mirror of
https://github.com/cookiengineer/audacity
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6da48db127
This is based on my old loudness effect prototype which was included in the Normalize effect. Create all source files and add them to all build systems. Currently, the effect only consists of a GUI mockup. Create Octave+mod-script-pipe based dummy unit-test as well.
127 lines
3.8 KiB
Matlab
127 lines
3.8 KiB
Matlab
## Audacity Loudness effect unit test
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#
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# Max Maisel
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#
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# This tests the Loudness effect with 30 seconds long pseudo-random stereo
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# noise sequences. The test sequences have different amplitudes per
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# channel and sometimes a DC component. For best test coverage, irrelevant
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# parameters for the current operation are randomly varied.
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#
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printf("Running Loudness effect tests.\n");
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printf("This requires the octave-forge-signal package to be installed.\n");
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pkg load signal;
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EXPORT_TEST_SIGNALS = true;
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TEST_LUFS_HELPER = true;
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# LUFS need a higher epsilon because they are a logarithmic unit.
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LUFS_epsilon = 0.02;
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# A straightforward and simple LUFS implementation which can
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# be easily compared with the specification ITU-R BS.1770-4.
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function [gated_lufs] = calc_LUFS(x, fs)
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# HSF
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f0 = 38.13547087602444;
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Q = 0.5003270373238773;
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K = tan(pi * f0 / fs);
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rb0 = 1.0;
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rb1 = -2.0;
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rb2 = 1.0;
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ra0 = 1.0;
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ra1 = 2.0 * (K * K - 1.0) / (1.0 + K / Q + K * K);
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ra2 = (1.0 - K / Q + K * K) / (1.0 + K / Q + K * K);
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rb = [rb0 rb1 rb2];
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ra = [ra0 ra1 ra2];
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# HPF
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db = 3.999843853973347;
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f0 = 1681.974450955533;
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Q = 0.7071752369554196;
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K = tan(pi * f0 / fs);
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Vh = power(10.0, db / 20.0);
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Vb = power(Vh, 0.4996667741545416);
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pa0 = 1.0;
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a0 = 1.0 + K / Q + K * K;
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pb0 = (Vh + Vb * K / Q + K * K) / a0;
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pb1 = 2.0 * (K * K - Vh) / a0;
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pb2 = (Vh - Vb * K / Q + K * K) / a0;
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pa1 = 2.0 * (K * K - 1.0) / a0;
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pa2 = (1.0 - K / Q + K * K) / a0;
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pb = [pb0 pb1 pb2];
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pa = [pa0 pa1 pa2];
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# Apply k-weighting
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x = filter(rb, ra, x, [], 1);
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x = filter(pb, pa, x, [], 1);
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# - gating blocks (every 100 ms over 400 ms)
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block_size = 0.4*fs;
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block_overlap = 0.3*fs;
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block_count = floor((size(x)(1)-block_size)/(block_size-block_overlap))+1+1;
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x_blocked = zeros(block_size, block_count, size(x)(2));
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for i=1:1:size(x)(2)
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x_blocked(:,:,i) = buffer(x(:,i), block_size, 0.3*fs, 'nodelay');
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end
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lufs_blocked = 1/(block_size)*sum(x_blocked.^2, 1);
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lufs_blocked = sum(lufs_blocked, 3);
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# Apply absolute threshold
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GAMMA_A = -70;
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lufs_blocked = -0.691 + 10*log10(lufs_blocked);
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valid_blocks = length(lufs_blocked);
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valid_blocks = valid_blocks - length(lufs_blocked(lufs_blocked < GAMMA_A));
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lufs_blocked(lufs_blocked < GAMMA_A) = -100;
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lufs_blocked = 10.^((lufs_blocked+0.691)/10);
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# Apply relative threshold
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GAMMA_R = -0.691 + 10*log10(sum(lufs_blocked)/valid_blocks) - 10;
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lufs_blocked = -0.691 + 10*log10(lufs_blocked);
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valid_blocks = length(lufs_blocked);
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valid_blocks = valid_blocks - length(lufs_blocked(lufs_blocked < GAMMA_R));
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lufs_blocked(lufs_blocked < GAMMA_R) = -100;
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lufs_blocked = 10.^((lufs_blocked+0.691)/10);
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hold off
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gated_lufs = -0.691 + 10*log10(sum(lufs_blocked)/valid_blocks);
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end
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if TEST_LUFS_HELPER
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printf("Running calc_LUFS() selftest.\n");
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printf("Compare the following results with a trusted LUFS calculator.\n");
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fs = 44100;
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k = 1:1:60*fs;
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x = 0.3*sin(2*pi*1000/fs*k) + 0.2*sin(2*pi*1200/fs*k);
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x = (x .* [1:1:30*fs, 30*fs:-1:1]./60./fs).';
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audiowrite(cstrcat(pwd(), "/LUFS-selftest1.wav"), x, fs);
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printf("LUFS-selftest1.wav should be %f LUFS\n", calc_LUFS(x, fs));
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randn("seed", 1);
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x = [0.2*randn(2, 10*fs) zeros(2, 10*fs) 0.1*randn(2, 10*fs)].';
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x(:,1) = x(:,1) * 0.4 + 0.2;
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audiowrite(cstrcat(pwd(), "/LUFS-selftest2.wav"), x, fs);
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printf("LUFS-selftest2.wav should be %f LUFS\n", calc_LUFS(x, fs));
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fs = 8000;
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randn("seed", 2);
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x = [0.2*randn(2, 10*fs) zeros(2, 10*fs) 0.1*randn(2, 10*fs)].';
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x(:,1) = x(:,1) * 0.6 - 0.1;
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# MMM: I'm not sure how trustworthy free loudness meters are
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# in case of non-standard sample rates.
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audiowrite(cstrcat(pwd(), "/LUFS-selftest3.wav"), x, fs);
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printf("LUFS-selftest3.wav should be %f LUFS\n", calc_LUFS(x, fs));
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end
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# TODO: add tests here
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