You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
98 lines
4.5 KiB
98 lines
4.5 KiB
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(1025, 6*pi);
|
|
kaiserSumLong = sum(kaiserLong);
|
|
kaiserShort = kaiser(129, 4*pi);
|
|
kaiserSumShort = sum(kaiserShort);
|
|
|
|
kaiserWindowLong(1:1024) = movsum(kaiserLong(1:1024), [1024 0]);
|
|
kaiserWindowLong(1025:2048) = movsum(flipud(kaiserLong(1:1024)), [0 1024]);
|
|
kaiserWindowLong = sqrt(kaiserWindowLong ./ kaiserSumLong);
|
|
|
|
sinWindowLong = sin(pi * ((0:2047) + 0.5) / 2048);
|
|
|
|
kaiserWindowShort(1:128) = movsum(kaiserShort(1:128), [128 0]);
|
|
kaiserWindowShort(129:256) = movsum(flipud(kaiserShort(1:128)), [0 128]);
|
|
kaiserWindowShort = sqrt(kaiserWindowShort ./ kaiserSumShort);
|
|
|
|
sinWindowShort = sin(pi * ((0:255) + 0.5) / 256);
|
|
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
|
|
|