Method for encoding and decoding moving picture signals

Abstract

A method for encoding and decoding digital moving picture signals which can decode subframes appropriately in relation to time if a part of a bit stream is missing or an error occurs in the bit stream, and can suppress degradation of a reproduced picture if decoding of a subframe including a picture in motion in relation to time becomes unfeasible. In the method for encoding and decoding digital moving picture signals of this invention, information for one frame is encoded correspondingly to a spatial hierarchy of a frame, subframes and blocks. A subframe time position number and a subframe space number are attached to an identifier of each of the subframe, thereby resuming appropriate decoding of the subframes immediately after a trouble if an error occurs. The subframe identifiers are placed at a certain interval in the bit stream so as to give a smaller size to a subframe including a block which is in motion and difficult to be encoded, thereby suppressing degradation of a reproduced picture if decoding of the subframe becomes unfeasible.

Description

lacksor an error ofth e the second embodiment of this invention, a subframe 12 including a block 13 which contains a motion in relation to time, and is thus difficult to be coded is made smaller in relation to space. If such subframe 12 cannot be decoded, it is possible to suppress degradation of a quality of a reproduced picture to a small extent. In a region within a frame in which no motion in relation to time exists and degradation of the picture quality is hardly detected even if the decoding is unfeasible, a size of one subframe is large in relation to space, which allows a less volume of side information such as the subframe identifier SFSC 16, subframe number SFNT 16 and subframe number SFNT 17. This can prevent an encoding efficiency from being lowered.

As having been described the second embodiment by way of an example, it is alternatively possible that the frame 11, subframe 12 and the block 13 are in different sizes and shapes. It is also possible to employ values of a quantity of codes of one frame and a subframe interval SFD different from those employed in the above example.

As obvious from the above embodiments, this invention enables correct decoding of each subframe 12 an a unit in relation to time even if a part of the bit stream 14 is missing or an error occurs therein.

Further, according to this invention, it is possible to suppress degradation of a quality of the reproduced picture to a small extent if a subframe 13 including a block which is in motion in relation to time cannot be decoded.

Still further, in a region within a frame in which no motion in relation to time exists and degradation of a quality of the reproduced picture quality is hardly detected even if the decoding in unfeasible, side information of the region is allowed to be in a small volume so that it is possible to prevent an encoding efficiency from being lowered.

Claims

1. A method for encoding digital motion picture signals of a frame, comprising the steps of:

dividing said frame into plural blocks each including N×M pixels;

forming a subframe composed of a set of said blocks, said subframe being a unit to be encoded;

setting an identifier to said subframe to identify said subframe; and

specifying a frame to which said subframe belongs by adding to said identifier time position information to said identifier representing an order of displaying said subframe;

encoding said time position information along with said subframe, and

multiplexing said encoded time position information and a bit stream of said encoded subframe to transmit said encoded time position information and said bit stream.

2. A method for encoding digital motion picture signals of a frame, comprising the steps of:

dividing said frame into plural blocks each including N×M pixels;

forming a subframe composed of a set of said blocks, said subframe being a unit to be encoded; and

varying the number of said blocks included in said subframe according to a quantity of information generated by encoding each block to vary a spatial size of each of said subframes included in each frame.

3. A method for encoding digital motion picture signals of a frame, comprising the steps of:

dividing said frame into plural blocks each including N×M pixels.

forming a subframe composed of a set of said blocks, said subframe being a unit to be encoded;

setting an identifier to said subframe to identify said subframe;

specifying a frame to which said subframe belongs by adding to said identifier time position information representing an order of displaying said subframe;

encoding said time position information along with said subframe, and

multiplexing said encoded time position information and a bit stream of said encoded subframe to transmit said encoded time position information and said bit stream; and

varying the number of said blocks included in said subframe according to a quantity of information generated by encoding each block to vary a spatial size of each of said subframes included in each frame.

4. The method for encoding digital motion picture signals of a frame according to claim 2, wherein each of said subframes included in said frame has an equal sum of quantities of generated information of said blocks included in said subframe.

5. The method for encoding digital motion picture signals of a frame according to claim 3, wherein each of said subframes included in said frame has an equal sum of quantities of generated information of said blocks included in said subframe.

6. A method for encoding and decoding digital motion picture signals of a frame, comprising the steps of:

dividing said frame into plural blocks each including N×M pixels;

forming a subframe composed of a set of said blocks, said subframe being a unit to be encoded;

setting an identifier to said subframe to identify said subframe;

specifying a frame to which said subframe belongs by adding to said identifier time position information representing an order of displaying said subframe;

encoding said time position information along with said subframe;

multiplexing said encoded time position information and a bit stream of said encoded subframe to transmit said encoded time position information and said bit stream; and

decoding each of said subframes appropriately in relation to time by decoding and using said time position information to form said frame of said digital moving picture signals.

7. A method for encoding and decoding digital motion picture signals of a frame, comprising the steps of:

dividing said frame into plural blocks each including N×M pixels;

forming a subframe composed of a set of said blocks, said subframe being a unit to be encoded;

varying the number of said blocks included in said subframe according to a quantity of information generated by encoding each block to vary a spatial size of each of said subframes included in each frame; and

decoding each of said subframes to form said frame of said digital moving picture signal.

8. A method for encoding and decoding digital motion picture signals of a frame, comprising the steps of:

dividing said frame into plural blocks each including N×M pixels;

forming a subframe composed of a set of said blocks, said subframe being a unit to be encoded,

setting an identifier to said subframe to identify said subframe;

specifying a frame to which said subframe belongs by adding to said identifier time position information representing an order of displaying said subframe;

encoding said time position information along with said subframe;

multiplexing said encoded time position information and a bit stream of said encoded subframe to transmit said encoded time position information and said bit stream;

varying the number of said blocks included in said subframe according to a quantity of information generated by encoding each block to vary a spatial size of each of said subframes included in each frame; and

decoding said subframe appropriately in relation to time by decoding and using said time position information to form said frame of said digital moving picture signal.

9. The method for encoding and decoding digital motion picture signals of a frame according to claim 7, wherein each of said subframes included in said frame has an equal sum of quantities of generated information of said blocks included in said subframe.

10. The method for encoding and decoding digital motion picture signals of a frame according to claim 8, wherein each of said subframes included in said frame has an equal sum of quantities of generated information of said blocks included in said subframe.

11. The method for encoding digital motion picture signals of a frame according to claim 1, wherein said step of adding time position information comprises adding the time information to each subframe of said frame.

12. The method for encoding digital motion picture signals of a frame according to claim 11, further comprising the step of maintaining substantially constant a quantity of information generated for each subframe within said frame thereby to vary spatial dimensions represented by each said subframe.

13. The method for encoding digital motion picture signals of a frame according to claim 1, further comprising the step of maintaining substantially constant a quantity of information generated for each subframe within said frame thereby to vary spatial dimensions represented by each said subframe.

14. The method for encoding and decoding digital motion picture signals of a frame according to claim 6, wherein said step of adding time position information comprises adding the time information to each subframe of said frame.

15. The method for encoding digital motion picture signals of a frame according to claim 14, further comprising the step of maintaining substantially constant a quantity of information generated for each subframe within said frame thereby to vary spatial dimensions represented by each said subframe.

16. The method for encoding digital motion picture signals of a frame according to claim 6, further comprising the step of maintaining substantially constant a quantity of information generated for each subframe within said frame thereby to vary spatial dimensions represented by each said subframe.

17. A method for encoding digital motion picture signals of a frame, comprising:

dividing said frame into plural blocks each including N×M pixels;

forming a subframe composed of at least one of said blocks, said subframe being a unit to be encoded;

setting an identifier to said subframe to identify said subframe;

specifying a frame to which said subframe belongs by adding time position information to said identifier, the time position information representing an order of displaying said subframe;

specifying a spatial position of said subframe within said frame by adding spatial position information to said identifier, the spatial position information representing said spatial position of said subframe within said frame;

encoding said time position information and said spatial position information along with said subframe, and

multiplexing said encoded time position information, said encoded spatial position information and a bit stream of said encoded subframe to transmit said encoded spatial position information, said encoded time position information and said bit stream.

18. A method for encoding and decoding digital motion picture signals of a frame, said method comprising:

dividing said frame into plural blocks each including N×M pixels;

forming a subframe composed of at least one of said blocks, said subframe being a unit to be encoded;

setting an identifier to said subframe to identify said sub-frame;

specifying a frame to which said subframe belongs by adding time position information to said identifier, the time position information representing an order of displaying said subframe;

specifying a spatial position of said subframe within said frame by adding spatial position information to said identifier, the spatial position information representing said spatial position of said subframe within said frame;

encoding said time position information and said spatial position information along with said subframe;

multiplexing said encoded time position information, said encoded spatial position information and said encoded subframe to transmit said encoded spatial position information, said encoded time position information and said encoded subframe as an encoded bitstream;

receiving said encoded bitstream;

detecting said identifier to extract said encoded time position information and said encoded spatial position information from said encoded bitstream;

decoding said extracted encoded time position information to obtain decoded time position information;

decoding said extracted encoded spatial position information to obtain decoded spatial position information; and

decoding said encoded subframe to form said frame according to said decoded spatial position information and said decoded time position information.

19. A method for decoding an encoded bitstream, said method comprising:

(a) receiving said encoded bitstream containing an identifier, an encoded subframe obtained by encoding a subframe composed of at least one of said blocks, and an encoded spatial position information representing a spatial position of said subframe within a frame composed of a plurality of subframes and an encoded time position information representing an order of displaying said subframe,

wherein

said identifier is set to said encoded subframe to identify said subframe,

said encoded time position information is added to said identifier by specifying a frame to which said subframe belongs, and

said encoded spatial position information is added to said identifier by specifying a spatial position of said subframe within said frame;

(b) detecting said identifier to extract said encoded spatial position information and said encoded time position information from said encoded bitstream;

(c) decoding said extracted encoded time position information to obtain decoded time position information;

(d) decoding said extracted encoded spatial position information to obtain decoded spatial position information; and

(e) decoding said encoded subframe to form said frame according to said decoded spatial position information and said decoded time position information.

20. The method for decoding according to claim 19, wherein in the case any conflict is detected in at least one of the decoded time position information and the decoded spatial position information corresponding to current encoded subframe, a procedure of detecting said identifier is executed to establish synchronization of a subframe layer without decoding said current encoded subframe.

21. The method for decoding according to claim 19, wherein in the case any conflict is detected in a process of decoding a current block layer within said encoded subframe, a procedure of detecting said identifier is executed to establish synchronization of a subframe layer without decoding said current block layer.