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38 lines
1.6 KiB
38 lines
1.6 KiB
function frameFout = iTNS(frameFin, frameType, TNScoeffs)
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%Implementation of the reverse TNS step
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% Usage frameFout = iTNS(frameFin, frameType, TNScoeffs), where:
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% Inputs
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% - frameFin is the frame in the frequency domain, in MDCT coefficients
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% representation containing both channels of the audio stored in an
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% array of dimensions 1024X2
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% - frameType is the type of the current frame in string
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% representation, can be one of "OLS" (ONLY_LONG_SEQUENCE), "LSS"
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% (LONG_START_SEQUENCE), "ESH" (EIGHT_SHORT_SEQUENCE), "LPS"
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% (LONG_STOP_SEQUENCE)
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% - TNScoeffs is the quantized TNS coefficients array of dimensions
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% 4X8 for EIGHT_SHORT_SEQUENCE frames and 4X1 otherwise
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%
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% Output
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% - frameFout is the frame in the frequency domain after Temporal Noise
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% Shaping, in MDCT coefficients representation containing both channels
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% of the audio stored in an array of dimensions 1024X2
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% Declares persistent variable holding the TNS tables and initializes if empty
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persistent TNSTables;
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if isempty(TNSTables)
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TNSTables = load('TableB219.mat');
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end
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if ~strcmp(frameType, 'ESH')
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% Inverses MDCT coefficients filtering
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frameFout = filter(1, [1; TNScoeffs], frameFin);
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else
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for subFrameIndex = 1:8
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subFrame = frameFin((subFrameIndex - 1) * 128 + 1:subFrameIndex * 128);
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% Inverses MDCT coefficients filtering
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frameFout((subFrameIndex - 1) * 128 + 1:subFrameIndex * 128) = ...
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filter(1, [1; TNScoeffs((subFrameIndex - 1) * 4 + 1:subFrameIndex * 4)], subFrame);
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end
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end
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end
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