US5589829A
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US
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Decoding variable-length encoded signals
Assignee: Micron Technology Inc
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Filing: 1994-10-26
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Granted: 1996-12-31
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Expires: 2014-10-26
Abstract
Abstract Variable-length encoded signals (e.g., those corresponding to video signals) are decoded using a lookup table whose indices are shorter than the longest possible variable-length encoded signal. N bits from the encoded bit stream are used as the index to retrieve from the lookup table a table entry, which comprises a flag bit indicating whether the variable-length encoded signal is a short code signal or a long code signal, one or more code-length bits, and one or more code-value bits. If the flag bit indicates that the variable-length encoded signal is a short code signal, then the decoded signal is generated using the code-value bits, wherein the code-length bits indicate the length of the variable-length encoded signal. If the flag bit indicates that the variable-length encoded signal is a long code signal, then the decoded signal is generated using the code-value bits and one or more additional bits from the bit stream, wherein the code-length bits indicate the number of additional bits to be read from the bit stream to complete the variable-length encoded signal.
Inventors
- 👤 Brian Astle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:21
CPC Classifications
H; H03; H03M; H03M7/00; H03M7/30; H03M7/40; H03M7/42; H03M7/425; H04; H04N; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N19/126; H04N19/85; H04N19/86; H04N19/13; H04N19/60; H04N19/90; H04N19/91
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
199 words
A computer-implemented process for transforming a variable-length encoded signal into a decoded signal, wherein the variable-length encoded signal comprises up to M bits, comprising the steps of: (a) reading N bits from a bit stream comprising the variable-length encoded signal, wherein N is less than M; (b) accessing an N-bit lookup table using the N bits from the bit stream as an index to retrieve a table entry, wherein the table entry comprises: a flag bit indicating whether the variable-length encoded signal is a short code signal or a long code signal; one or more code-length bits; and one or more code-value bits; (c) if the flag bit indicates that the variable-length encoded signal is a short code signal, then generating the decoded signal using the code-value bits, wherein the code-length bits indicate the length of the variable-length encoded signal; and (d) if the flag bit indicates that the variable-length encoded signal is a long code signal, then generating the decoded signal using the code-value bits and one or more additional bits from the bit stream, wherein the code-length bits indicate the number of additional bits to be read from the bit stream to complete the variable-length encoded signal.
Claim 2
Dependent Claim
199 words
A computer-implemented process for transforming a variable-length encoded signal into a decoded signal, wherein the variable-length encoded signal comprises up to M bits, comprising the steps of: (a) reading N bits from a bit stream comprising the variable-length encoded signal, wherein N is less than M; (b) accessing an N-bit lookup table using the N bits from the bit stream as an index to retrieve a table entry, wherein the table entry comprises: a flag bit indicating whether the variable-length encoded signal is a short code signal or a long code signal; one or more code-length bits; and one or more code-value bits; (c) if the flag bit indicates that the variable-length encoded signal is a short code signal, then generating the decoded signal using the code-value bits, wherein the code-length bits indicate the length of the variable-length encoded signal; and (d) if the flag bit indicates that the variable-length encoded signal is a long code signal, then generating the decoded signal using the code-value bits and one or more additional bits from the bit stream, wherein the code-length bits indicate the number of additional bits to be read from the bit stream to complete the variable-length encoded signal.
Claim 3
Dependent Claim
31 words
The process of claim 1, wherein step (d) comprises the step of generating the decoded signal by adding the value of the code-value bits to the value of the additional bits.
Claim 4
Dependent Claim
35 words
The process of claim 1, further comprising the steps of: (e) adjusting a bit stream pointer in accordance with the code-length bits; and (f) repeating steps (a)-(d) for another N bits of the bit stream.
Claim 5
Dependent Claim
71 words
The process of claim 3, wherein step (e) comprises the steps of: (1) adjusting the bit stream pointer by the value of the code-length bits, if the flag bit indicates that the variable-length encoded signal is a short code signal; and (2) adjusting the bit stream pointer by N plus the value of the code-length bits, if the flag bit indicates that the variable-length encoded signal is a long code signal.
Claim 6
Dependent Claim
72 words
The process of claim 1, wherein: N equals 8; the table entry comprises 4 code-length bits, 1 flag bit, and 1 sign bit; if the flag bit indicates that the variable-length encoded signal is a short code signal, then the table entry further comprises 8 code-value bits; and if the flag bit indicates that the variable-length encoded signal is a long code signal, then the table entry further comprises 10 code-value bits.
Claim 7
Dependent Claim
17 words
The process of claim 1, wherein the variable-length encoded signal corresponds to signals of a video image.
Claim 8
Dependent Claim
204 words
The process of claim 1, wherein: N equals 8; the table entry comprises 4 code-length bits, 1 flag bit, and 1 sign bit; if the flag bit indicates that the variable-length encoded signal is a short code signal, then the table entry further comprises 8 code-value bits; if the flag bit indicates that the variable-length encoded signal is a long code signal, then the table entry further comprises 10 code-value bits; the variable-length encoded signal corresponds to signals of a video image; step (d) comprises the step of generating the decoded signal by adding the value of the code-value bits to the value of the additional bits; and further comprising the steps of: (e) adjusting a bit stream pointer in accordance with the code-length bits; and (f) repeating steps (a)-(d) for another N bits of the bit stream, wherein step (e) comprises the steps of: (1) adjusting the bit stream pointer by the value of the code-length bits, if the flag bit indicates that the variable-length encoded signal is a short code signal; and (2) adjusting the bit stream pointer by N plus the value of the code-length bits, if the flag bit indicates that the variable-length encoded signal is a long code signal.
Claim 9
Independent Claim
207 words
An apparatus for transforming a variable-length encoded signal into a decoded signal, wherein the variable-length encoded signal comprises up to M bits, comprising: (a) means for reading N bits from a bit stream comprising the variable-length encoded signal, wherein N is less than M; (b) means for accessing an N-bit lookup table using the N bits from the bit stream as an index to retrieve a table entry, wherein the table entry comprises: a flag bit indicating whether the variable-length encoded signal is a short code signal or a long code signal; one or more code-length bits; and one or more code-value bits; (c) means for generating the decoded signal, wherein: if the flag bit indicates that the variable-length encoded signal is a short code signal, then the decoded signal is generated using the code-value bits, wherein the code-length bits indicate the length of the variable-length encoded signal; and if the flag bit indicates that the variable-length encoded signal is a long code signal, then the decoded signal is generated using the code-value bits and one or more additional bits from the bit stream, wherein the code-length bits indicate the number of additional bits to be read from the bit stream to complete the variable-length encoded signal.
Claim 10
Independent Claim
207 words
An apparatus for transforming a variable-length encoded signal into a decoded signal, wherein the variable-length encoded signal comprises up to M bits, comprising: (a) means for reading N bits from a bit stream comprising the variable-length encoded signal, wherein N is less than M; (b) means for accessing an N-bit lookup table using the N bits from the bit stream as an index to retrieve a table entry, wherein the table entry comprises: a flag bit indicating whether the variable-length encoded signal is a short code signal or a long code signal; one or more code-length bits; and one or more code-value bits; (c) means for generating the decoded signal, wherein: if the flag bit indicates that the variable-length encoded signal is a short code signal, then the decoded signal is generated using the code-value bits, wherein the code-length bits indicate the length of the variable-length encoded signal; and if the flag bit indicates that the variable-length encoded signal is a long code signal, then the decoded signal is generated using the code-value bits and one or more additional bits from the bit stream, wherein the code-length bits indicate the number of additional bits to be read from the bit stream to complete the variable-length encoded signal.
Claim 11
Dependent Claim
42 words
The apparatus of claim 8, wherein means (c) generates the decoded signal by adding the value of the code-value bits to the value of the additional bits, if the flag bit indicates that the variable-length encoded signal is a long code signal.
Claim 12
Dependent Claim
39 words
The apparatus of claim 8, further comprising: (d) means for adjusting a bit stream pointer in accordance with the code-length bits; and (e) means for repeating the processing of means (a)-(c) for another N bits of the bit stream.
Claim 13
Dependent Claim
67 words
The apparatus of claim 10, wherein means (d): (1) adjusts the bit stream pointer by the value of the code-length bits, if the flag bit indicates that the variable-length encoded signal is a short code signal; and (2) adjusts the bit stream pointer by N plus the value of the code-length bits, if the flag bit indicates that the variable-length encoded signal is a long code signal.
Claim 14
Dependent Claim
72 words
The apparatus of claim 8, wherein: N equals 8; the table entry comprises 4 code-length bits, 1 flag bit, and 1 sign bit; if the flag bit indicates that the variable-length encoded signal is a short code signal, then the table entry further comprises 8 code-value bits; and if the flag bit indicates that the variable-length encoded signal is a long code signal, then the table entry further comprises 10 code-value bits.
Claim 15
Dependent Claim
17 words
The apparatus of claim 8, wherein the variable-length encoded signal corresponds to signals of a video image.
Claim 16
Dependent Claim
215 words
The apparatus of claim 8, wherein: N equals 8; the table entry comprises 4 code-length bits, 1 flag bit, and 1 sign bit; if the flag bit indicates that the variable-length encoded signal is a short code signal, then the table entry further comprises 8 code-value bits; if the flag bit indicates that the variable-length encoded signal is a long code signal, then the table entry further comprises 10 code-value bits; the variable-length encoded signal corresponds to signals of a video image; means (c) generates the decoded signal by adding the value of the code-value bits to the value of the additional bits, if the flag bit indicates that the variable-length encoded signal is a long signal; and further comprising: (d) means for adjusting a bit stream pointer in accordance with the code-length bits; and (e) means for repeating the processing of means (a)-(c) for the next N bits of the bit stream, wherein means (d): (1) adjusts the bit stream pointer by the value of the code-length bits, if the flag bit indicates that the variable-length encoded signal is a short code signal; and (2) adjusts the bit stream pointer by N plus the value of the code-length bits, if the flag bit indicates that the variable-length encoded signal is a long code signal.
Claim 17
Dependent Claim
25 words
The apparatus of claim 14, wherein the apparatus is a microprocessor and the microprocessor is electrically connected to a memory device via a data bus.
Claim 18
Dependent Claim
25 words
The apparatus of claim 8, wherein the apparatus is a microprocessor and the microprocessor is electrically connected to a memory device via a data bus.
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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) | 1999-12-31 | 2000-07-01 | 2000-12-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-12-31 | 2004-07-01 | 2004-12-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-12-31 | 2008-07-01 | 2008-12-31 | $7700.00 | Window Closed / Lapsed |