JP2002142227A - Hierarchy-type coding device of image signal, and hierarchy-type decoding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that two types of coding sections are required for coding an image signal that is divided in frame units in the direction of a time axis by a different method. SOLUTION: A bit stream division section 21 divides a coding bit stream 200 obtained by the coding sections 20 into a first bit stream 211a comprising I and P pictures, and a second bit stream 212a made of only a B picture. A picture header modification section 22 changes the number of display of a frame included in the frame header of the first bit stream 211a so that the reproduction time of the first bit stream 211a becomes equal to that of the coding bit stream 200, and obtains a first bit stream 211b after the change. A hierarchy type decoding device 11 performs an inverse processing to a hierarchy-type coding device 10, and decodes two bit streams.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hierarchical encoder for hierarchically encoding a video signal in a time axis direction or in both a time axis and a spatial axis, and a hierarchical decoder corresponding thereto. .

[0002]

2. Description of the Related Art Hierarchical coding techniques for hierarchically coding a video signal in a time axis direction or a space axis direction have been known. For example, MPEG-2 (ISO / IEC)
In 138812-2), a temporal scalability profile which is a hierarchical coding method in the time axis direction and a spatial scalability profile which is a hierarchical coding method in the spatial axis direction are standardized. There is also known a method of hierarchically encoding a video signal in both the time axis and the space axis by combining these two profiles.

FIG. 15 is a block diagram showing a configuration of a conventional hierarchical coding device and a hierarchical decoding device in the time axis direction. The hierarchical coding device 70 shown in FIG. 15 performs hierarchical coding on the input video signal 100 in the time axis direction, and outputs two bit streams. The hierarchical decoding device 71
The two bit streams received via the communication network 1 are hierarchically decoded in the time axis direction, and the output video signal 1
76 is output.

[0004] The hierarchical coding device 70 includes a frame division unit 80, a basic coding unit 81, and a high-order coding unit 82. The frame dividing unit 80 divides the input video signal 100 into the basic video signal 171 and the high-order video signal 17
Divide into two. The basic encoding unit 81 outputs the basic video signal 1
71 is encoded by a first predetermined method, and a basic bit stream 271 and a basic local decoded video signal 173 obtained by decoding the basic bit stream 271 are obtained. The high-order encoding unit 82 encodes the high-order video signal 172 by a second predetermined method with reference to the basic local decoded video signal 173,
A high-order bit stream 272 is determined. The base bitstream 271 may be referred to as a lower layer or base layer bitstream, and the higher bitstream 272 may be referred to as an upper layer or enhancement layer bitstream.

[0005] The hierarchical decoding device 71 includes a frame synthesizing section 90, a basic decoding section 91, and a high-order decoding section 92. These components are sequentially arranged in the frame dividing unit 8.
0, a process reverse to that of the basic encoding unit 81 and the high-order encoding unit 82 is performed. The basic decoding unit 91 decodes the basic bit stream 271 by a first predetermined method, and obtains a basic decoded video signal 174. The high-order decoding unit 92 refers to the basic decoded video signal 174 and
Is decoded by the second predetermined method, and the high-order decoded video signal 17 is decoded.
Find 5 The frame synthesizing unit 90 obtains an output video signal 176 by synthesizing the basic decoded video signal 174 and the high-order decoded video signal 175.

[0006]

However, the conventional hierarchical coding apparatus in the time axis direction is provided with two types of coding units for performing different coding on the video signal divided on a frame basis. There is a problem that the hierarchical decoding apparatus corresponding to this needs to have two types of decoding units in order to perform different decoding on the bit stream divided in frame units. In addition, since the conventional hierarchical coding apparatus divides a video signal before coding, it has a problem that it cannot be applied to a bit stream already obtained by coding.

[0007] Therefore, the present invention provides a hierarchical code that includes one type of encoding unit and performs hierarchical encoding in the time axis direction by performing post-processing on the bit stream obtained by the encoding unit. It is an object to provide a decoding device and a hierarchical decoding device corresponding to the decoding device.

[0008]

Means for Solving the Problems and Effects of the Invention A first invention is a hierarchical coding apparatus for hierarchically coding a video signal in a time axis direction, and performs an inter-frame prediction on an input video signal. An encoding unit that performs encoding based on the encoded bit stream, and a bit stream that divides the encoded bit stream into a first bit stream that can be reproduced independently and a remaining second bit stream in frame units A dividing unit, and a bitstream changing unit that changes a parameter value related to display of a frame included in the first bitstream such that a reproduction time of the first bitstream is equal to a reproduction time of the encoded bitstream. Prepare.

According to the first aspect, the parameter value related to the display of the frame included in the first bit stream is changed to a predetermined value. Therefore, even when only the first bit stream is supplied to the decoding device, the playback time matches the playback time of the original coded bit stream. When two bit streams are supplied to the decoding device, the restored original coded bit stream is reproduced. Therefore, the video signal can be hierarchically encoded in the time axis direction by providing one type of encoding unit and performing post-processing on the bit stream obtained by the encoding unit.

[0010] In a second aspect based on the first aspect, the bit stream changing section changes the number of times of display of a frame included in a frame header of the first bit stream.

According to the second aspect of the invention, the number of display times of each frame included in the frame header of the first bit stream is changed, so that the number of display times of each frame is controlled for each frame. Can be reproduced at the same time as the original coded bit stream.

[0012] In a third aspect based on the first aspect, the bit stream changing section changes a frame rate included in a sequence header of the first bit stream.

According to the third aspect, by changing the frame rate included in the sequence header of the first bit stream, the display time of each frame is controlled in sequence units, and the first bit stream is controlled. The stream can be played at the same time as the original coded bit stream.

According to a fourth aspect, in the first aspect, the first aspect is provided.
Is characterized by including at least all intra-coded frames and all forward inter-frame predictively coded frames.

[0015] According to the fourth aspect of the present invention, the coded bits are referred to by referring to the frame header included in the picture header of the first bit stream so that the first bit stream can be independently reproduced. Streams can be split.

According to a fifth aspect, in the first aspect, the first aspect is provided.
Is characterized by including only all intra-coded frames.

According to the fifth aspect of the present invention, the coded bits are referred to by referring to the frame header included in the picture header of the first bit stream so that the first bit stream can be independently reproduced. The stream can be divided and the data amount of the first bit stream can be reduced.

According to a sixth aspect, in the first aspect, the second aspect is provided.
And a count value insertion unit that inserts a count value updated for each frame into the frame header of the bit stream.

According to the sixth aspect, when the two bit streams are combined to obtain the original coded bit stream, the synchronization between the two bit streams can be ensured.

According to a seventh aspect of the present invention, a coded bit stream is obtained by coding a video signal, and the coded bit stream is divided into a first bit stream that can be reproduced independently in frame units and a remaining second bit stream. Divided into the first
And the second and third parameters obtained by changing the parameter values related to the display of the frames included in the first bit stream so that the playback time of the bit stream of the first bit stream is equal to the playback time of the encoded bit stream. A hierarchical stream decoding device for hierarchically decoding a bit stream, wherein the bit stream restoring section restores a parameter value included in the first bit stream to an original value, thereby restoring the first bit stream; A first bit stream restored by the bit stream restoring unit and a second bit stream, and a bit stream synthesizing unit for obtaining an encoded bit stream; and decoding the encoded bit stream. A decoding unit for obtaining a signal.

According to the seventh aspect, even when only the first bit stream is supplied, the reproduction time is
Matches the playback time of the original coded bitstream. When two bit streams are supplied, the restored original coded bit stream is reproduced. Therefore, it is possible to perform hierarchical decoding corresponding to hierarchical encoding in the time axis direction by providing one type of encoding unit and performing post-processing on the bit stream obtained by the encoding unit.

According to an eighth aspect, in the seventh aspect, the first aspect is provided.
The number of times of display of the frame included in the frame header of the bit stream is changed, and the bit stream restoration unit restores the number of times of display of the frame to the original value.

According to the eighth aspect, the display count of each frame included in the frame header of the first bit stream is restored to the original value, so that the display count of each frame is controlled for each frame. Thus, the first bit stream can be reproduced at the same time as the original coded bit stream.

According to a ninth aspect, in the seventh aspect, the first aspect is provided.
The frame rate included in the sequence header of the bit stream is changed, and the bit stream restoration unit restores the frame rate to the original value.

According to the ninth aspect, by restoring the frame rate included in the sequence header of the first bit stream to the original value, the display time of each frame is controlled in sequence units, The first bit stream can be played at the same time as the original coded bit stream.

In a tenth aspect based on the seventh aspect, the count value updated for each frame is inserted in the frame header of the second bit stream, and the count value inserted in the second bit stream is changed. Is further provided.

According to the tenth aspect, when combining two bit streams to obtain an original coded bit stream, it is possible to reliably synchronize the two bit streams.

An eleventh invention is a hierarchical encoding apparatus for hierarchically encoding a video signal in a time axis direction and a spatial axis direction, wherein an input video signal is encoded in a spatial axis direction based on inter-frame prediction. An encoding unit that performs hierarchical encoding to obtain a lower bit stream and an upper bit stream; and converts the lower bit stream into a first bit stream that can be played independently and a remaining second bit stream in frame units. A first bit stream dividing unit to be divided, and a third bit stream corresponding to the first bit stream and a remaining fourth bit in units of frames according to the division in the first bit stream dividing unit. A second bit stream division unit that divides the first and third bit streams into two streams; So that the between the playback time of the lower-order bit stream equals includes a bit stream changing unit for changing the parameter values for display of a frame included in the first and third bit stream.

According to the eleventh aspect, the parameter value related to the display of the frames included in the first and third bit streams is changed to a predetermined value. For this reason, even when only the first bit stream or only the first and third bit streams are supplied to the decoding device, the reproduction time matches the reproduction time of the original coded bit stream. Also, when four bit streams are supplied to the decoding device, the restored original coded bit stream is reproduced. Therefore, by providing one type of encoding unit that performs hierarchical encoding in the spatial axis direction, and performing post-processing on the bit stream obtained by the encoding unit, the video signal can be encoded in both the time axis and the spatial axis. Can be hierarchically encoded.

According to a twelfth aspect, in the eleventh aspect,
The bit stream changing unit changes the number of times of display of a frame included in the frame header of the first and third bit streams.

According to the twelfth aspect, by changing the number of display times of the frames included in the frame headers of the first and third bit streams, the decoding device can change the number of display times of each frame , And only the first and third bit streams are simultaneously
It can be played back at the same time as the original coded bit stream.

According to a thirteenth aspect, in the eleventh aspect,
The bit stream changing unit changes a frame rate included in a sequence header of the first bit stream.

According to the thirteenth aspect, by changing the frame rate included in the sequence header of the first and third bit streams, the decoding device can change the display time of each frame in units of a sequence. With control, the first and third bitstreams can be played simultaneously and at the same time as the original coded bitstream.

According to a fourteenth aspect, in the eleventh aspect,
The first bitstream is characterized in that it comprises at least all intra-coded frames and all forward inter-coded frames.

According to the fourteenth aspect, the coded bits are referred to by referring to the frame header included in the picture header of the first bit stream so that the first bit stream can be reproduced independently. Streams can be split.

According to a fifteenth aspect, in the eleventh aspect,
The first bitstream is characterized in that it comprises only all intra-coded frames.

According to the fifteenth aspect, the coded bits are referred to by referring to the frame header included in the picture header of the first bit stream so that the first bit stream can be reproduced independently. The stream can be divided, and the data amount of the first and third bit streams can be reduced.

According to a sixteenth aspect, in the eleventh aspect,
The apparatus further includes a count value insertion unit that inserts a count value updated for each frame into a frame header of the second and fourth bit streams.

According to the sixteenth aspect, when the four coded bit streams are combined to obtain the original coded bit stream, the four coded bit streams can be reliably synchronized.

According to a seventeenth aspect, in the eleventh aspect,
An encoding unit configured to convert the input video signal into a lower video signal having a relatively small number of pixels;
A lower encoding unit that encodes the lower video signal to obtain a lower bit stream and a decoding result obtained by decoding the lower bit stream; and converts the decoding result into a video signal having the same format as the input video signal. It is characterized by including an up-sampling unit and a higher-order encoding unit that encodes an input video signal with reference to the video signal obtained by the up-sampling unit and obtains an upper-order bit stream.

According to the seventeenth aspect, the input video signal can be hierarchically coded in the spatial axis direction to obtain a lower bit stream and an upper bit stream.

According to an eighteenth aspect, a video signal is hierarchically coded in a spatial axis direction to obtain a lower bit stream and an upper bit stream, and the lower bit stream can be independently reproduced in frame units in a first bit stream. And the remaining second bit stream. The upper bit stream is divided into a third bit stream corresponding to the first bit stream and a remaining fourth bit stream according to the division, and the first and second bit streams are divided. 3 is obtained by changing the parameter values related to the display of the frames included in the first and third bit streams so that the playback time when the bit stream of the third bit stream is played back at the same time as the playback time of the lower bit stream is equal. A hierarchical decoding device for hierarchically decoding the first to fourth bit streams; A bit stream restoration unit for restoring the first and third bit streams by restoring the parameter values included in the first and third bit streams to their original values, and a first stream restored by the bit stream restoration unit And a second bit stream, and a first bit stream synthesis unit that obtains a lower bit stream; a third bit stream restored by the bit stream restoration unit;
A second bit stream synthesis unit that synthesizes the fourth bit stream to obtain an upper bit stream; and a decoding unit that hierarchically decodes the lower bit stream and the upper bit stream in the spatial axis direction to obtain an output video signal. And a conversion unit.

According to the eighteenth aspect, even when only the first bit stream or only the first and third bit streams are supplied, the reproduction time is equal to that of the original coded bit stream. Matches playback time. When four bit streams are supplied, the restored original coded bit stream is reproduced. Therefore, it is provided with one type of encoding unit that performs hierarchical encoding in the spatial axis direction, and performs post-processing on the bit stream obtained by the encoding unit, and thus performs hierarchical encoding in both the time axis and the spatial axis. It is possible to perform hierarchical decoding corresponding to the encryption.

According to a nineteenth aspect, in the eighteenth aspect,
The display count of the frames included in the frame headers of the first and third bit streams has been changed, and the bit stream restoration unit restores the display count of the frame to the original value.

According to the nineteenth aspect, by restoring the display count of the frames included in the frame headers of the first and third bit streams to the original value,
The number of times of display of each frame is controlled for each frame,
And only the third bit stream can be played back simultaneously, at the same time as the original coded bit stream.

According to a twentieth aspect, in the eighteenth aspect,
The frame rate included in the sequence header of the first bit stream is changed, and the bit stream restoration unit restores the frame rate to the original value.

According to the twentieth aspect, the display time of each frame is controlled on a sequence basis by restoring the frame rate contained in the sequence header of the first and third bit streams to the original value. And the first
And only the third bit stream can be played back simultaneously, at the same time as the original coded bit stream.

According to a twenty-first aspect, in the eighteenth aspect,
The count value updated for each frame is inserted in the frame header of the second and fourth bit streams, and a count value deletion unit that deletes the count value inserted in the second and fourth bit streams is further provided. Prepare.

According to the twenty-first aspect, when the four bit streams are combined to obtain the original coded bit stream, the synchronization between the four bit streams can be ensured.

According to a twenty-second invention, in the eighteenth invention,
The decoding unit decodes the lower bit stream and obtains a lower video signal, an up-sampling unit that converts the lower video signal into a video signal having the same format as the output video signal, and an up-sampling unit. A high-order decoding unit that decodes the high-order bit stream with reference to the obtained video signal and obtains an output video signal.

According to the twenty-second aspect, an output video signal can be obtained by hierarchically decoding the lower bit stream and the upper bit stream in the spatial axis direction.

A twenty-third aspect of the present invention is a hierarchical encoding method for hierarchically encoding a video signal in the time axis direction, wherein an encoding is performed on an input video signal based on inter-frame prediction, and a coded bit stream is generated. , A bit stream dividing step of dividing the encoded bit stream into a single bit stream that can be reproduced independently and a remaining second bit stream in units of frames, and a bit stream dividing step of dividing the first bit stream. A bit stream changing step of changing a parameter value related to display of a frame included in the first bit stream so that the playback time is equal to the playback time of the encoded bit stream.

According to the twenty-third aspect, the parameter value related to the display of the frame included in the first bit stream is changed to a predetermined value. Therefore, even when only the first bit stream is supplied at the time of decoding, the playback time matches the playback time of the original coded bit stream. Also, when two bit streams are supplied during decoding, the restored original encoded bit stream is reproduced. Therefore, the video signal can be hierarchically encoded in the time axis direction by providing one type of encoding step and performing post-processing on the bit stream obtained in the encoding step.

According to a twenty-fourth aspect, a coded bit stream is obtained by coding a video signal, and the coded bit stream is divided into a first bit stream that can be reproduced independently and a remaining second bit stream in frame units. Obtained by changing the parameter values related to the display of the frames included in the first bit stream so that the playback time of the first bit stream is equal to the playback time of the encoded bit stream. A hierarchical decoding method for hierarchically decoding a first and a second bitstream, wherein the first bitstream is restored by restoring parameter values included in the first bitstream to original values. Bit stream restoring step, and the first bit stream restored in the bit stream restoring step Provided by synthesizing the second bit stream, the bit stream synthesizing step of obtaining an encoded bit stream, decodes the coded bit stream, and a decoding step of obtaining an output video signal.

According to the twenty-fourth aspect, even when only the first bit stream is supplied, the reproduction time matches the reproduction time of the original coded bit stream. When two bit streams are supplied, the restored original coded bit stream is reproduced. Therefore, it is possible to perform hierarchical decoding corresponding to hierarchical encoding in the time axis direction by providing one type of encoding step and performing post-processing on the bit stream obtained in the encoding unit step. .

A twenty-fifth aspect of the present invention is a hierarchical encoding method for hierarchically encoding a video signal in a time axis direction and a spatial axis direction, wherein an input video signal is encoded in a spatial axis direction based on inter-frame prediction. An encoding step of performing hierarchical encoding to determine a lower bit stream and an upper bit stream;
According to a first bit stream dividing step of dividing the lower bit stream into a first bit stream that can be reproduced alone and a second bit stream that can be reproduced independently on a frame basis, and according to the division in the first bit stream dividing step, The upper bit stream is frame-by-frame,
A second division into a third bit stream corresponding to the first bit stream and a remaining fourth bit stream
Of the frames included in the first and third bit streams so that the playback time when the first and third bit streams are simultaneously played and the playback time of the lower bit stream are equal. A bit stream changing step of changing a parameter value related to display.

According to the twenty-fifth aspect, the parameter value related to the display of the frames included in the first and third bit streams is changed to a predetermined value. For this reason, even when only the first bit stream or only the first and third bit streams are supplied during decoding, the playback time matches the playback time of the original coded bit stream. When four bit streams are supplied during decoding, the restored original coded bit stream is reproduced. Therefore, the video signal is provided with one type of encoding step for performing hierarchical encoding in the spatial axis direction, and the bit stream obtained in the encoding step is post-processed to thereby convert the video signal in both the time axis and the spatial axis. Can be hierarchically encoded.

According to a twenty-sixth aspect, a video signal is hierarchically coded in a spatial axis direction to obtain a lower bit stream and an upper bit stream, and the lower bit stream can be independently reproduced in frame units in a first bit stream. And the remaining second bit stream. The upper bit stream is divided into a third bit stream corresponding to the first bit stream and a remaining fourth bit stream according to the division, and the first and second bit streams are divided. 3 is obtained by changing the parameter values related to the display of the frames included in the first and third bit streams so that the playback time when the bit stream of the third bit stream is played back at the same time as the playback time of the lower bit stream is equal. A hierarchical decoding method for hierarchically decoding the first to fourth bit streams, By restoring the parameter values included in the first and third bitstreams to the original values, a bitstream restoring step of restoring the first and third bitstreams and a first stream restored in the bitstream restoring step And a bit stream of
Combining a second bit stream to obtain a lower bit stream, a first bit stream combining step, and combining a third bit stream restored in the bit stream restoring step and a fourth bit stream. , A second bit stream synthesizing step for obtaining an upper bit stream, and a decoding unit for hierarchically decoding the lower bit stream and the upper bit stream in the spatial axis direction to obtain an output video signal.

According to the twenty-sixth aspect, even when only the first bit stream or only the first and third bit streams are supplied, the reproduction time is equal to that of the original coded bit stream. Matches playback time. When four bit streams are supplied, the restored original coded bit stream is reproduced. Therefore, the present invention includes one type of encoding step for performing hierarchical encoding in the spatial axis direction, and performs post-processing on the bit stream obtained in the encoding step afterwards to perform hierarchical encoding in both the time axis and the spatial axis. It is possible to perform hierarchical decoding corresponding to the encryption.

A twenty-seventh aspect of the present invention is a computer-readable recording medium storing a program for executing a hierarchical encoding method for hierarchically encoding a video signal in a time axis direction by a computer. The encoding method performs encoding based on inter-frame prediction on an input video signal to obtain an encoded bit stream, and a first bit which can reproduce the encoded bit stream by itself in frame units. A bit stream dividing step of dividing the stream into a stream and a residual second bit stream, and the first bit stream is included in the first bit stream such that the playback time of the first bit stream is equal to the playback time of the encoded bit stream. Changing a parameter value related to display of a frame.

According to the twenty-seventh aspect, the parameter value related to the display of the frame included in the first bit stream is changed to a predetermined value. Therefore, even when only the first bit stream is supplied at the time of decoding, the playback time matches the playback time of the original coded bit stream. Also, when two bit streams are supplied during decoding, the restored original encoded bit stream is reproduced. Therefore, the video signal can be hierarchically encoded in the time axis direction by providing one type of encoding step and performing post-processing on the bit stream obtained in the encoding step.

According to a twenty-eighth aspect of the present invention, a coded bit stream is obtained by coding a video signal, and the coded bit stream is divided into a first bit stream that can be reproduced alone and a remaining second bit stream in frame units. Obtained by changing the parameter values related to the display of the frames included in the first bit stream so that the playback time of the first bit stream is equal to the playback time of the encoded bit stream. A computer-readable recording medium having recorded thereon a program for executing the hierarchical decoding method for hierarchically decoding the first and second bitstreams on a computer, the hierarchical decoding method comprising: By restoring the parameter values included in the bit stream of the first bit stream to the original values, the first bit stream is restored. A bit stream restoring step, a first bit stream restored in the bit stream restoring step, and a second bit stream are combined to obtain an encoded bit stream. Decoding to obtain an output video signal.

According to the twenty-eighth aspect, even when only the first bit stream is supplied, the reproduction time matches the reproduction time of the original coded bit stream. When two bit streams are supplied, the restored original coded bit stream is reproduced. Therefore, it is possible to perform hierarchical decoding corresponding to hierarchical encoding in the time axis direction by providing one type of encoding step and performing post-processing on the bit stream obtained in the encoding unit step. .

A twenty-ninth aspect of the present invention relates to a hierarchical encoding method for hierarchically encoding a video signal in a time axis direction and a spatial axis direction.
A computer-readable recording medium having recorded thereon a program to be executed by a computer, wherein the hierarchical encoding method performs hierarchical encoding in the spatial axis direction based on inter-frame prediction on an input video signal, An encoding step for obtaining a bit stream and an upper bit stream; and a first bit stream division for dividing the lower bit stream into a first bit stream that can be played independently and a second bit stream that remains independently for each frame. A second step of dividing the upper bit stream into a third bit stream corresponding to the first bit stream and a remaining fourth bit stream in frame units according to the step and the division in the first bit stream dividing step. A bitstream splitting step, and first and third bitstreams; A bit stream changing step of changing a parameter value related to display of a frame included in the first and third bit streams so that a playback time when the frames are simultaneously played and a playback time of the lower bit stream are equal. Prepare.

According to the twenty-ninth aspect, the parameter value related to the display of the frames included in the first and third bit streams is changed to a predetermined value. For this reason, even when only the first bit stream or only the first and third bit streams are supplied during decoding, the playback time matches the playback time of the original coded bit stream. When four bit streams are supplied during decoding, the restored original coded bit stream is reproduced. Therefore, the video signal is provided with one type of encoding step for performing hierarchical encoding in the spatial axis direction, and the bit stream obtained in the encoding step is post-processed to thereby convert the video signal in both the time axis and the spatial axis. Can be hierarchically encoded.

According to a thirtieth aspect of the present invention, a video signal is hierarchically coded in a spatial axis direction to obtain a lower bit stream and an upper bit stream, and the lower bit stream can be independently reproduced in frame units by a first bit stream. And the remaining second bit stream. The upper bit stream is divided into a third bit stream corresponding to the first bit stream and a remaining fourth bit stream according to the division, and the first and second bit streams are divided. 3 is obtained by changing the parameter values related to the display of the frames included in the first and third bit streams so that the playback time when the bit stream of the third bit stream is played back at the same time as the playback time of the lower bit stream is equal. Further, a hierarchical decoding method for hierarchically decoding the first to fourth bitstreams is described in US Pat. A computer-readable recording medium recording a program to be executed by a computer, wherein the hierarchical decoding method restores parameter values included in the first and third bitstreams to original values, A first bitstream restoring step of restoring the first and third bitstreams, a first bitstream restored in the bitstream restoring step, and a second bitstream synthesized to obtain a lower bitstream. A second bit stream synthesizing step of synthesizing the third bit stream restored in the bit stream restoring step and the fourth bit stream to obtain an upper bit stream, and a lower bit stream And upper bit stream with spatial axis And hierarchical decoding countercurrent, and a decoding unit for obtaining an output video signal.

According to the thirtieth aspect, even when only the first bit stream or only the first and third bit streams are supplied, the reproduction time is equal to that of the original coded bit stream. Matches playback time. When four bit streams are supplied, the restored original coded bit stream is reproduced. Therefore, the present invention includes one type of encoding step for performing hierarchical encoding in the spatial axis direction, and performs post-processing on the bit stream obtained in the encoding step afterwards to perform hierarchical encoding in both the time axis and the spatial axis. It is possible to perform hierarchical decoding corresponding to the encryption.

[0068]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a block diagram showing a configuration of a hierarchical coding device 10 and a hierarchical decoding device 11 according to a first embodiment of the present invention.
The hierarchical encoding device 10 hierarchically encodes the input video signal 100 in the time axis direction, and outputs two bit streams. The hierarchical decoding device 11 includes the hierarchical encoding device 10
2 are hierarchically decoded in the time axis direction and the output video signal 101 is output. Both the hierarchical encoding device 10 and the hierarchical decoding device 11 are used by connecting to the communication network 1.

First, the hierarchical encoder 10 will be described. The hierarchical encoding device 10 includes an encoding unit 20, a bit stream dividing unit 21, and a picture header changing unit 22.

The encoding section 20 encodes the input video signal 100 on a frame basis in accordance with MPEG-2, and outputs an encoded bit stream 200. Encoding unit 20
Determines the picture type for each frame, and performs either intra-frame coding, forward inter-frame predictive coding, or bidirectional inter-frame predictive coding for each frame. In the following, as specified in MPEG-2, a frame to be intra-coded, a frame to be subjected to forward inter-frame predictive coding, and a frame to be bi-directionally inter-frame predictively coded are respectively denoted by I These are called a picture, a P picture, and a B picture. Also,
The result of encoding the frame by each method is called an I-encoding result, a P-encoding result, and a B-encoding result, respectively. The encoded bit stream 200 includes these three types of encoded results.

As shown in FIG. 2, the coded bit stream 200 includes a sequence header 301 and a plurality of GOPs.
(Group Of Pictures) layer 302. The GOP layer 302 includes a GOP header 303 and a plurality of picture layers 304. The picture layer 304 includes a picture header 305 and picture layer data 306. The sequence header 301 includes a parameter that specifies a frame rate when the encoded bit stream 200 is reproduced. The picture header 305 includes a parameter for specifying the number of times each picture is displayed.

FIG. 3 is an explanatory diagram of a bit stream processing method in the hierarchical encoding device 10. In FIG. 3, each rectangle represents one frame or its encoding result, and the letters and numbers described inside each rectangle are
Each represents the picture type and frame number of each frame. In the example shown in FIG.
The picture type is switched in the order of BPBBPBBPBBPBB to encode each frame, and the encoded bit stream 200 shown in FIG. 3B is output.

The bit stream division unit 21
As shown in (c), the encoded bit stream 200
Is divided into a first bit stream 211a consisting of an I-coded result and a P-coded result and a second bit stream 212a consisting of only a B-coded result. The bit stream dividing unit 21 encodes the encoded bit stream 20
The picture header 305 included in 0 is detected, and the coded bit stream 200 is divided based on the picture type included in the detected picture header 305.

[0074] The picture header changing unit 22 converts the picture header 305 included in the first bit stream 211a.
Is detected, and the parameter value related to the number of display times of the frame included in the detected picture header 305 is changed to a predetermined value. Thereafter, the picture header changing unit 22 outputs the changed first bit stream 211b. FIG.
In (d), an asterisk indicates that the picture header 305 has been changed. Details of the picture header changing unit 22 will be described later.

The hierarchical coding apparatus 10 converts the first bit stream 211b after the change and the second bit stream 2
12a is output to the communication network 1. However, if the transmission state of the communication network 1 is not good,
The hierarchical encoding device 10 outputs only the changed first bit stream 211b.

Next, the hierarchical decoding device 11 will be described. The hierarchical decoding device 11 includes a decoding unit 30, a bit stream synthesis unit 31, and a picture header restoration unit 32. These components are in turn,
0, a process reverse to that of the bit stream dividing unit 21 and the picture header changing unit 22 is performed.

The hierarchical decoding device 11 receives the two bit streams output from the hierarchical encoding device 10. However, when the hierarchical encoding device 10 outputs only the changed first bit stream 211b, or when the communication network 1 cannot transmit the second bit stream 212a, the hierarchical decoding device 11 Only the changed first bit stream 211b is received. The hierarchical decoding device 11 performs different operations when two bit streams are received and when only the changed first bit stream 211b is received. Hereinafter, the former is called a high-quality mode, and the latter is called a standard mode.

In the high-quality mode, as shown in FIG. 1, the changed first bit stream 211b and second bit stream 212a are supplied to a picture header restoration unit 32 and a bit stream synthesis unit 31, respectively. You.

The picture header restoration unit 32 restores the changed first bit stream 211b to the original first bit stream 211a. That is, the picture header restoration unit 32 outputs the changed first bit stream 211
The picture header 305 included in the picture header 305 is detected, and the parameter value relating to the number of display times of the frame included in the detected picture header 305 is returned to the original value. The original value related to the number of display times of the frame may be determined in advance,
May be included in the user data of the bit stream 211a and supplied from the hierarchical encoding device 10.

The bit stream synthesizing unit 31 synthesizes the reconstructed first bit stream 211a and second bit stream 212a to obtain the same encoded bit stream 200 as output from the encoding unit 20. .
The decoding unit 30 calculates the encoded bit stream 200
Are subjected to decoding processing reverse to that of the encoding unit 20 to obtain an output video signal 101.

As described above, in the high quality mode, the encoding unit 2
The coded bit stream 200 obtained by 0 is converted into two bit streams by the bit stream dividing unit 21 and the picture header changing unit 22, and restored by the bit stream synthesizing unit 31 and the picture header restoring unit 32. Is done. Therefore, the output video signal 10
1 is equal to the video signal when the input video signal 100 is encoded by the encoding unit 20 and subsequently decoded by the decoding unit 30.

On the other hand, in the standard mode, the changed first bit stream 211b is immediately supplied to the decoding unit 30. The decoding unit 30 performs a decoding process reverse to that of the coding unit 20 on the changed first bit stream 211b to obtain an output video signal 101. The decoding unit 3
A value of 0 merely decodes the supplied bit stream according to MPEG-2 in both the high-quality mode and the standard mode.

Next, the picture header changing section 22 will be described in detail. The number of times each frame is displayed in MPEG-2 is specified by a combination of four parameters, as shown in FIG. In other words, when the encoded bit stream 200 is reproduced, each frame is displayed the number of times specified by a combination of four parameters. Note that among the four parameters,
progressive_sequence is included in the sequence header 301, and the other three parameters are included in the picture header 305.

The picture header changing section 22 repeats repeat_first_f included in the picture header 305 as follows.
Change the values of ield and top_field_first. First, the picture header changing unit 22 uses the picture header 305 to detect the frame number A of the picture and the frame number B of the next picture included in the first bit stream 211a. Next, the picture header changing unit 22
Determines two parameter values such that the number of display times of the frame becomes (BA) with reference to the table shown in FIG. Thereafter, the picture header changing unit 22 changes the two parameter values included in the picture header 305 of the frame having the frame number A to the determined values.

For example, when the input video signal 100 is a progressive video signal and two B pictures exist between I or P pictures, the picture header changing unit 22 sets the value of the repeat_first_field to “1”. To, top_fi
Change the value of eld_first to "1". When the hierarchical decoding device 11 decodes the changed first bit stream 211b in the standard mode, each frame is displayed three times as shown in FIG.

When the input video signal 100 is a progressive video signal and one B picture exists between I or P pictures, the picture header changing unit 22 sets the value of the repeat_first_field to “1”. To, top_fiel
Change the value of d_first to "0". Hierarchical decoding device 1
When 1 modifies the first bit stream 211b after the change in the standard mode, each frame is displayed twice as shown in FIG. 5B.

When the input video signal 100 is a progressive video signal and one or two B pictures are alternately present between I or P pictures, the picture header changing unit 22 sets the repeat_first_field and the
The value of top_field_first is alternately changed to (1, 1) and (1, 0). When the hierarchical decoding device 11 decodes the changed first bit stream 211b in the standard mode, each frame is alternately displayed three times or two times as shown in FIG. 5C. .

As described above, the picture header changing unit 22
When only the first bit stream 211b after the change is reproduced, the reproduction time becomes longer than that of the original coded bit stream 2b.
The number of times of display of a frame included in the picture header of the first bit stream 211a is changed so as to match the playback time of 00. In the above three examples, the input video signal 100 is assumed to be a progressive video signal, but the picture header changing unit 22 performs the same processing when the input video signal 100 is an interlaced video signal. If the parameter to be changed is not included in the picture header 305, the picture header changing unit 22 outputs
These parameters may be added to the first bit stream 211a according to the syntax specified in No. 2.

As described above, according to the present embodiment, the hierarchical coding apparatus divides the coded bit stream obtained by the coding section and displays the frame included in the picture header of the first bit stream. Change the number of times. The hierarchical decoding apparatus decodes only the changed first bit stream in the standard mode, and combines the two bit streams after restoring the number of display times of the frame in the high-quality mode, and decodes the combined bit stream. Become The number of times the frame is displayed is changed so that the playback time of the first bit stream and the playback time of the encoded bit stream are equal. Accordingly, a hierarchical encoding device including one type of encoding unit and performing post-processing on a bit stream obtained by encoding to perform hierarchical encoding in the time axis direction, A hierarchical decoding device corresponding to the encoding device can be obtained.

Note that as long as the first bit stream 211a satisfies the condition that the first bit stream 211a can be reproduced independently, that is, without reference to the second bit stream 212a, the bit stream dividing unit 21 performs the processing shown in FIG. The encoded bit stream 200 may be divided by another method. For example, as shown in FIG. 6A, the first bit stream 211a may include only the I-coded result. Alternatively, as shown in FIG. 6B, the first bit stream 211a may include the result of the B encoding. Alternatively, as shown in FIG. 6C, the first bit stream 211a may not include a P-encoding result that is behind each GOP and is not referred to from other frames.

(Modification of First Embodiment) FIG. 7 shows a hierarchical coding apparatus 1 according to a modification of the first embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a second and hierarchical decoding device 13. The hierarchical encoding device 12 includes the hierarchical encoding device 1
This is obtained by adding a count value insertion unit 24 to 0. The hierarchical decoding device 13 is obtained by adding a count value deletion unit 34 to the hierarchical decoding device 11.

The count value insertion unit 24 has a counter that is updated for each frame.
The count value is inserted into the picture header 305 of 12a. After that, the count value inserting unit 24 checks the changed second
Is output.

The count value deleting section 34 restores the changed second bit stream 212b to the original second bit stream 212a. That is, the count value deletion unit 3
No. 4 detects the picture header 305 included in the changed second bit stream 212b, and deletes the count value included in the detected picture header 305.

The bit stream synthesizing unit 31 refers to the deleted count value to generate the first bit stream 21.
1a and the second bit stream 212a.

Thus, the second bit stream 212
By inserting the count value updated for each frame into the picture header a, synchronization between the two bit streams can be ensured.

In this modification, in consideration of the fact that it is not necessary to refer to the count value in the standard mode, the count value is inserted not into the changed first bit stream 211b but into the second bit stream 212a. You are going to.

(Second Embodiment) FIG. 8 shows a second embodiment of the present invention.
It is a block diagram which shows the structure of the hierarchical coding apparatus 14 and the hierarchical decoding apparatus 15 which concern on embodiment. The hierarchical encoding device 14 hierarchically encodes the input video signal 100 in the time axis direction and outputs two bit streams. The hierarchical decoding device 15 hierarchically decodes the two bit streams output from the hierarchical encoding device 10 in the time axis direction, and outputs an output video signal 101. Both the hierarchical coding device 14 and the hierarchical decoding device 15 are used by connecting to the communication network 1.

The hierarchical encoder 14 changes the frame rate included in the first bit stream 211a, and changes the display frequency of the frames included in the bit stream 211a according to the first embodiment. Encoding device 1
Different from 0. The hierarchical encoding device 14 includes the encoding unit 2
0, a bit stream dividing unit 21 and a sequence header changing unit 23. The hierarchical decoding device 15
A decoding unit 30, a bit stream synthesizing unit 31, and
A sequence header restoration unit 33 is provided. Among the components of the present embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 9 is an explanatory diagram of a bit stream processing method in the hierarchical encoding device 14. As shown in FIGS. 9A to 9C, the hierarchical encoding device 14
As in the hierarchical encoding device 10 according to the embodiment, the first
Is obtained.

[0100] The sequence header changing unit 23 converts the sequence header 3 included in the first bit stream 211a.
01 is detected, and the parameter value related to the frame rate included in the detected sequence header 301 is changed to a predetermined value. Thereafter, the sequence header changing unit 23 outputs the changed first bit stream 211c. In FIG. 9D, the asterisk indicates that the sequence header (SH) has been changed. Details of the sequence header changing unit 23 will be described later.

The sequence header restoring unit 33 restores the changed first bit stream 211c to the original first bit stream 211a. That is, the sequence header restoration unit 33 outputs the changed first bit stream 2
11c is detected, and the parameter value related to the frame rate included in the detected sequence header 301 is returned to the original value. The original value for the frame rate may be predetermined,
May be supplied from the hierarchical encoding device 14 while being included in the user data of the bit stream 211a.

Next, details of the sequence header changing unit 23 will be described. The frame rate in MPEG-2 is specified by frame_rate_code as shown in FIG. In other words, the encoded bit stream 2
When 00 is played, each frame is frame_rate_c
Displayed at the frame rate specified by ode.
The frame_rate_code is included in the sequence header 301.

[0103] The sequence header changing unit 23 sets the frame_rate included in the sequence header 301 as follows.
Change the value of _code. First, the sequence header changing unit 23 obtains the number P of frames in one GOP, the number Q of frames in one GOP included in the first bit stream, and the original frame rate R. Next, the sequence header changing unit 23 refers to the table shown in FIG. 10 and determines that the frame rate is (Q / P) ×
The value of frame_rate_code is determined to be N. After that, the sequence header changing unit 23 sets the fr included in the sequence header 301 of the first bit stream 211a.
Change the value of ame_rate_code to the determined value.

For example, if the input video signal 100 is 60000/1001
When the video signal is [Hz] and one B picture exists between the I and P pictures, the sequence header changing unit 23 sets the value of frame_rate_code to “010”.
To "0". When the hierarchical decoding device 15 has changed the first
When the bit stream 211c is decoded in the standard mode, each frame is displayed twice as shown in FIG.

Also, if the input video signal 100 is 60000/1001
If the video signal is [Hz] and there are two B pictures between I or P pictures, the sequence header changing unit 23 sets the value of frame_rate_code to a value reserved in FIG. Change to "1001". The decoding unit 30 determines that the value of frame_rate_code is “100
1 ”, the frame rate is 20000/1001 [H
z]. Thereby, when the hierarchical decoding device 15 decodes the changed first bit stream 211c in the standard mode, each frame is as shown in FIG.
Are displayed three times as shown in FIG.

Thus, the sequence header changing unit 23
Is included in the sequence header of the first bit stream 211a so that when only the changed first bit stream 211c is reproduced, the reproduction time matches the reproduction time of the original coded bit stream 200. Change the frame rate. First bit stream 211a
Does not include the sequence header 301,
The sequence header changing unit 23 converts the first bit stream 2 into the first bit stream 2 according to the syntax specified in MPEG-2.
What is necessary is just to add the sequence header 301 to 11a.

As described above, according to the present embodiment, the hierarchical coding apparatus divides the coded bit stream obtained by the coding unit and sets only the frame rate contained in the sequence header of the first bit stream. To change. The hierarchical decoding device decodes the changed first bit stream in the standard mode, combines the two bit streams after restoring the frame rate in the high-quality mode, and decodes the combined bit stream. The frame rate is changed such that the playback time of the first bit stream and the playback time of the encoded bit stream are equal. Accordingly, a hierarchical encoding device including one type of encoding unit and performing post-processing on a bit stream obtained by encoding to perform hierarchical encoding in the time axis direction, A hierarchical decoding device corresponding to the encoding device can be obtained.

[0108] Also in this embodiment, similarly to the first embodiment, the bit stream dividing section 21 may divide the bit stream by another method. For example, the first
May be composed of only the I-encoding result, or may include the B-encoding result. Further, similarly to the modification of the first embodiment, a count value insertion unit that inserts a count value into the second bit stream 212a and a count value deletion unit that deletes the inserted count value may be provided.

(Third Embodiment) FIG. 12 is a block diagram showing a configuration of a hierarchical encoder 16 and a hierarchical decoder 17 according to a third embodiment of the present invention. The hierarchical encoding device 16 hierarchically encodes the input video signal 100 in both the time axis and the spatial axis, and outputs four bit streams. The hierarchical decoding device 17 hierarchically decodes the four bit streams output from the hierarchical encoding device 16 in both the time axis and the spatial axis, and outputs an output video signal 104. Both the hierarchical encoding device 16 and the hierarchical decoding device 17 are used by connecting to the communication network 1.

First, the hierarchical encoder 16 will be described. The hierarchical encoding device 16 includes a spatial direction downsampling unit 40, a lower order encoding unit 41, a spatial direction upsampling unit 42, an upper order encoding unit 43, a first bit stream dividing unit 44, a first picture header changing unit. 45,
A second bit stream dividing unit 46 and a second picture header changing unit 47 are provided. Hierarchical coding device 1
6 performs the same processing as in the first embodiment on each of the lower bit stream 201 and the upper bit stream 202 obtained by hierarchically encoding the input video signal 100 in the spatial axis direction.

The spatial downsampling unit 40, the lower encoding unit 41, the spatial upsampling unit 42, and the upper encoding unit 43 convert the input video signal 100 into a hierarchical code in the spatial axis direction as shown below. Become The spatial downsampling unit 40 downsamples the input video signal 100 in the spatial axis direction to obtain a lower video signal 110 having a small number of pixels. The lower encoding unit 41 encodes the lower video signal 110 by a first predetermined method, and obtains a lower bit stream 201 and a lower local decoded video signal 111 obtained by decoding the lower bit stream 201. The spatial up-sampling unit 42 converts the lower local decoded video signal 111 into a local decoded video signal 102 having the same number of pixels as the input video signal 100.

The upper encoding section 43 encodes the input video signal 100 by a second predetermined method with reference to the local decoded video signal 102, and obtains an upper bit stream 202. In this case, the upper encoding unit 43
Performs prediction coding in the spatial axis direction for a frame that has been subjected to intra-frame coding or forward inter-frame prediction coding, and performs coding for a frame that has been bi-directionally inter-frame predicted coded by the lower coding unit 41. Predictive encoding is performed in both the time axis and the space axis.

The first bit stream dividing section 44 and the first
The picture header changing unit 45 performs the same processing on the lower bit stream 201 as the bit stream dividing unit 21 and the picture header changing unit 22 according to the first embodiment. As a result, the changed first bit stream 221b including the I encoding result and the P encoding result, and B
Second bit stream 222 consisting only of encoding result
a is required.

The second bit stream dividing section 46 and the second bit stream
Of the upper bit stream 202 with the first bit stream dividing unit 44
And the same processing as the first picture header changing unit 45 is performed.
As a result, the third bit stream 223b after the change including only the frame predictively encoded in the spatial axis direction is obtained.
And a fourth bit stream 224a consisting only of frames that have been predictively coded on both the time axis and the space axis.

FIG. 13 is a diagram showing a prediction direction between four bit streams output from the hierarchical encoding device 16. In FIG. 13, each rectangle represents the encoding result of one frame, and the letters and numbers described inside each rectangle represent the picture type and frame number of each frame, respectively. The characters “lower” or “higher” described in each rectangle indicate whether the encoding result is obtained from the lower bit stream 201 or the upper bit stream 202. The arrow drawn from rectangle A to rectangle B indicates that frame B was predicted from frame A. The character drawn over the arrow indicates which direction is predicted in the time axis or the space axis.

Next, the hierarchical decoding device 17 will be described. The hierarchical decoding device 17 includes a lower decoding unit 51, a spatial direction upsampling unit 52, an upper decoding unit 53,
A first bit stream combining unit 54, a first picture header restoring unit 55, a second bit stream combining unit 56,
And a second picture header restoration unit 57. These components are, in order, a lower encoding unit 41, a spatial direction upsampling unit 42, an upper encoding unit 43, a first bit stream dividing unit 44, a first picture header changing unit 45, a second bit stream An operation reverse to that of the dividing unit 46 and the second picture header changing unit 47 is performed.

The first bit stream synthesizing section 54 and the first
Of the first bit stream 221b after the change and the second bit stream 222
For a, the same processing as the bit stream synthesis unit 31 and the picture header restoration unit 32 according to the first embodiment is performed. As a result, the same lower bit stream 201 as that output from the lower encoder 41 is obtained.

The second bit stream synthesizing section 56 and the second bit stream
Of the third bit stream 223b after the change and the fourth bit stream 224
For a, the same processing as the first bit stream synthesizing unit 54 and the first picture header restoring unit 55 is performed. As a result, the same high-order bit stream 202 as that output from the high-order coding unit 43 is obtained.

The lower decoding unit 51, the spatial direction upsampling unit 52, and the upper decoding unit 53 convert the restored lower bit stream 201 and upper bit stream 202 in the spatial axis direction as shown below. Type decrypt. The lower-order decoding unit 51 outputs the lower-order bit stream 20
1 is decoded by a predetermined first method, and a lower local decoded video signal 112 is obtained. The spatial direction up-sampling unit 52 converts the lower local decoded video signal 112 into a local decoded video signal 103 having the same number of pixels as the input video signal 100. The high-order decoding unit 53 refers to the local decoded video signal 103 and outputs the high-order bit stream 202
And an output video signal 104 is obtained.

As described above, when the first and third bit streams 221b and 223b after the change are simultaneously reproduced, the first and second picture header changing units 45 and 47 reduce the reproduction time to the original encoding time. The display count of the frames included in the picture headers of the first and third bit streams 221a and 223a is changed so as to match the playback time of the bit stream 200. In addition, the first
When only the bit stream 211b is reproduced,
The playback time matches the playback time of the original coded bitstream 200.

As described above, according to the present embodiment, the hierarchical coding apparatus divides the lower bit stream and the upper bit stream obtained by the coding unit, and
And the number of times of display of a frame included in the picture header of the third bit stream is changed. The hierarchical decoding apparatus decodes only the changed first bit stream or only the changed first and third bit streams in the standard mode, and restores the number of display times of the frame in the high-quality mode. The four bit streams are combined, and the combined bit stream is decoded. The number of times of display of the frame is changed so that the reproduction time when the first and third bit streams are reproduced simultaneously and the reproduction time of the lower bit stream are equal. With this, one type of encoding unit that performs hierarchical encoding in the spatial axis direction is provided, and post-processing is performed on the bit stream obtained by encoding, so that hierarchical encoding is performed in both the time axis and the spatial axis. It is possible to obtain a hierarchical encoding device that performs encoding and a hierarchical decoding device corresponding to the hierarchical encoding device.

Note that, also in the present embodiment, similarly to the first embodiment, the first and second bit stream division units 44 and 46 may divide the bit stream by another method. For example, the first and third bit streams 221a, 223a may consist of only the I-encoding result, or may include the B-encoding result. Further, similarly to the modification of the first embodiment, a count value insertion unit that inserts a count value into the second and fourth bit streams 222a and 224a and a count value deletion unit that deletes the inserted count value are provided. You may.

(Fourth Embodiment) FIG. 14 is a block diagram showing a configuration of a hierarchical coding device 18 and a hierarchical decoding device 19 according to a fourth embodiment of the present invention. The hierarchical encoding device 18 hierarchically encodes the input video signal 100 in both the time axis and the spatial axis, and outputs four bit streams. The hierarchical decoding device 19 hierarchically decodes the four bit streams output from the hierarchical encoding device 18 in both the time axis and the spatial axis, and outputs an output video signal 104. Both the hierarchical encoding device 18 and the hierarchical decoding device 19 are used by connecting to the communication network 1.

[0124] The hierarchical encoding device 18 changes the frame rate included in the first bit stream 221a in that the first and third bit streams 221a, 221a,
This is different from the hierarchical coding device 16 according to the third embodiment in which the number of times of display of the frame included in 23a is changed. The hierarchical encoding device 18 includes the spatial downsampling unit 4
0, a lower encoding unit 41, a spatial direction upsampling unit 42, an upper encoding unit 43, a first bit stream division unit 44, a second bit stream division unit 46,
A sequence header changing unit 48 is provided. The hierarchical decoding device 19 includes a lower decoding unit 51, a spatial direction upsampling unit 52, an upper decoding unit 53, a first bitstream synthesizing unit 54, a second bitstream synthesizing unit 56, and a sequence header restoration. A portion 58 is provided. Among the components of the present embodiment, the same components as those of the third embodiment are denoted by the same reference numerals, and description thereof is omitted.

The first bit stream dividing section 44 and the sequence header changing section 48 form the lower bit stream 2
01, the same process as that performed by the bit stream dividing unit 21 and the sequence header changing unit 23 according to the second embodiment. As a result, the changed first bit stream 221c including the I encoding result and the P encoding result,
Second bit stream 22 consisting only of B-encoded result
2a is required.

The second bit stream division unit 46 performs the same process on the upper bit stream 202 as the first bit stream division unit 44. Thus, a third bit stream 223a composed of only frames predicted and encoded in the spatial axis direction and a fourth bit stream 224a composed of only frames predicted and encoded in both the time axis and the spatial axis are formed. Desired.

The first bit stream synthesizing section 54 and the sequence header restoring section 58 perform the bit stream according to the second embodiment on the changed first bit stream 221c and second bit stream 222a. The same processing as that performed by the combining unit 31 and the sequence header restoring unit 33 is performed. As a result, the same lower bit stream 201 as that output from the first encoder is obtained.

The second bit stream synthesizing section 56 performs the same processing as the first bit stream synthesizing section 54 on the third bit stream 223a and the fourth bit stream 224a. As a result, the same upper bit stream 202 as that output from the second encoder is obtained.

The prediction directions between the four bit streams output from the hierarchical encoding device 16 are as shown in FIG. 13 as in the third embodiment.

As described above, the sequence header changing unit 48
When only the first bit stream 221c and the third bit stream 223a after the change are reproduced,
The first bit stream 221 is set so that the playback time matches the playback time of the original encoded bit stream 200.
The frame rate included in the sequence header a is changed. Also, the first bit stream 211c of the change book
Even when only the playback is performed, the playback time matches the playback time of the original coded bit stream 200.

As described above, according to the present embodiment, the hierarchical coding apparatus divides the lower bit stream and the upper bit stream obtained by the coding unit, and
And the frame rate included in the sequence header of the third bit stream. The hierarchical decoding device decodes only the changed first bit stream in the standard mode, or the changed first and third bit streams, and restores the frame rate in the high-quality mode. The four bit streams are combined, and the combined bit stream is decoded. The frame rate is changed so that the playback time when the first and third bit streams are simultaneously played and the playback time of the lower bit stream are equal. This allows
Hierarchical coding including one type of coding unit for performing hierarchical coding in the spatial axis direction, and performing hierarchical coding in the time axis direction by performing post-processing on a bit stream obtained by encoding. An apparatus and a hierarchical decoding apparatus corresponding to the hierarchical encoding apparatus can be obtained.

Note that, also in the present embodiment, similarly to the first embodiment, the first and second bit stream division units 44 and 46 may divide the bit stream by another method. For example, the first and third bit streams 221a, 223a may consist of only the I-encoding result, or may include the B-encoding result. Further, similarly to the modification of the first embodiment, a count value insertion unit that inserts a count value into the second and fourth bit streams 222a and 224a and a count value deletion unit that deletes the inserted count value are provided. You may.

Although the hierarchical coding apparatus and the hierarchical decoding apparatus according to the first to fourth embodiments are both connected to a communication network, these apparatuses are capable of transmitting a bit stream by another method. It may be input and output. Further, these devices encode or decode the video signal in accordance with MPEG-2, but may encode or decode the video signal using another method based on inter-frame prediction. . For example, MPEG-4 (ISO / IE
When a video signal is encoded in accordance with C14496-2), VOP (Video Object Pla) is used.
A similar method can be realized by changing the parameter value indicating the time distance between ne).

The hierarchical coding apparatus and the hierarchical decoding apparatus according to the first to fourth embodiments are both realized by a combination of a computer and a program operating on the computer. Is also good.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a hierarchical encoding device and a hierarchical decoding device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an encoded bit stream conforming to MPEG-2.

FIG. 3 is an explanatory diagram of a bit stream processing method in the hierarchical encoding device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing the number of display times of a frame standardized by MPEG-2.

FIG. 5 is a diagram illustrating an operation in a standard mode of the hierarchical decoding device according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating another bitstream division method in the hierarchical encoding device according to the first embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of a hierarchical encoding device and a hierarchical decoding device according to a modification of the first embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration of a hierarchical coding device and a hierarchical decoding device according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram of a bit stream processing method in the hierarchical encoding device according to the second embodiment of the present invention.

FIG. 10 is a diagram showing a frame rate standardized by MPEG-2.

FIG. 11 is a diagram illustrating an operation in a standard mode of the hierarchical decoding device according to the second embodiment of the present invention.

FIG. 12 is a block diagram illustrating a configuration of a hierarchical coding device and a hierarchical decoding device according to a third embodiment of the present invention.

FIG. 13 is a diagram illustrating a prediction direction between bit streams output from the hierarchical encoding device according to the third and fourth embodiments of the present invention.

FIG. 14 is a block diagram showing a configuration of a hierarchical coding device and a hierarchical decoding device according to a fourth embodiment of the present invention.

FIG. 15 is a block diagram illustrating a configuration of a conventional hierarchical coding device and a conventional hierarchical decoding device.

[Explanation of symbols]

 10, 12, 14, 16, 18 ... Hierarchical coding device 11, 13, 15, 17, 19 ... Hierarchical decoding device 20: Encoding unit 21, 44, 46 ... Bit stream dividing unit 22, 45, 47 ... Picture header changing unit 23, 48. Sequence header changing unit 24. Count value inserting unit 30. Decoding unit 31, 54, 56 .. Bit stream synthesizing unit 32, 55, 57. Restoring unit 34 Count value deleting unit 40 Spatial direction downsampling unit 41 Lower encoding units 42, 52 Spatial direction upsampling unit 43 Upper encoding unit 51 Lower decoding unit 53 Upper decoding unit 100 Input video signals 101, 104 ... output video signals 102, 103 ... local decoded video signals 110 ... lower video signals 111, 112 ... lower local decoded video signal 200 ... coded bit stream 201 ... lower bit stream 202 ... upper bit stream 211a-c, 221a-c ... first bit stream 212a-b, 222a ... second bit stream 223a-b ... Third bit stream 224a Fourth bit stream 301 Sequence header 302 GOP layer 303 GOP header 304 Picture layer 305 Picture header 306 Picture layer data

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C059 KK06 MA00 MA33 PP04 RE07 UA02 UA05 5J064 BB03 BB09 BC02 BC05 BC23 BD03 BD04

Claims (30)

[Claims] 1. A hierarchical encoding apparatus for hierarchically encoding a video signal in a time axis direction, wherein the encoding is performed on an input video signal based on inter-frame prediction to obtain an encoded bit stream. A bit stream dividing unit that divides the coded bit stream into a first bit stream that can be played independently and a remaining second bit stream in frame units, and a playback time of the first bit stream. And a bit stream changing unit that changes a parameter value related to display of a frame included in the first bit stream so that a reproduction time of the coded bit stream becomes equal to a reproduction time of the coded bit stream. 2. The method according to claim 1, wherein the bit stream changing unit changes the number of times of display of a frame included in a frame header of the first bit stream.
3. The hierarchical coding device according to 1. 3. The hierarchical coding apparatus according to claim 1, wherein the bit stream changing unit changes a frame rate included in a sequence header of the first bit stream. 4. The method of claim 1, wherein the first bitstream comprises at least all intra-coded frames and all forward inter-coded frames. Hierarchical encoding device. 5. The hierarchical coding apparatus according to claim 1, wherein the first bit stream includes only all intra-coded frames. 6. The hierarchical coding apparatus according to claim 1, further comprising a count value inserting unit that inserts a count value updated for each frame into a frame header of the second bit stream. 7. An encoded bit stream is obtained by encoding a video signal, and the encoded bit stream is divided into a first reproducible bit stream and a second reproducible bit stream in frame units. , Obtained by changing a parameter value related to display of a frame included in the first bit stream such that a playback time of the first bit stream is equal to a playback time of the encoded bit stream. A hierarchical decoding device for hierarchically decoding the first and second bitstreams, wherein the parameter value included in the first bitstream is restored to an original value, whereby the first A bit stream restoring unit for restoring a bit stream; and the first video restored by the bit stream restoring unit. A bit stream synthesizing unit for synthesizing the bit stream and the second bit stream to obtain the encoded bit stream; and a decoding unit for decoding the encoded bit stream to obtain an output video signal. Also, a hierarchical decoding device. 8. The display method according to claim 1, wherein a display count of a frame included in a frame header of the first bit stream is changed, and the bit stream restoring unit restores the display count of the frame to an original value. The hierarchical decoding device according to claim 7, wherein: 9. The frame rate included in a sequence header of the first bit stream has been changed, and the bit stream restoring section restores the frame rate to an original value. 8. The hierarchical decoding device according to 7. 10. A count value update unit that inserts a count value updated for each frame into a frame header of the second bit stream, and deletes the count value inserted in the second bit stream. The hierarchical decoding device according to claim 7, further comprising: 11. A hierarchical encoding apparatus for hierarchically encoding a video signal in a time axis direction and a spatial axis direction, wherein the input video signal is hierarchically encoded in a spatial axis direction based on inter-frame prediction. And an encoding unit for obtaining a lower bit stream and an upper bit stream; and a second section that divides the lower bit stream into a first bit stream that can be played independently and a second bit stream that remains independently in frame units. A third bit stream corresponding to the first bit stream and a remaining fourth bit in units of frames according to the division in the first bit stream division unit; The second to split into streams
And the first and third bit streams so that the playback time when the first and third bit streams are simultaneously played and the playback time of the lower bit stream are equal. And a bit stream changing unit for changing a parameter value related to display of a frame to be displayed. 12. The hierarchical coding method according to claim 11, wherein the bitstream changing unit changes the number of times of displaying a frame included in a frame header of the first and third bitstreams. apparatus. 13. The apparatus according to claim 1, wherein the bit stream changing unit changes a frame rate included in a sequence header of the first bit stream.
2. The hierarchical encoding device according to 1. 14. The method of claim 11, wherein the first bitstream comprises at least all intra-coded frames and all forward inter-coded frames. Hierarchical encoding device. 15. The hierarchical coding apparatus according to claim 11, wherein the first bit stream includes only all intra-coded frames. 16. The hierarchical coding apparatus according to claim 11, further comprising a count value insertion unit that inserts a count value updated for each frame into a frame header of the second and fourth bit streams. . 17. The encoding unit, comprising: a downsampling unit that converts the input video signal into a lower video signal having a relatively small number of pixels; A lower encoding unit that obtains a decoding result obtained by decoding a lower bit stream; an upsampling unit that converts the decoding result into a video signal having the same format as the input video signal; The hierarchical coding apparatus according to claim 11, further comprising: a higher-order encoding unit that encodes the input video signal with reference to the obtained video signal and obtains the higher-order bit stream. 18. A video signal is hierarchically coded in a spatial axis direction to obtain a lower bit stream and an upper bit stream, and the lower bit stream and a first bit stream that can be independently reproduced in frame units and a remaining bit stream are obtained. A second bit stream, and dividing the upper bit stream into a third bit stream corresponding to the first bit stream and a remaining fourth bit stream according to the division, and 3 so that the reproduction time when the three bit streams are simultaneously reproduced is equal to the reproduction time of the lower bit stream.
And a hierarchical decoding device that hierarchically decodes the first to fourth bitstreams obtained by changing a parameter value related to display of a frame included in the third bitstream. By restoring the parameter values contained in the first and third bitstreams to the original values,
And a bit stream restoration unit for restoring a third bit stream; combining the first bit stream and the second bit stream restored by the bit stream restoration unit to obtain the lower bit stream First
A second bit stream combining unit that combines the third bit stream restored by the bit stream restoring unit and the fourth bit stream to obtain the upper bit stream.
And a decoding unit for hierarchically decoding the lower bit stream and the upper bit stream in the spatial axis direction to obtain an output video signal. 19. The display method according to claim 19, wherein a display count of a frame included in a frame header of the first and third bit streams is changed, and wherein the bit stream restoring unit restores the display count of the frame to an original value. 19. The hierarchical decoding device according to claim 18, wherein: 20. A frame rate included in a sequence header of the first bit stream is changed, and the bit stream restoring section restores the frame rate to an original value. 19. The hierarchical decoding device according to item 18. 21. A count value updated for each frame is inserted into a frame header of the second and fourth bit streams, and the count value inserted into the second and fourth bit streams is 19. The hierarchical decoding device according to claim 18, further comprising a count value deleting unit for deleting. 22. The decoding unit, which decodes the lower bit stream and obtains a lower video signal, and an up converter that converts the lower video signal into a video signal having the same format as the output video signal. The sampling unit according to claim 18, further comprising: a high-order decoding unit that decodes the high-order bit stream with reference to the video signal obtained by the up-sampling unit and obtains the output video signal. Hierarchical decoding device. 23. A hierarchical encoding method for hierarchically encoding a video signal in a time axis direction, wherein the encoding is performed on an input video signal based on inter-frame prediction to obtain an encoded bit stream. A step of dividing the coded bit stream into a first bit stream that can be reproduced independently and a second bit stream that can be reproduced independently in frame units; and a reproduction time of the first bit stream. And a bit stream changing step of changing a parameter value related to display of a frame included in the first bit stream so that a reproduction time of the coded bit stream becomes equal to the reproduction time of the coded bit stream. 24. A video signal is coded to obtain a coded bit stream, and the coded bit stream is divided into a first bit stream that can be reproduced independently and a second bit stream that can be reproduced independently in frame units. , Obtained by changing a parameter value related to display of a frame included in the first bit stream such that a playback time of the first bit stream is equal to a playback time of the encoded bit stream. A hierarchical decoding method for hierarchically decoding the first and second bitstreams, wherein the parameter value included in the first bitstream is restored to an original value, whereby the first A bit stream restoring step of restoring a bit stream; A step of combining the first bit stream and the second bit stream to obtain the coded bit stream; and a step of decoding the coded bit stream to obtain an output video signal. And a hierarchical decoding method. 25. A hierarchical encoding method for hierarchically encoding a video signal in a time axis direction and a spatial axis direction, wherein the input video signal is hierarchically encoded in a spatial axis direction based on inter-frame prediction. Performing an encoding step for obtaining a lower bit stream and an upper bit stream; and dividing the lower bit stream into a first bit stream that can be reproduced independently and a second bit stream that remains independently in frame units. A third bit stream corresponding to the first bit stream and a remaining fourth bit in units of frames, in accordance with the division in the first bit stream dividing step and the first bit stream dividing step. A second bit stream splitting step into a stream and a first bit and a third bit. A bitstream changing step of changing a parameter value related to display of a frame included in the first and third bitstreams so that a reproduction time when the trimming is simultaneously reproduced is equal to a reproduction time of the lower bitstream; A hierarchical coding method comprising: 26. A video signal is hierarchically coded in the spatial axis direction to obtain a lower bit stream and an upper bit stream, and the lower bit stream and a first bit stream that can be independently reproduced in frame units and a remaining bit stream are obtained. A second bit stream, and dividing the upper bit stream into a third bit stream corresponding to the first bit stream and a remaining fourth bit stream according to the division, and 3 so that the reproduction time when the three bit streams are simultaneously reproduced is equal to the reproduction time of the lower bit stream.
And a hierarchical decoding method for hierarchically decoding the first to fourth bitstreams obtained by changing a parameter value relating to display of a frame included in the third bitstream. By restoring the parameter values contained in the first and third bitstreams to the original values,
And a bit stream restoring step of restoring a third bit stream, and combining the first bit stream and the second bit stream restored in the bit stream restoring step to obtain the lower bit stream. A first bit stream combining step; a second bit stream combining step of combining the third bit stream restored in the bit stream restoring step and the fourth bit stream to obtain the upper bit stream A hierarchical decoding method comprising: a step; and a decoding unit that hierarchically decodes the lower bit stream and the upper bit stream in a spatial axis direction to obtain an output video signal. 27. A computer-readable recording medium having recorded thereon a program for executing a hierarchical encoding method for hierarchically encoding a video signal in a time axis direction on a computer. An encoding step of performing encoding based on inter-frame prediction to obtain an encoded bit stream; a first bit stream capable of reproducing the encoded bit stream alone in frame units and a second bit stream remaining And a parameter value related to display of a frame included in the first bit stream such that a playback time of the first bit stream is equal to a playback time of the encoded bit stream. A hierarchical encoding method comprising a step of changing a bit stream to be changed. A computer-readable recording medium on which a program to be executed by a computer is recorded. 28. A video signal is coded to obtain a coded bit stream, and the coded bit stream is divided into a first bit stream that can be reproduced independently and a second bit stream that can be independently reproduced in frame units. , Obtained by changing a parameter value related to display of a frame included in the first bit stream such that a playback time of the first bit stream is equal to a playback time of the encoded bit stream. A computer-readable recording medium on which a program for executing the hierarchical decoding method for hierarchically decoding the first and second bit streams by a computer is included, wherein the first bit stream is included in the first bit stream. The first bit stream is restored by restoring the parameter value to the original value. A bit stream restoring step of combining the first bit stream and the second bit stream restored in the bit stream restoring step to obtain the coded bit stream; A computer-readable recording medium storing a program for causing a computer to execute a hierarchical decoding method including a decoding step of decoding an encoded bit stream to obtain an output video signal. 29. A computer-readable recording medium having recorded thereon a program for executing a hierarchical encoding method for hierarchically encoding a video signal in a time axis direction and a spatial axis direction by a computer, comprising: An encoding step of performing hierarchical encoding in the spatial axis direction based on inter-frame prediction on the video signal, and determining a lower bit stream and an upper bit stream, and the lower bit stream can be reproduced independently in frame units. A first bit stream dividing step of dividing into a first bit stream and a remaining second bit stream; and the upper bit stream is divided into frames by the first bit stream dividing step in units of frames according to the division in the first bit stream dividing step. And a fourth bit stream corresponding to the third bit stream corresponding to the third bit stream. And a second bit stream dividing step for dividing the first and third bit streams so that a reproduction time when the first and third bit streams are simultaneously reproduced is equal to a reproduction time of the lower bit stream. A computer-readable recording medium storing a program for causing a computer to execute a hierarchical encoding method including a bitstream changing step of changing a parameter value related to display of a frame included in a third bitstream. 30. A video signal is hierarchically coded in a spatial axis direction to obtain a lower bit stream and an upper bit stream, and the lower bit stream and a first bit stream that can be independently reproduced in frame units and a residual bit stream are obtained. A second bit stream, and dividing the upper bit stream into a third bit stream corresponding to the first bit stream and a remaining fourth bit stream according to the division, and 3 so that the reproduction time when the three bit streams are simultaneously reproduced is equal to the reproduction time of the lower bit stream.
And a hierarchical decoding method for hierarchically decoding the first to fourth bitstreams obtained by changing a parameter value related to display of a frame included in the third bitstream. A computer-readable recording medium having recorded thereon a program for restoring the parameter values contained in the first and third bit streams to the original values,
And a bit stream restoring step of restoring a third bit stream, and combining the first bit stream and the second bit stream restored in the bit stream restoring step to obtain the lower bit stream. A first bit stream combining step; a second bit stream combining step of combining the third bit stream restored in the bit stream restoring step and the fourth bit stream to obtain the upper bit stream A program for executing, by a computer, a hierarchical decoding method comprising: a step; and a decoding unit that hierarchically decodes the lower bit stream and the upper bit stream in a spatial axis direction to obtain an output video signal. Computer readable Recording medium.