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function AACSeq3 = AACoder3(fNameIn, fnameAACoded)
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%Implementation of AAC encoder
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% Usage AACSeq3 = AACoder3(fNameIn, fnameAACoded), where:
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% Inputs
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% - fNameIn is the filename and path of the file to encode
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% - frameAACoded is the filename and path of the mat file that will
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% be written after encoding
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%
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% Output
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% - AACSeq3 is an array of structs containing K structs, where K is
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% the number of computed frames. Every struct of the array consists
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% of:
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% * a frameType,
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% * a winType,
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% * chl.TNScoeffs which are the quantized TNS coefficients of
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% this frame's left channel,
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% * chr.TNScoeffs which are the quantized TNS coefficients of
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% this frame's right channel,
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% * chl.T which are the psychoacoustic thresholds of this frame's
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% left channel,
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% * chr.T which are the psychoacoustic thresholds of this frame's
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% right channel,
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% * chl.G which are the quantized global gains of this frame's
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% left channel,
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% * chr.G which are the quantized global gains of this frame's
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% right channel,
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% * chl.sfc which is the Huffman encoded sfc sequence of this
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% frame's left channel,
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% * chr.sfc which is the Huffman encoded sfc sequence of this
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% frame's right channel,
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% * chl.stream which is the Huffman encoded quantized MDCT
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% sequence of this frame's left channel,
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% * chr.stream which is the Huffman encoded quantized MDCT
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% sequence of this frame's right channel,
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% * chl.codebook which is the Huffman codebook used for this
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% frame's left channel
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% * chr.codebook which is the Huffman codebook used for this
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% frame's right channel
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% Declares constant window type
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WINDOW_TYPE = 'KBD';
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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 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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% Reads the audio file
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[originalAudioData, ~] = audioread(fNameIn);
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% Splits the audio in frames and determines the type of each frame
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frameTypes{fix((length(originalAudioData) - 1025) / 1024), 1} = 'OLS';
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frameTypes{1} = 'OLS';
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for i = 1:length(frameTypes) - 2
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nextFrameStart = (i + 1) * 1024 + 1;
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nextFrameStop = nextFrameStart + 2047;
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frameTypes{i+1} = SSC(1, originalAudioData(nextFrameStart:nextFrameStop, :), frameTypes{i});
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end
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% Assigns a type to the last frame
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if strcmp(frameTypes{length(frameTypes) - 1}, 'LSS')
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frameTypes{length(frameTypes)} = 'ESH';
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elseif strcmp(frameTypes{length(frameTypes) - 1}, 'ESH')
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frameTypes{length(frameTypes)} = 'ESH';
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else
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frameTypes{length(frameTypes)} = 'OLS';
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end
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% Encodes audio file
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huffLUT = loadLUT();
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AACSeq3(length(frameTypes), 1) = struct;
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for i = 0:length(frameTypes) - 1
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currFrameStart = i * 1024 + 1;
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currFrameStop = currFrameStart + 2047;
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frameF = filterbank(originalAudioData(currFrameStart:currFrameStop, :), frameTypes{i+1}, WINDOW_TYPE);
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[frameF(:, 1), TNScoeffsL] = TNS(frameF(:, 1), frameTypes{i+1});
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[frameF(:, 2), TNScoeffsR] = TNS(frameF(:, 2), frameTypes{i+1});
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if i == 0
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SMRL = psycho(...
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originalAudioData(currFrameStart:currFrameStop, 1), ...
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frameTypes{i+1}, zeros(2048, 1), zeros(2048, 1));
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SMRR = psycho(...
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originalAudioData(currFrameStart:currFrameStop, 2), ...
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frameTypes{i+1}, zeros(2048, 1), zeros(2048, 1));
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elseif i == 1
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prev1FrameStart = (i - 1) * 1024 + 1;
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prev1FrameStop = prev1FrameStart + 2047;
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SMRL = psycho(...
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originalAudioData(currFrameStart:currFrameStop, 1), ...
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frameTypes{i+1}, ...
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originalAudioData(prev1FrameStart:prev1FrameStop, 1), ...
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zeros(2048, 1));
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SMRR = psycho(...
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originalAudioData(currFrameStart:currFrameStop, 2), ...
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frameTypes{i+1}, ...
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originalAudioData(prev1FrameStart:prev1FrameStop, 2), ...
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zeros(2048, 1));
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else
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prev1FrameStart = (i - 1) * 1024 + 1;
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prev1FrameStop = prev1FrameStart + 2047;
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prev2FrameStart = (i - 2) * 1024 + 1;
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prev2FrameStop = prev2FrameStart + 2047;
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SMRL = psycho(...
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originalAudioData(currFrameStart:currFrameStop, 1), ...
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frameTypes{i+1}, ...
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originalAudioData(prev1FrameStart:prev1FrameStop, 1), ...
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originalAudioData(prev2FrameStart:prev2FrameStop, 1));
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SMRR = psycho(...
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originalAudioData(currFrameStart:currFrameStop, 2), ...
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frameTypes{i+1}, ...
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originalAudioData(prev1FrameStart:prev1FrameStop, 2), ...
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originalAudioData(prev2FrameStart:prev2FrameStop, 2));
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end
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[SL, sfcL, GL] = AACquantizer(frameF(:, 1), frameTypes{i+1}, SMRL);
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[SR, sfcR, GR] = AACquantizer(frameF(:, 2), frameTypes{i+1}, SMRR);
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if ~strcmp(frameTypes{i+1}, 'ESH')
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TL(LONG_WINDOW_NUMBER_OF_BANDS, 1) = 0;
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TR(LONG_WINDOW_NUMBER_OF_BANDS, 1) = 0;
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for band = 1:LONG_WINDOW_NUMBER_OF_BANDS
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frameWlow = TNSTables.B219a(band, 2) + 1;
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frameWhigh = TNSTables.B219a(band, 3) + 1;
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subFrameF = frameF(frameWlow:frameWhigh);
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TL(band) = sumsqr(subFrameF) ./ SMRL(band);
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TR(band) = sumsqr(subFrameF) ./ SMRR(band);
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end
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else
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TL(SHORT_WINDOW_NUMBER_OF_BANDS, 1) = 0;
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TR(SHORT_WINDOW_NUMBER_OF_BANDS, 1) = 0;
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for subFrameIndex = 1:8
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currFrameStart = (subFrameIndex - 1) * 128 + 1;
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currFrameStop = currFrameStart + 127;
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subFrame = frameF(currFrameStart:currFrameStop);
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for band = 1:SHORT_WINDOW_NUMBER_OF_BANDS
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frameWlow = TNSTables.B219b(band, 2);
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frameWhigh = TNSTables.B219b(band, 3);
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subFrameF = subFrame(frameWlow + 1:frameWhigh + 1);
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TL(band, subFrameIndex) = sumsqr(subFrameF) ./ SMRL(band);
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TR(band, subFrameIndex) = sumsqr(subFrameF) ./ SMRR(band);
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end
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end
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end
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[streamL, huffcodebookL] = encodeHuff(SL, huffLUT);
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[streamR, huffcodebookR] = encodeHuff(SR, huffLUT);
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if strcmp(frameTypes(i+1), 'ESH')
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[sfcHuffL, ~] = encodeHuff(reshape(sfcL(2:end, :), 1, [])', ...
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huffLUT, 12);
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[sfcHuffR, ~] = encodeHuff(reshape(sfcR(2:end, :), 1, [])', ...
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huffLUT, 12);
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else
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[sfcHuffL, ~] = encodeHuff(sfcL(2:end), huffLUT, 12);
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[sfcHuffR, ~] = encodeHuff(sfcR(2:end), huffLUT, 12);
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end
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AACSeq3(i + 1).frameType = frameTypes(i + 1);
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AACSeq3(i + 1).winType = WINDOW_TYPE;
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AACSeq3(i + 1).chl.TNScoeffs = TNScoeffsL;
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AACSeq3(i + 1).chr.TNScoeffs = TNScoeffsR;
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AACSeq3(i + 1).chl.T = TL;
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AACSeq3(i + 1).chr.T = TR;
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AACSeq3(i + 1).chl.G = GL;
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AACSeq3(i + 1).chr.G = GR;
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AACSeq3(i + 1).chl.sfc = sfcHuffL;
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AACSeq3(i + 1).chr.sfc = sfcHuffR;
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AACSeq3(i + 1).chl.stream = streamL;
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AACSeq3(i + 1).chr.stream = streamR;
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AACSeq3(i + 1).chl.codebook = huffcodebookL;
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AACSeq3(i + 1).chr.codebook = huffcodebookR;
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clearvars TL TR
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end
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save(fnameAACoded, 'AACSeq3');
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end
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