Variable length code detection in a signal processing system
First Claim
1. An apparatus to detect a current entropy code word in a group of bits, and the current entropy code word having a bit length, wherein a predetermined number of possible bit lengths of the current entropy code word is t+1, the apparatus comprising:
- a plurality of matching modules, wherein the matching modules each receive the group of bits and each attempts to determine the bit length of the current entropy code word in the group of bits, and one of the matching modules determines the bit length of the current entropy code word in the group of bits and provides a unique output signal with respect to output signals of the remaining matching modules; and
t+1 matching module groups wherein each of the t+1 matching module groups includes a predetermined number of matching modules, and each of the t+1 matching module groups represents one of the t+1predetermined number of possible bit lengths of the current entropy code word, wherein each of the t+1 matching module groups has an output signal, and the one of the t+1 matching module groups having the matching module having the unique output signal has a unique output signal, with respect to output signals of the remaining t+1matching module groups, that indicates the bit length of the current entropy code word.
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Abstract
A group of incoming data stream bits having packed variable length code ("VLC") words is applied to an entropy code bit length searching module. The group of bits is replicated within a plurality of matching modules selectively distributed among entropy code bit length searching logic units. Each unit of entropy code bit length searching logic supports a VLC word table as characterized by, for example, standard compression formats such as MPEG-1, MPEG-2, H.261, and H.263. The matching modules are divided into groups within the entropy code bit length searching logic units. A group of matching modules is allocated to each VLC bit length represented in the associated VLC word supported table. A number of matching modules are allocated to each bit length equal to a minimum number of patterns unique to VLC words of a particular bit length. The matching modules compare an incoming data group to respective patterns. A detected match is indicated by an appropriately set group output signal. Each entropy code bit length searching logic unit includes a bit length encoder that receives the group output signals. The set group output signal indicates the bit length of a current VLC, and the bit length encoder encodes this information into a bit length code output signal. The bit length code signal is utilized by a shifter to parse a corresponding bit length of current data. The parsed current data may be directly applied to an address generator which generates an output signal for a decoding look up table.
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Citations
26 Claims
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1. An apparatus to detect a current entropy code word in a group of bits, and the current entropy code word having a bit length, wherein a predetermined number of possible bit lengths of the current entropy code word is t+1, the apparatus comprising:
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a plurality of matching modules, wherein the matching modules each receive the group of bits and each attempts to determine the bit length of the current entropy code word in the group of bits, and one of the matching modules determines the bit length of the current entropy code word in the group of bits and provides a unique output signal with respect to output signals of the remaining matching modules; and t+1 matching module groups wherein each of the t+1 matching module groups includes a predetermined number of matching modules, and each of the t+1 matching module groups represents one of the t+1predetermined number of possible bit lengths of the current entropy code word, wherein each of the t+1 matching module groups has an output signal, and the one of the t+1 matching module groups having the matching module having the unique output signal has a unique output signal, with respect to output signals of the remaining t+1matching module groups, that indicates the bit length of the current entropy code word. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of detecting a current entropy code word in a group of bits, and the current entropy code word having a bit length, wherein a predetermined number of possible bit lengths of the current entropy code word is t+1, the method comprising the steps of:
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receiving the group of bits in t+1 matching module groups, wherein each of the t+1 matching module groups includes a predetermined number of matching modules, each matching module includes a predetermined bit pattern, and each of the t+1 matching module groups represents one of the t+1 predetermined number of possible bit lengths of the current entropy code word; comparing the respective bit pattern of each matching module to a respective segment of the group of bits, wherein each bit pattern is associated with only one of the possible t+1 bit lengths of the current entropy code; determining which bit pattern matches the respective segment of the group of bits; and providing an output signal, responsive to the bit pattern determined to match the respective segment of the group of bits, that identifies the bit length of the current entropy code word. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method comprising the steps of:
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transmitting a group of bits to a plurality of matching modules in t+1 matching module groups, wherein the group of bits includes a current entropy code word, the current entropy code word has a bit length, and each of the t+1 matching module groups represents one of the t+1 predetermined number of possible bit lengths of the current entropy code word; determining the bit length of the current entropy code word in the group of bits with one of the matching modules; and providing a unique output signal with respect to output signals of the remaining matching modules from the matching module which determined the bit length of the current entropy code word in the group of bits that indicates the bit length of the current entropy code word. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A multimedia multiprocessor system further comprising:
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a host processor; a bus coupled to the host processor; system memory coupled to the host processor; and a multimedia signal processor to detect a current entropy code word in a group of bits, and the current entropy code word having a bit length, wherein a predetermined number of possible bit lengths of the current entropy code word is t+1, the multimedia signal processor comprising a bitstream processor, wherein the bitstream processor further comprises; a plurality of matching modules, wherein the matching modules each receive the group of bits and each attempts to determine the bit length of the current entropy code word in the group of bits, and one of the matching modules determines the bit length of the current entropy code word in the group of bits and provides a unique output signal with respect to output signals of the remaining matching modules; and t+1 matching module groups wherein each of the t+1 matching module groups includes a predetermined number of matching modules, and each of the t+1 matching module groups represents one of the t+1 predetermined number of possible bit lengths of the current entropy code word, wherein each of the t+1 matching module groups has an output signal, and the one of the t+1 matching module groups having the matching module having the unique output signal has a unique output signal, with respect to output signals of the remaining t+1 matching module groups, that indicates the bit length of the current entropy code word.
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Specification