JPH0955918A - Recovering device for moving picture whose frame rate is changed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To convert video data of 30 frames/sec., whose frame rate is changed from an original moving picture, into data of 24 frames/sec., and to equalize the converted frame rate to the original one. SOLUTION: An original data storage means 1 storing the moving picture whose frame rate is changed, a reference point extraction means 2 extracting a reference point for starting conversion in case of conversion, a data conversion means 5 restoring the frame rate based on the extracted reference point and a restored data storage means 6 storing the restored moving picture are provided. The reference point extraction means 2 is composed in detail of a difference calculation means 3 calculating a difference between odd fields between the adjacent frames of the moving picture whose frame rate is changed and the difference between even fields and of a reference point decision means 4 deciding the reference point based on the position of the calculated minimum difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for restoring a frame rate of a moving image whose frame rate is changed.

[0002]

2. Description of the Related Art Recently, a moving image called a video CD
The one recorded in ROM is commercially available and used in a personal computer or a dedicated player. A compression method called MPEG is adopted for converting (hereinafter referred to as encoding) moving image data for a video CD.

When a movie image is recorded on this video CD, the procedure is as follows. The image recorded on the film of a movie is composed of 24 screens (frames) per second, and there is no means to digitize this image as it is. Therefore, once the standard TV standard in Japan, NTSC It is converted to data and recorded on a digital video tape. Converting movie images to NTSC video data is called telecine conversion. Since the film of a movie is about 10 minutes per roll, the telecine-converted video data is edited to join the images. MPEG encoding is performed on the edited video data.

Since an image of NTSC is composed of 30 screens (frames) per second, the frame rate (the number of frames per second) is set to 2 as the main processing of telecine conversion.
There is work to convert from 4 to 30. A method of converting the frame rate is shown in FIG. First, a film frame of 24 frame / sec film data as shown in FIG. 5A is divided into odd-numbered scanning lines (odd fields) and even-numbered scanning lines (even fields). FIG. 5B shows a state in which the fields are divided. Next, the unit of 4 film frames is converted into 5 video frames. Figure 5
As shown in (c), the first film frame is copied to 2 video fields, and the second film frame is copied to 3 video fields by copying odd fields.
The second film frame is converted into two video fields by exchanging the odd field and the even field, and the fourth film frame is converted into the three video field by copying the even field.

[0005]

When the encoding is performed by the above method, the video data shown in FIG. 5 (c) is encoded. Therefore, one frame such as the third frame and the fourth frame is encoded. In addition, the originally different frame data is mixed, and the motion of the video after encoding becomes unnatural. In order to solve such a problem, it is an object of the present invention to provide a device for converting digitized video data of 30 frames / sec into 24 frames / sec so as to have the same frame rate as the original data. To do.

[0006]

Means for Solving the Problems The above-mentioned problems include an original data storage means for storing a moving image whose frame rate has been changed, and a reference point extraction means for extracting a reference point for starting conversion during conversion. The problem is solved by including a data conversion unit that restores the frame rate based on the extracted reference point and a restored data storage unit that stores the restored moving image.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram showing a first embodiment of the present invention. As shown in FIG. 1, the present apparatus includes an original data storage unit 1 that stores a moving image with a changed frame rate, a reference point extraction unit 2 that extracts a reference point for starting conversion at the time of conversion, and an extraction. The data conversion means 5 for restoring the frame rate and the restored data storage means 6 for storing the restored moving image on the basis of the selected reference points.
It is composed of Specifically, the reference point extracting means 2 is based on the difference calculating means 3 for calculating the difference between the odd fields and the even fields between the adjacent frames of the moving image whose frame rate has been changed, and the position of the calculated minimum difference. The reference point determining means 4 determines the reference point.

The processing operation of the first embodiment will be described with reference to the flowchart of FIG. First, the difference calculating unit 3 calculates, from the original data storage unit 1, the difference between odd fields and even fields between all adjacent frames of a moving image (original data) whose frame rate has been changed by telecine conversion. The difference is obtained by taking a difference in luminance or color difference for each pixel and calculating the total sum of the absolute values for the number of pixels.
(S101)

Next, the reference point determining means 4 extracts and compares the calculated odd-field difference and even-field difference in units of five, and determines the smallest one as the smallest difference. (S102)

Subsequently, the reference point determining means 4 determines the reference point based on the position of the detected minimum difference. The determination of the reference point will be described with reference to FIG. In the telecine conversion, since the conversion as shown in the above conventional technique is performed, if the position of the minimum difference between the odd field and the even field is known, it is the position where the field data is copied. Knowing, we know the reference point for the conversion. For example, as shown in FIG. 6 (a), when the minimum difference of the odd field is detected between the frame 2 and the frame 3 and the minimum difference of the even field is detected between the frame 4 and the frame 5, the frame 1 is converted. It can be seen that it is the reference point.
Since the reference point is a point at which the conversion is started when the data is converted by the data conversion means 5, it is not necessary to calculate a new reference point unless the pattern of the arrangement of the frames is changed, and it is the one determined first. Good. However, with videotapes, since the images are stitched together by editing, the pattern is often misaligned at that portion. In such a case, the reference point is set as shown in Fig. 6 (b). decide. FIG. 6 (b) is a diagram showing a state of a frame near the edited point which is edited and connected, and the images of the film 1 and the film 2 are connected between the frame 5 and the frame (a). Normally, if the pattern of frame arrangement is not changed, the minimum difference between the odd field and the even field is detected every 5 frames. However, in the example of FIG. 6B, the minimum difference in the odd field is detected at 8 frames and the minimum difference in the even field is detected at 3 frames. For this reason, the reference point determining means 4 recognizes that the pattern is changed here, and determines that the frame in which the odd field is copied is missing because the interval of the minimum difference of the odd field is large, and the even number is even. Based on the minimum difference position of the field, the video frame 4 of FIG. 6B is determined as the conversion reference point according to the pattern of FIG. 6A. (S103)

When the reference point is determined, the data conversion means 5
Performs data conversion using this reference point as a starting point. Basically, as shown in FIG. 7 (e), the video data is restored to 4 frames in 5 frame units. FIG. 7 is a diagram showing the relationship between the conversion target frame and the conversion creation frame immediately before the edit point, and FIG. 8 is a diagram showing the relationship between the conversion target frame and the conversion creation frame immediately after the edit point. 7 and 8 from (a)
(e) shows the case where the number of conversion target frames is 1 to 5, and the upper stage is the conversion target frame and the lower stage is the conversion creation frame. When there are multiple reference points as in the example of FIG. 6 (b), conversion is performed according to the reference points of the film 1 up to frame 5 where the frame pattern has not changed, and the film is changed from frame (a) where the frame pattern has changed. The conversion is performed according to the reference point of 2. At this time, the first conversion target based on the reference point of the film 2 is three frames from frame (A) to frame (C), which is immediately after the editing point, and therefore is converted into two frames according to the pattern of FIG. 8C. . The converted moving image data is stored in the restored data storage means 6. (S104)

Next, a second embodiment will be described. FIG. 3 is a functional block diagram of the second embodiment, and those having the same numbers as those in FIG. 1 indicate that the same processing as in the first embodiment is performed. In the second embodiment, in addition to the configuration of the first embodiment, an output means 7 for outputting the reference point extracted by the reference point extracting means 2 and an input for instructing the reference point to the data converting means 5. The means 8 is added.

The processing operation of the second embodiment will be described with reference to the flowchart of FIG. Also in FIG. 4, the same numbers as in FIG. 2 perform the same processing as in FIG. In the second embodiment, the same processing as in the first embodiment is performed until the determination of the reference point in S103. After determining the reference point, the reference point is output to the output means 7 such as a graphic display or a printer. (S201) Then, the operator looks at the output reference point and instructs the data converting means 5 from the input means 8 such as a keyboard to set the reference point. (S202) The data conversion means 5 performs data conversion from the designated reference point. (S104)

[0014]

According to the present invention, a reference point in the vicinity of a portion joined at the time of editing is extracted from a moving image with a changed frame rate, and the frame rate is restored based on the extracted reference point. Therefore, it becomes possible to return the moving image to the state before the frame rate conversion, and as a result, the encoded moving image also becomes good.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a functional configuration of a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing operation of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a functional configuration of a second embodiment of the present invention.

FIG. 4 is a flowchart showing a processing operation of the second embodiment of the present invention.

FIG. 5 is a diagram showing a procedure of telecine conversion.

FIG. 6 is a diagram showing a method of extracting reference points.

FIG. 7 is a diagram showing a relationship between a conversion target frame and a conversion creation frame immediately before an edit point.

FIG. 8 is a diagram showing a relationship between a conversion target frame and a conversion creation frame immediately after an edit point.

[Explanation of symbols]

 1 original data storage means 2 reference point extraction means 3 difference calculation means 4 reference point determination means 5 data conversion means 6 restored data storage means 7 output means 8 input means

Claims (2)

[Claims] 1. An original data storage means for storing a moving image having a changed frame rate, a reference point extraction means for extracting a reference point for starting conversion during conversion, and an extracted reference point based on the extracted reference points. A device for restoring a moving image with a changed frame rate, comprising: a data conversion unit for restoring the frame rate; and a restored data storage unit for storing the restored moving image. 2. The reference point extracting means calculates a difference between odd fields and even fields between adjacent frames of a moving image whose frame rate is changed, and a reference based on a position of the calculated minimum difference. 2. The apparatus for restoring a moving image with a changed frame rate according to claim 1, further comprising a reference point determining means for determining a point.