JP3898711B2 - Recording medium recording method and reproducing method - Google Patents

Description

  The present invention relates to a recording method and a reproducing method of a recording medium, and more particularly to high density recording / reproducing of an optical disc.

  FIG. 27 is a block diagram of a conventional optical disc recording / reproducing apparatus disclosed in Patent Document 1 below. In the figure, 40 is a video A / D converter that converts a video signal into digital information, 41 is video information compression means, and 69 is a frame sector conversion that converts compressed video information into sector information equal to an integral multiple of the frame period. Means 70 is an encoder, 71 is a modulator for converting to a predetermined modulation code in order to reduce intersymbol interference in the recording medium, 72 is a laser drive circuit for modulating the laser in accordance with the modulation code, 73 is a laser Output switch.

JP-A-4-114369

  76 is an optical disk, 74 is an optical head that emits laser light, 75 is an actuator that tracks a light beam emitted from the optical head 74, 78 is a traverse motor that sends the optical head 74, 77 is a disk motor that rotates the optical disk 76, Reference numeral 79 denotes a motor drive circuit, and 80 and 81 denote motor control circuits.

  Also, 82 is a reproduction amplifier that amplifies the reproduction signal from the optical head 74, 83 is a demodulator that obtains data from the recorded modulation signal, 84 is a decoder, 85 is a frame sector inverse conversion means, and 86 is the decompression of the compressed information. An information decompressing unit 87 is a D / A converter that converts the decompressed information into an analog video signal.

FIG. 23 is a simplified representation of the MPEG data arrangement structure (layer structure), which is being standardized to compress and transmit digital video information, and 59 is a plurality of frame information. GOP, 60 is a GOP layer composed of several pictures (screens), 61 is a slice obtained by dividing one screen into several blocks, 62 is a slice layer composed of several macroblocks (MB), 63 is a block layer composed of 8 pixels × 8 pixels.

  FIG. 24 is a diagram illustrating a coding structure when 15 screens are set to 1 GOP. 66 is an I picture which is video information for performing intra-frame DCT, and 68 is video information by DCT coding for performing forward motion compensation. The P picture 67, which is the B picture, is a B picture subjected to DCT coding with motion compensation using the I picture 61 and the P picture 68 positioned before and after in time as a reference screen.

  25 (a) and 25 (b) show a case where the amount of video data in one GOP is made variable in order to make the image quality between GOPs constant, and a fixed rate to make the recording time constant. FIG.

  FIG. 26A shows a data amount per 1 GOP when the image quality per 1 GOP is kept the same. Α represents the maximum data rate and β represents the average data rate. FIG. 26B is a diagram comparing the image quality per 1 GOP and the data amount in each of the images (e), (d), and (c).

  Next, the operation of the conventional example will be described. As digital video information compression technology advances, recording the compressed information on an optical disk realizes a video filing device that has excellent searchability and is extremely easy to use compared to conventional tape media such as VTR. It is possible to do. In addition, since such a disk file device handles digital information, there is no dubbing degradation compared to the case of recording an analog video signal, and since it is optical recording / reproducing, a non-contact and highly reliable system is realized. it can.

  Conventionally, when such compressed moving picture information is recorded on an optical disk, a method of recording digital compressed moving picture information such as the MPEG system shown in FIG. 23 on the optical disk 76 shown in the block circuit diagram of FIG. . At this time, the video information digitized by the video A / D converter 40 is converted by the video information compression means 41 by a standard compressed moving image system such as MPEG. The compressed video information is encoded and subjected to modulation for reducing the influence of intersymbol interference of the optical disc and recorded on the optical disc 76. At this time, for example, it is clear that the data amount in each GOP unit becomes almost the same amount, and it is possible to perform editing or the like in GOP unit by allocating to sectors equal to an integral multiple of the frame period.

  At the time of reproduction, video information recorded on the optical disk 76 is reproduced by the optical head 74, amplified by the reproduction amplifier 82, restored to digital data by the demodulator 83 and decoder 84, and then inversely converted to the frame sector. Means 85 restores the original video original data from which data such as address and parity are removed. Further, for example, MPEG decoding is performed by the information decompression means 86 to reproduce it into a video signal, which is converted into an analog video signal by the D / A converter 87 and can be displayed on a monitor or the like.

  As described above, when the MPEG method is used as a digital moving image compression method, as shown in FIG. 24, an I picture 66 for compression by intra-frame DCT and a video by DCT encoding for forward motion compensation are used. Coding structure in which P picture 68 as information and B picture 67 subjected to DCT coding with motion compensation using I picture 66 and P picture 68 positioned before and after in time as a reference screen are combined Are recorded in the optical disc 76 as they are.

  Among these pieces of information, since the I picture 66 performs the intra-frame DCT, it is possible to perform image reproduction with this information alone. However, since the P picture 68 performs forward motion compensation, Image reproduction cannot be performed unless the picture 66 is reproduced, and since the B picture 67 is a prediction screen from both directions, it must be reproduced after reproducing the I picture 66 or the P picture 68 before and after. Cannot be played. Of these pieces of information, naturally, the B picture 67 performing bi-directional prediction has the smallest amount of data and good coding efficiency.

  However, since the B picture 67 cannot be reproduced independently, the I picture 66 and the P picture 68 are required. However, if the number of the B pictures 67 is increased, the amount of buffer memory in the processing circuit increases, and the data input starts. There is a problem that the delay time until video reproduction increases. However, in a storage medium represented by an optical disk or the like, an encoding method with good compression efficiency is desired for long-time recording, and on the other hand, the delay time of the video reproduction is not a problem. An encoding scheme as shown in 24 is suitable.

  Next, when video data is recorded so that the image quality is constant in any part of one optical disk, a variable rate structure as shown in FIG. This is because when the image quality per GOP is constant, the amount of video data required for one GOP varies as shown in FIG. This is because, for example, when the amount of data required for an I picture increases in the case of a fine image, or when video data with fast motion is continuous, the compression efficiency in a P picture or B picture does not become so high. . As a matter of course, as shown in FIG. 26B, when the amount of data per GOP is increased, the S / N of the image is also improved, although it varies depending on the design.

  On the other hand, in order to make the recording time of one optical disk constant, the format for recording at a fixed rate shown in FIG. However, unlike a magnetic tape medium, in the case of a video recording / reproducing apparatus using an optical disk medium, since the total amount of data per package is small, it is necessary to increase the compression efficiency as much as possible while maintaining high image quality. For that purpose, it goes without saying that the variable rate method shown in FIG. 25A has better file efficiency of video data per optical disc.

  Therefore, for example, in a read-only optical disc apparatus, it is possible to know the data amount distribution of all the optical discs at the variable rate by encoding in advance, so the entire data distribution is adjusted at the second encoding. As a result, the playback time per disc can be adjusted to be constant even at a variable rate.

  As described above, in the conventional video recording system for optical disks, the file rate of video data recorded on one optical disk medium is improved by making the data rate per GOP variable. On the other hand, a file method with higher compression efficiency than before has been desired for an optical disk medium having a significantly smaller total data amount than the conventional one.

  In general, it was fixed at 24 frames / second for movie films and 30 frames / second for NTSC signals, so a decisive moment in sports video material was shot with a high-speed camera, etc. Could not handle video sources.

Also, when video sources with multiple frame rates are mixed on a single disc, there is no control information necessary to display them on the screen, so only a video with a specified frame rate can be displayed. In addition, there is a problem that even if the frame rate is different, the video data related to each other cannot be accessed smoothly.
The present invention has been made for the purpose of solving the above problems, and an object thereof is to enable a video recording / reproducing method with high compression efficiency.

  It is another object of the present invention to provide a recording method that can use information on the number of frames per second and a storage address included in a private packet when reproducing a video packet.

The present invention provides an I picture, which is video information subjected to intra-frame DCT, a P picture, which is video information obtained by DCT encoding with forward motion compensation, and the I picture located before and after in time, P In a recording method for recording on a recording medium digital information including video information including a B picture that is video information by DCT encoding with motion compensation performed using a picture as a reference screen, and control information of the video information ,
Before SL video information, the first image information for the normal reproduction is reproduced by receiving a reproduction request from outside, the second as the interpolated video information to interpolate the first video information to be normally reproduced Video information,
The digital information is configured in units of a video information unit having a private packet including the control information and a video packet including the first video information or the second video information.
The private packet is arranged before the video packet;
A first video information unit in which the first video information is stored in the video packet and a second video information unit in which the second video information is stored in the video packet are on the recording medium. To be placed alternately,
The control information of the private packet in the first video information unit includes the address of the second video information unit corresponding to the first video information unit and the size information of the second video information unit. ,
The address of the first video information unit corresponding to the second video information unit is included in the control information of the private packet in the second video information unit.
In addition, an I picture that is video information subjected to intra-frame DCT, a P picture that is video information obtained by DCT coding with forward motion compensation, and the I picture and P picture that are temporally located before and after In a disc-shaped recording medium on which digital information including video information including a B picture that is video information obtained by DCT encoding with motion compensation performed as a reference screen and control information of the video information is recorded.
The video information includes first video information for normal playback and second video as interpolated video information that is played back in response to an external playback request and interpolates the first video information that is normally played back. Information and
The digital information is configured in units of a video information unit having a private packet including the control information and a video packet including the first video information or the second video information.
The private packet is arranged before the video packet;
The disc-shaped recording includes a first video information unit in which the first video information is stored in the video packet and a second video information unit in which the second video information is stored in the video packet. Alternatingly placed on the medium track,
The control information of the private packet in the first video information unit includes the address of the second video information unit corresponding to the first video information unit and the size information of the second video information unit. ,
The control information of the private packet in the second video information unit includes the address of the first video information unit corresponding to the second video information unit,
The head of each of the first video information unit and the second video information unit is arranged at the head position of a sector in the disk-shaped recording medium.

According to the recording medium recording method of the present invention, the first video information unit and the second video information unit are alternately recorded, so that the second video information can be recorded during reproduction of the first video information. When a reproduction request is made, the second video information unit storing the second video information corresponding in time can be quickly read .

Embodiment 1 FIG.
FIG. 1 is a flowchart showing a decoding method when the control information of Embodiment 1 of the present invention is inserted into user data of a video stream. FIG. 2 is a block circuit diagram showing the configuration of the optical disk reproducing apparatus according to the first embodiment. 1 is an optical disk, 2 is a reproduction amplifier, 3 is a demodulator, 4 is error correction means, 5 is temporal reference control means, and 6 is Buffer, 7 is decoding means, 8 is a D / A converter, 9 is reproduction control means, 10 is optical head control means, and 11 is interpolation information reading control means. Further, the reproduction control means 9 receives a reproduction speed request signal indicating normal reproduction, ½ times or ¼ time reproduction, and transmits this signal to the temporal reference conversion control means 5.

  The temporal reference conversion control means 5 processes the value by multiplying the value of the temporal reference by 1/4 during normal reproduction. In addition, the value of the temporal reference is increased by a factor of 1/2 during low-speed playback at 1/2 times and the value is processed. In addition, the temporal reference value is processed as it is at the time of 1/4 times lower speed reproduction. Further, the playback control means 9 performs a temporal reference reset / set process on the decoding means 7 at the change of the playback mode.

  The interpolation information reading means 11 is an interpolation information recorded in a specific area of the optical disc 1 according to the interpolation information flag, the interpolation information start address, the interpolation information size, and the interpolation information rate recorded in the reproduction mode and the user area of the GOP layer. In order to read out information, the optical head is controlled via the optical head control means 10.

Figure 3 shows a flowchart at the time of normal reproduction. First, when reproduction is started, it is checked from the interpolation information flag whether there is interpolation information. When there is this interpolation information, the temporal reference value is not continuous in normal reproduction. For this purpose, the interpolation information rate is read and conversion is performed so that the temporal reference is continuous .

  FIG. 4 shows a flowchart during low-speed playback. First, when the reproduction is started, the operation according to the flow at the normal reproduction described above is performed. When a low speed reproduction request signal is input, it is first checked whether there is interpolation information. Otherwise, normal slow playback is performed. In some cases, temporal reference conversion is performed. Then, the interpolation information is read, and a video stream is formed on the low-speed playback buffer together with the basic information. Thereafter, this stream is sent to the decoding means for decoding and reproduction.

  FIG. 5 shows a system stream for normal playback according to the first embodiment. In the figure, a pack header (abbreviated as “PH” in the figure) 12 stores additional information for time reference reference for synchronous reproduction, and the system header (abbreviated as “SH” in the figure) 13 It is added to the pack at the beginning of the program, and describes and stores the outline of the entire stream. Private 2 packet (abbreviated as “P2P” in the figure) 14 stores packet data, audio packet (abbreviated as “AP” in the figure) 15 stores audio data, and character packet (in the figure, “ Character data is stored in 16 (abbreviated as “CP”), and video data is stored in video packet (abbreviated as “VP” in the figure) 17.

The private 2 packet 14 stores the following control information . That is , an information flag (abbreviated as “IF” in the figure) 18 indicating the presence / absence of an interpolation system stream storing interpolation frame information, and an information address (“IA” in the figure) indicating the address of a pack storing the interpolation system stream. "hereinafter) 19, in information size (Fig indicating the size of the information of the pack storing the interpolation system stream" iS "for short) 20, in (a view showing a picture rate of the video information of the interpolation system stream, is stored is hereinafter) 21 such as "PR", prior to, during packet length (diagram illustrating the size of the packet, "PL" for short) 22, a packet start code indicating the start of a packet (Fig. in, "PS" hereinafter) 23 is provided. Further, 1 GOP video information is stored in the pack, and the pack header 12 at the start point is arranged at the head of a sector which is an access unit such as an optical disk.

  FIG. 6 is a diagram showing a system stream for low speed reproduction according to the first embodiment. In the figure, the private 2 packet 14 includes a packet start code 23 and a return address value indicating the head position of a pack containing normal reproduction video information corresponding to the low-speed video information (“RA” in the figure). 24, and picture address data (abbreviated as “PAD” in the figure) 25 indicating the storage address of each picture stored in the packet is stored.

FIG. 7 is a diagram showing the storage arrangement of stream information on the optical disc 1 according to the first embodiment.
TOC (table of contents) 26 in FIG. 7 Ri region der the starting sector address is written in a program, that title is read immediately after starting. A pack 27 stores video information of 1 GOP and records system stream information for normal reproduction . 2 8 (a) and (b) are packs in which video information for low-speed playback is recorded.

  A pack in which video information for low speed reproduction is recorded is concentrated in a specific area on the optical disc 1 as shown in FIG. 7, or for normal reproduction as shown in 28 (b) in FIG. There is a method of recording after pack information, that is, a method of alternately recording a normal reproduction pack and a low-speed reproduction pack. FIG. 8 is a conceptual diagram showing a video stream (a) for normal reproduction and streams (b) and (c) for interpolation information. FIG. 9 is a diagram showing which field is selected and reproduced in a stream having a large number of frames.

  Next, the operation of the first embodiment will be described. FIG. 1 is a data flowchart in the GOP layer in the MPEG standard. In the figure, the group start code indicates the start code of the GOP, the time code indicates the time from the beginning of the sequence, and the closed GOP flag indicates that the images in the GOP can be reproduced independently of other GOPs. The flag indicates that the preceding GOP data cannot be used for editing. The extension start code starts the group extension area, the group extension data starts the group extension data, and the user data start code starts the user data area. The user data indicates data in the user data area, and the picture layer indicates attributes common to one screen.

  GOP is an abbreviation for Group of Picture, and is the smallest unit of a screen group that is a unit of random access. Here, the user data is an area where the user can freely insert data. In the first embodiment, whether or not there is interpolation information in this area, that is, using the interpolation information. Interpolation information flag indicating whether low-speed reproduction of the information is possible, interpolation information start address indicating the interpolation information start address indicating the start address of the area storing the interpolation information, and interpolation information indicating the size of the interpolation information Four areas of the interpolation information rate that indicate the size and the picture rate at which the image information including the interpolation information is captured are defined.

  Interpolation information is generated only in places that can be played back at low speed, and it is not necessary to encode all of the image information recorded on the optical disk by this method, and in sports programs such as baseball, soccer, golf, etc. It is only necessary to record interpolation information on the optical disc only in places where low-speed playback is highly necessary, such as following scenes. Therefore, the recording area for interpolation information can be made considerably lower than the area for recording basic information. Since the presence / absence of the interpolation information is described by the information flag 18 in the control information in the private 2 packet, these can be automatically determined in the player, and the presence / absence of the interpolation information during video reproduction is also possible. Can be displayed on the screen and selected by the operator.

  Further, since the interpolation information start address is described in the control information in the private two packets, the interpolation information recording area on the optical disc can be accessed instantaneously. Further, since the return address is described in the private 2 packet 14 in FIG. 5, the original normal playback video can be instantaneously restored. In addition, since the address of each picture is written in the private packet 14 of FIG. 5, the data can be smoothly read from the buffer memory of the player after the data is read.

  Here, a general method for compressing and encoding digital image information is as follows. As described above, there are three compressed picture types: “I”, “P”, and “B”. The “B” type is used as interpolation information used during low-speed playback. This is due to two reasons. The first is that the B picture type has the smallest amount of information among the three types, and the interpolation information recording area can be reduced. Secondly, since the interpolation information is a low-speed playback image, the degree of change is small and the correlation is high on continuous screens, so that high image quality can be maintained without using “I” and “P” type pictures. is there. Naturally, when decoding the interpolation information, the I picture and the P picture in the original normal reproduction video data are used to decode the B picture of the interpolation information, or the interpolation information itself includes the I picture necessary for decoding the B picture. And must have a P picture.

  FIG. 8 is a diagram showing the recording position of the configuration of the encoded and compressed image information in the first embodiment. In FIG. 8A, “I”, “P”, and “B” indicate image types compressed by the MPEG method. “I” represents an I picture, and is a screen encoded from information of only this I picture, and is generated without using inter-frame prediction that reduces temporal redundancy. “P” represents a P picture and is a screen on which prediction from an I or P picture can be performed. In general, a macroblock type in a P picture includes both an intra-frame prediction screen that does not use a prediction memory and a forward inter-frame prediction screen that uses a prediction memory. “B” represents a B picture and is generated by bidirectional prediction. The numbers below the screen type are called temporal references and indicate the playback order of pictures.

  The number of frames per second of a normal NTSC TV signal is approximately 30 frames / second). On the other hand, the image used in the first embodiment is, for example, an image taken at 120 frames per second or an animation similar thereto. When this is encoded at 30 frames / second that can be handled by a TV receiver, the reproduced image is reproduced at a low speed of 1/4 times. Therefore, when this image information is reproduced at a rate of 1 frame per 4 frames, it is reproduced at a normal speed. Similarly, when playback is performed at a rate of 1 frame per 2 frames, 1/2 times slower playback can be realized.

  A method of recording information on the optical disk is shown below. Assuming that image information to be read when reproducing at normal speed is basic information and image information to be read only at low speed reproduction is interpolation information, the basic information records normal image information as shown in FIG. Similarly to the above, recording is continuously performed in the recording area 27 provided on the inner periphery of the optical disc 1. On the other hand, the interpolation information is recorded together in a recording area 28 (b) provided on the outer periphery of the optical disc 1.

  In the first embodiment, since the basic information is a ratio of 1 out of 4 pictures, the NTSC system uses pictures taken at 120 frames / second, and in the case of 1/2 times reproduction, interpolation information is used. By reading b and basic information, low speed reproduction of 30 frames / second is performed. In the case of 1/4 times reproduction, interpolation information a, interpolation information b, and basic information are read and low speed reproduction of 30 frames / second is performed. Yes.

  FIG. 8 is a conceptual diagram of low-speed playback in this embodiment. Here, the frame rate of the camera used for shooting is 120 frames / sec. In this case, on a 30-frame / sec monitor, 1/4 times low-speed playback image (FIG. 8 (c)), and when playback is performed at a rate of 1 out of 2 images, 1 / 2-times low-speed playback image (FIG. 8 (c)). b)) When the reproduction is performed at a rate of one out of four, a normal reproduction image is obtained.

  MPEG-encoded pictures include an I picture of an in-plane encoding screen, a P picture using a unidirectional prediction screen, and a B picture using bi-directional prediction. In general, the number of pictures in a GOP (N) and the period (M) in which an I or P picture appears are generally selected to be N = 15 and M = 3. In the first embodiment, pictures used during normal reproduction are arranged in the same manner as conventional pictures, and interpolation information pictures used only during low-speed reproduction are streams using many B types. This is because if a picture of a type other than B is used, the picture for normal reproduction may not be constructed because it is not read out during normal reproduction. In FIG. 8, N = 60 and M = 12.

  Further, in FIG. 8, a picture not shaded is a picture obtained from the interpolation information, and is not used during normal reproduction. In addition, since information captured at a high frame rate has a smaller inter-frame difference than usual, it is effective in terms of disk capacity to use the B type with a small amount of information. For this reason, the ratio of the B picture type per GOP is such that the B picture occupation ratio in the interpolation information> the B picture occupation ratio during normal reproduction.

  When reproducing the image information recorded on the optical disc 1 by the method of the first embodiment, a number representing the reproduction order of images called a reference value (hereinafter referred to as “temporal reference value”) becomes a problem. Taking the number below the screen type in FIG. 8 (a) as an example, the temporal reference of the encoded video stream can be normally reproduced because it is arranged in order of 1, 2, 3, 4, 5. In the case of FIG. 8C, the reproduction speed is 1/4 times slower. When only basic information is reproduced, the temporal reference is located at a constant multiple of 1, 5, 9, 13,..., And may not be applied to a general decoder.

  In general video playback devices, the number of frames per second is fixed at, for example, about 30 frames / second in NTSC. Therefore, in the case of low speed playback, the time resolution is not improved no matter how low the playback is, and it is jerky. Only the reconstructed image obtained was obtained. Therefore, in the first embodiment, a video material having a large number of frames per second taken by a high-speed camera or the like is encoded, and the number of frames per second to be decoded is changed according to the reproduction speed.

  FIG. 9 is a diagram showing a field reproduction method in normal reproduction in the first embodiment. Normally, a frame in television is interlaced reproduction, and one frame is constituted by the first field and the second field. FIGS. 9A and 9B are diagrams showing playback fields during low speed playback. During normal playback, the field enclosed by the dotted line is played. Therefore, a field enclosed by a dotted line is a normal system stream, and a field not enclosed is an interpolation system stream.

  Such interpolation information can be arranged in another location on the optical disc as a separate data stream as shown in 28 (b) in FIG. 7, but FIG. 28 (a). As described above, it is also possible to arrange, for example, in units of GOP behind the normal reproduction stream. However, if they are arranged at the same place on the optical disc, it is necessary to increase the required buffer memory and improve the reading rate during normal reproduction. In addition, when interpolation information at another location on the optical disk is arranged, the access time for reproducing the interpolation information increases.

  In the field reproduction method of FIG. 9A, the time interval of the field is not constant during normal reproduction, and the reproduced image is jerky during image reproduction, whereas the field reproduction method of FIG. The time interval of the field during playback is constant, and a smooth playback image can be obtained. In addition, since the interpolation information does not need to exist for the entire image, it is possible to use this method only in places where the low-speed playback is frequently requested.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. FIG. 10 is a diagram illustrating a video recording / playback method according to the second embodiment. FIG. 10A is a diagram illustrating a screen type in a GOP of a normal video stream. FIG. 10B is a diagram in which frames are reduced. It is a figure which shows the screen type in GOP of a video stream. Here, the B2, B4, and B6 frames in the normal video stream are deleted, and at the time of playback, the immediately preceding frames B1, B3, and B5 are continuously played back at the deleted frame location. In this case, continuous playback is realized by freezing the playback image. Furthermore, by assigning the information amount of the deleted frame to another frame and re-encoding, higher image quality can be obtained, and the recording time corresponding to the deleted frame information amount can be increased.

  FIG. 11 is a diagram showing the structure of a video stream for realizing the screen freeze according to the second embodiment. In the figure, a picture header (abbreviated as “PCH”) 29 stores a start code of picture information and the like, and a picture encoding function expansion unit (abbreviated as “PCEX” in the figure) 30 encodes. The function expanded information is stored, and the quantization matrix function expansion unit (abbreviated as “QMFEX” in the figure) 31 stores the function expansion information of the quantization matrix, and the picture display function expansion unit (in the figure, In the picture space scalable function extension section (abbreviated as “PSEX” in the figure) 33, the picture space scalable function extended information is stored. The picture temporal scalable function expansion unit (abbreviated as “PTSEX” in the figure) 34 stores the picture temporal scalable function. Broadcast is stored, (in the figure, abbreviated as "SLICE") slice layer slice is the minimum unit of a series of data strings having a start code 35 is stored.

  Further, in the picture encoding function expansion unit 30, a top field first flag (abbreviated as “TFF” in the figure) 37 indicating whether or not the top field comes first in time, the first field for telecine conversion. There is a repeat first field flag (abbreviated as “RFF” in the figure) 38 indicating whether or not to redisplay, and a progressive frame flag (abbreviated as “PF” in the figure) 39 indicating whether or not the format is progressive. These are all defined in the MPEG standard. By making various settings for these three flags and the progressive sequence flag of the sequence extension section defined by the MPEG standard, it is possible to set frame or field reproduction. FIG. 18 is a diagram showing a playback mode by flag setting according to the second embodiment.

  FIG. 12 is a block circuit diagram of the second embodiment. When creating an optical disc on which digital moving image information is recorded, by creating a recorded video file in which the number of frames per second of the digital video information is reduced, It is intended to increase the compression efficiency of digital video. In the figure, 40 is a video A / D converter, 41 is video information compression means, 90 is a motion vector amount detection means for detecting a motion vector amount, 91 is a frame drop amount determination means, 42 is a disk format encoder, and 43 is a modulation. Means, 44 is a recording data file, 45 is a ROM disk mastering device, and 1 is a created ROM disk.

  FIG. 13 is a diagram showing how frame dropping is performed with respect to the motion vector amount in the second embodiment. FIG. 13A shows the motion vector amount at 24 frames / second and 30 frames / second. FIG. 13B shows a case where 30 frames / second, 27 frames / second and 24 frames / second are switched.

  The number of frames per second on the TV screen varies depending on the NTSC zone and the PAL zone, but for example, in the case of Japan or the United States, it is 30 frames / second. The number of frames displayed on the TV screen needs to correspond to the TV format, but the video data to be recorded on the optical disc does not necessarily have to be filed with all the frame numbers. It is possible to delete picture unit data within a conspicuous range. In this case, when displaying the screen, a flag for repeatedly reproducing the same previous screen is set in the header portion provided for each GOP composed of a plurality of pictures or the header portion provided in the head portion of the picture data. This is possible.

  However, apart from the movie film originally composed of data at 24 frames / second, it is not always necessary to keep the number of pictures reduced in a unit of 1 GOP constant depending on the picture when a frame is dropped. . Therefore, in the second embodiment shown in FIG. 12, the number of dropped frames is adaptively varied according to the speed of the screen movement.

  19, 20 and 21 are diagrams showing the structure of a video stream for realizing the screen freeze according to the second embodiment. In the figure, a sequence header (abbreviated as “SH” in the figure) 46 is used for cueing random access, GOP 47 is a collection of several pictures, a sequence header code (in the figure) 48 is abbreviated as “SHC”) 48 is a code for identifying the sequence header included in the sequence header 46, and a sequence extension part (abbreviated as “SQEX” in the figure) 49 is included in the sequence header 46 to distinguish between MPEG1 and MPEG2. The sequence display extension unit (abbreviated as “SQDP” in the figure) 50 is included in the sequence header 46 and stores a flag for performing a function extension related to display, etc., and the sequence scalable extension part (in the figure, “ 51 (abbreviated as “SQSC”) is a flag included in the sequence header 46 for scalable extension. Are stored in a user data section (abbreviated as “UD” in the figure) 52 and a user data start part (abbreviated as “UDSC” in the figure) 53 and user data (in the figure, “USRDT”). (Abbreviation) 54 is stored. In the GOP 47, a GOP header (abbreviated as “GPH” in the figure) 55, user data 52, and a picture layer 56 are stored. The picture layer 56 stores a picture header (abbreviated as “PCH” in the figure) 57 and a slice layer 58.

  By writing information about the number of frames per second and which screen is to be frozen in any one of the user data sections 52 in FIGS. 19, 20, and 21, reproduction control from the apparatus is facilitated.

FIG. 22 is a diagram showing a method for deleting a field of video material. In the case of a video material in which the movie material is telecine converted, the deletion field 88 is supplemented by a temporally previous field 89 as shown in FIG. At this time, each flag setting state shown in FIG. 18 is that the top field first flag 37 is 1, the repeat first field 38 is 1, and the progressive frame flag 39 is 1 at the deletion field portion 88a, and the top field first is at the deletion field portion 88b. The flag 37 is 0, the repeat first field 38 is 1, and the progressive frame flag 39 is 1.

Further, in the case of a movie (v-cinema) shot with a video camera, as shown in FIG. 22B, the deletion field can be deleted to form a stream of information of 24 frames per second. At this time, in the flag setting states shown in FIG. 18 , the top field first flag 37 is 0, the repeat first field 38 is 1 and the progressive frame flag 39 is 1 at the 59c deletion field location, and the top field first is 59d at the deletion field location. The flag 37 is 1, the repeat first field 38 is 1, and the progressive frame flag 39 is 1.

  Next, the operation of the second embodiment will be described. In FIG. 12, the motion vector amount detection means 90 extracts the motion vector amount of the video information compressed by the video information compression means 41. In general, a motion vector code is assigned a smaller number of bits to the one with less motion, and a larger number of bits is assigned to the one with more motion. Can be grasped quantitatively.

  Also, depending on the design, even if most of the screen is close to a still image, a part of the screen may move greatly. In such a case, not the average level of the entire picture but the macroblock (MB) unit. It is more appropriate to extract the maximum value of the motion vector data to obtain a motion vector amount.

  Therefore, the motion vector amount detection circuit 90 counts the motion vector amount per 1 GOP, and the frame drop amount determination means 91 determines the number of frame drops per 1 GOP depending on whether this count value exceeds or exceeds a predetermined value. It becomes possible to do. Also, in this case, the B picture data is deleted from the compressed video data once stored in the memory by the disk format encoder 42, and the header information allocated in units of 1 GOP or allocated in units of 1 picture. It rewrites the header information.

  This is because if the I picture or P picture is deleted, the preceding and following B pictures cannot be decoded, and the information of the deleted picture is written in the header to freeze the previous and subsequent screens during playback. This is because the number of frames can be matched to the required number of TV systems.

  In the second embodiment, the amount of data to be recorded on the optical disk is reduced by reducing frame dropping when the amount of motion vector is large, and by increasing frame dropping when the amount of motion vector is small, for example, close to a still image. It becomes possible. In such a system, the amount of dropped frames is varied according to the movement of the screen, so even if the dropped frames are not noticeable to human eyes. In this case, it is desirable to detect the amount of motion vectors from P pictures that are evenly allocated within 1 GOP, and even from B pictures, but the continuity of compressed images and the presence of bidirectional data complicate the system. There is a risk of making it.

  Further, in the frame drop amount determination means 91, as shown in FIG. 13 (a), the frame drop number is zero according to the magnitude of the motion vector amount and 6 frames per second (picture number 24 frames / second). Although it is possible to set two types, as shown in FIG. 13B, it is also possible to set between 6 frames per second from zero as multiple stages. In the case of a film movie or the like, the frame rate is 24 frames / second. Therefore, a reproduction method from 24 frames / second is also defined in standards such as MPEG. Therefore, in particular, if frame dropping is defined at the above-described two stages of 24 frames / second and 30 frames / second, the system configuration becomes simple and extremely practical.

  In FIG. 13, the number of dropped frames is determined stepwise in inverse proportion to the movement between pictures. However, considering the characteristics of the actual human eye, the movement is too fast and exceeds the range that the human eye can follow. If the number of dropped frames is increased, it may not be noticeable. This is because the human eye is expected to have a frame drop detection limit characteristic as shown in FIG. In this case, of course, frame dropping is hardly detected in a video close to a still image. On the other hand, even if the movement of the image is so intense that it is difficult to follow the human eye, it is naturally difficult to detect frame dropping. In the data conversion table 92 of FIG. 14, the extracted value of the motion vector amount is corrected using such characteristics.

  FIG. 14 is a block circuit diagram in which the number of frames is varied in consideration of the above human characteristics. The same reference numerals as those in FIG. 12 indicate the same parts, 92 is a data conversion table, and 93 is a frame drop amount determination means. is there. In the conversion table 92 in the figure, when the amount of motion vector is equal to or less than a predetermined absolute amount, the number of frames dropped in inverse proportion to the amount of motion vector, and when the amount is greater than the absolute amount, the number proportional to the amount of motion vector. It was designed to drop frames.

  FIG. 15 is a diagram showing an arrangement of digital compressed video data recorded on the optical disc before dropping frames in the second embodiment, and FIG. 16 is a diagram showing video information data recorded on the optical disc with a reduced number of frames. Fig. 16 (a) shows how the display on the screen looks, and Fig. 16 (a) shows a video data display screen with no frames dropped, and Fig. 16 (b) shows one frame dropped on three screens. 16 (c) is a video data display screen with 2 frames dropped on 3 screens, and FIG. 16 (d) is a video data display screen with 1 screen dropped on 5 screens. Respectively.

  FIG. 17 is a diagram showing human visual characteristics, and shows how many frames are detected with respect to the speed of image movement.

  The video information actually recorded on the optical disc has a form as shown in FIG. The original digital compressed video data has a data arrangement as shown in FIG. This is because the I picture can be reproduced independently, but the P picture requires a prediction screen from the previous I picture or P picture in time, and the B picture from the previous or next I picture or P picture. This is because a prediction screen is required. Therefore, unlike the playback order of the screen, the P picture data is arranged next to the I picture, and the B picture data is arranged next.

  However, regarding the data arrangement on the optical disk, for example, when only I picture and P picture are reproduced at the time of special reproduction, it is very convenient that I picture and P picture are arranged consecutively. They are rearranged as shown in 15 (c). This is because the data amount after compression is sufficiently smaller than the original video signal data amount, so that the memory of the optical disk playback device can be easily rearranged, which is sufficient for the above-described data array conversion. It is because it can respond to. In the case of this method, the B picture is partially deleted in the case of a GOP in which video data with faster movement is continuous, so that the data amount is further reduced and the file efficiency is improved as shown in FIG. It has improved.

  Such rearrangement of data and reduction of picture data are performed by, for example, the disk format encoder 42 shown in FIGS. 12 and 14, but for the purpose of removing intersymbol interference when performing higher density recording. For example, modulation such as EFM modulation or 1-7 modulation is performed, and recording is once performed on a recordable file device (for example, a magnetic disk, a magnetic tape, or a magneto-optical disk). For example, a master disk is created by the ROM disk mastering device 45 using the data once stored in this manner, and the ROM disk 9 is mass-produced by the stamper. Naturally, when the optical disk is a recording / reproducing apparatus, the above operation is performed without going through the recording data file 7 and the ROM disk mastering apparatus, and data is directly recorded on the optical disk.

  Next, when the above-described compressed video data is read from the optical disk and reproduced and displayed on the screen, the result is as shown in FIG. FIG. 16A shows a case where there is a certain amount of motion between pictures that does not allow frame dropping, and corresponds to a video before encoding in units of pictures. On the other hand, if one frame is allowed to be dropped on three screens, as shown in FIG. 16B, the B2, B4, and B6 pictures are dropped, and the B1, B3, and B5 pictures are frozen ( Display again). Further, when two frames are dropped on three screens, a screen without a B picture is reproduced. In the case shown in FIG. 16C, the frame drop state is easily detected by the human eye, but if it is very close to a still image, even if the frame drop is allowed so far, it is not noticeable.

  Further, as shown in FIG. 16 (d), there may be a case where frame dropping of one frame is allowed for every five screens that are intermediate between FIG. 16 (a) and FIG. 16 (b). Frames can be dropped and this can be handled by freezing the previous and next pictures. In this case, for example, in the case of FIG. 16D, it is desirable to fix the position of the freeze on the five screens in order to make the eye conspicuous. In order to perform frame dropping of only the B picture, as shown in FIG. 16D, not only the previous image is necessarily frozen, but also the subsequent image is frozen. Such freeze control is performed by providing a flag or the like in the header part provided at the head of the GOP or the header part provided at the head part of the picture data.

  Here, it is important to first determine whether the video data is interlaced or non-interlaced in the control information for overlappingly displaying the dropped video data. As shown in FIG. 19, the information for that purpose is preferably described in user data 52 in a sequence header 46 described at the beginning of one or a plurality of video information units GOP 47 in which a plurality of video data are collected. . This is because the interlace system is not switched in units of pictures because of motion compensation and the like, and once set, it does not change much.

  Further, it is desirable to control which field is to be displayed in duplicate in order to eliminate the awkwardness of movement and the like, and it is desirable to control in the user data area 52 provided at the head of the picture layer 56 in FIG. It is good to write it down.

  As a method of pulling up video data originally having a small number of frames to a predetermined frame rate at the time of display, a film source movie material is often used. In this case, as shown in FIG. 22A, when the original film is used as a television signal, an image created from the same film is generated in three or two fields. Therefore, as shown in the figure, one field in five is displayed in a duplicated manner and reproduced on the television. However, the first field and the second field are alternately inserted every several sheets. In this way, it is possible to convert the frame rate in such a way that smoothness is maintained even when video is displayed in duplicate. When the original signal is a television signal, frames are dropped, so that there is a temporal order in units of fields, and therefore, overlapping display is performed based on the information of the previous field.

It is a flowchart which shows the decoding method at the time of inserting the control information of Embodiment 1 of this invention in the user data of a video stream. 1 is a block circuit diagram showing a configuration of an optical disk reproducing device in Embodiment 1. FIG. 3 is a flowchart at the time of normal reproduction in the first embodiment. 3 is a flowchart at the time of low speed reproduction in the first embodiment. 3 is a diagram showing a system stream for normal playback according to Embodiment 1. FIG. 3 is a diagram showing a system stream for low-speed playback according to Embodiment 1. FIG. 6 is a diagram illustrating a storage arrangement of stream information on the optical disc according to the first embodiment. FIG. FIG. 3 is a conceptual diagram illustrating a normal reproduction video stream and an interpolation information stream according to the first embodiment. 6 is a diagram showing a field reproduction method during normal reproduction according to Embodiment 1. FIG. It is a figure which shows the video recording / reproducing method of Embodiment 2 of this invention. 6 is a diagram illustrating a structure of a video stream for realizing screen freeze according to Embodiment 2. FIG. FIG. 3 is a block circuit diagram of a second embodiment. In Embodiment 2, it is the figure which showed how a frame drop is performed with respect to the amount of motion vectors. FIG. 10 is a block circuit diagram that varies the number of frames in consideration of human characteristics in the second embodiment. FIG. 10 is a diagram showing an arrangement of digital compressed video data recorded on an optical disc before dropping frames in the second embodiment. In Embodiment 2, it is the figure which showed what the display on a screen becomes like at the time of reproduction | regeneration of the video information data recorded on the optical disk by reducing the number of frames. 6 is a diagram illustrating human visual characteristics in Embodiment 2. FIG. FIG. 10 is a diagram illustrating a reproduction mode by setting a flag according to the second embodiment. 6 is a diagram illustrating a structure of a video stream for realizing screen freeze according to Embodiment 2. FIG. 6 is a diagram illustrating a structure of a video stream for realizing screen freeze according to Embodiment 2. FIG. FIG. 10 is a diagram illustrating a structure of a video stream for realizing screen freeze according to the second embodiment. FIG. 10 is a diagram illustrating a method of deleting a field of video material according to the second embodiment. It is the figure which simplified and represented the data arrangement structure (layer structure) of the conventional MPEG system. It is the figure which showed the encoding structure when the conventional 15 screens are set to 1 GOP. It is the figure which compared the case where the conventional video data amount in 1 GOP was made into the variable structure in order to make the image quality between each GOP constant, and what was made into the fixed rate in order to make recording time constant. It is the figure which showed the data amount per 1GOP when the image quality per 1 conventional GOP is kept the same. It is a block circuit diagram of the conventional optical disk apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Optical disk, 2 Playback amplifier, 3 Demodulator, 4 Error correction means, 5 Temporal reference conversion control means, 6 Buffer, 7 Decoding means, 8 D / A converter, 9 Playback control means, 10 Optical head control means, 11 Interpolation information reading control means, 12 pack header, 13 system header, 14 private 2 packets, 15 audio packets, 16 private packets, 17 video packets, 18 information flags, 19 information address, 20 information size, 21 picture rate, 22 packet length , 23 packet start code, 24 return address value, 25 picture address data, 26 TOC, 27 video information for normal playback, 28 video information for low speed playback, 29 picture header, 30 pictures Coding function expansion section, 31 Quantization matrix function expansion section, 32 Picture display function expansion section, 33 Picture space scalable function expansion section, 34 Picture temporal scalable function expansion section, 35 Slice layer, 37 Top field first flag, 38 Repeat first Field flag, 39 progressive frame flag, 40 video A / D converter, 41 video information compression means, 42 disk format encoder, 43 modulation means, 44 data storage, 45 ROM disk mastering device, 46 sequence header, 47 GOP, 48 sequence Header code, 49 Sequence extension part, 50 Sequence display extension part, 51 Sequence scalable extension part, 52 User data part 53 user data start section, 54 user data, 55 GOP header, 56 picture layer, 57 picture header, 58 slice layer, 59 GOP, 60 GOP layer, 61 slice, 62 slice layer, 63 block layer, 66 I picture, 67 B Picture, 68 P picture, 69 Frame sector means, 70 Encoder, 71 Modulator, 72 Laser drive circuit, 73 Laser output switch, 74 Optical head, 75 Actuator, 76 Optical disc, 77 Disc motor, 78 Traverse motor, 79 Motor drive circuit , 80 motor control circuit, 81 motor control circuit, 82 reproduction amplifier, 83 demodulator, 84 decoder, 85 frame sector inverse conversion means, 86 information decompression means 87 D / A converter, 88 deletion field, 89 field, 90 motion vector amount detection means, 91 frame drop amount determination means, 92 data conversion table, 93 frame drop amount determination means.

Claims (4)

Reference picture is an I picture that is video information subjected to intra-frame DCT, a P picture that is video information obtained by DCT coding with forward motion compensation, and the I picture and P picture that are temporally located before and after In a recording method for recording digital information including video information including a B picture, which is video information by DCT encoding subjected to motion compensation, and control information of the video information on a recording medium ,
Before SL video information, the first image information for the normal reproduction is reproduced by receiving a reproduction request from outside, the second as the interpolated video information to interpolate the first video information to be normally reproduced Video information,
The digital information is configured in units of a video information unit having a private packet including the control information and a video packet including the first video information or the second video information.
The private packet is arranged before the video packet;
A first video information unit in which the first video information is stored in the video packet and a second video information unit in which the second video information is stored in the video packet are on the recording medium. To be placed alternately,
The control information of the private packet in the first video information unit includes the address of the second video information unit corresponding to the first video information unit and the size information of the second video information unit. ,
The recording method according to claim 1, wherein the control information of the private packet in the second video information unit includes an address of the first video information unit corresponding to the second video information unit. A reproduction method for reproducing a recording medium recorded using the recording method according to claim 1,
When a reproduction request for the second video information is made, an address of the second video information unit stored in a private packet of the first video packet is acquired,
A reproduction method, wherein the second video information is read based on an address of the second video information unit. Reference picture is an I picture that is video information subjected to intra-frame DCT, a P picture that is video information obtained by DCT coding with forward motion compensation, and the I picture and P picture that are temporally located before and after As a disc-shaped recording medium on which digital information including video information including a B picture which is video information by DCT encoding subjected to motion compensation and control information of the video information is recorded .
Before SL video information, the first image information for the normal reproduction is reproduced by receiving a reproduction request from outside, the second as the interpolated video information to interpolate the first video information to be normally reproduced Video information,
The digital information is configured in units of a video information unit having a private packet including the control information and a video packet including the first video information or the second video information.
The private packet is arranged before the video packet;
The disc-shaped recording includes a first video information unit in which the first video information is stored in the video packet and a second video information unit in which the second video information is stored in the video packet. Alternatingly placed on the medium track,
The control information of the private packet in the first video information unit includes the address of the second video information unit corresponding to the first video information unit and the size information of the second video information unit. ,
The control information of the private packet in the second video information unit includes the address of the first video information unit corresponding to the second video information unit,
A disc-shaped recording medium, characterized in that a head of each of the first video information unit and the second video information unit is arranged at a head position of a sector in the disc-shaped recording medium. A reproduction method for reproducing the recording medium according to claim 3,
When a reproduction request for the second video information is made, an address of the second video information unit stored in a private packet of the first video packet is acquired,
A reproduction method, wherein the second video information is read based on an address of the second video information unit.

Images