Semester assignment for the course "Multimedia systems and virtual reality" of THMMY in AUTH university.
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function AACSeq3 = AACoder3(fNameIn, fnameAACoded)
%Implementation of AAC encoder
% Usage AACSeq3 = AACoder3(fNameIn, fnameAACoded), where:
% Inputs
% - fNameIn is the filename and path of the file to encode
% - frameAACoded is the filename and path of the mat file that will
% be written after encoding
%
% Output
% - AACSeq3 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.T which are the psychoacoustic thresholds of this frame's
% left channel,
% * chr.T which are the psychoacoustic thresholds of this frame's
% right channel,
% * chl.G which are the quantized global gains of this frame's
% left channel,
% * chr.G which are the quantized global gains of this frame's
% right channel,
% * chl.sfc which is the Huffman encoded sfc sequence of this
% frame's left channel,
% * chr.sfc which is the Huffman encoded sfc sequence of this
% frame's right channel,
% * chl.stream which is the Huffman encoded quantized MDCT
% sequence of this frame's left channel,
% * chr.stream which is the Huffman encoded quantized MDCT
% sequence of this frame's right channel,
% * chl.codebook which is the Huffman codebook used for this
% frame's left channel
% * chr.codebook which is the Huffman codebook used for this
% frame's right channel
% Declares constant window type
WINDOW_TYPE = 'KBD';
% Declares constant numbers of bands for long and short windows
LONG_WINDOW_NUMBER_OF_BANDS = 69;
SHORT_WINDOW_NUMBER_OF_BANDS = 42;
% Declares persistent variable holding the TNS tables and initializes if empty
persistent TNSTables;
if isempty(TNSTables)
TNSTables = load('TableB219.mat');
end
% 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), 1} = '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
% Assigns 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
huffLUT = loadLUT();
AACSeq3(length(frameTypes), 1) = struct;
for i = 0:length(frameTypes) - 1
currFrameStart = i * 1024 + 1;
currFrameStop = currFrameStart + 2047;
frameF = filterbank(originalAudioData(currFrameStart:currFrameStop, :), frameTypes{i+1}, WINDOW_TYPE);
[frameF(:, 1), TNScoeffsL] = TNS(frameF(:, 1), frameTypes{i+1});
[frameF(:, 2), TNScoeffsR] = TNS(frameF(:, 2), frameTypes{i+1});
if i == 0
SMRL = psycho(...
originalAudioData(currFrameStart:currFrameStop, 1), ...
frameTypes{i+1}, zeros(2048, 1), zeros(2048, 1));
SMRR = psycho(...
originalAudioData(currFrameStart:currFrameStop, 2), ...
frameTypes{i+1}, zeros(2048, 1), zeros(2048, 1));
elseif i == 1
prev1FrameStart = (i - 1) * 1024 + 1;
prev1FrameStop = prev1FrameStart + 2047;
SMRL = psycho(...
originalAudioData(currFrameStart:currFrameStop, 1), ...
frameTypes{i+1}, ...
originalAudioData(prev1FrameStart:prev1FrameStop, 1), ...
zeros(2048, 1));
SMRR = psycho(...
originalAudioData(currFrameStart:currFrameStop, 2), ...
frameTypes{i+1}, ...
originalAudioData(prev1FrameStart:prev1FrameStop, 2), ...
zeros(2048, 1));
else
prev1FrameStart = (i - 1) * 1024 + 1;
prev1FrameStop = prev1FrameStart + 2047;
prev2FrameStart = (i - 2) * 1024 + 1;
prev2FrameStop = prev2FrameStart + 2047;
SMRL = psycho(...
originalAudioData(currFrameStart:currFrameStop, 1), ...
frameTypes{i+1}, ...
originalAudioData(prev1FrameStart:prev1FrameStop, 1), ...
originalAudioData(prev2FrameStart:prev2FrameStop, 1));
SMRR = psycho(...
originalAudioData(currFrameStart:currFrameStop, 2), ...
frameTypes{i+1}, ...
originalAudioData(prev1FrameStart:prev1FrameStop, 2), ...
originalAudioData(prev2FrameStart:prev2FrameStop, 2));
end
[SL, sfcL, GL] = AACquantizer(frameF(:, 1), frameTypes{i+1}, SMRL);
[SR, sfcR, GR] = AACquantizer(frameF(:, 2), frameTypes{i+1}, SMRR);
if ~strcmp(frameTypes{i+1}, 'ESH')
TL(LONG_WINDOW_NUMBER_OF_BANDS, 1) = 0;
TR(LONG_WINDOW_NUMBER_OF_BANDS, 1) = 0;
for band = 1:LONG_WINDOW_NUMBER_OF_BANDS
frameWlow = TNSTables.B219a(band, 2) + 1;
frameWhigh = TNSTables.B219a(band, 3) + 1;
subFrameF = frameF(frameWlow:frameWhigh);
TL(band) = sumsqr(subFrameF) ./ SMRL(band);
TR(band) = sumsqr(subFrameF) ./ SMRR(band);
end
plot(TL);
else
TL(SHORT_WINDOW_NUMBER_OF_BANDS, 1) = 0;
TR(SHORT_WINDOW_NUMBER_OF_BANDS, 1) = 0;
for subFrameIndex = 1:8
currFrameStart = (subFrameIndex - 1) * 128 + 1;
currFrameStop = currFrameStart + 127;
subFrame = frameF(currFrameStart:currFrameStop);
for band = 1:SHORT_WINDOW_NUMBER_OF_BANDS
frameWlow = TNSTables.B219b(band, 2);
frameWhigh = TNSTables.B219b(band, 3);
subFrameF = subFrame(frameWlow + 1:frameWhigh + 1);
TL(band, subFrameIndex) = sumsqr(subFrameF) ./ SMRL(band);
TR(band, subFrameIndex) = sumsqr(subFrameF) ./ SMRR(band);
end
end
end
[streamL, huffcodebookL] = encodeHuff(SL, huffLUT);
[streamR, huffcodebookR] = encodeHuff(SR, huffLUT);
if strcmp(frameTypes(i+1), 'ESH')
[sfcHuffL, ~] = encodeHuff(reshape(sfcL(2:end, :), 1, [])', ...
huffLUT, 12);
[sfcHuffR, ~] = encodeHuff(reshape(sfcR(2:end, :), 1, [])', ...
huffLUT, 12);
else
[sfcHuffL, ~] = encodeHuff(sfcL(2:end), huffLUT, 12);
[sfcHuffR, ~] = encodeHuff(sfcR(2:end), huffLUT, 12);
end
AACSeq3(i + 1).frameType = frameTypes(i + 1);
AACSeq3(i + 1).winType = WINDOW_TYPE;
AACSeq3(i + 1).chl.TNScoeffs = TNScoeffsL;
AACSeq3(i + 1).chr.TNScoeffs = TNScoeffsR;
AACSeq3(i + 1).chl.T = TL;
AACSeq3(i + 1).chr.T = TR;
AACSeq3(i + 1).chl.G = GL;
AACSeq3(i + 1).chr.G = GR;
AACSeq3(i + 1).chl.sfc = sfcHuffL;
AACSeq3(i + 1).chr.sfc = sfcHuffR;
AACSeq3(i + 1).chl.stream = streamL;
AACSeq3(i + 1).chr.stream = streamR;
AACSeq3(i + 1).chl.codebook = huffcodebookL;
AACSeq3(i + 1).chr.codebook = huffcodebookR;
end
save(fnameAACoded, 'AACSeq3');
end