JP2003037818A - Special reproduction data generating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in a conventional technique that image quality is remarkably degraded because the amount of special reproduction data is far smaller than the amount of usual reproduction data, and that it is difficult to retrieve a scene if an image update ratio is lowered for better image quality. SOLUTION: Image data of a specified program stored in an image memory 16 is converted in image size in an image size converting circuit 23, by using a filter coefficient from an image conversion filter setting device 22. An image TP data forming circuit 24 codes the input image data after image size conversion. Also, when the input image data is an interlace image, the circuit 24 outputs an image coding stream formed by synthesizing N (N being an integer not less than one) of a half-field I-picture, one-field P-picture and one-frame P-picture in time series. Further, the input image data is a progressive image, the circuit 24 outputs an image coding stream formed by synthesizing one-frame P-picture with N pieces of P-pictures in time series.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a special reproduction data creating apparatus, and more particularly to a digital reproducing / recording apparatus for recording and reproducing MPEG2 (Moving Picture Experts Group 2) data, which is an international standard of image compression method, on a recording medium such as a magnetic tape. The present invention relates to a trick play data creating apparatus for creating trick play data for recording trick play data to be played at a speed different from that at the time of recording.

[0002]

2. Description of the Related Art In a digital signal recording / reproducing apparatus for recording and reproducing a digital information signal on a recording medium such as a magnetic tape, a digital information signal compression-coded by MPEG2 is recorded and reproduced. Here, as well known, the MPEG2 encoding employs motion compensation prediction, DCT (discrete cosine) conversion, and entropy encoding, and transmits encoded data in frame units called pictures.

The above pictures are classified into three types: I pictures, P pictures and B pictures. I picture is
This is an intra-frame coded image coded in the same order as the original image, and the I picture alone can be reconstructed into one frame. A P picture is an inter-frame forward prediction coded image that is predicted from an I picture or P picture that is temporally ahead. A B picture is an interframe bidirectional predictive coded image that is predicted from an I picture or a P picture that is temporally later and earlier.

The above three types of pictures are appropriately combined to form a GOP (Group of Picture) and transmitted. Here, GOP is a unit of random access, and as shown in FIG. 4, one GOP includes one I picture and starts from an I picture, and one GOP includes two I pictures or P pictures. One B picture is inserted. The arrows in the figure indicate the direction of prediction, and in order to reconstruct the P picture and B picture, the data of the frame (picture) that is the basis of these predictions is required. Pictures cannot be reconstructed alone. In addition, since the encoded data amount of each picture is not fixed, the position on the recording tape and the position of the image are not constant.

Here, only the I-picture coding method will be briefly described with reference to the block diagram of the example of the coding apparatus shown in FIG. The input original image is subjected to Discrete Cosine Transform (DCT) in the DCT unit 1 of FIG. 5, and sent to the quantizer 2. The DCT-transformed coefficient is quantized by a quantizer 2 according to a value of a quantization scale, and a variable length coding (VLC) unit 3 is used.
Sent to. Among the quantized DCT coefficients, the VLC unit 3 performs variable-length coding by assigning a short code to the one having a high appearance probability and a long code to the one having a low appearance probability, thereby performing compression with reduced statistical redundancy. Generate and output data.

Next, the compressed data as described above (MPEG
Data) to a digital VCR (DVCR: Digital Vide)
o The format (HD Digital VCR Council standard) for recording on the Cassette Recorder will be briefly described.

FIG. 6 shows a recording format of the HD digital VCR conference standard. In the figure, each track whose longitudinal direction is inclined with respect to the tape running direction is formed on the magnetic tape by a VCR which records and reproduces a digital signal with respect to a running cassette type magnetic tape by a rotary head. Is composed of an ITI area consisting of insert information and track information, an audio data area, a video data area, and a subcode data area. Data such as voice and image is recorded in sync block units. However, the MPEG data is recorded only in the video data area.

The video data area is divided into a normal reproduction data area (NPA) and a special reproduction data area (TPA) for high speed reproduction as shown in FIG. The reason why NPA and TPA are separated will be described. When there is no TPA, normal reproduction data is recorded in all the video data areas. In this case, when reproduction is performed at a relative speed between the tape and head different from that at the time of recording due to a request for fast-forward reproduction, the rotary head runs across a plurality of recording tracks, and naturally MPEG data is only partially acquired. become unable.

As described above, with regard to MPEG data, since each data of P picture and B picture cannot be reconstructed independently, in the case of the above special reproduction, the special reproduction image can be obtained by using only the I picture which can be decoded independently. However, since the reproduced I picture data is fragmentary data that is not continuous on the screen and is variable length encoded data, the position of the data on the screen corresponds to the position on the tape. Since it is not played, it may not be possible to play for a long time,
The special reproduction image is extremely difficult to see as it is.

Therefore, a position where the rotary head traces when reproducing at a specific double speed, that is, an area where data can be read is secured in the track as TPA, and an I picture is recorded there as special reproduction data. Creation of special playback data is done by broadcasting MPE
This is performed at the same time as the G transport stream is recorded in the NPA as it is.

Next, the MPEG transport stream will be briefly described with reference to FIG. In the MPEG transport stream (MPEG-TS), various kinds of programs (programs) sent from each broadcasting station, or
Images taken by various types of cameras can be transmitted by multiplexing voices and characters. The method of designating a program (program) in this MPEG-TS uses a two-step pointer as follows.

First, the transport packet identification signal (PI) of the transport packet shown in FIG.
Reference is made to the program association table (PAT) included in the packet in which D) has PID = 0. In this table, as shown in FIG. 8B, a table in which the program number indicating each program and the PID of the transport packet including each PMT (program map table) are associated is described.

As shown in FIG. 8 (C), the PMT is an elementary stream (image, audio,
It is a table in which information such as PIDs of transport packets in which individual streams of character information and the like) and PIDs of packets including clocks are described. Therefore, if the program number of the desired program is specified by referring to the PAT, then the PI of that program number
By referring to the PMT included in D, the PID in which each elementary stream of the desired program is transmitted is obtained, and the image, voice, character information, etc. of each program are obtained.

Next, a conventional trick play data creating apparatus will be described with reference to the block diagram of FIG. First, the case of recording a specific program will be described. The MPEG-TS input from the input terminal 11 is supplied to the program extracting circuit 12I, and the data of the specific program to be recorded is extracted here. The data of this specific program is data in which streams of image, audio, character information, etc. are multiplexed, as described in the method of acquiring a specified program from a transport stream. Since the data of this specific program is recorded in the NPA as data to be reproduced at normal speed, NP is used.
It is once written in the buffer 13.

On the other hand, since the data of the specific program extracted by the program extracting circuit 12 is multiplexed with the stream of image, voice, character information, etc. as described above, the image stream extracting circuit 14 extracts the image stream. Only the video signal is extracted and a stream including only the image signal of the specific program is output. The extracted image stream is decoded into an image signal in the image decoding circuit 15, and then temporarily stored in the image memory 16. The image data read out after being stored in the image memory 16 is generated as an encoded stream by the image TP data generation circuit 17 and is used as T (tender data) for special reproduction.
It is written in the P buffer 18.

Each of the NP and TP MPEG-TS written in the NP buffer 13 and the TP buffer 18 is read out and supplied to the track data creating circuit 19, where it is converted into a format to be written on a recording medium. The data formatted by the track data creation circuit 19 is recorded at a predetermined position on the recording medium.

When the input data is an image signal, the image signal is directly written from the terminal 10 to the image memory 16. Image TP
The data creation circuit 17 is arranged in the image memory 1 at a predetermined timing.
The image data is extracted from 6. Subsequent processing is the same as that described above.

As described above, the data area TPA for special reproduction has a limited area, and it is necessary to reduce the data amount per recording time as compared with the original image data amount. Therefore, in general, only the I picture of the image data is extracted and then encoded so that the data amount is smaller than the writable data amount in the TPA to reduce the data amount.

As a reduction method, a method of discarding other I pictures by using only a part of I pictures in the I picture, a method of reducing the image signal high frequency component of the I picture, and an image stream are reconfigured. A method of encoding again with MPEG can be considered.

[0020]

Here, the amount of coded data of each picture in MPEG is not constant due to the amount of high frequency components of the image, the speed of motion of the image, and the like. In general,
Since it is preferable to record normal playback with high image quality, NP
It is desirable that a large amount of data is allocated and recorded in the area, and the TP area is a sufficiently small data area compared to the NP area.

Therefore, in the above-described conventional special reproduction data creation apparatus, the amount of special reproduction data to be written in the TP area per image is set to MP per image in the NP area.
The data amount is extremely small compared to the EG data amount. As a result, the image of the MPEG stream in the TP region (that is, special reproduction image) is significantly worse than the image of the MPEG stream in the NP region (that is, normal reproduction image).

It is also possible to reduce the image update rate and increase the code amount per image in order to improve the image, but if the image update rate is low as an image for image search, it is difficult to search for a scene. There is a problem.

The present invention has been made in view of the above points,
An object of the present invention is to provide a trick-play data creating apparatus capable of improving the image quality of trick-play data created when recording transmitted MPEG-TS data on a recording medium.

Another object of the present invention is to provide a special reproduction data creating apparatus capable of improving the image quality of special reproduction data and improving the image search capability.

[0025]

In order to achieve the above object, a first aspect of the invention is to provide special reproduction data to be reproduced from a tape-shaped recording medium at a relative speed between a tape and a head different from that at the time of recording. Decoding circuit for decoding coded image data compression-encoded by the MPEG system in a special reproduction data creation device created for recording on a tape-shaped recording medium, and coded image data input to the decoding circuit Image size that determines the image update rate while converting the image size of the image data decoded by the decoding circuit to the same or small using at least one of the image size, the image update rate, and the data size of one picture Intra-field coding and inter-field forward prediction coding are performed on the image data whose image size has been converted by the conversion means and the image size conversion means. 1 frame of coded image data composed of two field-coded image data, or intraframe coding is performed on the image data of which the image size has been converted to generate 1 frame of intraframe code. First encoding means for generating encoded image data;
N pieces (where N is an integer of 1 or more) of the same image information by performing interframe forward predictive encoding on the encoded image data generated and extracted by the encoding unit And second encoding means for generating and adding to the encoded image data generated and extracted by the first encoding means and outputting as special reproduction data.

According to the present invention, the image size conversion is performed so that the image size is converted into the same or small size and the image update rate is increased from the input coded image data compressed and encoded by the MPEG system. From the image data after the image size conversion, special reproduction data composed of encoded image data encoded in the field or in the frame and N pieces of inter-frame forward prediction encoded image data can be created.

In order to achieve the above-mentioned object, the second invention is such that a calculation circuit for calculating the activity of the input image data, an image size of the input image data, an image update rate, and an activity calculated by the calculation circuit. Using at least one, the image size of the input image data is converted to the same or small, and the image size conversion unit that determines the image update rate and the image data whose image size has been converted by the image size conversion unit Then, intra-field coding and inter-field forward prediction coding are performed to generate coded image data for one frame consisting of two field-coded image data, or image data whose image size has been converted. A first encoding means for performing intra-frame encoding to generate intra-frame encoded image data for one frame; Of the coded unit coded image data taken are generated by, N pieces of the same image information by inter-frame forward predictive coding (where, N is the 1
Second encoding means for generating a predictive encoded image of the above integer), adding it to the encoded image data generated by the first encoding means and taken out, and outputting it as special reproduction data. It is configured.

In the present invention, from the input image data,
The image size is converted so that the image size is the same or small and the image update rate is increased, and the image data after the image size conversion and the encoded image data encoded in the field or in the frame and N It is possible to create special reproduction data composed of one frame of inter-frame forward prediction encoded image data.

In order to achieve the above-mentioned object, a third aspect of the present invention uses the image size conversion means of the above-mentioned invention by using the image size and the image update rate of the encoded image data input to the decoding circuit. The image size of the image data decoded by the decoding circuit is converted to the same or small, the image update rate is determined, and the high frequency component is cut off according to the product of the data size of one picture and the quantization scale. It is characterized in that the image size conversion is performed with the low-pass filter characteristic in which the ratio is changed.

In order to achieve the above object, a fourth invention is the image size converting means of the invention, wherein the image size of the input image data is made the same by using the image size of the input image data and the image update rate. Alternatively, the image size conversion is performed by converting to a small value, determining the image update rate, and imparting a low-pass filter characteristic in which the ratio of blocking the high-frequency component is changed according to the activity calculated by the calculation circuit. It is characterized by having done.

In the above third invention or fourth invention, as the image data after the image size conversion, the product of the data size of only one picture and the scale is added, or the low-pass filter characteristic according to the activity is added. Therefore, the high-frequency component of the image information can be reduced, which facilitates the subsequent encoding.

In order to achieve the above object, a fifth aspect of the present invention is the first encoding means of the first or second aspect, wherein the image data whose image size is converted by the image size converting means is When the interlace structure is detected based on the image update rate, intra-field coding and inter-field forward prediction coding are performed on the image data whose image size has been converted by the image size conversion means. The configuration is such that encoded image data for one frame consisting of two field encoded image data is generated and output. In the present invention, when the image data after the image size conversion is detected as an interlaced image, an intra-field coded image (I picture) of one field is obtained, so that the code amount per pixel is increased. be able to.

In order to achieve the above object, a sixth aspect of the present invention is that the first and second encoding means are generated from image data before the image size is converted by the image size converting means. It is characterized in that encoded image data having the same encoding structure as the normal reproduction data is generated and output. According to the present invention, when the image data after the image size conversion is a progressive image, the special reproduction data that is a progressive image is output, and when the image data is an interlaced image, the special reproduction data that is an interlaced image is output.

Here, since the image data before the above-mentioned image size conversion is encoded as normal reproduction data, when normal reproduction data and special reproduction data are recorded in a mixed manner, The image data having the same data structure can be switched and reproduced.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of a first embodiment of a trick play data creating apparatus according to the present invention. In the figure, the same components as those in FIG. 9 are designated by the same reference numerals. The present embodiment is characterized in that an image information acquisition circuit 21, an image conversion filter setting device 22, and an image size conversion circuit 23 are added to the conventional device shown in FIG.

In FIG. 1, the MPEG-TS input through the input terminal 11 is extracted by the program extracting circuit 12 from the data of a specific program to be recorded. The data of the specific program to be recorded has a stream of images, audio, character information, etc. multiplexed therein, and is used as data for reproduction at a normal speed.
It is once written in the NP buffer 13 for recording.

On the other hand, special reproduction data (TP data)
Is created at the same time as the above normal reproduction data as follows. The data of the specific program to be recorded (transport stream) output from the program extracting circuit 12 is multiplexed with the stream of the image, voice, character information, etc. as described above, and therefore the image stream extracting circuit 14 Only the image stream is extracted from the data, and the stream containing only the image signal of the specific program is output.

The image stream of the specific program extracted by the image stream extracting circuit 14 is decoded into image data by the image decoding circuit 15 and then stored in the image memory 16. The image information acquisition circuit 21
When the image decoding circuit 15 decodes the input image stream, the vertical and horizontal sizes and image update rate (frame rate) of the image of the image stream and the data size of one picture are acquired from the image decoding circuit 15. Since the vertical and horizontal sizes of the image and the image update rate are described in the header of the MPEG image stream, the information can be obtained by detecting them, and the data size of one picture is determined by the image decoding circuit 15. Obtained by measuring.

The vertical and horizontal sizes of the image, the image update rate, and the data size of one picture, which are acquired by the image information acquisition circuit 15, are supplied to the image conversion filter setting unit 22, and the filter corresponding to them is supplied here. Set the coefficient. The image size of the image data of the specific program stored in the image memory 16 is converted by the image size conversion circuit 23 according to Table 1 using the filter coefficient from the image conversion filter setting unit 22.

[0040]

[Table 1] As shown in Table 1, the TP image size is set smaller than the input image size, and the resolution is set to be low. In addition,
In Table 1, if the vertical and horizontal sizes of the input image and the image update rate are determined, the vertical and horizontal sizes and the image update rate of the output TP image are uniquely determined, and the image size conversion is performed. In addition, the image size is converted to T by the filter coefficient determined based on the data size of one picture.
Signal processing of P image data is also performed at the same time.

That is, the larger the product of the input coded image data size and the quantization scale is, the more the decoded image includes the high frequency component, and therefore the coding at the time of creating the TP image is difficult,
Image conversion filter setting device 2 used for the above image conversion
The filter coefficient from 2 is set to a value in consideration of the LPF (low pass filter) characteristic that blocks the high pass component of the input image. For example, the filter coefficient that makes the image softer is set as the product of the input encoded image data size and the quantization scale is larger. At this time, a plurality of filter coefficients may be provided, and the filter coefficient may be changed according to the image quality of the TP image to be obtained.

The image data after the image size conversion by the image size conversion circuit 23 is included in the image TP data generation circuit 24 together with the vertical and horizontal sizes of the input image acquired by the image information acquisition circuit 21, the image update rate and the data size of one picture. And is created as final TP image data.

Next, the configuration and operation of the image TP data creation circuit 24 will be described in detail with reference to the block diagram of FIG. In FIG. 2, the image data input from the image size conversion circuit 23 to the image TP creation circuit 24 is temporarily
It is stored in the image memory 241. For the image data stored in the image memory 241, the code amount assigned to the I picture by the control signal output from the TP format controller 246 based on the vertical and horizontal sizes of the image from the image information acquisition circuit 21 and the image update rate. , P field addition, the number of P frames to be added, and the like are determined.

That is, the image data read from the image memory 241 is first supplied to the I picture encoding circuit 242, where the TP format controller 246.
One field (1 field) according to the target code amount and coding structure set based on the control signal supplied from
Only field encoded. If the target code amount is not reached, invalid data is added to adjust the target code amount.

Regarding the selection of the coding structure to be the interlaced structure or the progressive structure, the one matching the coding structure of the NP transport stream stored in the NP buffer 13 is selected. This is because if the encoding structures are not unified, when switching from normal reproduction to special reproduction, some display devices are reset at the time of switching and it takes time to switch the display.

The P field adder 243 generates a P field encoded stream (1 field P picture) only when the encoded structure of the encoded data input from the I picture encoding circuit 242 is the interlaced structure. Add. Here, the TP format controller 246 determines whether the coding structure of the input coded data is a progressive structure or an interlaced structure. Specifically, in Table 1, an input image having a TP image update rate of 60 fields / sec is an interlaced image, and an input image having a TP image update rate of 60 frames / sec is a progressive image.

As shown in Table 1, when the NP image update rate is 60 fields / sec, the P field adder 243 creates two TP image sizes of 352 × 480 and 1440 × 1088. Two types of P-field (352 x 24
0, 1440 × 544) is created in advance, and when it is determined that the input coded data has an interlaced structure based on the control signal from the TP format controller 246 (when the input image is an interlaced image), One of the created two types of P fields is selected according to the TP image size at that time, and is added to the I picture which is the encoded data of one field input from the I picture encoding circuit 242 and output. To do. The P field to be created is added with data so that it becomes the same image as the I picture.

On the other hand, in the case of a progressive image, T
Based on the control signal from the P format controller 246, the I picture coding circuit 242 is controlled to generate one frame of I picture from the input coded data, and the P field adder 243 controls the I picture coding circuit. The encoded data (I-frame of one frame) input from 242 is passed as it is. That is, in the case of a progressive image, the above P field adder 243 is not used.

As described above, in the present embodiment, in the case of an interlaced image, since the P picture of one field is added by the P field adder 243, the I picture coding of only one field can be performed, so that per pixel The code amount of can be increased.

The encoded data output from the P field adder 243 is supplied to the P frame adder 244. The P frame adder 244 uses all the TP image sizes (352 × 480, 720 × 480, 1280 × 72) created in Table 1.
0, 1440 × 1088) P picture is created in advance, and
The P frame encoded data (that outputs the same image as the image of the encoded data with one image size selected corresponding to the image size of the encoded data input from the field adder 243 ( P picture).

In special reproduction for displaying scattered images,
The images cannot be recognized unless the same image is output several times. Therefore, the number of frames determined by the TP format controller 246 is realized by the number of P pictures added by the P frame adder 244. The number of frames to be added (the number of P pictures) is set by the image size and the image update rate. For example, the larger the image size of the input encoded data stream, the larger the TP image size,
Since the code amount is required, the number of P pictures to be added is increased. As a result, the code amount that can be given by the I picture can be increased.

In this way, the P frame adder 244
From the above, when the input image is an interlaced image, one field I picture, one field P picture (P field), and one frame P picture are N (N
Is an integer greater than or equal to 1), an image encoded stream is sequentially extracted in time series, and when the input image is a progressive image, one frame I picture has N P pictures (N is 1 or more). The image coded stream in which (the integer of the) is combined in time series is extracted. The P picture is inter-frame forward prediction coded image data and is obtained by coding the error value with respect to the previous reference image, and therefore the data size of itself is extremely smaller than that of the I picture. Therefore, even if N P pictures are added to I pictures, it is possible to record in a narrow TPA.

The multiplexer 245 is the P frame adder 24.
M of the TP image which is the special reproduction data by multiplexing the necessary information in the above-mentioned image coded stream extracted from
It is supplied as PEG-TS to the TP buffer 18 of FIG.
Supply to. The track data creation circuit 19 formats the recording medium for each of the MPEG-TS of the NP image from the NP buffer 13 and the MPEG-TS of the TP image from the TP buffer 18, and transfers it to the recording medium recording circuit at a predetermined timing. Output. As a result, when the recording medium is a magnetic tape, a tape pattern similar to the tape pattern shown in FIGS. 6 and 7 is formed.

However, in the present embodiment, the special reproduction data recorded in the special reproduction data area (TPA) is the TP image data created according to FIG. 1, and in the case of an interlaced image, one-field I By obtaining a picture, the code amount per pixel can be increased, and unnatural block noise and mosquito noise peculiar to MPEG are reduced.
The image quality can be improved. Further, in both cases of the interlaced image and the progressive image, the trick play data of the present embodiment is designed to have an increased image update rate, and thus can be easily searched.

Next, a second embodiment of the present invention will be described. FIG. 3 shows a block diagram of a second embodiment of a trick play data creating apparatus according to the present invention. In the figure, the same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. The second embodiment shown in FIG. 3 is different from the first embodiment in that special reproduction data considering activity values is created from image data obtained by decoding MPEG video data instead of MPEG-TS. There is.

In FIG. 3, the image data input through the input terminal 30 is supplied to the image memory 31 and temporarily stored therein, and then supplied to the activity calculation circuit 32 and the image encoding circuit 33. The image coding circuit 33 performs compression coding on the input image data by a known MPEG method to generate MPEG video data, and outputs it to the NP buffer 13 as normal reproduction data.

On the other hand, the activity calculation circuit 32 obtains the activity (image complexity) that can be calculated by the sum of absolute sums of the adjacent pixel difference values. Although various calculation methods are known for activities, any calculation method may be adopted. The activity value calculated by the activity calculation circuit 32 is input to the image information acquisition circuit 35.

In addition to this activity value, the image information acquisition circuit 35 has an image memory 31 similar to that of the first embodiment.
Decoding circuit (not shown) for obtaining image data supplied to the
MPEG when decoding MPEG video data
Information about the vertical and horizontal sizes of the image and the image update rate (frame rate) acquired from the header is input, and the data size of one picture is measured. The image conversion filter setting unit 36 sets the filter coefficient based on Table 1, the activity value which is the moving image information from the image information acquisition circuit 35, the vertical and horizontal sizes of the image, the image update rate, and the like.

The image size conversion circuit 37 converts the size of the image data from the image memory 31 based on Table 1 based on the filter coefficient from the image conversion filter setting unit 36. Here, the filter coefficient used for image conversion is
Since the larger the activity value is, the more the high frequency components of the image information are, and it is difficult to encode. Therefore, the operation of blocking the high frequency components of the image information by the low pass filter (LPF) is set to be performed at the same time as the image size conversion. .

For example, in the image size conversion circuit 37, when performing image size conversion, when the activity value is higher than the pixel value of (126, 180, 123, 156, 125) in the image data from the image memory 31, the image is considerably blurred. A low-pass filter characteristic of (1, 2, 1) / 4 of 3 taps is added to the pixel value to obtain a pixel value of (104, 152, 146, 140, 102). Also, when the activity value is normal, a pixel value of (106,158,141,143,106) is obtained by adding a low-pass filter characteristic of (1,3,1) / 5 of 3 taps so that the image is slightly blurred, and the activity value is When it is low, for example, the same pixel value as the input of (126,180,123,156,125) is obtained by giving the low-pass filter characteristic of (0,1,0) / 1 of 3 taps so that the image is left as it is. It should be noted that a plurality of filter coefficients may be provided and changed according to the image size and the activity value.

The image data after the image size conversion by the image size conversion circuit 23 is included in the image TP data creation circuit 24 together with the vertical and horizontal sizes of the input image acquired by the image information acquisition circuit 35, the image update rate and the data size of one picture. And is created as TP image data by the same operation as in the first embodiment.

The low-pass filter characteristic according to the activity value is not limited to be given simultaneously when the size conversion filter is used in the image size conversion circuit 37 described above. It may be provided in the signal path from 37 to the image TP data creation circuit 24 or in the signal path from the image memory 31 to the image size conversion circuit 37.

The present invention is not limited to the above embodiment. For example, when the special reproduction data is created, the vertical and horizontal image sizes of the input video coded data, the image update rate and one picture Even if not based on all of the data size or the image activity, any one of them may be used to determine the image size and the image update rate of the trick play data. For example, when the image size is fixedly converted to the expected minimum image size, it is not necessary to detect the vertical and horizontal image sizes of the input encoded data.

[0064]

As described above, according to the present invention,
Image size conversion is performed on the encoded image data compressed or encoded by the MPEG method or the decoded image data so that the image size is converted to the same or small and the image update rate is increased. Since special reproduction data composed of encoded image data that has been encoded in the field or intraframe and N pieces of inter-frame forward prediction encoded image data is created from the converted image data, it is easy to search after recording. It is possible to create various special reproduction image data.

Further, according to the present invention, when it is detected that the image data after the image size conversion is an interlaced image, an intra-field coded image (I picture) of one field is obtained to obtain a code per pixel. Since the amount is increased, the unnatural block noise and mosquito noise peculiar to the MPEG system can be reduced, and thus the image quality can be visually improved.

Further, according to the present invention, since the coding structure of the special reproduction data is made to coincide with the coding structure of the normal reproduction data, the special reproduction data is recorded together with the normal reproduction data. It is possible to prevent the reset occurring at the time of switching the normal reproduction and the special reproduction at the time of reproducing the recorded recording medium and shorten the display switching time of the display device.

[Brief description of drawings]

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

FIG. 2 is a block diagram of an embodiment of an image TP data creating circuit in FIG.

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

FIG. 4 is a diagram showing types of MPEG pictures and the like.

FIG. 5 is a block diagram of an example of an I-picture encoding circuit.

FIG. 6 is a recording format of a digital VCR.

FIG. 7 is a video data area of a digital VCR.

FIG. 8 is a diagram illustrating an MPEG transport stream.

FIG. 9 is a block diagram of an example of a conventional device.

[Explanation of symbols]

11 MPEG transport stream input terminal 12 Program extraction circuit 13 NP buffer 14 Image stream extraction circuit 15 Image decoding circuit 16, 31, 241 image memory 18 TP buffer 19 Track data creation circuit 21, 35 Image information acquisition circuit 22, 36 Image conversion filter setting device 23, 37 Image size conversion circuit 24 Image TP data creation circuit 242 I-picture encoding circuit 243 P-field adder 244 P frame adder 245 multiplexer 246 TP format controller 32 Activity calculation circuit 33 image coding circuit

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) G11B 27/032 H04N 5/92 H H04N 5/783 7/137 Z 7/32 G11B 27/02 C 27 / 08 F-term (reference) 5C018 NA01 NA05 5C053 FA22 GB01 GB06 GB08 GB22 GB30 GB37 HA21 JA21 KA11 5C059 KK01 LA06 MA00 MA02 MA03 MA05 PP05 PP06 RB09 RB10 RC32 RC34 SS16 TA21 TA24 TA69 TB05 TC10 TC25 TC38 UA02 UA15 DE014 DE014 DE28 DE96 FG24 GK08 5D110 AA04 AA29 CA05 CA42

Claims (6)

[Claims] 1. A special reproduction data creation device for creating special reproduction data to be reproduced from a tape-shaped recording medium at a relative speed between a tape and a head different from that at the time of recording on the tape-shaped recording medium. A decoding circuit for decoding encoded image data compressed and encoded by the MPEG method, and at least an image size of the encoded image data input to the decoding circuit, an image update rate, and a data size of one picture. An image size conversion unit that converts the image size of the image data decoded by the decoding circuit into the same or small size and determines an image update rate using one of them; and the image size conversion unit converts the image size. Intra-field coding and inter-field forward predictive coding are respectively performed on the image data thus obtained to obtain two field-coded images. Generating one frame of encoded image data of data, or performing intra-frame encoding of the image data whose image size has been converted to generate one frame of intra-frame encoded image data No. 1 encoding unit and N pieces of the same image information (where N is the same as the image information generated by the first encoding unit and subjected to interframe forward prediction encoding). Second coding means for generating a predictive coded image of an integer of 1 or more), adding it to the coded image data generated and taken out by the first coding means, and outputting it as the special reproduction data. A data reproduction device for special reproduction, comprising: 2. A special reproduction data creation device for creating special reproduction data to be reproduced from a tape-shaped recording medium at a tape-head relative speed different from that at the time of recording on the tape-shaped recording medium. In the calculation circuit for calculating the activity of the input image data, and using at least one of the image size of the input image data, the image update rate and the activity calculated by the calculation circuit, Image size conversion means for converting the size to the same or small and determining an image update rate; intra-field coding and inter-field forward prediction for the image data whose image size has been converted by the image size conversion means. Each frame is encoded to generate encoded image data for one frame consisting of two field encoded image data. A first encoding means for generating intraframe-encoded image data for one frame by performing intraframe encoding on the image data whose image size has been converted; or the first code. Interframe forward predictive coding is performed on the coded image data generated and extracted by the coding means to generate N (where N is an integer of 1 or more) predictive coded images of the same image information. Data for special reproduction, which is added to the encoded image data generated and taken out by the first encoding means and output as the data for special reproduction. Creation device. 3. The image size conversion means uses the image size and the image update rate of the encoded image data input to the decoding circuit to determine the image size of the image data decoded by the decoding circuit. An image that is converted to the same or small value, determines the image update rate, and is provided with a low-pass filter characteristic in which the ratio of blocking the high-frequency component is changed according to the product of the data size of one picture and the quantization scale. The special reproduction data creation device according to claim 1, wherein size conversion is performed. 4. The image size conversion means converts the image size of the input image data to the same or small by using the image size and the image update rate of the input image data, and determines the image update rate. The data for special reproduction according to claim 2, further comprising: performing image size conversion with a low-pass filter characteristic in which a ratio of blocking a high-frequency component is changed according to the activity calculated by the calculation circuit. Creation device. 5. When the first encoding means detects that the image data whose image size has been converted by the image size converting means has an interlaced structure based on the image update rate, the image size is changed. The intra-field coding and the inter-field forward predictive coding are respectively performed on the image data whose image size has been converted by the converting means to generate coded image data for one frame composed of two field coded image data. 5. The special reproduction data creating apparatus according to claim 1, wherein the special reproduction data creating apparatus outputs the special reproduction data. 6. The encoded image having the same encoding structure as the normal reproduction data generated from the image data before the image size conversion by the image size conversion means, in the first and second encoding means. The special reproduction data creating apparatus according to any one of claims 1 to 4, wherein data is created and output.