JP4217504B2 - Image reproduction method and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an image reproduction method and method, and more particularly to a method for reproducing still image data recorded using a recording method for compressing and recording a moving image using interframe coding, such as the MPEG-1 and 2 methods. Regarding the method.
[0002]
[Prior art]
Products such as D-VHS have been developed by a technique for recording MPEG data on a home digital video recorder, and a technique for recording HD (High Definition) video on a DV standard compact cassette is disclosed in Patent Document 1 and the like. .
[0003]
On the other hand, in the SD standard SD recording format, a method for recording a still image on a tape medium together with a predetermined search ID for a certain period is standardized, and a still image search technique on a tape using this is disclosed in Patent Document 2 and the like. ing. This is not a special compression encoding for still images, but is recorded as a moving image in which the same frame continues, and only flag information indicating that it is a still image is added. This method is disadvantageous for disc media and other media that can be accessed at random, because the recording capacity increases. It is possible to reproduce a still image for a predetermined time without performing special processing.
[0004]
[Patent Document 1]
JP 2001-275077 A
[Patent Document 2]
JP-A-7-98965
[0005]
[Problems to be solved by the invention]
However, when a conventional tape still image recording in the SD recording format is applied to video recording based on MPEG data, there is a difference in encoding distortion among I pictures, P pictures, and B pictures. Since this is a still image sequence in which digitally identical frames are continuous, the P picture and the B picture encode the intra-frame coding error signal of the I picture, and the coding distortion amount as a frame is I This is because there are many scenes where> P> B.
[0006]
When a still image sequence in which coding distortion varies between frames as described above is reproduced as a moving image, a temporal change in the coding distortion is perceived as flicker, and there is essentially no motion, so a still image that should be advantageous as an encoded image quality. In spite of the sequence, the reproduced image is deteriorated.
[0007]
In addition, it is not desirable for reproduction of a still image sequence that the image quality may change with time due to code amount control during encoding.
[0008]
The present invention has been made in view of the above points, and an object of the present invention is to realize image reproduction in which flicker due to coding distortion does not occur during reproduction of a still image sequence recorded using a moving image compression method. To do.
[0009]
[Means for Solving the Problems]
  The image reproduction method of the present invention is an image reproduction method for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding, wherein the duration of the still image sequence is increased. Means for detecting and the still image sequenceCompressed by the inter-frame encoding at a position where a predetermined number of frames have elapsed from the beginning of the still image sequence among a plurality of decoded frames decoded by the decoding means Between encoded framesFrame holding means for holding a decoded frame of the encoded frame, and at least a still image sequence continuation period after the reproduction time of the held decoded frame, the decoding of the encoded data after the held decoded frame And a means for outputting in place of the frame.
  Another image reproduction method of the present invention includes a still image sequence composed of a sequence of the same still image frames compressed and encoded by the MPEG method, the still image sequence recorded as additional information of the still image sequence, and its continuous reproduction. An image reproduction method for reproducing identification information for specifying a period from a recording medium, a reproducing means for reproducing data recorded on the recording medium, and the identification information from the data reproduced by the reproducing means. Detecting means for detecting; decoding means for decoding image data out of data reproduced by the reproducing means; and starting reproduction of a still image sequence specified by the identification information detected by the detecting means, and Among the plurality of decoded frames obtained by decoding the image data corresponding to the sequence by the decoding means, the static A frame holding means for holding a decoded frame of an inter-frame encoded frame that has been compression-encoded by inter-frame coding at a position where a predetermined number of frames have passed from the beginning of the image sequence; and an identification detected by the detecting means During the continuous reproduction period of the still image sequence specified by the information, the decoded frame decoded by the decoding unit is sequentially output until the decoded frame is held in the frame holding unit, and the frame holding unit And after the decoded frame is held, output means for repeatedly outputting the held decoded frame is provided.
  The image reproduction method of the present invention is an image reproduction method for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding, wherein the duration of the still image sequence is increased. A procedure for detecting, a procedure for decoding encoded data of the still image sequence, and the frame at a position where a predetermined number of frames have elapsed from the beginning of the still image sequence among the plurality of decoded frames decoded The procedure for the frame holding means to hold the decoded frame of the inter-frame encoded frame that has been compression-encoded by the inter-coding, and at least the still image sequence duration after the playback time of the held decoded frame is held as described above And a procedure for outputting the decoded frame in place of the decoded frame of the subsequent encoded data. With a butterfly.
  Another image reproduction method of the present invention includes a still image sequence composed of a sequence of identical still image frames compression-encoded by the MPEG method, the still image sequence recorded as additional information of the still image sequence, and its continuous reproduction. An image reproduction method for reproducing identification information for specifying a period from a recording medium, a reproduction procedure for reproducing data recorded on the recording medium, and the identification information from the data reproduced by the reproduction procedure. A detection procedure for detecting, a decoding procedure for decoding image data of the data reproduced by the reproduction procedure, and a reproduction of the still image sequence specified by the identification information detected by the detection procedure. Among the plurality of decoded frames obtained by decoding the image data corresponding to the sequence, the still image sequence is selected. The frame holding means holds the decoded frame of the inter-frame encoded frame that has been compression-encoded by the inter-frame encoding at the position where a predetermined number of frames have passed from the beginning of the frame, and is detected by the above detection procedure. During the continuous reproduction period of the still image sequence specified by the identification information, the decoded frames decoded in the decoding procedure are sequentially output until the decoded frame is held in the frame holding means, and the frame After the decoded frame is held in the holding means, there is a feature in that it has an output procedure for repeatedly outputting the held decoded frame.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of an image reproduction method and method according to the present invention will be described below with reference to the drawings.
[0014]
(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a digital video playback apparatus according to an embodiment. Reference numeral 101 denotes a recording medium using a magnetic tape, on which a still image sequence including a moving image and a continuous still image compressed and encoded by, for example, the MPEG2 encoding method is recorded.
[0015]
A reproduction head 102 reproduces a recording signal by scanning a recording track on the recording medium 101. A reproduction amplifier circuit 103 amplifies a reproduction signal from the reproduction head 102. A modulation / decoding circuit 104 obtains digital reproduction data from a reproduction signal subjected to recording modulation.
[0016]
A recording format decoding circuit 105 separates payload data for each track and other additional data from the obtained digital reproduction data. The payload data may include a plurality of data strings such as image data and audio data. In the present embodiment, only image data encoded by MPEG2 will be described.
[0017]
An error correction decoding circuit 106 detects and corrects a data error using parity information added at the time of recording. A system decoding circuit 107 separates video data, audio data, and header information from the MPEG2 bit stream.
[0018]
Reference numeral 108 denotes a compression decoding circuit having a still image hold function, which is a feature of the present invention, and decodes MPEG2 video data to obtain reproduced image data. The operation at the time of decoding will be described in detail later. Reference numeral 109 denotes a D / A conversion circuit which converts the decoded digital video data into an analog video signal and outputs it from the terminal 110.
[0019]
  FIG. 2 is a diagram showing a configuration example of the compression decoding circuit 108 having a still picture hold function which is a feature of the present invention. The terminal 201 is supplied with MPEG2 video data andissueThe data is supplied to the buffer memory circuit 202 that absorbs the amount variation.
[0020]
The variable length decoding circuit 203 decodes the encoded coefficient sequence from the entropy encoded bit sequence. The inverse quantization circuit 204 inversely quantizes the encoded coefficient to obtain a DCT coefficient sequence. The inverse DCT circuit 205 converts the DCT coefficient sequence into pixel data or difference data.
[0021]
The adder circuit 206 controls the switch 209 to obtain reproduced image data by adding the difference data to the predicted image for the P picture and B picture as they are for the I picture according to the MPEG2 picture structure.
[0022]
During normal video playback, the switch 215 is connected to the adder circuit 206 side, and the playback image data is output from the terminal 216 as it is, and the I picture and P picture images are held in the video memory 207 to generate predicted images. The The motion compensation prediction circuit 208 generates a motion compensation prediction image from the I picture and P picture held by the decoded motion vector, and supplies the motion compensation prediction image to the switch 209.
[0023]
The still image period detection circuit 211 detects the duration of the still image sequence based on the image reproduction method that is a feature of the present invention. In this embodiment, it is assumed that the duration of the still image sequence is made by a still image identification ID recorded as additional information of MPEG2 at the time of recording. It is assumed that the still image identification ID is recorded in such a manner that not only a moving image / still image is distinguished but also a continuous still image sequence can be distinguished even when still image sequences are recorded continuously.
[0024]
The still picture identification ID information corresponding to the bit stream of the still picture sequence obtained at the time of system decoding by the system decoding circuit 107 shown in FIG. 1 is supplied from the terminal 210 to the still picture period detection circuit 211, and the video currently being decoded. When the data is a still image sequence, still duration data consisting of the start point and end point is supplied to the hold control circuit 212. The hold control circuit 212 selects a playback frame image in the still image sequence by the switch 213 in accordance with the image playback method of the present invention to be described later, holds it in the frame memory 214, and connects the switch 215 to the frame memory 214 side for holding. The reproduced frame images are output from the terminal 216 continuously.
[0025]
FIG. 3 is a diagram for explaining an example of reproduction of a still image sequence in the present embodiment. FIG. 3A is a diagram showing a recorded MPEG2 video bit stream, in which a still image sequence n and a still image sequence n + 1 are recorded following the moving image m. The still image identification ID described above is added to each of the still image sequences n and n + 1. As a result, moving images and still images are identified, the duration of the still image sequence is determined, and the hold period of the playback frame is determined.
[0026]
FIG. 3B is a diagram showing the configuration of the still picture sequence n. In this example, for the purpose of explanation, the still picture sequence n is represented by n to n + 3 of GOP (group of pictures) which is a unit of interframe coding. Is configured.
[0027]
FIG. 3C is a diagram showing a frame configuration of GOPn, and it is assumed that the GOP is configured with 15 frames from B picture B1 to P picture P4. As for the still picture sequence, since the input picture is a series of frame data in which the input picture is completely digitally matched, the I picture is the compression coding using the correlation in the frame like the moving picture, whereas the P picture is the I picture. If the bit allocation appropriate for the coding of the P picture is performed as well as the re-encoding of the difference data between the original picture and the I picture, that is, the coding error of the I picture, The conversion error is reduced. Similarly, since the B picture is a re-encoding of the coding error by the P picture, when the bit distribution to the B picture is not restricted, the reproduced image by the B picture has the smallest coding error.
[0028]
Therefore, it is possible to reproduce a beautiful still image sequence free from flicker due to fluctuations in coding error by using this and holding a reproduced frame of a B picture with a small coding error and outputting it instead of the subsequent decoded image. is there. In FIG. 3C, since the top two B pictures B1 and B2 are sequence heads, there is a high possibility that they are limited to backward prediction from I pictures. B pictures B3 and B4 are B pictures, but one side of the prediction is an I picture I1 that seems to have the largest coding error. Therefore, the B picture B5 that is bidirectionally predicted from the P picture has a small coding error and It seems to be ahead in time.
[0029]
Therefore, in the present embodiment, the hold control circuit 212 considers the still picture duration, the picture type of each frame, and the prediction direction, and as shown in FIG. The B picture B5 and subsequent pictures are held and output instead of the decoded picture during the duration of the still picture sequence n.
[0030]
FIGS. 3C and 3D show the GOP structure shown in the playback frame order. In the MPEG2 bit stream, the frame data is rearranged in accordance with the prediction order at the time of decoding. FIG. 3E shows the rearranged frame order, and the actual processing in FIG. 2 is applied to the rearranged frame order.
[0031]
In the present embodiment, the first B picture that is bi-directionally predicted from the P picture is held. However, since the P picture is a sequential prediction, the prediction error decreases as the P picture later in the same GOP. As a result, it is possible to select frames B7 and B9 as the B picture to be selected. In this case, since the prediction error is improved and the delay time until the hold is traded off, the frame position to be held may be set in accordance with the characteristics of the system using the present invention.
[0032]
In addition, as a setting of the recording / reproducing system, it is also conceivable to limit the bit allocation to the B picture at the time of recording the still image sequence and reduce the coding error of the I picture and the P picture. In such a system, an image with a small coding error can be obtained by holding a P picture, and therefore the P picture may be held by the control of the hold control circuit 212.
[0033]
FIG. 4 is a diagram for explaining another example of reproduction of a still image sequence in the present embodiment. FIG. 4A is a diagram showing a recorded MPEG2 video bit stream, in which a still image sequence n and a still image sequence n + 1 are recorded following the moving image m.
[0034]
FIG. 4B is a diagram showing the configuration of the still image sequence n. In this example, for the sake of explanation, it is assumed that the still image sequence n is configured from GOPn to n + 3.
[0035]
In this example, the still picture hold operation is not performed in GOPn which is the first GOP of the still picture sequence, and the above-described B picture hold process is started from GOPn + 1. This is because there is a possibility that the top GOP is not finely quantized for code amount control at the time of recording. For example, in a system in which a still image sequence is recognized at the time of recording and a subsequent generated code amount is predicted by encoding the leading GOP, and encoding is performed so as to obtain an optimum image quality for the subsequent GOP, A higher quality still image can be obtained by holding the subsequent GOP than by holding the playback frame. In the present embodiment, an example in which the second GOP is held has been described. However, as a system including a recording system, the necessary number of frames for stabilizing the encoding of a still image sequence and the continuation of the normal playback mode until the hold is performed. It may be set arbitrarily depending on time.
[0036]
FIG. 4C is a diagram showing the frame configuration of GOPn + 1. As described in the example of FIG. 3, the playback frame of the B picture B5 in the GOP is held.
[0037]
FIG. 5 is a diagram for explaining another reproduction example of the still image sequence in the present embodiment. FIG. 5A is a diagram showing a recorded MPEG2 video bit stream, in which a still image sequence n and a still image sequence n + 1 are recorded following the moving image m.
[0038]
FIG. 5B is a diagram showing the configuration of the still image sequence n. In this example, it is assumed that the still image sequence n is configured from GOPn to n + 3 for the sake of explanation.
[0039]
In this example, the hold start flag indicating the timing for starting the still image hold operation is recorded at the time of recording. In GOPn, n + 1, the still image hold operation is not performed, and the above-mentioned B picture is read from GOPn + 2 indicated by the hold start flag. The hold process is started. For example, in a system in which a still image sequence is recognized at the time of recording, a subsequent generated code amount is predicted by encoding with respect to the first number GOP, and encoding is performed so as to obtain an optimum image quality for the subsequent GOP. Occasionally, the generated code amount for the above still image sequence is predicted and a hold start flag indicating that the hold can be performed from the point when the optimization of the encoding control is completed is recorded. This is for use in a system that allows more optimal still image reproduction by holding a frame. As a result, an optimal GOP is selected between the GOPs, and a reproduction frame with the least coding error can be held in the GOP, and a more beautiful still image reproduction can be performed.
[0040]
FIG. 6 is a diagram for explaining an example of still image period detection. In this example, a discontinuity flag (Discontinuity Flag) defined in the MPEG2-TS stream and a still image flag which is additional information added at the time of recording to indicate a still image sequence are used. The image duration is determined. The discontinuity flag is added at the start of scene recording, and is also added at the start of each still image sequence. From these, it is determined whether the image data currently being decoded is a still image sequence based on the still image flag, and the start and end of each still image sequence is detected by detecting the discontinuity flag for continuous still images. Is possible.
[0041]
FIG. 7 is a diagram for explaining another example of still image period detection. In this example, the still image period is detected using an FC (frame change) flag and SC (still camera) flag recorded in VAUX (video AUX) data in the DV format. The FC flag is 1 when there is a change between frames, and 0 when the data is the same. As the bit stream after MPEG2 encoding, the encoded data for the same image frame also changes, but here it is defined that the FC flag indicates a change between input frames. In this case, the FC flag is always 1 for moving image data, and is 1 because only the first frame is different from the previous image in the still image sequence, and thereafter 0 until the end of the sequence. Since the SC flag is 0 when recording a still image sequence, it can be determined that the still image sequence is detected by detecting the SC flag. Even when the still image sequence is continuous, the SC flag does not change, but the next still image sequence is detected. Since the FC flag is set to 1 only in the first frame of the image sequence, the start and end of each still image sequence can be detected.
[0042]
(Second Embodiment)
In the second embodiment, a function of detecting image degradation due to an uncorrectable error and holding an optimum still image is provided. FIG. 8 is a diagram showing a schematic configuration of the digital video reproducing apparatus according to the embodiment. Reference numeral 801 denotes a magnetic tape recording medium on which a still image sequence including a moving image and a continuous still image that are compression-encoded by, for example, the MPEG2 encoding method is recorded.
[0043]
A reproducing head 802 reproduces a recording signal by scanning a recording track on the recording medium 801. A reproduction amplifier circuit 803 amplifies a reproduction signal from the reproduction head 802. A modulation / decoding circuit 804 obtains digital reproduction data from a reproduction signal subjected to recording modulation.
[0044]
A recording format decoding circuit 805 separates payload data for each track and other additional data from the obtained digital reproduction data. The payload data may include a plurality of data strings such as image data and audio data. In the present embodiment, only image data encoded by MPEG2 will be described.
[0045]
An error correction decoding circuit 806 corrects a data error using parity information added at the time of recording, and notifies the compression decoding circuit 808 of the occurrence of an error for an uncorrectable error. A system decoding circuit 807 separates video data, audio data, and header information from the MPEG2 bit stream.
[0046]
Reference numeral 808 denotes a compression decoding circuit having a still image hold function, which is a feature of the present invention, and decodes MPEG2 video data to obtain reproduced image data. The operation at the time of decoding will be described in detail later. Reference numeral 809 denotes a D / A conversion circuit which converts the decoded digital video data into an analog video signal and outputs it from a terminal 810.
[0047]
  FIG. 9 is a diagram showing a configuration example of a compression decoding circuit 808 having a still picture hold function which is a feature of the present invention. The terminal 901 is supplied with MPEG2 video data,issueThe data is supplied to a buffer memory circuit 902 that absorbs the amount variation.
[0048]
The variable length decoding circuit 903 decodes the encoded coefficient sequence from the entropy encoded bit sequence. The inverse quantization circuit 904 inversely quantizes the encoded coefficient to obtain a DCT coefficient sequence. The inverse DCT circuit 905 converts the DCT coefficient sequence into pixel data or difference data.
[0049]
The adder circuit 906 controls the switch 909 to obtain reproduced image data by adding the difference data to the predicted image for the P picture and B picture as they are for the I picture according to the MPEG2 picture structure.
[0050]
During normal video playback, the switch 915 is connected to the addition circuit 906 side, and the playback image data is output as it is from the terminal 916, and the I picture and P picture images are held in the video memory 907 to generate predicted images. The The motion compensation prediction circuit 908 generates a motion compensation prediction image from the I picture and P picture held by the decoded motion vector, and supplies the motion compensation prediction image to the switch 909.
[0051]
The still image period detection circuit 911 detects the duration of the still image sequence based on the image reproduction method that is a feature of the present invention. The details of the still image period detection have already been described in the first embodiment, and are omitted here.
[0052]
If the video data currently being decoded is a still image sequence, still duration data consisting of the start point and end point is supplied to the hold control circuit 912. The degree of deterioration of the uncorrectable error occurrence information in the error correction decoding circuit 806 supplied from the terminal 917 is estimated in the image deterioration estimation circuit 918 in consideration of the frequency and the picture type, and is notified to the hold control circuit 912. .
[0053]
The hold control circuit 912 selects the playback frame image in the still image sequence by the switch 913 according to the image playback method described later based on the result of comparing the still picture period, the picture type, and the image quality deterioration amount with a predetermined threshold value, and stores it in the frame memory 914. At the same time, the switch 915 is connected to the frame memory 914 side, and the held reproduction frame images are continuously output from the terminal 916.
[0054]
FIG. 10 is a diagram for explaining the playback frame hold operation when an uncorrectable error is included. Now, an uncorrectable error has occurred in the first GOPn of the still image sequence, and image quality deterioration is propagated in the GOP due to interframe coding. In this case, the hold control circuit 912 prohibits the holding of the still image frame in GOPn, and starts the hold operation from GOPn + 1 without error.
[0055]
FIG. 11 is a diagram for explaining the difference in error propagation depending on the picture type. An error that occurs in an I picture in a GOP propagates throughout the GOP, but an error in a P picture propagates only to subsequent P and B pictures, and an error in a B picture that is not used for inter-frame prediction. do not do. Actually, errors in the variable-length encoded data cannot be decoded regardless of the picture type until the synchronization of the variable-length code is restored. For example, in the case of a variable-length code capable of bidirectional decoding used in MPEG4, Since it is possible to limit the influence of errors locally, a frame that can be held in the GOP may be selected in consideration of the influence of error propagation shown in FIG.
[0056]
FIG. 12 is a diagram for explaining an example in which holding is performed in consideration of error propagation by picture type. Now, an error has occurred in the B picture B2 of GOPn, but error propagation by the variable length code has converged in the B picture B2 due to synchronous recovery or bidirectional decoding of variable length coding as described above. Since the picture type of the error-occurring frame is a B picture and there is no propagation due to inter-frame coding, it is possible to hold a reproduction frame by the B picture B5 with a small coding error as described above.
[0057]
(Third embodiment)
As a third embodiment, an example in which a still image held with image quality deterioration due to an error uncorrectable error is updated with an image with few errors will be described with reference to FIG. Although it is not desirable to hold an image that contains an error in the normal playback state, it is applicable when the playback state is very poor and image quality deterioration below a predetermined threshold is allowed and the noise caused by the error is not noticeable. Is.
[0058]
If an error has occurred in GOPn but the image quality degradation amount A estimated by the image degradation estimation circuit 918 depending on the picture type and frequency falls below a predetermined threshold th, the hold control circuit 912 holds the reproduced frame.
[0059]
Further, the hold control circuit 912 continuously monitors the image quality deterioration amount of the subsequent frames over the still image continuation period. If the image quality deterioration amount B of the frame that can be held in GOPn + 2 is lower than the image quality deterioration amount A of the previously held image, the hold control circuit 912 Update the frame to be updated. As a result, it is possible to provide an image reproduction method capable of holding still image frames and updating to a better hold screen even when the reproduction state is poor.
[0060]
(Other embodiments)
Software program for realizing the functions of the above-described embodiment for an apparatus or a computer in the system connected to the various devices so as to operate the various devices to realize the functions of the above-described embodiments. What was implemented by supplying the code and operating the various devices in accordance with a program stored in a computer (CPU or MPU) of the system or apparatus is also included in the scope of the present invention.
[0061]
In this case, the program code of the software itself realizes the functions of the above-described embodiments, and the program code itself constitutes the present invention. As a transmission medium for the program code, a communication medium (wired line or wireless line such as an optical fiber) in a computer network (LAN, WAN such as the Internet, wireless communication network, etc.) system for propagating and supplying program information as a carrier wave Etc.) can be used.
[0062]
Further, means for supplying the program code to the computer, for example, a recording medium storing the program code constitutes the present invention. As a recording medium for storing the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
[0063]
Further, by executing the program code supplied by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) or other application software in which the program code is running on the computer. Needless to say, the program code is also included in the embodiment of the present invention even when the functions of the above-described embodiment are realized in cooperation with the above.
[0064]
Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the CPU provided in the function expansion board or function expansion unit based on the instruction of the program code Needless to say, the present invention also includes the case where the functions of the above-described embodiment are realized by performing part or all of the actual processing.
[0065]
It should be noted that the shapes and structures of the respective parts shown in the above embodiments are merely examples of implementation in carrying out the present invention, and these limit the technical scope of the present invention. It should not be interpreted. That is, the present invention can be implemented in various forms without departing from the spirit or the main features thereof.
[0066]
Examples of embodiments of the present invention are listed below.
(Embodiment 1) An image reproduction method for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
Means for detecting the duration of the still image sequence;
Frame holding means for holding a decoded frame of a predetermined encoded frame in the still image sequence;
Means for outputting the held decoded frame in place of the decoded frame of the subsequent encoded data at least during the still image sequence continuation period after the reproduction time of the held decoded frame. Image playback method to be used.
[0067]
According to the image reproduction method of the first embodiment, for example, a frame image of a B picture with the least coding distortion is held, and subsequently output continuously, so that a still image sequence recorded using the moving image compression method can be output. It is possible to realize image reproduction that does not cause flicker due to coding distortion during reproduction.
[0068]
(Embodiment 2) An embodiment characterized in that the process of holding a decoded frame in the frame holding means is performed on a coded frame after a predetermined interframe coding unit has elapsed from the beginning of the still image sequence. The image reproduction method according to aspect 1.
[0069]
(Embodiment 3) The image reproduction method according to Embodiment 1, wherein the process of holding the decoded frame in the frame holding means is started in synchronization with the additional information in the still image sequence.
[0070]
(Embodiment 4) The image reproduction method according to Embodiment 1, wherein the duration of the still image sequence is detected from still image ID information for identifying a still image recording portion in the recording data.
[0071]
(Embodiment 5) The duration of the still image sequence is detected from a still image recording flag indicating a still image recording portion in recording data and a flag indicating discontinuity of an inter-frame coding unit. The image reproduction method according to aspect 1.
[0072]
(Embodiment 6) An implementation characterized in that the duration of the still image sequence is detected from a still image recording flag indicating a still image recording portion in the recording data and a flag indicating presence / absence of an image change between frames. The image reproduction method according to aspect 1.
[0073]
(Embodiment 7) The image reproduction method according to any one of Embodiments 1 to 6, wherein the frame held in the frame holding means is selected from B pictures based on prediction from preceding and following frames.
[0074]
(Embodiment 8) The image reproduction according to any one of Embodiments 1 to 6, wherein the frame held in the frame holding means is selected from P pictures predicted from temporally preceding frames. method.
[0075]
(Embodiment 9) An image reproduction system for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
Means for detecting the duration of the still image sequence;
Means for calculating an uncorrectable error amount in encoded data necessary for decoding an encoded frame by interframe encoding;
Means for calculating the image quality degradation amount of the corresponding decoded frame from the uncorrectable error amount;
Frame holding means for holding a decoded frame of an encoded frame in which the image quality degradation amount is equal to or less than a predetermined value among the encoded frames in the still image sequence;
Means for outputting the held decoded frame in place of the decoded frame of the subsequent encoded data at least during the still image sequence continuation period after the reproduction time of the held decoded frame. Image playback method to be used.
[0076]
According to the image reproduction method of the ninth embodiment, for example, a B picture frame image with the least coding distortion is held and output continuously after avoiding an image including reproduction noise due to media damage or the like. By doing so, it is possible to realize image reproduction that does not cause flicker due to encoding distortion when reproducing a still image sequence recorded using the moving image compression method.
[0077]
(Embodiment 10) The process of holding the decoded frame in the frame holding means is performed on the encoded frame after a predetermined interframe coding unit has elapsed from the beginning of the still image sequence. The image reproduction system according to aspect 9.
[0078]
(Embodiment 11) The image reproduction system according to embodiment 9, wherein the process of holding the decoded frame in the frame holding means is started in synchronization with the additional information in the still image sequence.
[0079]
(Embodiment 12) The image reproduction method according to Embodiment 9, wherein the duration of the still image sequence is detected from still image ID information for identifying a still image recording portion in the recording data.
[0080]
(Embodiment 13) An implementation characterized in that the duration of the still image sequence is detected from a still image recording flag indicating a still image recording portion in recording data and a flag indicating discontinuity of an inter-frame coding unit. The image reproduction system according to aspect 9.
[0081]
(Embodiment 14) The duration of the still image sequence is detected from a still image recording flag indicating a still image recording portion in the recording data and a flag indicating presence / absence of an image change between frames. The image reproduction system according to aspect 9.
[0082]
(Embodiment 15) The image reproduction method according to any one of Embodiments 9 to 14, wherein the frame held in the frame holding means is selected from B pictures based on prediction from preceding and following frames.
[0083]
(Embodiment 16) The image reproduction according to any one of Embodiments 9 to 14, wherein the frame held in the frame holding means is selected from P pictures predicted from temporally preceding frames. method.
[0084]
(Embodiment 17) The frame held in the frame holding means is selected according to the amount of image quality degradation due to an uncorrectable error from a B picture predicted from preceding and following frames or a P picture predicted from temporally preceding frames. 15. The image reproduction method according to any one of embodiments 9 to 14, characterized by:
[0085]
(Embodiment 18) An image reproduction system for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
Means for detecting the duration of the still image sequence;
Means for calculating an uncorrectable error amount in encoded data necessary for decoding an encoded frame by interframe encoding;
Means for calculating the image quality degradation amount of the corresponding decoded frame from the uncorrectable error amount;
Frame holding means for holding a decoded frame of an encoded frame in which the image quality degradation amount is equal to or less than a predetermined value among the encoded frames in the still image sequence;
Means for outputting the held decoded frame in place of the decoded frame of the subsequent encoded data in the still image sequence duration after the reproduction time of the held decoded frame;
When a predetermined encoded frame having a lower image quality degradation amount than the held decoded frame is detected after holding the decoded frame, the held decoded frame is decoded as the newly detected encoded frame. An image reproduction method comprising: a means for updating with a frame.
[0086]
According to the image reproduction method of the above embodiment 18, even when the reproduction state is bad, the reproduction noise due to media damage or the like is not included as much as possible, for example, the B picture frame image with the least coding distortion is retained, Subsequently, by continuously outputting, it is possible to realize image reproduction that does not cause flicker due to encoding distortion when reproducing a still image sequence recorded using the moving image compression method.
[0087]
(Embodiment 19) An implementation characterized in that the process of holding a decoded frame in the frame holding means is performed on a coded frame after a predetermined interframe coding unit has elapsed from the beginning of the still image sequence. The image reproduction system according to aspect 18.
[0088]
(Embodiment 20) The image reproduction system according to embodiment 18, wherein the process of holding the decoded frame in the frame holding means is started in synchronization with the additional information in the still image sequence.
[0089]
(Embodiment 21) The image reproduction system according to embodiment 18, wherein the duration of the still image sequence is detected from still image ID information for identifying a still image recording portion in the recording data.
[0090]
(Embodiment 22) An implementation characterized in that the duration of the still image sequence is detected from a still image recording flag indicating a still image recording portion in recording data and a flag indicating discontinuity of an inter-frame coding unit. The image reproduction system according to aspect 18.
[0091]
(Embodiment 23) An implementation characterized in that the duration of the still image sequence is detected from a still image recording flag indicating a still image recording portion in the recording data and a flag indicating presence / absence of an image change between frames. The image reproduction system according to aspect 18.
[0092]
(Embodiment 24) The image reproduction system according to any one of embodiments 18 to 23, wherein the frame held in the frame holding means is selected from B pictures based on prediction from preceding and following frames.
[0093]
(Embodiment 25) The image reproduction according to any one of Embodiments 18 to 23, wherein the frame held in the frame holding means is selected from P pictures predicted from temporally preceding frames. method.
[0094]
(Embodiment 26) The frame held in the frame holding means is selected according to the amount of image quality degradation due to an uncorrectable error from a B picture predicted from preceding and following frames or a P picture predicted from a temporally preceding frame. 24. The image reproduction method according to any one of embodiments 18 to 23, wherein:
[0095]
(Embodiment 27) An image reproduction system for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
An image reproduction method characterized by holding a decoded frame of a predetermined encoded frame in the still image sequence and outputting it instead of a decoded frame of subsequent encoded data.
[0096]
(Embodiment 28) An image reproduction method for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
A procedure for detecting the duration of the still image sequence;
A procedure for holding a decoded frame of a predetermined encoded frame in the still image sequence;
And a procedure for outputting the held decoded frame in place of the decoded frame of the subsequent encoded data at least during the still image sequence continuation period after the reproduction time of the held decoded frame. Image playback method.
[0097]
(Embodiment 29) An image reproduction method for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
A procedure for detecting the duration of the still image sequence;
A procedure for calculating an uncorrectable error amount in encoded data necessary for decoding an encoded frame by interframe encoding;
A procedure for calculating the image quality degradation amount of the corresponding decoded frame from the uncorrectable error amount;
A procedure for holding a decoded frame of an encoded frame in which the image quality degradation amount is equal to or less than a predetermined value among the encoded frames in the still image sequence;
And a procedure for outputting the held decoded frame in place of the decoded frame of the subsequent encoded data at least during the still image sequence continuation period after the reproduction time of the held decoded frame. Image playback method.
[0098]
(Embodiment 30) An image reproduction method for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
A procedure for detecting the duration of the still image sequence;
A procedure for calculating an uncorrectable error amount in encoded data necessary for decoding an encoded frame by interframe encoding;
A procedure for calculating the image quality degradation amount of the corresponding decoded frame from the uncorrectable error amount;
A procedure for holding a decoded frame of an encoded frame in which the image quality degradation amount is equal to or less than a predetermined value among the encoded frames in the still image sequence;
The still image sequence duration after the reproduction time of the held decoded frame is a procedure for outputting the held decoded frame in place of the decoded frame of the subsequent encoded data,
When a predetermined encoded frame having a lower image quality degradation amount than the held decoded frame is detected after holding the decoded frame, the held decoded frame is decoded as the newly detected encoded frame. An image reproducing method comprising: a step of updating with a conversion frame.
[0099]
(Embodiment 31) An image reproduction method for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
An image reproduction method characterized by holding a decoded frame of a predetermined encoded frame in the still image sequence and outputting it instead of a decoded frame of subsequent encoded data.
[0100]
(Embodiment 32) A computer program for causing a computer to execute a process of reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
Processing for detecting the duration of the still image sequence;
A process of holding a decoded frame of a predetermined encoded frame in the still image sequence;
At least a still picture sequence continuation period after the reproduction time of the held decoded frame is to execute a process of outputting the held decoded frame in place of a decoded frame of the subsequent encoded data. A computer program.
[0101]
(Embodiment 33) A computer program for causing a computer to execute a process of reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
Processing for detecting the duration of the still image sequence;
A process of calculating an uncorrectable error amount in encoded data necessary for decoding an encoded frame by interframe encoding;
A process of calculating the image quality degradation amount of the corresponding decoded frame from the uncorrectable error amount;
A process of holding a decoded frame of an encoded frame in which the image quality degradation amount is equal to or less than a predetermined value among the encoded frames in the still image sequence;
At least a still picture sequence continuation period after the reproduction time of the held decoded frame is to execute a process of outputting the held decoded frame in place of a decoded frame of the subsequent encoded data. A computer program.
[0102]
(Embodiment 34) A computer program for causing a computer to execute a process of reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
Processing for detecting the duration of the still image sequence;
A process of calculating an uncorrectable error amount in encoded data necessary for decoding an encoded frame by interframe encoding;
A process of calculating the image quality degradation amount of the corresponding decoded frame from the uncorrectable error amount;
A process of holding a decoded frame of an encoded frame in which the image quality degradation amount is equal to or less than a predetermined value among the encoded frames in the still image sequence;
The still image sequence continuation period after the reproduction time point of the held decoded frame is a process of outputting the held decoded frame in place of the decoded frame of the subsequent encoded data; and
When a predetermined encoded frame having a lower image quality degradation amount than the held decoded frame is detected after holding the decoded frame, the held decoded frame is decoded as the newly detected encoded frame. A computer program for executing a process of updating with a computerized frame.
[0103]
(Embodiment 35) A computer program for causing a computer to execute a process of reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
A computer program for holding a decoded frame of a predetermined encoded frame in the still image sequence and outputting it instead of a decoded frame of subsequent encoded data.
[0104]
(Embodiment 36) A computer-readable storage medium storing the computer program according to any one of Embodiments 32 to 35.
[0105]
【The invention's effect】
  As described above, according to the present invention, the still image sequenceOf frames that have been compression-encoded by inter-frame encoding at a position where a predetermined number of frames have passed since the beginningSince the decoded frame is held and output in place of the decoded frame of the subsequent encoded data, flicker due to encoding distortion occurs when reproducing a still image sequence recorded using the moving image compression method.Still images with high image qualityReproduction can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a digital video playback apparatus according to a first embodiment.
2 is a diagram illustrating a configuration example of a compression decoding circuit 108. FIG.
FIG. 3 is a diagram for explaining an example of reproduction of a still image sequence.
FIG. 4 is a diagram for explaining another example of reproduction of a still image sequence.
FIG. 5 is a diagram for explaining another example of reproduction of a still image sequence.
FIG. 6 is a diagram for explaining an example of still image period detection;
FIG. 7 is a diagram for explaining another example of still image period detection.
FIG. 8 is a diagram illustrating a schematic configuration of a digital video reproduction device according to a second embodiment;
9 is a diagram illustrating a configuration example of a compression decoding circuit 808. FIG.
FIG. 10 is a diagram for explaining a playback frame hold operation when an uncorrectable error is included.
FIG. 11 is a diagram for explaining a difference in error propagation depending on a picture type.
FIG. 12 is a diagram for explaining an example in which holding is performed in consideration of error propagation depending on a picture type;
FIG. 13 is a diagram for describing an example in which a still image held with image quality deterioration due to an error uncorrectable error is updated with an image with few errors as a third embodiment;
[Explanation of symbols]
101, 801 Recording media
102, 802 Playback head
103, 803 reproduction amplifier circuit
104, 804 Modulation decoding circuit
105, 805 Recording format decoding circuit
106,806 Error correction decoding circuit
107, 807 System decoding circuit
108,808 Compression decoding circuit having still image hold function
109, 809 D / A conversion circuit
110, 810 terminals
201,901 terminals
202, 902 Buffer memory circuit
203, 903 Variable length decoding circuit
204, 904 Inverse quantization circuit
205, 905 Inverse DCT circuit
206, 906 Adder circuit
207, 907 Video memory
208, 908 Motion compensation prediction circuit
209, 909 switch
210, 910 terminals
211, 911 Still image period detection circuit
212, 912 Hold control circuit
213, 913 switch
214, 914 frame memory
215, 915 switch
216, 916 terminals
917 terminal
918 Image degradation estimation circuit

Claims (11)

An image reproduction method for reproducing a still image sequence consisting of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
Means for detecting the duration of the still image sequence;
Decoding means for decoding the encoded data of the still image sequence ;
Decoding of inter-frame encoded frames compression-encoded by the inter-frame encoding at a position where a predetermined number of frames have elapsed from the beginning of the still image sequence among a plurality of decoded frames decoded by the decoding means Frame holding means for holding the frame,
Means for outputting the held decoded frame in place of the decoded frame of the subsequent encoded data at least during the still image sequence continuation period after the reproduction time of the held decoded frame. Image playback method to be used. The frame holding means is a decoded frame of the inter-frame encoded frame that is compression-encoded by prediction from another inter-frame encoded frame at a position where a predetermined number of frames have elapsed from the beginning of the still image sequence. image reproduction method according to claim 1, characterized in that to hold the. The process of holding the decoded frame in the frame holding means is the duration of the still picture sequence according to the information indicating that the decoded frame can be held and reproduced together with the encoded data of the still picture sequence. image reproduction method according to claim 1 or 2, characterized in that it is started from the middle.   2. The image reproduction system according to claim 1, wherein the duration of the still image sequence is detected from still image ID information for identifying a still image recording portion in the recording data. 2. The image according to claim 1, wherein the duration of the still image sequence is detected from a still image recording flag indicating a still image recording portion in the recording data and a flag indicating discontinuity of the recording data. Playback method.   The duration of the still image sequence is detected from a still image recording flag indicating a still image recording portion in recording data and a flag indicating presence / absence of an image change between frames. Image playback method. The image reproduction method according to claim 1, wherein the held decoded frame is a B picture that is bidirectionally predicted from a P picture . The image reproduction method according to claim 1, wherein the held decoded frame is a P picture . A still image sequence consisting of a sequence of identical still image frames compression-encoded in the MPEG system, the still image sequence recorded as additional information of the still image sequence, and identification information for specifying the continuous reproduction period An image reproduction method for reproducing from a recording medium,
Reproducing means for reproducing data recorded on the recording medium;
Detecting means for detecting the identification information from the data reproduced by the reproducing means;
Decoding means for decoding image data among the data reproduced by the reproducing means;
After starting reproducing the thus still-image sequence that will be identified in the detected identification information by said detection means, among the plurality of decoded frames of image data corresponding to the still-image sequence obtained by decoding in the decoding means, Frame holding means for holding a decoded frame of an inter-frame encoded frame that has been compression-encoded by inter-frame encoding at a position where a predetermined number of frames have elapsed from the beginning of the still image sequence ;
During continuous playback duration of the still-image sequence specified by the identification information detected by said detecting means, until the decoded frame in the frame holding means Ru is held the decoded frame decoded by the decoding means An image reproduction system comprising: output means for sequentially outputting and outputting the held decoded frame repeatedly after the decoded frame is held in the frame holding means . An image reproduction method for reproducing a still image sequence composed of a sequence of identical still image frames compression-encoded by intra-frame and inter-frame encoding,
A procedure for detecting the duration of the still image sequence;
A procedure for decoding the encoded data of the still image sequence ;
Of the plurality of decoded frames, a decoded frame of an inter-frame encoded frame that has been compression-encoded by the inter-frame encoding at a position where a predetermined number of frames has elapsed from the beginning of the still image sequence. A procedure that the frame holding means holds;
And a procedure for outputting the held decoded frame in place of the decoded frame of the subsequent encoded data at least during the still image sequence continuation period after the reproduction time of the held decoded frame. Image playback method. A still image sequence consisting of a sequence of identical still image frames compression-encoded in the MPEG system, the still image sequence recorded as additional information of the still image sequence, and identification information for specifying the continuous reproduction period An image reproduction method for reproducing from a recording medium,
A playback procedure for playing back the data recorded on the recording medium;
A detection procedure for detecting the identification information from the data reproduced by the reproduction procedure;
A decoding procedure for decoding image data among the data reproduced by the reproduction procedure;
After starting reproducing the still picture sequence in the detected identification information thus Ru specified by the detection procedure, among the plurality of decoded frames of image data corresponding to the still-image sequence obtained by the decoding, the still picture A holding procedure in which a frame holding unit holds a decoded frame of an inter-frame encoded frame that has been compression-encoded by inter-frame encoding at a position where a predetermined number of frames has elapsed from the beginning of the sequence ;
During continuous playback duration of the still-image sequence specified by the identification information detected by the detection procedure, until decoded frame in the frame holding means Ru is held the decoded frame decoded by the decoding procedure An image reproducing method comprising: sequentially outputting and outputting the held decoded frame repeatedly after the decoded frame is held in the frame holding means .

Images