Decoding apparatus, decoding method, encoding apparatus, encoding method, image processing system, and image processing method
First Claim
1. A decoding apparatus comprising:
- decoding means for decoding an input bit stream to generate image data;
parameter generating means for generating coding parameters of each layer, to be used to encode the image data again, which has been generated by the decoding means; and
error flag generating means for generating an error flag which indicates whether the coding parameters generated for each layer by the parameter generating means can be effectively used to encode the image data again;
whereby the operation of encoding the image data again includes counting a number of times that image data corresponding to a picture-coding type employed in the prior coding is continuously input from said decoding means, and the operation of generating said coding parameters is performed in accordance with the count; and
whereby when a predetermined number of pictures of one type are continuously input from said decoding means, the picture coding type is changed for at least one of said predetermined number of pictures of said one type.
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Abstract
An image processing system comprising a decoder 10 and an encoder 30. The decoder 10 comprises a section 12 for decoding a bit stream to generate image data, generating coding parameters for each layer and generating an error flag indicating whether the coding parameters can be effectively used. The encoder 30 comprises a control section 41, an MB-parameter calculating section 36, an encoding section 38 and a variable-length encoding section 39. The section 41 determines, from the error flag, whether or not the coding parameters can be effectively used or not. The section 36 calculates coding parameters when the coding parameters generated by the section 12 are invalid. The sections 38 and 39 encodes the image data by using the coding parameters generated by the section 12 when these parameters are valid, and by using the coding parameters calculated by the section 36 when the coding parameters generated by the section 12 are invalid.
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Citations
19 Claims
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1. A decoding apparatus comprising:
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decoding means for decoding an input bit stream to generate image data;
parameter generating means for generating coding parameters of each layer, to be used to encode the image data again, which has been generated by the decoding means; and
error flag generating means for generating an error flag which indicates whether the coding parameters generated for each layer by the parameter generating means can be effectively used to encode the image data again;
whereby the operation of encoding the image data again includes counting a number of times that image data corresponding to a picture-coding type employed in the prior coding is continuously input from said decoding means, and the operation of generating said coding parameters is performed in accordance with the count; and
whereby when a predetermined number of pictures of one type are continuously input from said decoding means, the picture coding type is changed for at least one of said predetermined number of pictures of said one type. - View Dependent Claims (2)
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3. A decoding method comprising:
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decoding an input bit stream to generate image data;
generating coding parameters of each layer, to be used to encode the image data again; and
generating an error flag which indicates whether the coding parameters generated for each layer can be effectively used to encode the image data again;
whereby the operation of encoding the image data again includes counting a number of times that image data corresponding to a picture-coding type employed in the prior coding is continuously input from the decoding step, and the operation of generating coding parameters in accordance with the count; and
whereby when a predetermined number of pictures of one type are continuously input from said decoding step, the picture coding type is changed for at least one of said predetermined number of pictures of said one type. - View Dependent Claims (4)
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5. An encoding apparatus comprising:
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parameter evaluating means for determining whether coding parameters for each layer, which have been input from a decoding apparatus, can be used effectively to encode image data input from the decoding apparatus, from an error flag that indicates whether the coding parameters can be used effectively;
parameter calculating means for calculating coding parameters from the image data supplied from the decoding apparatus, in accordance with data supplied from the parameter evaluating means and indicating that the coding parameters are invalid; and
encoding means for encoding the image data by using the coding parameters input from the decoding apparatus when the parameter-evaluating mean determines that the coding parameters supplied from the decoding apparatus are valid, and by using the coding parameters generated by the parameter calculating means when the parameter-evaluating mean determines that the coding parameters supplied from the decoding apparatus are invalid;
whereby the operation of encoding the image data again includes counting a number of times that image data corresponding to a picture-coding type employed in the prior coding is continuously input from said decoding apparatus, and the operation of calculating said coding parameters is performed in accordance with the count; and
whereby when a predetermined number of pictures of one type are continuously input from said decoding apparatus, the picture coding type is changed for at least one of said predetermined number of pictures of said one type. - View Dependent Claims (6, 7)
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8. An encoding apparatus comprising:
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counting means for counting a number of times that image data corresponding to a picture-coding type employed in the prior coding is continuously input from a decoding apparatus;
picture type changing means for generating coding parameters in accordance with data supplied from the counting means and indicating that the count of the counting means has reached a predetermined value, so that the image data may be encoded to image data of a different picture type; and
encoding means for encoding the image data by using the coding parameters supplied from the picture type changing means;
whereby when a predetermined number of pictures of one type are continuously input from said decoding apparatus, the picture coding type is changed for at least one of said predetermined number of pictures of said one type.
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9. An encoding method comprising:
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a process of determining whether coding parameters for each layer, which have been input from a decoding apparatus, can be used effectively to encode image data input from the decoding apparatus, from an error flag that indicates whether the coding parameters can be used effectively;
a process of calculating coding parameters from the image data supplied from the decoding apparatus, in accordance with data indicating that the coding parameters supplied from the decoding apparatus are invalid; and
a process of encoding the image data by using the coding parameters input from the decoding apparatus when the coding parameters supplied from the decoding apparatus are determined to be valid, and by using the coding parameters generated in the process of calculating coding parameters when the coding parameters supplied from the decoding apparatus are determined to be invalid;
whereby the operation of encoding the image data again includes counting a number of times that image data corresponding to a picture-coding type employed in the prior coding is continuously input from said decoding apparatus, and the operation of calculating said coding parameters is performed in accordance with the count; and
whereby when a predetermined number of pictures of one type are continuously input from said decoding apparatus, the picture coding type is changed for at least one of said predetermined number of pictures of said one type. - View Dependent Claims (10, 11)
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12. An encoding method comprising:
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counting a number of times that image data corresponding to a picture-coding type employed in the prior coding is continuously input from a decoding apparatus;
generating coding parameters in accordance with data supplied from the counting means and indicating that the count of the counting means has reached a predetermined value, so that the image data may be encoded to image data of a different picture type; and
encoding the image data by using the coding parameters supplied from the picture type changing means; and
whereby when a predetermined number of pictures of one type are continuously input from said decoding apparatus, the picture coding type is changed for at least one of said predetermined number of pictures of said one type.
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13. An image processing system comprising:
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an decoding apparatus comprising;
decoding means for decoding an input bit stream to generate image data;
parameter generating means for generating coding parameters of each layer, to be used to encode the image data again, which has been generated by the decoding means; and
error flag generating means for generating an error flag which indicates whether the coding parameters generated for each layer by the parameter generating means can be effectively used to encode the image data again; and
an encoding apparatus comprising;
parameter evaluating means for determining whether coding parameters for each layer, which have been input from a decoding apparatus, can be used effectively to encode image data input from the decoding apparatus, from an error flag that indicates whether the coding parameters can be used effectively;
parameter calculating means for calculating coding parameters from the image data supplied from the decoding apparatus, in accordance with data supplied from the parameter evaluating means and indicating that the coding parameters are invalid; and
encoding means for encoding the image data by using the coding parameters input from the decoding apparatus when the parameter-evaluating mean determines that the coding parameters supplied from the decoding apparatus are valid, and by using the coding parameters generated by the parameter calculating means when the parameter-evaluating mean determines that the coding parameters supplied from the decoding apparatus are invalid;
whereby the operation of encoding the image data again includes counting a number of times that image data corresponding to a picture-coding type employed in the prior coding is continuously input from said decoding apparatus, and the operation of calculating said coding parameters is performed in accordance with the count; and
whereby when a predetermined number of pictures of one type are continuously input from said decoding apparatus, the picture coding type is changed for at least one of said predetermined number of pictures of said one type. - View Dependent Claims (14, 15)
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16. An image processing system comprising:
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decoding means for decoding an input bit stream to generate image data;
inverse quantization means for performing inverse quantization on the image data supplied from the decoding means, thereby to generate DCT coefficients;
quantization means for performing quantization on the DCT coefficients supplied from the inverse quantization means, thereby to generated image data;
parameter generating means for generating coding parameters for each layer, to be used to encode the image data decoded by the decoding means;
error flag generating means for generating an error flag which indicates whether the coding parameters generated for each layer by the parameter generating means can be effectively used to encode the image data again;
calculating means for calculating coding parameters in accordance with the error flag supplied from the error flag generating means;
encoding means for encoding the image data supplied from the quantization means, by using the coding parameters supplied from the parameter generating means or the calculating means; and
control means for causing the encoding means to encode the image data by using the coding parameters generated by the parameter generating means, when the encoding parameters are determined to be valid, from the error flag generated by the error flag generating means, and by using the coding parameters generated by the calculating means, when the encoding parameters generated by the parameter generating means are determined to be invalid, from the error flag generated by the error flag generating means. - View Dependent Claims (17)
a video buffer for outputting the bit stream encoded by the encoding means, at a rate equal to or lower than a prescribed bit rate; and
quantization control means for controlling a quantization step at which the quantization means quantizes the image data so that the video buffer may output the bit stream at a rate equal to or lower than the prescribed bit rate, in accordance with a percentage of a storage area that data bits occupy in the video buffer.
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18. An image processing method comprising:
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a process of decoding an input bit stream to generate image data, generating coding parameters of each layer, to be used to encode the image data again, and an error flag which indicates whether the coding parameters generated for each layer may be effectively used to encode the image data again;
a process of performing inverse quantization on the image data supplied from the decoding means, thereby to generate DCT coefficients;
a process of performing quantization on the DCT coefficients supplied from the inverse quantization means, thereby to generated image data;
a process of calculating coding parameters in accordance with the error flag; and
a process of encoding the image data by using the coding parameters generated in the process of decoding the input bit stream, when it is determined from the error flat that the encoding parameters are valid, and by using the coding parameters generated in the process of calculating coding parameters, when it is determined from the error flat that the encoding parameters are invalid. - View Dependent Claims (19)
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Specification