer of the next first field in the timing of the display start of the first second field after the transfer completion of the second field of the current frame memory for two fields It has a storage capacity for digital moving image data, and retains the digital moving image data of the current first field even after the transfer of the current second field . As a result, when the transfer is in time, the rendering and transfer fields are processed in units of each field at a timing that is not affected by each other. Even if the transfer is not in time, the old image is not displayed and the correct pair is used. Since the fields are displayed continuously, there is no occurrence of field discontinuity or time reversal, and smooth display without failure is possible.
[0023]
According to a second aspect of the present invention, when the transfer time of one field of digital moving image data is longer than the scanning time length of one field of the display means, the transfer means stores the digital moving image stored in the auxiliary storage device. The data is transferred to the display means every other frame. As a result, the image data is skipped when the transfer time of the digital moving image data is longer than the scanning time length, but the image can be reproduced in the same time as when it was recorded.
[0024]
According to the fourth aspect of the present invention, when the transfer speed of the digital moving image data of one field is slower than the display speed of one field of the display means, the transfer of the digital moving image data is reduced to the display time of 2 without data loss. It is characterized by being performed twice as long.
Thereby, when the transfer speed of the digital moving image data is slower than the display speed, the display speed is halved, but the recorded image data can be displayed without loss.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration when digital data of an interlaced moving image is transferred and displayed.
FIG. 2 is a transfer time chart when the transfer system has a speed at which moving image data can be transferred sufficiently.
FIG. 3 is a time chart of transfer when a problem occurs because the transfer system does not have sufficient speed to transfer moving image data.
FIG. 4 is a time chart of transfer according to an embodiment of the present invention.
5 is an explanatory diagram showing a relationship between a scanning position and a transfer position in the embodiment of FIG.
FIG. 6 is an explanatory diagram showing the relationship between accumulated data and display data in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... CPU, 2 ... Memory, 3 ... Auxiliary storage device, 4 ... Graphic chip, 5 ... Graphic memory, 6 ... Monitor apparatus, 7 ... System bus.

Claims (2)

Transfer of digital moving image provided with transfer means for transferring digital moving image data to be displayed from an auxiliary storage device to a frame memory for display means for displaying a moving image in an interlaced manner in which one frame is composed of two fields In the method,
The transfer means transfers the digital moving image data of one field in a time longer than the scanning time length of one field of the display means and shorter than 1.5 times the scanning time length of one field of the display means. Transfer to the frame memory, start the transfer of the first field of this time at the start of the display of the second field of the previous transfer, and complete the transfer of the first field of this time by the end of the display of the second field of the previous transfer If not, the transfer of the second field of this time is started following the end of the transfer of the first field of this time, and the display of the first second field after the transfer of the second field of current time is started. Start the transfer of one field ,
The frame memory has a storage capacity of the digital moving image data for two fields, and holds the digital moving image data of the current first field even after the transfer of the current second field is completed. Video transfer method. When the transfer time of one field of digital moving image data is longer than the scanning time length of one field of the display means, the transfer means stores the digital moving image data stored in the auxiliary storage device every other frame. 2. The digital moving image transfer system according to claim 1, wherein the transfer is performed to the display means .

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