Systems and methods for decoding compressed data
First Claim
Patent Images
1. A bitstream decoding method comprising the step of:
- performing a two-table lookup, said two-table lookup comprising the steps of;
addressing a first table in response to a first plurality of bits from said bitstream; and
generating an address into a second table using a first value in an entry in said first table accessed in said addressing step; and
outputting a second value contained in an entry in said second table at said address from said generating step.
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Abstract
A method of decoding an encoded bitstream. The method includes performing a two-table lookup. A first table is addressed in response to a first plurality of bits from the bitstream. An address into a second table is generated using a value in an entry in said first table accessed in the addressing step. A value (representing the decoded value corresponding to the codeword in the bitstream) in an entry in said second table at the address from the generating step is output.
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Citations
26 Claims
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1. A bitstream decoding method comprising the step of:
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performing a two-table lookup, said two-table lookup comprising the steps of;
addressing a first table in response to a first plurality of bits from said bitstream; and
generating an address into a second table using a first value in an entry in said first table accessed in said addressing step; and
outputting a second value contained in an entry in said second table at said address from said generating step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
retrieving said first value from a first portion of said entry in said first table; and
offsetting said first value by a third value represented by an additional number of bits in said bitstream.
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3. The method of claim 2 wherein said step of generating said address further comprises the steps of:
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retrieving a third value from a second portion of said entry in said first table; and
extracting said additional number of bits from said bitstream, wherein said additional number of bits corresponds to said third value.
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4. The method of claim 2 wherein said second value contained in said entry in said second table is contained in a first portion of said entry in said second table, and wherein said two-table lookup further comprises the steps of:
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retrieving a fifth value from a second portion of said entry in said second table; and
returning to said bitstream a number of bits from said first plurality of bits corresponding to a difference between a number of bits in said first plurality of bits and said fifth value.
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5. The method of claim 1 further comprising the step of:
selecting a decoding process from a predetermined set of decoding processes in response to a code descriptor obtained from a portion of said bitstream, said set of decoding processes including said two-table lookup.
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6. The method of claim 5 wherein said set of decoding processes further includes a binary search process.
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7. The method of claim 1 wherein said first table comprises a plurality of entries, each entry of said plurality of entries comprising a first portion for holding a base address and a second portion holding a value representing a number of additional bits to be extracted from said bitstream.
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8. The method of claim 1 wherein said second table comprises a plurality of entries, each entry of said plurality of entries comprising a first portion for holding an output value and a second portion for holding a length of a codeword representing an encoding of said output value.
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9. A signal processing system comprising:
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an input port configured to receive an encoded digital signal; and
a processor, including;
a first table;
a second table; and
a decoder, coupled to said first and second tables, configured to decode said encoded digital signal;
wherein said decoder comprises;
circuitry configured to address an entry in said first table in response to a plurality of bits in a bitstream of said encoded digital signal;
circuitry configured to generate an address into said second table in response to a value in a first portion of said entry in said first table; and
circuitry configured to output a value in a first portion of an entry in said second table, said entry corresponding to said address, said value representing a decoded value of a codeword in said encoded digital signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
circuitry configured to retrieve said value in said first portion of said entry in said first table; and
circuitry configured to offset said value in said first portion of said entry by a value of an additional number of bits in said bitstream.
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11. The system of claim 10 wherein said circuitry configured to generate said address into said second table further includes:
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circuitry configured to retrieve a value in a second portion of said entry in said first table; and
circuitry configured to extract said additional number of bits in response to said value in said second portion of said entry in said first table.
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12. The system of claim 10 wherein said decoder further comprises circuitry configured to return a number of bits to said bitstream corresponding to a difference between a value in a second portion of said entry in said second table and said number of additional bits.
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13. The system of claim 9 further comprising a memory, wherein at least a portion of said memory comprises memory for storing said first table and said second table.
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14. The system of claim 9 wherein said circuitry configured to address an entry in said first table, said circuitry configured to generate an address into said second table, and circuitry configured to output a value in a first portion of an entry in said second table comprises circuitry for performing a first decode process, and wherein said decoder further comprises circuitry configured to select, in response to a code descriptor in a portion of said bitstream, between said circuitry for performing said first decode process and circuitry configured to perform a second decode process.
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15. The system of claim 14 wherein said second decode process comprises a binary search process.
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16. The system of claim 9 wherein said first table comprises a plurality of entries, each entry of said plurality of entries comprising a first portion for holding a base address and a second portion for holding a value representing a number of additional bits to be extracted from said bitstream.
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17. The system of claim 9 wherein said second table comprises a plurality of entries, each entry of said plurality of entries comprising a first portion for holding an output value and a second portion for holding a length of a codeword representing an encoding of said output value.
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18. A bitstream decoding method comprising the step of:
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selecting a decoding process from a predetermined set of decoding processes in response to a current codebook used to encode said bitstream; and
decoding said bitstream using said decoding process from said selecting step. - View Dependent Claims (19, 20, 21, 22)
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23. A signal processing system comprising:
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an input port configured to receive an encoded digital signal; and
a decoder, configured to decode said encoded digital signal;
wherein said decoder comprises;
circuitry configured for selecting a decoding process from a predetermined set of decoding processes in response to a current codebook used to encode said bitstream; and
circuitry configured for decoding said bitstream using said decoding process from said selecting step. - View Dependent Claims (24, 25, 26)
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Specification