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57 lines
2.3 KiB
57 lines
2.3 KiB
function AACSeq2 = AACoder2(fNameIn)
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%Implementation of AAC encoder
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% Usage AACSeq2 = AACoder2(fNameIn), 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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%
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% Output
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% - AACSeq2 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 a frameType, a winType, chl.TNScoeffs which are the quantized TNS
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% coefficients of this frame's left channel, chr.TNScoeffs which are
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% the quantized TNS coefficients of this frame's right channel,
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% chl.frameF which are the MDCT coefficients of this frame's left
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% channel, chr.frameF which are the MDCT coefficients of this frame's
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% right channel
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% Declares constant window type
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WINDOW_TYPE = 'KBD';
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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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AACSeq2(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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AACSeq2(i + 1).frameType = frameTypes(i + 1);
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AACSeq2(i + 1).winType = WINDOW_TYPE;
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AACSeq2(i + 1).chl.TNScoeffs = TNScoeffsL;
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AACSeq2(i + 1).chr.TNScoeffs = TNScoeffsR;
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AACSeq2(i + 1).chl.frameF = frameF(:, 1);
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AACSeq2(i + 1).chr.frameF = frameF(:, 2);
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end
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end
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