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authMultimediaAssignment2018
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Init level 2

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Apostolos Fanakis 6 years ago
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0f7ada3bf3
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c4966b1fe7
14 changed files with 771 additions and 1 deletions
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  1. 2
      Level_1/AACoder1.m
  2. 65
      Level_2/AACoder2.m
  3. BIN
      Level_2/LicorDeCalandraca.wav
  4. 85
      Level_2/SSC.m
  5. 172
      Level_2/TNS.m
  6. BIN
      Level_2/TableB219.mat
  7. BIN
      Level_2/decoded2.wav
  8. 27
      Level_2/demoAAC2.m
  9. 103
      Level_2/filterbank.m
  10. 41
      Level_2/iAACoder2.m
  11. 103
      Level_2/iFilterbank.m
  12. 38
      Level_2/iTNS.m
  13. 61
      Level_2/imdct4.m
  14. 75
      Level_2/mdct4.m

2
Level_1/AACoder1.m
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@ -34,7 +34,7 @@ function AACSeq1 = AACoder1(fNameIn)
% Encodes audio file
AACSeq1(length(frameTypes)) = struct;
for i = 0:length(frameTypes)-1
for i = 0:length(frameTypes) - 1
currFrameStart = i * 1024 + 1;
currFrameStop = currFrameStart + 2047;
frameF = filterbank(originalAudioData(currFrameStart:currFrameStop, :), frameTypes{i+1}, 'KBD');

65
Level_2/AACoder2.m
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@ -0,0 +1,65 @@
function AACSeq2 = AACoder2(fNameIn)
%Implementation of WHAT?? //TODO!!
% Usage AACSeq2 = AACoder2(fNameIn), where:
% Inputs
% - fNameIn is the filename and path of the file to encode
%
% Output
% - AACSeq2 is an array of structs containing K structs, where K is
% the number of computed frames. Every struct of the array consists
% of a frameType, a winType, chl.TNScoeffs which are the quantized TNS
% coefficients of this frame's left channel, chr.TNScoeffs which are
% the quantized TNS coefficients of this frame's right channel,
% chl.frameF which are the MDCT coefficients of this frame's left
% channel, chr.frameF which are the MDCT coefficients of this frame's
% right channel
% Reads the audio file
[originalAudioData, ~] = audioread(fNameIn);
% Splits the audio in frames and determines the type of each frame
frameTypes{fix((length(originalAudioData) - 1025) / 1024)} = 'OLS';
frameTypes{1} = 'OLS';
for i = 1:length(frameTypes) - 2
nextFrameStart = (i + 1) * 1024 + 1;
nextFrameStop = nextFrameStart + 2047;
frameTypes{i+1} = SSC(1, originalAudioData(nextFrameStart:nextFrameStop, :), frameTypes{i});
end
% Assignes a type to the last frame
if strcmp(frameTypes{length(frameTypes) - 1}, 'LSS')
frameTypes{length(frameTypes)} = 'ESH';
elseif strcmp(frameTypes{length(frameTypes) - 1}, 'ESH')
frameTypes{length(frameTypes)} = 'ESH';
else
frameTypes{length(frameTypes)} = 'OLS';
end
% Encodes audio file
AACSeq2(length(frameTypes)) = struct;
for i = 0:length(frameTypes) - 1
currFrameStart = i * 1024 + 1;
currFrameStop = currFrameStart + 2047;
frameF = filterbank(originalAudioData(currFrameStart:currFrameStop, :), frameTypes{i+1}, 'KBD');
[frameF(:, 1), TNScoeffsL] = TNS(frameF(:, 1), frameTypes{i+1});
[frameF(:, 2), TNScoeffsR] = TNS(frameF(:, 2), frameTypes{i+1});
AACSeq2(i + 1).frameType = frameTypes(i + 1);
AACSeq2(i + 1).winType = 'KBD';
AACSeq2(i + 1).chl.TNScoeffs = TNScoeffsL;
AACSeq2(i + 1).chr.TNScoeffs = TNScoeffsR;
AACSeq2(i + 1).chl.frameF = frameF(:, 1);
AACSeq2(i + 1).chr.frameF = frameF(:, 2);
end
if true
[idx,label] = grp2idx(sort(frameTypes));
hist(idx,unique(idx));
set(gca,'xTickLabel',label)
sum(idx(:) == 1)
sum(idx(:) == 2)
sum(idx(:) == 3)
sum(idx(:) == 4)
end
end

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Level_2/LicorDeCalandraca.wav
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85
Level_2/SSC.m
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function frameType = SSC(~, nextFrameT, prevFrameType)
%Implementation of the Sequence Segmentation Control step
% Usage frameType = SSC(frameT, nextFrameT, prevFrameType), where:
% Inputs
% - frameT is a frame in the time domain, containing both channels of
% the audio stored in an array of dimensions 2048X2
% - nextFrameT is the next frame in the time domain, containing both
% channels of the audio stored in an array of dimensions 2048X2
% - prevFrameType is the type of the previous frame in string
% representation, can be one of "OLS" (ONLY_LONG_SEQUENCE), "LSS"
% (LONG_START_SEQUENCE), "ESH" (EIGHT_SHORT_SEQUENCE), "LPS"
% (LONG_STOP_SEQUENCE)
%
% Output
% - frameType is the type of the current frame in string
% representation, can be one of "OLS" (ONLY_LONG_SEQUENCE), "LSS"
% (LONG_START_SEQUENCE), "ESH" (EIGHT_SHORT_SEQUENCE), "LPS"
% (LONG_STOP_SEQUENCE)
% Examines the cases where the determination of the type of the next
% frame isn't needed for
if strcmp(prevFrameType, 'LSS')
frameType = 'ESH';
return;
elseif strcmp(prevFrameType, 'LPS')
frameType = 'OLS';
return;
end
% Determines the type of the next frame
% Filters frame
nextFrameT = filter([0.7548, -0.7548], [1, -0.5095], nextFrameT, [], 1);
channelFrameType = {'nan', 'nan'};
for channel = 1:2
% Calculates sub-frame energy estimation
[subFrames, ~] = buffer(nextFrameT(449:end - 448, channel), 256, 128, 'nodelay');
energyEstimations = sum(subFrames .^ 2, 1);
% Calculates the ratio of the sub-frame energy to the average energy of
% the previous sub-frames
nextIsESH = false;
for subFrameIndex = 2:8
energyRatio = energyEstimations(subFrameIndex) / ...
mean(energyEstimations(1:subFrameIndex - 1));
if (energyEstimations(subFrameIndex) > 10^(-3)) && (energyRatio > 10)
nextIsESH = true;
break;
end
end
if nextIsESH == true
if strcmp(prevFrameType, 'ESH')
% This frame of this channel is an EIGHT_SHORT_SEQUENCE type
% frame. This means the frames of both channels will be encoded
% as EIGHT_SHORT_SEQUENCE type frames.
frameType = 'ESH';
return;
elseif strcmp(prevFrameType, 'OLS')
channelFrameType{channel} = 'LSS';
end
else
if strcmp(prevFrameType, 'ESH')
channelFrameType{channel} = 'LPS';
elseif strcmp(prevFrameType, 'OLS')
channelFrameType{channel} = 'OLS';
end
end
end
if strcmp(channelFrameType{1}, 'nan') || strcmp(channelFrameType{2}, 'nan')
error('SSC, l[73]: Internal error occured!')
end
if strcmp(channelFrameType{1}, 'OLS')
frameType = channelFrameType{2};
elseif strcmp(channelFrameType{2}, 'OLS')
frameType = channelFrameType{1};
elseif strcmp(channelFrameType{1}, channelFrameType{2})
frameType = channelFrameType{1};
else
frameType = 'ESH';
end
end

172
Level_2/TNS.m
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@ -0,0 +1,172 @@
function [frameFout, TNScoeffs] = TNS(frameFin, frameType)
%Implementation of the TNS step
% Usage [frameFout, TNScoeffs] = TNS(frameFin, frameType), where:
% Inputs
% - frameFin is the frame in the frequency domain, in MDCT coefficients
% representation containing both channels of the audio stored in an
% array of dimensions 1024X2
% - frameType is the type of the current frame in string
% representation, can be one of "OLS" (ONLY_LONG_SEQUENCE), "LSS"
% (LONG_START_SEQUENCE), "ESH" (EIGHT_SHORT_SEQUENCE), "LPS"
% (LONG_STOP_SEQUENCE)
%
% Output
% - frameFout is the frame in the frequency domain after Temporal Noise
% Shaping, in MDCT coefficients representation containing both channels
% of the audio stored in an array of dimensions 1024X2
% - TNScoeffs is the quantized TNS coefficients array of dimensions
% 4X8 for EIGHT_SHORT_SEQUENCE frames and 4X1 otherwise
% Declares constant numbers of bands for long and short windows
LONG_WINDOW_NUMBER_OF_BANDS = 69;
SHORT_WINDOW_NUMBER_OF_BANDS = 42;
% Declares constant order of the linear prediction filter
LPF_ORDER = 4;
% Declares constant coefficients' resolution
COEF_RES = 4;
% Declares persistent variable holding the TNS tables and initializes if empty
persistent TNSTables;
if isempty(TNSTables)
TNSTables = load('TableB219.mat');
end
if ~strcmp(frameType, 'ESH')
% Calculates the energy per band
bandEnergy(LONG_WINDOW_NUMBER_OF_BANDS) = 0;
for band = 1:LONG_WINDOW_NUMBER_OF_BANDS - 1
bandEnergy(band) = sumsqr(frameFin(TNSTables.B219a(band, 2) + 1:TNSTables.B219a(band + 1, 2)));
end
bandEnergy(LONG_WINDOW_NUMBER_OF_BANDS) = sumsqr( ...
frameFin(TNSTables.B219a(LONG_WINDOW_NUMBER_OF_BANDS, 2) + 1:...
TNSTables.B219a(LONG_WINDOW_NUMBER_OF_BANDS, 3) + 1));
% Calculates the normalization factors
% PROBABLY WRONG, THE ONE BELLOW SHOULD BE RIGHT AND BETTER
% normalizationFactor(1024) = 0;
% for normIndex = 1:1024
% bandIndices = find(TNSTables.B219a(:, 2) >= (normIndex - 1), 1);
% if ~isempty(bandIndices)
% normalizationFactor(normIndex) = sqrt(bandEnergy(bandIndices));
% else
% normalizationFactor(normIndex) = sqrt(bandEnergy(find(TNSTables.B219a(:, 3) >= normIndex - 1, 1)));
% end
% end
bandIndices = quantiz(0:1023, TNSTables.B219a(:, 2) - 1);
normalizationFactor = sqrt(bandEnergy(bandIndices));
% Smooths normalization factors
for normIndex = 1023:-1:1
normalizationFactor(normIndex) = (normalizationFactor(normIndex) + normalizationFactor(normIndex + 1)) / 2;
end
for normIndex = 2:1024
normalizationFactor(normIndex) = (normalizationFactor(normIndex) + normalizationFactor(normIndex - 1)) / 2;
end
% Normalizes MDCT coefficients according to each band energy
normalizedFrameFin = frameFin ./ normalizationFactor';
% Calculates the linear prediction coefficients
[linPredCoeff, ~] = lpc(normalizedFrameFin, LPF_ORDER);
% Quantizes these coefficients
quantizedLinPredCoeff(LPF_ORDER) = 0;
for coeffIndex = 2:length(linPredCoeff)
quantizedLinPredCoeff(coeffIndex - 1) = asin(linPredCoeff(coeffIndex));
if linPredCoeff(coeffIndex) >= 0
quantizedLinPredCoeff(coeffIndex - 1) = round(quantizedLinPredCoeff(coeffIndex - 1) * ...
(bitshift(1, COEF_RES - 1) - 0.5) / (pi / 2));
quantizedLinPredCoeff(coeffIndex - 1) = quantizedLinPredCoeff(coeffIndex - 1) / ...
(bitshift(1, COEF_RES - 1) - 0.5) / (pi / 2);
quantizedLinPredCoeff(coeffIndex - 1) = sin (quantizedLinPredCoeff(coeffIndex - 1));
else
quantizedLinPredCoeff(coeffIndex - 1) = round(quantizedLinPredCoeff(coeffIndex - 1) * ...
(bitshift(1, COEF_RES - 1) + 0.5) / (pi / 2));
quantizedLinPredCoeff(coeffIndex - 1) = quantizedLinPredCoeff(coeffIndex - 1) / ...
(bitshift(1, COEF_RES - 1) + 0.5) / (pi / 2);
quantizedLinPredCoeff(coeffIndex - 1) = sin (quantizedLinPredCoeff(coeffIndex - 1));
end
end
% Filters MDCT coefficients
if ~isstable(1, [1 (quantizedLinPredCoeff * (-1))])
error('TNS, l[79]: Inverse filter not stable!');
else
TNScoeffs = quantizedLinPredCoeff;
frameFout = filter([1 (quantizedLinPredCoeff * (-1))], 1, frameFin);
end
else
% Initializes output vectors
TNScoeffs(LPF_ORDER * 8) = 0;
frameFout(1024) = 0;
bandEnergy(SHORT_WINDOW_NUMBER_OF_BANDS) = 0;
for subFrameIndex = 1:8
subFrame = frameFin((subFrameIndex - 1) * 128 + 1:subFrameIndex * 128);
% Calculates the energy per band
for band = 1:SHORT_WINDOW_NUMBER_OF_BANDS - 1
bandEnergy(band) = sumsqr(subFrame(TNSTables.B219b(band, 2) + 1:TNSTables.B219b(band + 1, 2)));
end
bandEnergy(SHORT_WINDOW_NUMBER_OF_BANDS) = sumsqr( ...
subFrame(TNSTables.B219b(SHORT_WINDOW_NUMBER_OF_BANDS, 2) + 1:...
TNSTables.B219b(SHORT_WINDOW_NUMBER_OF_BANDS, 3) + 1));
% Calculates the normalization factors
normalizationFactor(128) = 0;
for normIndex = 1:128
bandIndices = find(TNSTables.B219b(:, 2) >= normIndex - 1, 1);
if ~isempty(bandIndices)
normalizationFactor(normIndex) = sqrt(bandEnergy(bandIndices));
else
normalizationFactor(normIndex) = sqrt(bandEnergy(find(TNSTables.B219b(:, 3) <= normIndex - 1, 1)));
end
end
% Smooths normalization factors
for normIndex = 127:-1:1
normalizationFactor(normIndex) = (normalizationFactor(normIndex) + normalizationFactor(normIndex + 1)) / 2;
end
for normIndex = 2:128
normalizationFactor(normIndex) = (normalizationFactor(normIndex) + normalizationFactor(normIndex - 1)) / 2;
end
% Normalizes MDCT coefficients according to each band energy
normalizedFrameFin = subFrame ./ normalizationFactor';
% Calculates the linear prediction coefficients
[linPredCoeff, ~] = lpc(normalizedFrameFin, LPF_ORDER);
% Quantizes these coefficients
quantizedLinPredCoeff(LPF_ORDER) = 0;
for coeffIndex = 1:length(linPredCoeff)
quantizedLinPredCoeff(coeffIndex - 1) = asin(linPredCoeff(coeffIndex));
if linPredCoeff(coeffIndex) >= 0
quantizedLinPredCoeff(coeffIndex - 1) = round(quantizedLinPredCoeff(coeffIndex - 1) * ...
(bitshift(1, COEF_RES - 1) - 0.5) / (pi / 2));
quantizedLinPredCoeff(coeffIndex - 1) = quantizedLinPredCoeff(coeffIndex - 1) / ...
(bitshift(1, COEF_RES - 1) - 0.5) / (pi / 2);
quantizedLinPredCoeff(coeffIndex - 1) = sin (quantizedLinPredCoeff(coeffIndex - 1));
else
quantizedLinPredCoeff(coeffIndex - 1) = round(quantizedLinPredCoeff(coeffIndex - 1) * ...
(bitshift(1, COEF_RES - 1) + 0.5) / (pi / 2));
quantizedLinPredCoeff(coeffIndex - 1) = quantizedLinPredCoeff(coeffIndex - 1) / ...
(bitshift(1, COEF_RES - 1) + 0.5) / (pi / 2);
quantizedLinPredCoeff(coeffIndex - 1) = sin (quantizedLinPredCoeff(coeffIndex - 1));
end
end
% Filters MDCT coefficients
if ~isstable(1, [1 (quantizedLinPredCoeff * (-1))])
error('TNS, l[79]: Inverse filter not stable!');
else
TNScoeffs((subFrameIndex - 1) * 4 + 1:subFrameIndex * 4) = quantizedLinPredCoeff;
frameFout((subFrameIndex - 1) * 128 + 1:subFrameIndex * 128) = ...
filter([1 (quantizedLinPredCoeff * (-1))], 1, subFrame);
end
end
end
end

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Level_2/TableB219.mat
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Level_2/decoded2.wav
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27
Level_2/demoAAC2.m
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@ -0,0 +1,27 @@
function SNR = demoAAC2(fNameIn, fNameOut)
%Implementation of WHAT?? //TODO!!
% Usage SNR = demoAAC2(fNameIn, fNameOut), where:
% Inputs
% - fNameIn is the filename and path of the file to encode
% - fNameOut is the filename and path of the file that will be
% written after decoding
%
% Output
% - SNR is the signal to noise ration computed after successively
% encoding and decoding the audio signal
AACSeq2 = AACoder2(fNameIn);
decodedAudio = iAACoder2(AACSeq2, fNameOut);
[audioData, ~] = audioread(fNameIn);
figure()
plot(audioData(1:length(decodedAudio), 1) - decodedAudio(1:end, 1))
figure()
plot(audioData(1:length(decodedAudio), 2) - decodedAudio(1:end, 2))
snr(audioData(1:length(decodedAudio), 1), audioData(1:length(decodedAudio), 1) - decodedAudio(1:end, 1))
snr(audioData(1:length(decodedAudio), 2), audioData(1:length(decodedAudio), 2) - decodedAudio(1:end, 2))
SNR = 10*log10((sum(audioData(1:length(decodedAudio), :)) .^ 2) ./ ...
(sum(audioData(1:length(decodedAudio), :) - decodedAudio) .^ 2));
end

103
Level_2/filterbank.m
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@ -0,0 +1,103 @@
function frameF = filterbank(frameT, frameType, winType)
%Implementation of the Filter Bank step
% Usage frameF = filterbank(frameT, frameType, winType), where:
% Inputs
% - frameT is a frame in the time domain, containing both channels of
% the audio stored in an array of dimensions 2048X2
% - frameType is the type of the current frame in string
% representation, can be one of "OLS" (ONLY_LONG_SEQUENCE), "LSS"
% (LONG_START_SEQUENCE), "ESH" (EIGHT_SHORT_SEQUENCE), "LPS"
% (LONG_STOP_SEQUENCE)
% - winType is the type of the window selected, can be one of "KBD",
% "SIN"
%
% Output
% - frameF is the frame in the frequency domain, in MDCT coefficients
% representation containing both channels of the audio stored in an
% array of dimensions 1024X2
% Declares persistent windows variables and initializes if empty
persistent kaiserWindowLong kaiserWindowShort sinWindowLong sinWindowShort;
if isempty(kaiserWindowLong) || isempty(kaiserWindowShort) || ...
isempty(sinWindowLong) || isempty(sinWindowShort)
kaiserLong = kaiser(1024, 6*pi);
kaiserSumLong = sum(kaiserLong);
kaiserShort = kaiser(128, 4*pi);
kaiserSumShort = sum(kaiserShort);
for n = 1:1024
kaiserWindowLong(n) = sqrt(sum(kaiserLong(1:n))/kaiserSumLong);
kaiserWindowLong(1024 + n) = sqrt(sum(kaiserLong(1:end-n+1))/kaiserSumLong);
sinWindowLong(n) = sin(pi*(n + 0.5)/2048);
sinWindowLong(1024 + n) = sin(pi*(1024 + n + 0.5)/2048);
end
for n = 1:128
kaiserWindowShort(n) = sqrt(sum(kaiserShort(1:n))/kaiserSumShort);
kaiserWindowShort(128 + n) = sqrt(sum(kaiserShort(1:end-n+1))/kaiserSumShort);
sinWindowShort(n) = sin(pi*(n + 0.5)/256);
sinWindowShort(128 + n) = sin(pi*(128 + n + 0.5)/256);
end
end
frameF(1024, 2) = 0;
% Applies appropriate window to the frame
for channel=1:2
if strcmp(frameType, 'OLS')
if strcmp(winType, 'KBD')
frameT(:, channel) = frameT(:, channel) .* kaiserWindowLong(:);
elseif strcmp(winType, 'SIN')
frameT(:, channel) = frameT(:, channel) .* sinWindowLong(:);
else
error('filterbank, l[20]: Unsupported window type input!')
end
frameF(:, channel) = mdct4(frameT(:, channel));
elseif strcmp(frameType, 'LSS')
if strcmp(winType, 'KBD')
frameT(1:1024, channel) = frameT(1:1024, channel) .* kaiserWindowLong(1:1024)';
frameT(1473:1600, channel) = frameT(1473:1600, channel) .* kaiserWindowShort(129:end)';
frameT(1601:end, channel) = 0;
elseif strcmp(winType, 'SIN')
frameT(1:1024, channel) = frameT(1:1024, channel) .* sinWindowLong(1:1024)';
frameT(1473:1600, channel) = frameT(1473:1600, channel) .* sinWindowShort(129:end)';
frameT(1601:end, channel) = 0;
else
error('filterbank, l[20]: Unsupported window type input!')
end
frameF(:, channel) = mdct4(frameT(:, channel));
elseif strcmp(frameType, 'LPS')
if strcmp(winType, 'KBD')
frameT(1:448, channel) = 0;
frameT(449:576, channel) = frameT(449:576, channel) .* kaiserWindowShort(1:128)';
frameT(1025:end, channel) = frameT(1025:end, channel) .* kaiserWindowLong(1025:end)';
elseif strcmp(winType, 'SIN')
frameT(1:448, channel) = 0;
frameT(449:576, channel) = frameT(449:576, channel) .* sinWindowShort(1:128)';
frameT(1025:end, channel) = frameT(1025:end, channel) .* sinWindowLong(1025:end)';
else
error('filterbank, l[20]: Unsupported window type input!')
end
frameF(:, channel) = mdct4(frameT(:, channel));
elseif strcmp(frameType, 'ESH')
% Splits the frame into sub-frames
[subFrames, ~] = buffer(frameT(449:end-448, channel), 256, 128, 'nodelay');
if strcmp(winType, 'KBD')
subFrames = subFrames .* repmat(kaiserWindowShort', [1 8]);
elseif strcmp(winType, 'SIN')
subFrames = subFrames .* repmat(sinWindowShort', [1 8]);
end
for subFrameIndex = 1:8
frameF((subFrameIndex - 1) * 128 + 1:subFrameIndex * 128, channel) = mdct4(subFrames(:, subFrameIndex));
end
end
end
end

41
Level_2/iAACoder2.m
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@ -0,0 +1,41 @@
function x = iAACoder2(AACSeq2, fNameOut)
%Implementation of WHAT?? //TODO!!
% Usage x = iAACoder2(AACSeq2, fNameOut), where:
% Inputs
% - fNameOut is the filename and path of the file that will be
% written after decoding
% - AACSeq2 is an array of structs containing K structs, where K is
% the number of computed frames. Every struct of the array consists
% of a frameType, a winType, chl.TNScoeffs which are the quantized TNS
% coefficients of this frame's left channel, chr.TNScoeffs which are
% the quantized TNS coefficients of this frame's right channel,
% chl.frameF which are the MDCT coefficients of this frame's left
% channel, chr.frameF which are the MDCT coefficients of this frame's
% right channel
%
% Output
% - x is an array containing the decoded audio samples
% Initializes an array to hold the decoded samples
decodedAudio(1024 * (length(AACSeq2) + 1), 2) = 0;
% Initializes an array to hold both audio channels
frameF(1024, 2) = 0;
% Decodes audio file
for i = 0:length(AACSeq2)-1
currFrameStart = i * 1024 + 1;
currFrameStop = currFrameStart + 2047;
frameF(:, 1) = AACSeq2(i+1).chl.frameF;
frameF(:, 2) = AACSeq2(i+1).chr.frameF;
TNScoeffsL = AACSeq2(i + 1).chl.TNScoeffs;
TNScoeffsR = AACSeq2(i + 1).chr.TNScoeffs;
frameF(:, 1) = iTNS(frameF(:, 1), AACSeq2(i+1).frameType, TNScoeffsL);
frameF(:, 2) = iTNS(frameF(:, 2), AACSeq2(i+1).frameType, TNScoeffsR);
frameT = iFilterbank(frameF, AACSeq2(i+1).frameType, AACSeq2(i+1).winType);
decodedAudio(currFrameStart:currFrameStop, :) = decodedAudio(currFrameStart:currFrameStop, :) + frameT;
end
audiowrite(fNameOut, decodedAudio, 48000);
x = decodedAudio;
end

103
Level_2/iFilterbank.m
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function frameT = iFilterbank(frameF, frameType, winType)
%Implementation of the Inverse Filter Bank step
% Usage frameT = iFilterbank(frameF, frameType, winType), where:
% Inputs
% - frameF is the frame in the frequency domain, in MDCT coefficients
% representation containing both channels of the audio stored in an
% array of dimensions 1024X2
% - frameType is the type of the current frame in string
% representation, can be one of "OLS" (ONLY_LONG_SEQUENCE), "LSS"
% (LONG_START_SEQUENCE), "ESH" (EIGHT_SHORT_SEQUENCE), "LPS"
% (LONG_STOP_SEQUENCE)
% - winType is the type of the window selected, can be one of "KBD",
% "SIN"
%
% Output
% - frameT is a frame in the time domain, containing both channels of
% the audio stored in an array of dimensions 2048X2
% Declares persistent windows variables and initializes if empty
persistent kaiserWindowLong kaiserWindowShort sinWindowLong sinWindowShort;
if isempty(kaiserWindowLong) || isempty(kaiserWindowShort) || ...
isempty(sinWindowLong) || isempty(sinWindowShort)
kaiserLong = kaiser(1024, 6*pi);
kaiserSumLong = sum(kaiserLong);
kaiserShort = kaiser(128, 4*pi);
kaiserSumShort = sum(kaiserShort);
for n = 1:1024
kaiserWindowLong(n) = sqrt(sum(kaiserLong(1:n))/kaiserSumLong);
kaiserWindowLong(1024 + n) = sqrt(sum(kaiserLong(1:end-n+1))/kaiserSumLong);
sinWindowLong(n) = sin(pi*(n + 0.5)/2048);
sinWindowLong(1024 + n) = sin(pi*(1024 + n + 0.5)/2048);
end
for n = 1:128
kaiserWindowShort(n) = sqrt(sum(kaiserShort(1:n))/kaiserSumShort);
kaiserWindowShort(128 + n) = sqrt(sum(kaiserShort(1:end-n+1))/kaiserSumShort);
sinWindowShort(n) = sin(pi*(n + 0.5)/256);
sinWindowShort(128 + n) = sin(pi*(128 + n + 0.5)/256);
end
end
frameT(2048, 2) = 0;
% Applies appropriate window to the frame
for channel=1:2
if strcmp(frameType, 'OLS')
frameT(:, channel) = imdct4(frameF(:, channel));
if strcmp(winType, 'KBD')
frameT(:, channel) = frameT(:, channel) .* kaiserWindowLong(:);
elseif strcmp(winType, 'SIN')
frameT(:, channel) = frameT(:, channel) .* sinWindowLong(:);
else
error('filterbank, l[20]: Unsupported window type input!')
end
elseif strcmp(frameType, 'LSS')
frameT(:, channel) = imdct4(frameF(:, channel));
if strcmp(winType, 'KBD')
frameT(1:1024, channel) = frameT(1:1024, channel) .* kaiserWindowLong(1:1024)';
frameT(1473:1600, channel) = frameT(1473:1600, channel) .* kaiserWindowShort(129:end)';
frameT(1601:end, channel) = 0;
elseif strcmp(winType, 'SIN')
frameT(1:1024, channel) = frameT(1:1024, channel) .* sinWindowLong(1:1024)';
frameT(1473:1600, channel) = frameT(1473:1600, channel) .* sinWindowShort(129:end)';
frameT(1601:end, channel) = 0;
else
error('filterbank, l[20]: Unsupported window type input!')
end
elseif strcmp(frameType, 'LPS')
frameT(:, channel) = imdct4(frameF(:, channel));
if strcmp(winType, 'KBD')
frameT(1:448, channel) = 0;
frameT(449:576, channel) = frameT(449:576, channel) .* kaiserWindowShort(1:128)';
frameT(1025:end, channel) = frameT(1025:end, channel) .* kaiserWindowLong(1025:end)';
elseif strcmp(winType, 'SIN')
frameT(1:448, channel) = 0;
frameT(449:576, channel) = frameT(449:576, channel) .* sinWindowShort(1:128)';
frameT(1025:end, channel) = frameT(1025:end, channel) .* sinWindowLong(1025:end)';
else
error('filterbank, l[20]: Unsupported window type input!')
end
elseif strcmp(frameType, 'ESH')
for subFrameIndex = 1:8
subFrame = imdct4(frameF((subFrameIndex - 1) * 128 + 1:subFrameIndex * 128, channel));
if strcmp(winType, 'KBD')
subFrame = subFrame .* kaiserWindowShort';
elseif strcmp(winType, 'SIN')
subFrame = subFrame .* sinWindowShort';
end
frameT(448 + (subFrameIndex - 1) * 128 + 1:448 + (subFrameIndex + 1) * 128, channel) = ...
frameT(448 + (subFrameIndex - 1) * 128 + 1:448 + (subFrameIndex + 1) * 128, channel) + subFrame;
end
end
end
end

38
Level_2/iTNS.m
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function frameFout = iTNS(frameFin, frameType, TNScoeffs)
%Implementation of the reverse TNS step
% Usage frameFout = iTNS(frameFin, frameType, TNScoeffs), where:
% Inputs
% - frameFin is the frame in the frequency domain, in MDCT coefficients
% representation containing both channels of the audio stored in an
% array of dimensions 1024X2
% - frameType is the type of the current frame in string
% representation, can be one of "OLS" (ONLY_LONG_SEQUENCE), "LSS"
% (LONG_START_SEQUENCE), "ESH" (EIGHT_SHORT_SEQUENCE), "LPS"
% (LONG_STOP_SEQUENCE)
% - TNScoeffs is the quantized TNS coefficients array of dimensions
% 4X8 for EIGHT_SHORT_SEQUENCE frames and 4X1 otherwise
%
% Output
% - frameFout is the frame in the frequency domain after Temporal Noise
% Shaping, in MDCT coefficients representation containing both channels
% of the audio stored in an array of dimensions 1024X2
% Declares persistent variable holding the TNS tables and initializes if empty
persistent TNSTables;
if isempty(TNSTables)
TNSTables = load('TableB219.mat');
end
if ~strcmp(frameType, 'ESH')
% Inverses MDCT coefficients filtering
frameFout = filter(1, [1 (-1 * TNScoeffs)], frameFin);
else
for subFrameIndex = 1:8
subFrame = frameFin((subFrameIndex - 1) * 128 + 1:subFrameIndex * 128);
% Inverses MDCT coefficients filtering
frameFout((subFrameIndex - 1) * 128 + 1:subFrameIndex * 128) = ...
filter(1, [1 (-1 * TNScoeffs)], subFrame);
end
end
end

61
Level_2/imdct4.m
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function y = imdct4(x)
% IMDCT4 Calculates the Modified Discrete Cosine Transform
% y = imdct4(x)
%
% x: input signal (can be either a column or frame per column)
% y: IMDCT of x
%
% Vectorize ! ! !
% ------- imdct4.m -----------------------------------------
% Marios Athineos, marios@ee.columbia.edu
% http://www.ee.columbia.edu/~marios/
% Copyright (c) 2002 by Columbia University.
% All rights reserved.
% ----------------------------------------------------------
[flen,fnum] = size(x);
% Make column if it's a single row
if (flen==1)
x = x(:);
flen = fnum;
fnum = 1;
end
% We need these for furmulas below
N = flen;
M = N/2;
twoN = 2*N;
sqrtN = sqrt(twoN);
% We need this twice so keep it around
t = (0:(M-1)).';
w = diag(sparse(exp(-j*2*pi*(t+1/8)/twoN)));
% Pre-twiddle
t = (0:(M-1)).';
c = x(2*t+1,:) + j*x(N-1-2*t+1,:);
c = (0.5*w)*c;
% FFT for N/2 points only !!!
c = fft(c,M);
% Post-twiddle
c = ((8/sqrtN)*w)*c;
% Preallocate rotation matrix
rot = zeros(twoN,fnum);
% Sort
t = (0:(M-1)).';
rot(2*t+1,:) = real(c(t+1,:));
rot(N+2*t+1,:) = imag(c(t+1,:));
t = (1:2:(twoN-1)).';
rot(t+1,:) = -rot(twoN-1-t+1,:);
% Shift
t = (0:(3*M-1)).';
y(t+1,:) = rot(t+M+1,:);
t = (3*M:(twoN-1)).';
y(t+1,:) = -rot(t-3*M+1,:);

75
Level_2/mdct4.m
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@ -0,0 +1,75 @@
function y = mdct4(x)
% MDCT4 Calculates the Modified Discrete Cosine Transform
% y = mdct4(x)
%
% Use either a Sine or a Kaiser-Bessel Derived window (KBDWin)with
% 50% overlap for perfect TDAC reconstruction.
% Remember that MDCT coefs are symmetric: y(k)=-y(N-k-1) so the full
% matrix (N) of coefs is: yf = [y;-flipud(y)];
%
% x: input signal (can be either a column or frame per column)
% length of x must be a integer multiple of 4 (each frame)
% y: MDCT of x (coefs are divided by sqrt(N))
%
% Vectorize ! ! !
% ------- mdct4.m ------------------------------------------
% Marios Athineos, marios@ee.columbia.edu
% http://www.ee.columbia.edu/~marios/
% Copyright (c) 2002 by Columbia University.
% All rights reserved.
% ----------------------------------------------------------
[flen,fnum] = size(x);
% Make column if it's a single row
if (flen==1)
x = x(:);
flen = fnum;
fnum = 1;
end
% Make sure length is multiple of 4
if (rem(flen,4)~=0)
error('MDCT4 defined for lengths multiple of four.');
end
% We need these for furmulas below
N = flen; % Length of window
M = N/2; % Number of coefficients
N4 = N/4; % Simplify the way eqs look
sqrtN = sqrt(N);
% Preallocate rotation matrix
% It would be nice to be able to do it in-place but we cannot
% cause of the prerotation.
rot = zeros(flen,fnum);
% Shift
t = (0:(N4-1)).';
rot(t+1,:) = -x(t+3*N4+1,:);
t = (N4:(N-1)).';
rot(t+1,:) = x(t-N4+1,:);
clear x;
% We need this twice so keep it around
t = (0:(N4-1)).';
w = diag(sparse(exp(-j*2*pi*(t+1/8)/N)));
% Pre-twiddle
t = (0:(N4-1)).';
c = (rot(2*t+1,:)-rot(N-1-2*t+1,:))...
-j*(rot(M+2*t+1,:)-rot(M-1-2*t+1,:));
% This is a really cool Matlab trick ;)
c = 0.5*w*c;
clear rot;
% FFT for N/4 points only !!!
c = fft(c,N4);
% Post-twiddle
c = (2/sqrtN)*w*c;
% Sort
t = (0:(N4-1)).';
y(2*t+1,:) = real(c(t+1,:));
y(M-1-2*t+1,:) = -imag(c(t+1,:));
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