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| <title>WaveShaperNode interface - Curve tests | WebAudio</title> |
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| var sampleRate=44100.0; |
| var tolerance=0.01; |
| |
| /* |
| Testing that -1, 0 and +1 map correctly to curve (with 1:1 correlation) |
| ======================================================================= |
| From the specification: |
| The input signal is nominally within the range -1 -> +1. |
| Each input sample within this range will index into the shaping curve with a signal level of zero corresponding |
| to the center value of the curve array. |
| */ |
| (function() { |
| var threeElementCurve=[2.0, -3.0, 4.0]; |
| var inputData=[-1.0, 0, 1.0]; |
| var expectedData=[2.0, -3.0, 4.0]; |
| executeTest(threeElementCurve, inputData, expectedData, "Testing that -1, 0 and +1 map correctly to curve (with 1:1 correlation)"); |
| })(); |
| |
| /* |
| Testing interpolation (where inputs don't correlate directly to curve elements) |
| =============================================================================== |
| From the specification: |
| The implementation must perform linear interpolation between adjacent points in the curve. |
| */ |
| (function() { |
| var threeElementCurve=[2.0, -3.0, 4.0]; |
| var inputData=[-0.5, +0.5, +0.75]; |
| var expectedData=[-0.5, +0.5, +2.25]; |
| executeTest(threeElementCurve, inputData, expectedData, "Testing interpolation (where inputs don't correlate directly to curve elements)"); |
| })(); |
| |
| /* |
| Testing out-of-range inputs (should be mapped to the first/last elements of the curve) |
| ====================================================================================== |
| From the specification: |
| Any sample value less than -1 will correspond to the first value in the curve array. |
| Any sample value greater than +1 will correspond to the last value in the curve array. |
| */ |
| (function() { |
| var threeElementCurve=[2.0, -3.0, 4.0]; |
| var inputData=[-1.5, +1.5]; |
| var expectedData=[2.0, 4.0]; |
| executeTest(threeElementCurve, inputData, expectedData, "Testing out-of-range inputs (should be mapped to the first/last elements of the curve)"); |
| })(); |
| |
| /* |
| Testing a 2-element curve (does not have a middle element) |
| ========================================================== |
| From the specification: |
| Each input sample within this range will index into the shaping curve with a signal level of zero corresponding |
| to the center value of the curve array. |
| The implementation must perform linear interpolation between adjacent points in the curve. |
| */ |
| (function() { |
| var twoElementCurve=[2.0, -2.0]; |
| var inputData=[-1.0, 0, 1.0]; |
| var expectedData=[2.0, 0.0, -2.0]; |
| executeTest(twoElementCurve, inputData, expectedData, "Testing a 2-element curve (does not have a middle element)"); |
| })(); |
| |
| /* |
| Testing a 4-element curve (does not have a middle element) |
| ========================================================== |
| From the specification: |
| Each input sample within this range will index into the shaping curve with a signal level of zero corresponding |
| to the center value of the curve array. |
| The implementation must perform linear interpolation between adjacent points in the curve. |
| */ |
| (function() { |
| var fourElementCurve=[1.0, 2.0, 4.0, 7.0]; |
| var inputData=[-1.0, 0, 1.0]; |
| var expectedData=[1.0, 3.0, 7.0]; |
| executeTest(fourElementCurve, inputData, expectedData, "Testing a 4-element curve (does not have a middle element)"); |
| })(); |
| |
| /* |
| Testing a huge curve |
| ==================== |
| From the specification: |
| Each input sample within this range will index into the shaping curve with a signal level of zero corresponding |
| to the center value of the curve array. |
| */ |
| (function() { |
| var bigCurve=[]; |
| for(var i=0;i<=60000;i++) { bigCurve.push(i/3.5435); } |
| var inputData=[-1.0, 0, 1.0]; |
| var expectedData=[bigCurve[0], bigCurve[30000], bigCurve[60000]]; |
| executeTest(bigCurve, inputData, expectedData, "Testing a huge curve"); |
| })(); |
| |
| /* |
| Testing single-element curve (boundary condition) |
| ================================================= |
| From the specification: |
| Each input sample within this range will index into the shaping curve with a signal level of zero corresponding |
| to the center value of the curve array. |
| Any sample value less than -1 will correspond to the first value in the curve array. |
| Any sample value greater than +1 will correspond to the last value in the curve array. |
| The implementation must perform linear interpolation between adjacent points in the curve. |
| Note: |
| I found a post on the W3C audio mailing list (from one of the Chris's) that suggested it would be feasible |
| to use the WaveShaperNode to create constant values. |
| */ |
| (function() { |
| var oneElementCurve=[1.0]; |
| var inputData=[-1.0, 0, 1.0, -2.0, 2.0]; |
| var expectedData=[1.0, 1.0, 1.0, 1.0, 1.0]; |
| executeTest(oneElementCurve, inputData, expectedData, "Testing single-element curve (boundary condition)"); |
| })(); |
| |
| /* |
| Testing null curve (should return input values) |
| =============================================== |
| From the specification: |
| Initially the curve attribute is null, which means that the WaveShaperNode will pass its input to its output |
| without modification. |
| */ |
| (function() { |
| var inputData=[-1.0, 0, 1.0, 2.0]; |
| var expectedData=[-1.0, 0.0, 1.0, 2.0]; |
| executeTest(null, inputData, expectedData, "Testing null curve (should return input values)"); |
| })(); |
| |
| /* |
| Testing zero-element curve (unspecified result) |
| =============================================== |
| From the specification: |
| Unspecified result (I assume it will be treated in the same way as a null curve). |
| Note: |
| Mozilla test_waveShaperNoCurve.html indicates they expect same results as a null curve. |
| */ |
| (function() { |
| var zeroElementCurve=[]; |
| var inputData=[-1.0, 0, 1.0, 2.0]; |
| var expectedData=[-1.0, 0.0, 1.0, 2.0]; |
| executeTest(zeroElementCurve, inputData, expectedData, "Testing zero-element curve (unspecified result)"); |
| })(); |
| |
| |
| /** |
| * Function that does the actual testing (using an asynchronous test). |
| * @param {?Array.<number>} curveData - Array containing values for the WaveShaper curve. |
| * @param {!Array.<number>} inputData - Array containing values for the input stream. |
| * @param {!Array.<number>} expectedData - Array containing expected results for each of the corresponding inputs. |
| * @param {!string} testName - Name of the test case. |
| */ |
| function executeTest(curveData, inputData, expectedData, testName) { |
| var stTest=async_test("WaveShaperNode - "+testName); |
| |
| // Create offline audio context. |
| var ac=new OfflineAudioContext(1, inputData.length, sampleRate); |
| |
| // Create the WaveShaper and its curve. |
| var waveShaper=ac.createWaveShaper(); |
| if(curveData!=null) { |
| var curve=new Float32Array(curveData.length); |
| for(var i=0;i<curveData.length;i++) { curve[i]=curveData[i]; } |
| waveShaper.curve=curve; |
| } |
| waveShaper.connect(ac.destination); |
| |
| // Create buffer containing the input values. |
| var inputBuffer=ac.createBuffer(1, Math.max(inputData.length, 2), sampleRate); |
| var d=inputBuffer.getChannelData(0); |
| for(var i=0;i<inputData.length;i++) { d[i]=inputData[i]; } |
| |
| // Play the input buffer through the WaveShaper. |
| var src=ac.createBufferSource(); |
| src.buffer=inputBuffer; |
| src.connect(waveShaper); |
| src.start(); |
| |
| // Test the outputs match the expected values. |
| ac.oncomplete=function(ev) { |
| var d=ev.renderedBuffer.getChannelData(0); |
| |
| stTest.step(function() { |
| for(var i=0;i<expectedData.length;i++) { |
| var curveText="null"; |
| if(curve!=null) { |
| if(curveData.length<20) { |
| curveText=curveData.join(","); |
| } else { |
| curveText="TooBigToDisplay ("+(curveData.length-1)+" elements)"; |
| } |
| } |
| var comment="Input="+inputData[i]+", Curve=["+curveText+"] >>> "; |
| assert_approx_equals(d[i], expectedData[i], tolerance, comment); |
| } |
| }); |
| |
| stTest.done(); |
| }; |
| ac.startRendering(); |
| } |
| </script> |
| </body> |
| </html> |