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232 lines
10 KiB
232 lines
10 KiB
function SMR = psycho(frameT, frameType, frameTprev1, frameTprev2)
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%Implementation of Psychoacoustic Model
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% Usage SMR = psycho(frameT, frameType, frameTprev1, frameTprev2), where:
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% Inputs
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% - frameT is a frame in the time domain, containing only one of the
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% audio channels stored in a vector of length 2048
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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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% - frameTprev1 is the previous frame in the time domain, containing
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% only one of the audio channels stored in a vector of length 2048
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% - frameTprev2 is the frame before frameTprev1 in the time domain,
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% containing only one of the audio channels stored in a vector of
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% length 2048
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%
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% Output
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% - SMR is the signal to mask ratio array of dimensions 42X8 for
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% EIGHT_SHORT_SEQUENCE frames and 69X1 otherwise
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% Declares constant numbers of bands for long and short windows
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LONG_WINDOW_NUMBER_OF_BANDS = 69;
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SHORT_WINDOW_NUMBER_OF_BANDS = 42;
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% Declares constant noise masking tone and tone masking noise decibels
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NOISE_MASKING_TONE = 6;
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TONE_MASKING_NOISE = 18;
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% Declares persistent variable holding the TNS tables and initializes if empty
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persistent TNSTables spreadingLong spreadingShort hannLong hannShort;
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if isempty(TNSTables) || isempty(spreadingLong) || ...
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isempty(spreadingShort) || isempty(hannLong) || isempty(hannShort)
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TNSTables = load('TableB219.mat');
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spreadingLong = zeros(LONG_WINDOW_NUMBER_OF_BANDS);
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spreadingShort = zeros(SHORT_WINDOW_NUMBER_OF_BANDS);
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% Calculates all possible spreading function results for long
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% windows
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tmpx = repmat(TNSTables.B219a(:, 5)', LONG_WINDOW_NUMBER_OF_BANDS, 1);
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tmpx = tmpx - repmat(TNSTables.B219a(:, 5), 1, LONG_WINDOW_NUMBER_OF_BANDS);
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indeces = logical(tril(ones(LONG_WINDOW_NUMBER_OF_BANDS)));
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tmpx(indeces) = tmpx(indeces) .* 3;
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indeces = ~indeces;
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tmpx(indeces) = tmpx(indeces) .* 1.5;
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tmpz = 8 * min((tmpx - 0.5) .^ 2 - 2 * (tmpx - 0.5), 0);
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tmpy = 15.811389 + 7.5 * (tmpx + 0.474) - 17.5 * sqrt(1 + (tmpx + 0.474) .^ 2);
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tmpSum = tmpz + tmpy;
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spreadingLong(tmpy >= -100) = 10 .^ (tmpSum(tmpy >= -100) ./ 10);
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% Calculates all possible spreading function results for short
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% windows
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tmpx = repmat(TNSTables.B219b(:, 5)', SHORT_WINDOW_NUMBER_OF_BANDS, 1);
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tmpx = tmpx - repmat(TNSTables.B219b(:, 5), 1, SHORT_WINDOW_NUMBER_OF_BANDS);
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indeces = logical(tril(ones(SHORT_WINDOW_NUMBER_OF_BANDS)));
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tmpx(indeces) = tmpx(indeces) .* 3;
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indeces = ~indeces;
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tmpx(indeces) = tmpx(indeces) .* 1.5;
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tmpz = 8 * min((tmpx - 0.5) .^ 2 - 2 * (tmpx - 0.5), 0);
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tmpy = 15.811389 + 7.5 * (tmpx + 0.474) - 17.5 * sqrt(1 + (tmpx + 0.474) .^ 2);
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tmpSum = tmpz + tmpy;
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spreadingShort(tmpy >= -100) = 10 .^ (tmpSum(tmpy >= -100) ./ 10);
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hannLong = 0.5 - 0.5 * cos(pi * ((0:2047) + 0.5) / 1024);
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hannShort = 0.5 - 0.5 * cos(pi * ((0:255) + 0.5) / 128);
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clearvars tmpx tmpz tmpy
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end
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if ~strcmp(frameType, 'ESH')
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% Applies window to the frames
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windowedFrameT = frameT .* hannLong';
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windowedFrameTprev1 = frameTprev1 .* hannLong';
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windowedFrameTprev2 = frameTprev2 .* hannLong';
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% Calculates the FFT of each frame
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frameF = fft(windowedFrameT);
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frameFMag = abs(frameF(1:1024));
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frameFPhase = angle(frameF(1:1024));
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frameFrameFprev1 = fft(windowedFrameTprev1);
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frameFrameFprev1Mag = abs(frameFrameFprev1(1:1024));
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frameFrameFprev1Phase = angle(frameFrameFprev1(1:1024));
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frameFrameFprev2 = fft(windowedFrameTprev2);
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frameFrameFprev2Mag = abs(frameFrameFprev2(1:1024));
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frameFrameFprev2Phase = angle(frameFrameFprev2(1:1024));
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% Calculates the predicted magnitude and phase compontents of each
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% frequency
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magPred = 2 .* frameFrameFprev1Mag - frameFrameFprev2Mag;
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phasePred = 2 .* frameFrameFprev1Phase - frameFrameFprev2Phase;
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% Calculates this frame's predictability
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framePredictability = sqrt((frameFMag .* cos(frameFPhase) - ...
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magPred .* cos(phasePred)) .^ 2 + ...
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(frameFMag .* sin(frameFPhase) - ...
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magPred .* sin(phasePred)) .^ 2) ./ ...
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(frameFMag + abs(magPred));
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% Calculates the energy and weighted predictability in the
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% threshold calculation partitions
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bandEnergy(LONG_WINDOW_NUMBER_OF_BANDS) = 0;
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bandPredictability(LONG_WINDOW_NUMBER_OF_BANDS) = 0;
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for band = 1:LONG_WINDOW_NUMBER_OF_BANDS
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bandEnergy(band) = sumsqr(frameFMag(TNSTables.B219a(band, 2) + 1: ...
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TNSTables.B219a(band, 3) + 1));
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bandPredictability(band) = sum(frameFMag( ...
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TNSTables.B219a(band, 2) + 1:TNSTables.B219a(band, 3) + 1) .^ 2 .* ...
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framePredictability(TNSTables.B219a(band, 2) + 1: ...
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TNSTables.B219a(band, 3) + 1));
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end
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% Convolves the partitioned energy and predictability with the
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% spreading function
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bandEnergyConv = sum(bandEnergy .* spreadingLong', 2);
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bandPredictabilityConv = sum(bandPredictability .* spreadingLong', 2);
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% Renormalizes values
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bandPredictabilityConv = bandPredictabilityConv ./ bandEnergyConv;
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bandEnergyConv = bandEnergyConv ./ sum(spreadingLong, 1)';
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% Calculates the tonality index
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tonalIndex = -0.299 - 0.43 .* log(bandPredictabilityConv);
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tonalIndex(tonalIndex < 0) = 0;
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tonalIndex(tonalIndex > 1) = 1;
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% Calculates SNR and converts from dB to power ratio
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signalToNoiseRatio = tonalIndex .* TONE_MASKING_NOISE + ...
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(1 - tonalIndex) .* NOISE_MASKING_TONE;
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powerRatio = 10 .^ (-signalToNoiseRatio ./ 10);
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% Calculates the energy threshold
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energyThreshold = bandEnergyConv .* powerRatio;
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% Calculates the noise level
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qThrN = eps() * 1024 .* 10 .^ (TNSTables.B219a(:, 6) ./ 10);
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noiseLevel = max(energyThreshold, qThrN);
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SMR = bandEnergy ./ noiseLevel';
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else
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% Splits the frame into sub-frames
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[subFramesT, ~] = buffer(frameT(449:end-448), 256, 128, 'nodelay');
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[subFramesTprev1, ~] = buffer(frameTprev1(449:end-448), 256, 128, 'nodelay');
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bandEnergy(SHORT_WINDOW_NUMBER_OF_BANDS) = 0;
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bandPredictability(SHORT_WINDOW_NUMBER_OF_BANDS) = 0;
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qThrN = eps() * 128 .* 10 .^ (TNSTables.B219b(:, 6) ./ 10);
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SMR(SHORT_WINDOW_NUMBER_OF_BANDS, 8) = 0;
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for subFrameIndex = 1:8
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% Applies window to the frames
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windowedFrameT = subFramesT(:, subFrameIndex) .* hannShort';
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if subFrameIndex == 1
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windowedFrameTprev1 = subFramesTprev1(:, 8) .* hannShort';
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windowedFrameTprev2 = subFramesTprev1(:, 7) .* hannShort';
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elseif subFrameIndex == 2
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windowedFrameTprev1 = subFramesT(:, subFrameIndex - 1) .* hannShort';
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windowedFrameTprev2 = subFramesTprev1(:, 8) .* hannShort';
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else
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windowedFrameTprev1 = subFramesT(:, subFrameIndex - 1) .* hannShort';
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windowedFrameTprev2 = subFramesT(:, subFrameIndex - 1) .* hannShort';
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end
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% Calculates the FFT of each frame
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frameF = fft(windowedFrameT);
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frameFMag = abs(frameF(1:128));
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frameFPhase = angle(frameF(1:128));
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frameFrameFprev1 = fft(windowedFrameTprev1);
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frameFrameFprev1Mag = abs(frameFrameFprev1(1:128));
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frameFrameFprev1Phase = angle(frameFrameFprev1(1:128));
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frameFrameFprev2 = fft(windowedFrameTprev2);
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frameFrameFprev2Mag = abs(frameFrameFprev2(1:128));
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frameFrameFprev2Phase = angle(frameFrameFprev2(1:128));
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% Calculates the predicted magnitude and phase compontents of each
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% frequency
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magPred = 2 .* frameFrameFprev1Mag - frameFrameFprev2Mag;
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phasePred = 2 .* frameFrameFprev1Phase - frameFrameFprev2Phase;
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% Calculates this frame's predictability
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framePredictability = sqrt((frameFMag .* cos(frameFPhase) - ...
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magPred .* cos(phasePred)) .^ 2 + ...
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(frameFMag .* sin(frameFPhase) - ...
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magPred .* sin(phasePred)) .^ 2) ./ ...
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(frameFMag + abs(magPred));
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% Calculates the energy and weighted predictability in the
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% threshold calculation partitions
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for band = 1:SHORT_WINDOW_NUMBER_OF_BANDS
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bandEnergy(band) = sumsqr(frameFMag(TNSTables.B219b(band, 2) + 1: ...
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TNSTables.B219b(band, 3) + 1));
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bandPredictability(band) = sum(frameFMag( ...
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TNSTables.B219b(band, 2) + 1:TNSTables.B219b(band, 3) + 1) .^ 2 .* ...
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framePredictability(TNSTables.B219b(band, 2) + 1: ...
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TNSTables.B219b(band, 3) + 1));
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end
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% Convolves the partitioned energy and predictability with the
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% spreading function
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bandEnergyConv = sum(bandEnergy .* spreadingShort', 2);
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bandPredictabilityConv = sum(bandPredictability .* spreadingShort', 2);
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% Renormalizes values
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bandPredictabilityConv = bandPredictabilityConv ./ bandEnergyConv;
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bandEnergyConv = bandEnergyConv ./ sum(spreadingShort, 1)';
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% Calculates the tonality index
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tonalIndex = -0.299 - 0.43 .* log(bandPredictabilityConv);
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tonalIndex(tonalIndex < 0) = 0;
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tonalIndex(tonalIndex > 1) = 1;
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% Calculates SNR and converts from dB to power ratio
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signalToNoiseRatio = tonalIndex .* TONE_MASKING_NOISE + ...
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(1 - tonalIndex) .* NOISE_MASKING_TONE;
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powerRatio = 10 .^ (-signalToNoiseRatio ./ 10);
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% Calculates the energy threshold
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energyThreshold = bandEnergyConv .* powerRatio;
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% Calculates the noise level
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noiseLevel = max(energyThreshold, qThrN);
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SMR(:, subFrameIndex) = bandEnergy ./ noiseLevel';
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end
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end
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end
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