US5969768A
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Methods and apparatus for re-using decoder circuitry
Assignee: Hitachi America Ltd
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Filing: 1998-10-26
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Granted: 1999-10-19
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Expires: 2018-10-26
Abstract
Abstract An implementation efficient video decoder suitable for use as a picture in picture decoder is described. In one embodiment, the video decoder receives primary and secondary bitstreams with the secondary bitstream including the video data intended to be displayed as inset pictures. The decoder uses many of the same circuit components on a time shared basis to decode both the main and inset pictures reducing the amount of circuitry required to implement the decoder. In one embodiment a preparser discards the majority of DCT coefficients in the secondary bitstream and the remaining data is variable length decoded and then variable length encoded using a non-MPEG compliant coding scheme prior to storing the inset picture data in a coded data buffer. Re-encoding of the selected inset picture data in this manner greatly reduces data storage requirements and simplifies the circuitry required to subsequently decode the inset picture data. To reduce frame memory requirements inset picture data is downsampled, stored and then upsampled prior to display thereby reducing inset picture frame memory buffer requirements.
Inventors
- 👤 Jill MacDonald Boyce
- 👤 Larry Pearlstein
- 👤 Frank Anton Lane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:40
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H04N5/445; H04N5/45; G; G06; G06T; G06T3/00; G06T3/40; G06T3/4084; H04N19/00; H04N19/10; H04N19/102; H04N19/12; H04N19/122; H04N19/132; H04N19/134; H04N19/157; H04N19/159; H04N19/162; H04N19/169; H04N19/17; H04N19/172; H04N19/176; H04N19/18; H04N19/184; H04N19/40; H04N19/42; H04N19/423; H04N19/426; H04N19/427; H04N19/428; H04N19/44; H04N19/48; H04N19/50; H04N19/59; H04N19/60; H04N19/61; H04N21/00; H04N21/40; H04N21/41; H04N21/426; H04N21/43; H04N21/431; H04N21/4312; H04N21/4316; H04N21/434; H04N21/44; H04N21/4402; H04N21/440254; H04N5/44504; H04N19/13; H04N19/30; H04N19/90; H04N19/91; H04N5/46
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
124 words
A method of performing inverse discrete cosine transform operations on first and second sets of data representing first and second image portions, respectively, the method comprising the steps of: performing a first inverse discrete cosine transform operation using a one dimensional inverse discrete cosine transform unit on the first set of image data, during a first portion of a frame time corresponding to the amount of time intended to be used to display a first image at least a portion of which is represented by the first set of image data; and performing a second inverse discrete cosine transform operation, using said one dimensional inverse discrete cosine transform unit, on the second set of image data during a second portion of said frame time.
Claim 2
Independent Claim
124 words
A method of performing inverse discrete cosine transform operations on first and second sets of data representing first and second image portions, respectively, the method comprising the steps of: performing a first inverse discrete cosine transform operation using a one dimensional inverse discrete cosine transform unit on the first set of image data, during a first portion of a frame time corresponding to the amount of time intended to be used to display a first image at least a portion of which is represented by the first set of image data; and performing a second inverse discrete cosine transform operation, using said one dimensional inverse discrete cosine transform unit, on the second set of image data during a second portion of said frame time.
Claim 3
Dependent Claim
21 words
The method of claim 1, wherein the first and second inverse discrete cosine transform operations are two dimensional cosine transform operations.
Claim 4
Dependent Claim
22 words
The method of claim 2, wherein said one dimensional inverse discrete cosine transform unit is an 8×1 inverse discrete cosine transform circuit.
Claim 5
Dependent Claim
20 words
The method of claim 2, wherein the first and second sets of image data represent first and second images, respectively.
Claim 6
Dependent Claim
24 words
The method of claim 4, wherein the first image is a main picture image; and wherein the second image is an inset picture image.
Claim 7
Independent Claim
130 words
A method of decoding first and second sets of image data in a frame time, where a frame time is the time in which an image corresponding to the first image data is intended to be displayed, the method comprising the steps of: providing an inverse discrete cosine transform unit including a one dimensional inverse discrete cosine transform circuit; using the one dimensional inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation using a portion of the set of first picture data in a first portion of a frame time; and using the one dimensional inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation on a portion of the set of second picture data in a second portion of the frame time.
Claim 8
Independent Claim
130 words
A method of decoding first and second sets of image data in a frame time, where a frame time is the time in which an image corresponding to the first image data is intended to be displayed, the method comprising the steps of: providing an inverse discrete cosine transform unit including a one dimensional inverse discrete cosine transform circuit; using the one dimensional inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation using a portion of the set of first picture data in a first portion of a frame time; and using the one dimensional inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation on a portion of the set of second picture data in a second portion of the frame time.
Claim 9
Dependent Claim
52 words
The method of claim 6, further comprising the step of: performing a first two dimensional inverse discrete cosine transform operation which includes said step of using the one dimensional inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation using a portion of the set of first picture data.
Claim 10
Dependent Claim
52 words
The method of claim 7, further comprising the step of: performing a first two dimensional inverse discrete cosine transform operation which includes said step of using the one dimensional inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation on a portion of the set of second picture data.
Claim 11
Dependent Claim
45 words
The method of claim 6, wherein the one dimensional inverse discrete cosine transform circuit is an 8×1 inverse discrete cosine transform circuit; wherein the set of first picture data represents a main image; and wherein the set of second picture data represents an inset image.
Claim 12
Dependent Claim
29 words
The method of claim 9, further comprising the step of displaying the main and inset images during a single period of time equal in duration to said frame time.
Claim 13
Independent Claim
122 words
A method of decoding first picture data, intended to be displayed in a frame time, and second picture data, the method comprising the steps of: providing an inverse discrete cosine transform unit including an 8×1 inverse discrete cosine transform circuit; using the 8×1 inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation on a set of the first picture data in a first portion of a frame time; using the 8×1 inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation on a set of the second picture data in a second portion of a frame time, the first and second portions of a frame time being equal to or less than the frame time.
Claim 14
Independent Claim
122 words
A method of decoding first picture data, intended to be displayed in a frame time, and second picture data, the method comprising the steps of: providing an inverse discrete cosine transform unit including an 8×1 inverse discrete cosine transform circuit; using the 8×1 inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation on a set of the first picture data in a first portion of a frame time; using the 8×1 inverse discrete cosine transform circuit to perform an inverse discrete cosine transform operation on a set of the second picture data in a second portion of a frame time, the first and second portions of a frame time being equal to or less than the frame time.
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