Apparatus for and method of reproducing digital video signals at a varied speed
First Claim
1. An apparatus for reproducing digital video signals at a varied speed, comprising:
- a digital video signal transmitter for recording the maximum one of coded length information of macroblocks included in each one of slices corresponding to an input digital video signal on each corresponding slice header and transmitting it together with the macroblocks;
a digital video cassette tape recorder for detecting the position of a discontinuous interval of each discontinuous-interval-involving one of the slices transmitted from the transmitter via a transmission channel in a speed-varied reproduction mode, and inserting slice condition information and slice length information generated at the detected discontinuous interval position in each corresponding slice header, thereby formatting the information together with digital video signals for the slice; and
a digital video signal receiver for decoding the digital video signals for each slice reproduced in the digital video cassette tape recorder up to a macroblock just preceding a macroblock involving the discontinuous interval by use of the maximum coded length information, slice condition information and slice length information reproduced in the digital video cassette tape recorder.
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Abstract
An apparatus for, and a method of, reproducing digital video signals at a varied speed, adapted to insert information about the maximum coded lengths of digital video signals in slices resulting from encoding and compressing of the digital video signals by a digital video signal transmitter so that the inserted information can be transmitted together with the compressed digital video signal, and to insert slice condition information and slice length information in slice headers of slices upon reproducing the digital video signals recorded on a tape at a varied speed so that the inserted slice condition information and slice length information can be deformatted together with the slices. The apparatus and method is thus capable of decoding the digital video signals for macroblocks preceding the macroblock involving a discontinuous interval based on the maximum coded length information, slice condition information and slice length information.
53 Citations
9 Claims
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1. An apparatus for reproducing digital video signals at a varied speed, comprising:
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a digital video signal transmitter for recording the maximum one of coded length information of macroblocks included in each one of slices corresponding to an input digital video signal on each corresponding slice header and transmitting it together with the macroblocks; a digital video cassette tape recorder for detecting the position of a discontinuous interval of each discontinuous-interval-involving one of the slices transmitted from the transmitter via a transmission channel in a speed-varied reproduction mode, and inserting slice condition information and slice length information generated at the detected discontinuous interval position in each corresponding slice header, thereby formatting the information together with digital video signals for the slice; and a digital video signal receiver for decoding the digital video signals for each slice reproduced in the digital video cassette tape recorder up to a macroblock just preceding a macroblock involving the discontinuous interval by use of the maximum coded length information, slice condition information and slice length information reproduced in the digital video cassette tape recorder. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for reproducing digital video signals at a varied speed, comprising the steps of:
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(a) initializing an index indicative of the number of encoded macroblocks of a slice for compressed digital video signals and maximum coded length information indicative of the number of bits coded with the maximum length when a slice start code is detected from one of the digital video signals; (b) comparing the index with the total number of macroblocks included in the slice to be encoded, encoding a macroblock just following the encoded macroblocks when the index is not more than the total macroblock number, counting the coded length of the currently encoded macroblock, and comparing the counted coded length with the maximum coded length information; (c) storing the counted coded length as new maximum coded length information when the coded length is determined to be more than the maximum coded length information at the step (b), and incrementing the index by one; (d) only incrementing the index by one without storing the counted coded length as new maximum coded length information when the coded length is not determined to be more than the maximum coded length information at the step (b); and (e) repeatedly executing the steps (b) to (d) when the index is not determined to be more than the total macroblock number at the step (b), and inserting the maximum coded length information in a slice header of the slice when the index is determined to be more than the total macroblock number at the step (b).
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9. A method for reproducing digital video signals at a varied speed, comprising the steps of:
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(a) clearing a coded length of a previously decoded slice just preceding a slice to be currently decoded when a slice start code of the current slice is detected, initializing an index, indicative of the number of decoded macroblocks of the current slice, to be "1", and detecting maximum coded length information and slice condition information inserted in a slice header of the current slice; (b) checking whether the detected slice condition information is "0" indicative of a completely decodable slice or "1" indicative of an incomplete slice involving a discontinuous interval, and executing a decoding for all the macroblocks included in the current slice when the detected slice condition information is "0"; (c) detecting slice length information when the detected slice condition information is "1", and executing a decoding for one of the macroblocks of the current slice, based on the detected slice length information; (d) counting the coded length of the decoded macroblock, and comparing the difference between the counted coded length and the detected slice length information with the detected maximum coded length information; (e) executing a next macroblock just following the decoded macroblock when the difference between the counted coded length and the detected slice length information is not less than the maximum coded length information, and adding the coded length of the decoded next macroblock to the coded length of the first macroblock to count the total decoded length of the current slice; (f) incrementing the index by one after completing the step (e), repeatedly executing the steps (c) to (e) until the difference between the total decoded length of the current slice and the detected slice length information is less than the maximum coded length information, and stopping the decoding of the step (c) until a slice start code of a next slice just following the current slice when the difference between the total decoded length of the current slice decoded and the detected slice length information is less than the maximum coded length information.
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Specification