模拟信号压缩与解压matlab.doc

function [y,G_out] = expanderINT16clip(x,Fd,G_in,M) %expander % y = expanderINT16clip(x,Fd,G_in,M) %x -- the input signal array %Fd -- the full deviated amplitude %G_in -- the initial Gain %M -- update the expander gain every M samples % %y -- the expanded signal array %G_out -- the output Gain % %Companding Specificationn % Compression Ratio 2:1 % Crossover Point 60% of full audio deviation % Attack Time 3.3 ms % Recovery Time 14.85 ms % % INT16_SCALE = 32768; persistent ae ae_1 average counter mean old_x_array ae1 ae1_1 ae2 ae2_1 ae_diff ae_diff_1; %initialization if isempty(ae) ae1 = float2Fract(0.99436); ae1_1 = 2^31 - fract2LongFract(ae1); %float2LongFract((1-0.99436)); ae2 = float2Fract(0.99985); ae2_1 = 2^31 - fract2LongFract(ae2); %float2LongFract((1-0.99985)); ae_diff = float2Fract(0.9995); ae_diff_1 = 2^31 - fract2LongFract(ae_diff); counter = 0; average = 0; mean = 0; old_x_array = zeros(1,40); end Ue = fractMult(float2Fract(0.6366),Fd); ae = ae1; ae_1 = ae1_1; global mean_e_g average_e_g diff_e_g avg_dif_e_g Ge_g flag_e_g avg_dif_float_e_g; %test only avg_dif = 0; avg_dif_float = 0; %test only OneForty = float2Fract(1/40); temp1 = 0; temp2 = 0; scale_flag = 0; for i = 1:length(x) abstract = abs(x(i)); temp1 = longLongFractMult(temp1,ae) + longLongFractMult(ae_1,abstract); %averager. divide 2^15 for fractional multiplication. average = longFract2Fract(temp1); average_e_g(i) = average; %test only mean = mean - fractMult(OneForty,old_x_array(1)) + fractMult(OneForty,abstract); %update mean mean_e_g(i)= mean; %test only if counter == 0 %update gain every M times G_in = average/Ue; G_in_floor = floor(G_in); G_in_fract = float2Fract(G_in - floor(G_in));