Encoder rate control
First Claim
Patent Images
1. A system comprising:
- a buffer;
a wavelet transform unit having an input coupled to the buffer to perform a reversible wavelet transform on pixels stored in the buffer and to generate coefficients at an output;
a coder coupled to the wavelet transform unit to code biplanes of wavelet transformed pixels from the wavelet transform unit and stored bitplanes of wavelet transformed pixels received from the buffer.
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Abstract
A method and apparatus for performing compression and/or decompression is described. In one embodiment, the present invention comprises a system having a buffer, a wavelet transform unit, and a coder. The wavelet transform unit has an input coupled to the buffer to perform a wavelet transform on pixels stored therein and to generate coefficients at an output. The coder is coupled to the wavelet transform unit to code the transformed pixels received from the buffer.
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Citations
78 Claims
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1. A system comprising:
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a buffer;
a wavelet transform unit having an input coupled to the buffer to perform a reversible wavelet transform on pixels stored in the buffer and to generate coefficients at an output;
a coder coupled to the wavelet transform unit to code biplanes of wavelet transformed pixels from the wavelet transform unit and stored bitplanes of wavelet transformed pixels received from the buffer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for compressing information comprising the steps of:
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wavelet transforming pixel information received from a buffer, wherein at least one bitplane of coefficients represents reversible wavelet transformed pixels;
replacing pixels in the buffer with encoded bitplanes; and
coding bitplanes stored in the buffer.
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9. A decompression system comprising:
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a band buffer;
a plurality of coding units for coefficients to undergo an inverse transform operation;
at least one coding unit for storing pixels to be output to an output device;
at least one coding unit for pixels corresponding to previously inversed transformed coefficients to be sent to the output device;
a decompressor coupled to the band buffer, wherein the decompressor decompresses compressed data to transformed coefficients, writes the transformed coefficients to the band buffer, reads back transformed coefficients from the band buffer, performs an inverse transform on transformed coefficients read back from the band buffer to generate pixel values and writes pixels values to the band buffer. - View Dependent Claims (10, 11, 12)
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13. A method comprising the steps of:
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dividing a coefficient into most important data and less important data;
sending the most important data to a context model for coding immediately in coefficient order;
storing the less important data and a plurality of signaling bits in memory; and
after coding most important data of all coefficients in the set of coefficients, coding the less important data and embedding by order based, in part, on the plurality of signaling bits. - View Dependent Claims (14, 15, 16)
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17. A forward transform comprising:
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an input buffer having an input coupled to receive input data and first and second outputs to transfer even and odd samples;
a first level transform unit coupled to receive the even and odd samples and generate coefficients, wherein horizontal low pass and vertical high pass coefficients are outputs of the forward transform a memory having a first input coupled to receive ss coefficients generated by the first level transform the first level transform unit and a second input to receive ss coefficients from higher level transform filtering;
an order unit having a first input coupled to the memory to order ss coefficients for higher levels of filtering; and
a first filter unit coupled to the order unit to apply a plurality of transform levels, wherein the filter unit performs a higher level transform ss coefficients received from the order unit, wherein the filter unit generates ss coefficients values that are fed back to the second input of the memory and the second input the order unit. - View Dependent Claims (18, 19)
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20. An apparatus for compressing an image, said apparatus comprising:
a compressor;
a workspace memory coupled to the compressor, wherein the workspace memory is the same size as the image and the compressor uses the workspace memory for encoding the image using coefficients that are larger than the pixels in the image.
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21. A method for coding information comprising most important data and less important data, said method comprising the steps of:
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coding the most important data;
coding the position of the first bit plane in the less important data for each coefficient that is not comprised entirely of zero head bits;
coding each bit plane of less important data that does not entirely comprise of zero head bits. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. An apparatus for coding information comprising most important data and less important data, said apparatus comprising:
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means for coding the most important data;
means for coding the position of the first bit plane in the less important data for each coefficient that is not comprised entirely of zero headbits;
means for coding each bit plane of less important data that does not entirely comprise of zero head bits. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A method for m-ary coding of information, said method comprising the steps of:
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examining a predetermined number of coefficients;
entropy coding all of the head bits one per cycle until all head bits in the predetermined number of coefficients are coded;
coding the sign and tail bits of the predetermined number of coefficients in the same cycle.
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44. An integrated circuit (IC) chip comprising:
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a pixel data interface to transfer pixel data between the IC chip and memory;
a reversible wavelet transform coupled to the pixel data interface to transfer information to and from the memory via the pixel data interface;
a context model coupled to the reversible wavelet transform to provide contexts for coding the data provided therefrom;
an encoder to encode coefficients generated by the reversible wavelet transform based on contexts provided by the context model. - View Dependent Claims (45, 46, 47, 48, 49, 50)
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51. A decoder for decoding coded data, said decoder comprising:
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at least one bit generator coupled to receive the coded data and to decode the coded data based on a probability estimation, wherein said at least one bit generator generates a decoded bit from a current line;
a probability estimation machine coupled to said at least one bit generator to provide the probability estimate based on the decoded bit from the current line;
a context model coupled to the probability estimation machine to provide a plurality of contexts to the probability estimation machine based on a partial context address, wherein the probability estimation machine selects among the plurality of context based on the decoded bit. - View Dependent Claims (52, 53, 54)
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55. A context model comprising:
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a first bit plane unit coupled to receive less important data and most important data to determine which bit planes have data in them, wherein the first bit plane unit generates an indication of the bit plane with the first on bit for the entire coding unit for use when processing the less important data;
a comparison mechanism coupled to receive the less important data and the most important data to generate signaling information for the less important data;
a memory coupled to receive the sign bit, the most important data and an indication of the first bit plane having data, wherein the memory delays coefficients to provide conditioning information. a first context model coupled to the memory to provide contexts for sign bits;
a second context model coupled to the memory and the most important data to provide contexts for head bits; and
the third context model coupled to the memory and the most important data to provide contexts for tail bits. - View Dependent Claims (56, 57, 58, 59, 60, 61, 62, 63, 64)
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65. A method for performing compression comprising the steps of:
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determining the average length of codewords to identify an encoding rate; and
adjusting a compression rate based on a desired amount of compression. - View Dependent Claims (66, 67, 68, 69, 70, 71)
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72. A system comprising:
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a context model;
a probability estimation machine coupled to the context model;
a bit generator coupled to the probability estimation machine; and
an encoder rate control coupled to an output of the bit generator to control the encoding rate by determining average codeword length. - View Dependent Claims (73, 74, 75, 76)
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77. A method for processing a least important portion of data bitplanes for a set of transformed coefficients, and method comprising the steps of:
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reading a first portion of data from memory; and
writing a second amount of data greater than the first to memory while reading the first amount of data to compensate for transformed bitplanes with less data in the lower order bitplanes of the set of transformed coefficients. - View Dependent Claims (78)
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Specification