convolver-response-1-chan.html

<!DOCTYPE html>

<html>

  <head>

    <title>

      Test Convolver Channel Outputs for Response with 1 channel

    </title>

    <script src="/resources/testharness.js"></script>

    <script src="/resources/testharnessreport.js"></script>

    <script src="/webaudio/resources/audit-util.js"></script>

    <script src="/webaudio/resources/audit.js"></script>

  </head>

  <body>

    <script id="layout-test-code">

      // Test various convolver configurations when the convolver response has

      // one channel (mono).

      // This is somewhat arbitrary.  It is the minimum value for which tests

      // pass with both FFmpeg and KISS FFT implementations for 256 points.

      // The value was similar for each implementation.

      const absoluteThreshold = Math.pow(2, -21);

      // Fairly arbitrary sample rate, except that we want the rate to be a

      // power of two so that 1/sampleRate is exactly representable as a

      // single-precision float.

      let sampleRate = 8192;

      // A fairly arbitrary number of frames, except the number of frames should

      // be more than a few render quanta.

      let renderFrames = 10 * 128;

      let audit = Audit.createTaskRunner();

      // Convolver response

      let response;

      audit.define(

            label: 'initialize',

            description: 'Convolver response with one channel'

},

          (task, should) => {

            // Convolver response

            should(

                () => {

                  response = new AudioBuffer(

                      {numberOfChannels: 1, length: 2, sampleRate: sampleRate});

                  response.getChannelData(0)[1] = 1;

},

                'new AudioBuffer({numberOfChannels: 1, length: 2, sampleRate: ' +

                    sampleRate + '})')

                .notThrow();

            task.done();

});

      audit.define(

          {label: '1-channel input', description: 'produces 1-channel output'},

          (task, should) => {

            // Create a 3-channel context:  channel 0 = convolver under test,

            // channel 1: test that convolver output is not stereo, channel 2:

            // expected output.  The context MUST be discrete so that the

            // channels don't get mixed in some unexpected way.

            let context = new OfflineAudioContext(3, renderFrames, sampleRate);

            context.destination.channelInterpretation = 'discrete';

            let src = new OscillatorNode(context);

            let conv = new ConvolverNode(

                context, {disableNormalization: true, buffer: response});

            // Splitter node to verify that the output of the convolver is mono.

            // channelInterpretation must be 'discrete' so we don't do any

            // mixing of the input to the node.

            let splitter = new ChannelSplitterNode(

                context,

                {numberOfOutputs: 2, channelInterpretation: 'discrete'});

            // Final merger to feed all of the individual channels into the

            // destination.

            let merger = new ChannelMergerNode(context, {numberOfInputs: 3});

            src.connect(conv).connect(splitter);

            splitter.connect(merger, 0, 0);

            splitter.connect(merger, 1, 1);

            // The convolver response is a 1-sample delay.  Use a delay node to

            // implement this.

            let delay =

                new DelayNode(context, {delayTime: 1 / context.sampleRate});

            src.connect(delay);

            delay.connect(merger, 0, 2);

            merger.connect(context.destination);

            src.start();

            context.startRendering()

                .then(audioBuffer => {

                  // Extract out the three channels

                  let actual = audioBuffer.getChannelData(0);

                  let c1 = audioBuffer.getChannelData(1);

                  let expected = audioBuffer.getChannelData(2);

                  // c1 is expected to be zero.

                  should(c1, '1: Channel 1').beConstantValueOf(0);

                  // The expected and actual results should be identical

                  should(actual, 'Convolver output')

                    .beCloseToArray(expected,

                                    {absoluteThreshold: absoluteThreshold});

})

                .then(() => task.done());

});

      audit.define(

          {label: '2-channel input', description: 'produces 2-channel output'},

          (task, should) => {

            downMixTest({numberOfInputs: 2, prefix: '2'}, should)

                .then(() => task.done());

});

      audit.define(

            label: '3-channel input',

            description: '3->2 downmix producing 2-channel output'

},

          (task, should) => {

            downMixTest({numberOfInputs: 3, prefix: '3'}, should)

                .then(() => task.done());

});

      audit.define(

            label: '4-channel input',

            description: '4->2 downmix producing 2-channel output'

},

          (task, should) => {

            downMixTest({numberOfInputs: 4, prefix: '4'}, should)

                .then(() => task.done());

});

      audit.define(

            label: '5.1-channel input',

            description: '5.1->2 downmix producing 2-channel output'

},

          (task, should) => {

            // Scale tolerance by maximum amplitude expected in down-mix

            // output.

            let threshold = (1.0 + Math.sqrt(0.5) * 2) * absoluteThreshold;

            downMixTest({numberOfInputs: 6, prefix: '5.1',

                         absoluteThreshold: threshold}, should)

                .then(() => task.done());

});

      audit.define(

            label: '3-channel input, explicit',

            description: '3->2 explicit downmix producing 2-channel output'

},

          (task, should) => {

            downMixTest(

                  channelCountMode: 'explicit',

                  numberOfInputs: 3,

                  prefix: '3 chan downmix explicit'

},

                should)

                .then(() => task.done());

});

      audit.define(

            label: '4-channel input, explicit',

            description: '4->2 explicit downmix producing 2-channel output'

},

          (task, should) => {

            downMixTest(

                  channelCountMode: 'explicit',

                  numberOfInputs: 4,

                  prefix: '4 chan downmix explicit'

},

                should)

                .then(() => task.done());

});

      audit.define(

            label: '5.1-channel input, explicit',

            description: '5.1->2 explicit downmix producing 2-channel output'

},

          (task, should) => {

            // Scale tolerance by maximum amplitude expected in down-mix

            // output.

            let threshold = (1.0 + Math.sqrt(0.5) * 2) * absoluteThreshold;

            downMixTest(

                  channelCountMode: 'explicit',

                  numberOfInputs: 6,

                  prefix: '5.1 chan downmix explicit',

                  absoluteThreshold: threshold

},

                should)

                .then(() => task.done());

});

      audit.define(

            label: 'mono-upmix-explicit',

            description: '1->2 upmix, count mode explicit'

},

          (task, should) => {

            upMixTest(should, {channelCountMode: 'explicit'})

                .then(buffer => {

                  let length = buffer.length;

                  let input = buffer.getChannelData(0);

                  let out0 = buffer.getChannelData(1);

                  let out1 = buffer.getChannelData(2);

                  // The convolver is basically a one-sample delay.  Verify that

                  // that each channel is delayed by one sample.

                  should(out0.slice(1), '1->2 explicit upmix: channel 0')

                      .beCloseToArray(

                          input.slice(0, length - 1),

                          {absoluteThreshold: absoluteThreshold});

                  should(out1.slice(1), '1->2 explicit upmix: channel 1')

                      .beCloseToArray(

                          input.slice(0, length - 1),

                          {absoluteThreshold: absoluteThreshold});

})

                .then(() => task.done());

});

      audit.define(

            label: 'mono-upmix-clamped-max',

            description: '1->2 upmix, count mode clamped-max'

},

          (task, should) => {

            upMixTest(should, {channelCountMode: 'clamped-max'})

                .then(buffer => {

                  let length = buffer.length;

                  let input = buffer.getChannelData(0);

                  let out0 = buffer.getChannelData(1);

                  let out1 = buffer.getChannelData(2);

                  // The convolver is basically a one-sample delay.  With a mono

                  // input, the count set to 2, and a mode of 'clamped-max', the

                  // output should be mono

                  should(out0.slice(1), '1->2 clamped-max upmix: channel 0')

                      .beCloseToArray(

                          input.slice(0, length - 1),

                          {absoluteThreshold: absoluteThreshold});

                  should(out1, '1->2 clamped-max upmix: channel 1')

                      .beConstantValueOf(0);

})

                .then(() => task.done());

});

      function downMixTest(options, should) {

        // Create an 4-channel offline context.  The first two channels are for

        // the stereo output of the convolver and the next two channels are for

        // the reference stereo signal.

        let context = new OfflineAudioContext(4, renderFrames, sampleRate);

        context.destination.channelInterpretation = 'discrete';

        // Create oscillators for use as the input.  The type and frequency is

        // arbitrary except that oscillators must be different.

        let src = new Array(options.numberOfInputs);

        for (let k = 0; k < src.length; ++k) {

          src[k] = new OscillatorNode(

              context, {type: 'square', frequency: 440 + 220 * k});

        // Merger to combine the oscillators into one output stream.

        let srcMerger =

            new ChannelMergerNode(context, {numberOfInputs: src.length});

        for (let k = 0; k < src.length; ++k) {

          src[k].connect(srcMerger, 0, k);

        // Convolver under test.

        let conv = new ConvolverNode(context, {

          disableNormalization: true,

          buffer: response,

          channelCountMode: options.channelCountMode

});

        srcMerger.connect(conv);

        // Splitter to get individual channels of the convolver output so we can

        // feed them (eventually) to the context in the right set of channels.

        let splitter = new ChannelSplitterNode(context, {numberOfOutputs: 2});

        conv.connect(splitter);

        // Reference graph consists of a delay node to simulate the response of

        // the convolver.  (The convolver response is designed this way.)

        let delay = new DelayNode(context, {delayTime: 1 / context.sampleRate});

        // Gain node to mix the sources to stereo in the desired way.  (Could be

        // done in the delay node, but let's keep the mixing separated from the

        // functionality.)

        let gainMixer = new GainNode(

            context, {channelCount: 2, channelCountMode: 'explicit'});

        srcMerger.connect(gainMixer);

        // Splitter to extract the channels of the reference signal.

        let refSplitter =

            new ChannelSplitterNode(context, {numberOfOutputs: 2});

        gainMixer.connect(delay).connect(refSplitter);

        // Final merger to bring back the individual channels from the convolver

        // and the reference in the right order for the destination.

        let finalMerger = new ChannelMergerNode(

            context, {numberOfInputs: context.destination.channelCount});

        // First two channels are for the convolver output, and the next two are

        // for the reference.

        splitter.connect(finalMerger, 0, 0);

        splitter.connect(finalMerger, 1, 1);

        refSplitter.connect(finalMerger, 0, 2);

        refSplitter.connect(finalMerger, 1, 3);

        finalMerger.connect(context.destination);

        // Start the sources at last.

        for (let k = 0; k < src.length; ++k) {

          src[k].start();

        return context.startRendering().then(audioBuffer => {

          // Extract the various channels out

          let actual0 = audioBuffer.getChannelData(0);

          let actual1 = audioBuffer.getChannelData(1);

          let expected0 = audioBuffer.getChannelData(2);

          let expected1 = audioBuffer.getChannelData(3);

          let threshold = options.absoluteThreshold ?

              options.absoluteThreshold : absoluteThreshold;

          // Verify that each output channel of the convolver matches

          // the delayed signal from the reference

          should(actual0, options.prefix + ': Channel 0')

              .beCloseToArray(expected0, {absoluteThreshold: threshold});

          should(actual1, options.prefix + ': Channel 1')

              .beCloseToArray(expected1, {absoluteThreshold: threshold});

});

      function upMixTest(should, options) {

        // Offline context with 3 channels:  0 = source

        // 1 = convolver output, left, 2 = convolver output, right.  Context

        // destination must be discrete so that channels don't get mixed in

        // unexpected ways.

        let context = new OfflineAudioContext(3, renderFrames, sampleRate);

        context.destination.channelInterpretation = 'discrete';

        let merger = new ChannelMergerNode(

            context, {numberOfInputs: context.destination.maxChannelCount});

        merger.connect(context.destination);

        let src = new OscillatorNode(context);

        // Mono response for convolver.  Just a simple 1-frame delay.

        let response =

            new AudioBuffer({length: 2, sampleRate: context.sampleRate});

        response.getChannelData(0)[1] = 1;

        // Set mode to explicit and count to 2 so we manually force the

        // convolver to produce stereo output.  Without this, it would be

        // mono input with mono response, which produces a mono output.

        let conv;

        should(

            () => {conv = new ConvolverNode(context, {

                     buffer: response,

                     disableNormalization: true,

                     channelCount: 2,

                     channelCountMode: options.channelCountMode

                   })},

            `new ConvolverNode({channelCountMode: '${

                options.channelCountMode}'})`)

            .notThrow();

        // Split output of convolver into individual channels.

        let convSplit = new ChannelSplitterNode(context, {numberOfOutputs: 2});

        src.connect(conv);

        conv.connect(convSplit);

        // Connect signals to destination in the desired way.

        src.connect(merger, 0, 0);

        convSplit.connect(merger, 0, 1);

        convSplit.connect(merger, 1, 2);

        src.start();

        return context.startRendering();

      audit.run();

    </script>

  </body>

</html>

Source code

Revision control

Copy as Markdown

Other Tools

Test Info: