US5668599A
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US
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Memory management for an MPEG2 compliant decoder
Assignee: International Business Machines Corp
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Filing: 1996-03-19
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Granted: 1997-09-16
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Expires: 2016-03-19
Abstract
Abstract Disclosed is a digital signal decoder system for receiving compressed encoded digitized video signals and transmitting decompressed decoded digital video signals. This is accomplished with a minimum of DRAM demand through the use of a Spill Buffer.
Inventors
- 👤 Dennis Phillip Cheney
- 👤 Mark Louis Ciacelli
- 👤 Steven Bradford Herndon
- 👤 John David Myers
- 👤 Chuck Hong Ngai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:15
CPC Classifications
H; H04; H04N; H04N21/00; H04N21/40; H04N21/43; H04N21/4302; H04N21/4305; H04N21/41; H04N21/426; H04N19/00; H04N19/42; H04N19/423; H04N19/426; H04N19/427; H04N19/60; H04N19/61; H04N21/44; H04N21/44004; H04N5/00; H04N5/76; H04N5/907
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
131 words
A digital video decoder comprising an input data buffer, a variable length decoder, a dequantizer, an inverse discrete cosine transform decoder, a motion compensator, and a frame memory, said frame memory having at least a past reference frame buffer, a future reference frame buffer, a frame buffer for a frame currently being decoded, and a Spill Buffer, said Spill Buffer being dynamically allocable within said frame memory as frames are decoded, and where said three frame buffers are accessed on a rotating basis according to the following algorithm: C=D*NBF+ NBF*(T*(PREV =B)+P*(PREV=B*PRES =B)); P=C*NBF+ NBF*F*(PRES =B); F=T*(PREV =B*PRES= B)+P*(PREV=B*PRES =B); D=C*NBF+ NBF*(F*(PRES =B)+T*(PREV =B*PRES=B)); and T=D; where C=Current picture pointer; P=Past picture pointer; F=Future picture pointer; D=Display picture pointer; T=Temporary pointer; PRES=Present picture type; PREV=Previous picture type; and NBF=No B frame mode.
Claim 2
Dependent Claim
131 words
A digital video decoder comprising an input data buffer, a variable length decoder, a dequantizer, an inverse discrete cosine transform decoder, a motion compensator, and a frame memory, said frame memory having at least a past reference frame buffer, a future reference frame buffer, a frame buffer for a frame currently being decoded, and a Spill Buffer, said Spill Buffer being dynamically allocable within said frame memory as frames are decoded, and where said three frame buffers are accessed on a rotating basis according to the following algorithm: C=D*NBF+ NBF*(T*(PREV =B)+P*(PREV=B*PRES =B)); P=C*NBF+ NBF*F*(PRES =B); F=T*(PREV =B*PRES= B)+P*(PREV=B*PRES =B); D=C*NBF+ NBF*(F*(PRES =B)+T*(PREV =B*PRES=B)); and T=D; where C=Current picture pointer; P=Past picture pointer; F=Future picture pointer; D=Display picture pointer; T=Temporary pointer; PRES=Present picture type; PREV=Previous picture type; and NBF=No B frame mode.
Claim 3
Dependent Claim
21 words
The digital video decoder of claim 1 wherein the three frame buffers are each large enough to hold a decoded frame.
Claim 4
Dependent Claim
36 words
The digital video decoder of claim 1 wherein a picture being displayed comes from either the past reference frame buffer for an I- or P- picture, or from the current frame buffer for a B- picture.
Claim 5
Dependent Claim
19 words
The digital video decoder of claim 1 wherein said decoder supports normal mode decoding and low delay mode decoding.
Claim 6
Dependent Claim
34 words
The digital video decoder of claim 4 wherein said decoder supports normal mode decoding and wherein said frame buffer memory is allocated at between 2 and 4 MBytes with an 8 byte data bus.
Claim 7
Dependent Claim
30 words
The digital video decoder of claim 4 wherein said decoder supports low mode decoding and said frame buffer memory is allocated at 1 MByte with a 4 byte data bus.
Claim 8
Independent Claim
180 words
A method of decoding a digital video datastream in a digital video decoder comprising an input data buffer, a variable length decoder, a dequantizer, an inverse discrete cosine transform decoder, a motion compensator, and a frame memory, said frame memory having at least a past reference frame buffer, a future reference frame buffer, a frame buffer for a frame currently being decoded, and a Spill Buffer, said Spill Buffer being dynamically allocable within said frame memory as frames are decoded, and where said three frame buffers are accessed on a rotating basis according to the following algorithm: C=D*NBF+ NBF*(T*(PREV =B)+P*(PREV=B*PRES =B)); P=C*NBF+ NBF*F*(PRES =B); F=T*(PREV =B*PRES= B)+P*(PREV=B*PRES =B); D=C*NBF+ NBF*(F*(PRES =B)+T*(PREV =B*PRES=B)); and T=D; where C=Current picture pointer; P=Past picture pointer; F=Future picture pointer; D=Display picture pointer; T=Temporary pointer; PRES=Present picture type; PREV=Previous picture type; and NBF=No B frame mode; which method comprises: a. storing a frame currently being decoded in the current frame buffer; b. storing a past reference frame in the past reference frame buffer; and c. storing a future reference frame in the future reference frame buffer.
Claim 9
Independent Claim
180 words
A method of decoding a digital video datastream in a digital video decoder comprising an input data buffer, a variable length decoder, a dequantizer, an inverse discrete cosine transform decoder, a motion compensator, and a frame memory, said frame memory having at least a past reference frame buffer, a future reference frame buffer, a frame buffer for a frame currently being decoded, and a Spill Buffer, said Spill Buffer being dynamically allocable within said frame memory as frames are decoded, and where said three frame buffers are accessed on a rotating basis according to the following algorithm: C=D*NBF+ NBF*(T*(PREV =B)+P*(PREV=B*PRES =B)); P=C*NBF+ NBF*F*(PRES =B); F=T*(PREV =B*PRES= B)+P*(PREV=B*PRES =B); D=C*NBF+ NBF*(F*(PRES =B)+T*(PREV =B*PRES=B)); and T=D; where C=Current picture pointer; P=Past picture pointer; F=Future picture pointer; D=Display picture pointer; T=Temporary pointer; PRES=Present picture type; PREV=Previous picture type; and NBF=No B frame mode; which method comprises: a. storing a frame currently being decoded in the current frame buffer; b. storing a past reference frame in the past reference frame buffer; and c. storing a future reference frame in the future reference frame buffer.
Claim 10
Dependent Claim
16 words
The method of claim 7 comprising storing a complete frame in each of said frame buffers.
Claim 11
Dependent Claim
34 words
The method of claim 7 wherein a picture being displayed comes from either the past reference frame buffer for an I- or P- picture, or from the current frame buffer for a B- picture.
Claim 12
Dependent Claim
15 words
The method of claim 7 comprising assigning the Spill Buffer dynamically while decoding a picture.
Claim 13
Dependent Claim
18 words
The method of claim 10 comprising dynamically assigning the Spill Buffer to one of the three frame buffers.
Claim 14
Dependent Claim
10 words
The method of claim 7 further comprising seamless sequence switching.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-09-15 | 2001-03-17 | 2001-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-09-15 | 2005-03-17 | 2005-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-09-15 | 2009-03-17 | 2009-09-16 | $7700.00 | Window Closed / Lapsed |