apostolof-ece-auth-gr
/
authMultimediaAssignment2018
1
0
Fork 0
Code Releases Activity
Browse Source

Init level 2

master
Apostolos Fanakis 6 years ago
parent
0f7ada3bf3
commit
c4966b1fe7
14 changed files with 771 additions and 1 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Unified View
Diff Options
Show Stats Download Patch File Download Diff File
  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
View File

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

65
Level_2/AACoder2.m
View File

@ -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

BIN
Level_2/LicorDeCalandraca.wav
View File

Binary file not shown.

85
Level_2/SSC.m
View File

@ -0,0 +1,85 @@
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
View File

@ -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

BIN
Level_2/TableB219.mat
View File

Binary file not shown.

BIN
Level_2/decoded2.wav
View File

Binary file not shown.

27
Level_2/demoAAC2.m
View File

@ -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
View File

@ -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
View File

@ -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
View File

@ -0,0 +1,103 @@
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
View File

@ -0,0 +1,38 @@
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
View File

@ -0,0 +1,61 @@
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
View File

@ -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,:));
Write Preview
Loading…
Cancel
Save