Efficient system and method for converting between different transform-domain signal representations
First Claim
1. A system for efficiently converting a signal from a first transform-domain representation to a second transform-domain representation comprising:
- first means for obtaining an input signal expressed via said first transform-domain signal representation and second means for expressing said input signal via a second transform-domain signal representation without intermediate time-domain conversion, in response to the receipt of said input signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A memory-efficient system converting a signal from a first transform domain to a second transform domain. The system includes a first mechanism that obtains an input signal expressed via a first transform-domain signal representation. A second mechanism expresses the input signal via a second transform-domain signal representation without intermediate time-domain conversion. In the specific embodiment, the input signal is a Modified Discrete Cosine Transform (MDCT) signal. The second transform-domain signal representation is a Discrete Fourier Transform (DFT) signal. The second mechanism further includes a third mechanism that combines effects of an inverse MDCT, a synthesis window function, and an analysis window function, and provides a first signal in response thereto. A fourth mechanism converts the MDCT signal to the DFT signal based on the first signal. In a more specific embodiment, the synthesis window function is an MDCT synthesis window function, while the analysis window function is a DFT analysis window function. The fourth mechanism includes a mechanism for performing a fast transform on the MDCT signal and providing a first transformed signal in response thereto. The fourth mechanism further includes a mechanism for selectively delaying and updating the first transformed signal to yield second and third transformed signals, respectively, in response thereto. The fourth mechanism further includes a mechanism for operating on the first, second, and third transformed signals via third, second, and first combined window functions, respectively, and providing third, second, and first windowed signals, respectively, in response thereto. An adder adds the first, second, and third windowed functions to provide an added digital signal. An inverse DFT circuit performs an inverse DFT on the added digital signal to provide the DFT signal as output.
-
Citations
40 Claims
-
1. A system for efficiently converting a signal from a first transform-domain representation to a second transform-domain representation comprising:
-
first means for obtaining an input signal expressed via said first transform-domain signal representation and second means for expressing said input signal via a second transform-domain signal representation without intermediate time-domain conversion, in response to the receipt of said input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
-
-
19. A system for facilitating compression-domain modification of a digital signal comprising:
-
first means for converting a compression-domain signal to a modification-domain signal without intermediate time-domain conversion and second means for modifying signal components of said modification-domain signal and providing a modified modification-domain signal in response thereto. - View Dependent Claims (20, 21, 22, 23)
-
-
24. An efficient digital system for facilitating coding and signal component modification comprising:
-
first means for converting a time-domain digital input signal to a first frequency domain that accommodates coding and providing a first transform-domain digital signal in response thereto;
second means for coding said first transform-domain digital signal and providing an encoded signal in response thereto;
third means for decoding said encoded signal and providing a decoded signal in response thereto;
fourth means for transforming said decoded signal from a first transform domain directly to a second transform domain for accommodating signal component modification and providing a second transform-domain digital signal in response thereto;
sixth means for modifying components of said second transform-domain digital signal and providing a modified signal in response thereto; and
seventh means for converting said modified signal to a digital output time-domain signal. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33)
-
-
34. A system for efficiently transforming a digital signal from the Modified Discrete Cosine Transform (MDCT) domain to the Discrete Fourier Transform (DFT) domain comprising:
-
a fast transform circuit in communication with an input MDCT digital signal in an MDCT domain;
a first delay and update circuit having an input connected to an output of said fast transform circuit;
a second delay and update circuit having an input connected to an output of said first delay and update circuit;
a first combined window multiplier incorporating a first MDCT synthesis window function and a first DFT analysis window function and having an input connected to an output of said second delay and update circuit;
a second combined window multiplier incorporating a second MDCT synthesis window function and a second DFT analysis window function and having an input connected to an output of said first delay and update circuit;
a third combined window multiplier incorporating a third MDCT synthesis window function and a third DFT analysis window function and having an input connected to an output of said fast transform circuit;
an adder having inputs connected to outputs of said first combined window multiplier, said second combined window multiplier, and said third combined window multiplier; and
an Inverse Discrete Fourier Transform (IDFT) circuit having an input connected to an output of said adder, an output of said IDFT circuit representing a DFT signal associated with said input MDCT digital signal.
-
-
35. An efficient method for facilitating coding and signal component modification of a digital signal comprising the steps of:
-
converting a time-domain digital input signal to a first frequency domain that accommodates coding and providing a first transform-domain digital signal in response thereto;
coding said first transform-domain digital signal and providing an encoded signal in response thereto;
transferring said encoded signal through an intermediate medium;
decoding said encoded signal and providing a decoded signal in response thereto;
transforming said decoded signal from a first transform domain directly to a second transform domain that accommodates signal component modification and providing a second transform-domain digital signal in response thereto;
modifying components of said second transform-domain digital signal and providing a modified signal in response thereto; and
converting said modified signal to a digital output time-domain signal. - View Dependent Claims (36, 37)
-
-
38. A method for efficiently converting a signal from a first transform domain to a second transform domain comprising the steps of:
-
determining steps required to convert a first signal from said first transform domain to a time domain and then to a second transform domain and selectively combining said steps to eliminate intermediate time-domain conversion.
-
-
39. A method for converting a signal from a first transform domain to a second transform domain comprising the steps of:
-
determining an expression for a segment of an intermediate time-domain signal based on a first transform-domain signal expression, said expression incorporating a second transform-domain analysis window and a first transform-domain synthesis window;
applying a second transform associated with said second transform domain to said expression to yield a second transform-domain expression;
computing a first transform-domain function and a second transform-domain function from said second transform-domain expression;
expressing a second transform-domain signal in terms that may include a convolution of the first transform-domain function with the second transform-domain function and/or corresponding conjugate functions;
performing an inverse second transform of the product between the second transform of the first transform-domain function and the second transform of the second transform-domain function and/or the product between corresponding conjugate functions to yield a second transform-domain representation; and
employing a fast algorithm based on said second transform-domain representation and symmetry thereof to compute a second transform-domain signal corresponding to said first transform-domain signal. - View Dependent Claims (40)
-
Specification