Method for efficient decoding of variable length codes
View Patent ↗A method, system, and computer program product for decoding a variable length code. A decoding module is configured to receive the variable length code. The variable length code is a plurality of bits. The decoding module is also configured to identify a number of times the lead bit is repeated consecutively at the beginning of the plurality of bits. The lead bit is predetermined to be one of a 1 or 0. The decoding module is also configured to identify a code word in a table of code words by using the number of times the lead bit is repeated.
1. A method for decoding a variable length code, the method comprising:
receiving the variable length code, wherein the variable length code is a plurality of bits;
identifying a number of times a lead bit is repeated consecutively at the beginning of the plurality of bits, wherein the lead bit is predetermined to be one of a 1 or 0; and
identifying a code word in a table of code words by using the number of times the lead bit is repeated, comprising:
determining whether the number is less than a threshold; and
responsive to determining that the number is less than the threshold, identifying the code word in a first table of code words.
2. The method of claim 1 further comprising:
responsive to determining that the number is equal to or greater than the threshold, identifying the code word in a second table of code words.
3. The method of claim 2 , wherein the step of identifying the code word in the second table comprises:
identifying a string of bits in the plurality of bits;
matching the string of bits to an entry in the second table; and
identifying the code word associated with the entry.
4. The method of claim 3 , wherein the string of bits is seven bits after nine bits at the beginning of the plurality of bits.
5. The method of claim 1 , wherein the step of identifying the code word in the first table comprises:
identifying a location on a first axis of the first able using the number;
identifying a location on a second axis of the first table using a string of bits in the plurality of bits; and
identifying the code word using the location on the first axis and the location on the second axis.
6. The method of claim 5 , wherein any lead bits are followed by a 0 bit, and wherein the string of bits is three bits following the 0 bit.
7. The method of claim 1 , wherein the threshold is 9, and wherein the lead bit is a 1.
8. The method of claim 1 , wherein the variable length code is from an image file.
9. The method of claim 1 , wherein the step of identifying the code word in the table comprises:
identifying a location on a first axis of the table using the number;
identifying a location on a second axis of the table using a string of bits in the plurality of bits; and
identifying the code word using the location on the first axis and the location on the second axis.
10. The method of claim 9 , wherein any lead bits are followed by a 0 bit, and wherein the string of bits is any bits following the 0 bit.
11. A system for decoding a variable length code, the system comprising:
a memory unit;
a processing unit connected to the memory unit;
a decoding module configured to receive the variable length code, wherein the variable length code is a plurality of bits; identify a number of times the lead bit is repeated consecutively at the beginning of the plurality of bits, wherein the lead bit is predetermined to be one of a 1 or 0; and identify a code word in a table of code words by using the number of times the lead bit is repeated, comprising the decoding module being configured to:
determine whether the number is less than a threshold; and
identify the code word in a first table of code words in response to determining that the number is less than the threshold.
12. The system of claim 11 , wherein the decoding module is further configured to:
identify the code word in a second table of code words in response to determining that the number is equal to or greater than the threshold.
13. The system of claim 12 , wherein in identifying the code word in the second table, the decoding module is further configured to:
identify a string of bits in the plurality of bits;
match the string of bits to an entry in the second table; and
identify the code word associated with the entry.
14. The system of claim 11 , wherein the threshold is 9, and wherein the lead bit is a 1.
15. The system of claim 11 , wherein in identifying a code word in a first table, the decoding module is further configured to:
identify a location on a first axis of the first able using the number;
identify a location on a second axis of the first table using a string of bits in the plurality of bits; and
identify the code word using the location on the first axis and the location on the second axis.
16. A computer program product comprising logic encoded on a non-transitory computer-readable media for decoding a variable length code, the logic comprising instructions, to be executed by one or more processors, for:
receiving the variable length code, wherein the variable length code is a plurality of bits;
identifying a number of times a lead bit is repeated consecutively at the beginning of the plurality of bits, wherein the lead bit is predetermined to be one of a 1 or 0; and
identifying a code word in a table of code words by using the number of times the lead bit is repeated.
17. The computer program product of claim 16 , further comprising instructions for:
determining whether the number is less than a threshold; and
responsive to determining that the number is less than the threshold, identifying the code word in a first table of code words.
18. The computer program product of claim 17 further comprising instructions for:
responsive to determining that the number is equal to or greater than the threshold, identifying the code word in a second table of code words.