时间戳

首页 > 解决方案 > 通过 Tone.js 连续改变和弦频率

web-audio-api - 通过 Tone.js 连续改变和弦频率

问题描述

如何使用tone.js为吉他制作和弦基频连续交互变化？

显然，将 Tone.Sampler 与可能命名为“pitchBend”或“pitchShift”的 API 一起使用是一种可行的方法，但我不确定实际选择。换句话说，如何制作“变调夹滑块”？

我解决了本机 window.AudioContext 的这个问题，用于一组振荡器（每个振荡器用于一个吉他弦），使用滑块的频率更新，例如：

振荡器.频率.setValueAtTime（频率，context.currentTime）；

当振荡器仍然活跃并正在播放时，它可以很好地改变所有弦的音调。

但是 1) 音色不完全是吉他的默认正弦声波形状和 2) 弦有时会干扰或回响，使声音过于不自然。

也许除了tone.js 平台之外的其他平台可以解决问题？

谢谢你。

标签： web-audio-apitone.js

解决方案

我做了更多的研究，现在看来本机 WebAudio API 解决了这个问题，但还不清楚可靠和精确。我确实加载了吉他弦样本并让滑块改变了它们的速度比以重新调整。下面是代码：

    <!DOCTYPE html>
    <html>
      <head>
        <title>Continuous chord. Capo effect.</title>
        <meta charset="utf-8">
        <meta name="viewport"
              content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
        <script>
    
            window.onload = function () {
    
    
                //==================================================
                // //\\ configures sound parameters
                //==================================================
    
                // //\\ scale constants
                /*
                var logStep         = Math.log( 2 ) / 12;
                var semitone        = Math.exp( logStep );
                console.log( semitone );
                var semi2           = semitone * semitone;
                var semi4           = semi2 * semi2;
                var semi7           = semi2 * semitone;
                */
                // \\// scale constants
    
    
                //E3, A3, C3#,
                //165, 220, 277
                var initSpeed       = 1;
                var clipStart       = 0; //0.65; //0.7;
                var clipLenOriginal = 3.2; //0.43;
                var doLoop          = false; //true;
    
    
    
                //speed raise
                //if it is expected only one url for all tones in chord,
                //adjust here speeds to generate different tones according to
                //frequency ratios,
                var clipLenSpeeds   = [
                    //minor
                    /*
                    var smR0  = 1;
                    var smR1  = 262/220;
                    var smR2  = 330/220;
                    */
                    //major
                    1,                      
                    1, // 277/220, //220/165
                    1, // 330/220, //277/165
                ];
                var clipLengs       = clipLenSpeeds.map( sp => clipLenOriginal*sp );
                var clipLenSpeeds   = clipLenSpeeds.map( sp => initSpeed*sp );
    
                var dataPath        = 'data';
                //data are from this path:
                //var dataPath      = 'https://github.com/nbrosowsky/tonejs-instruments/tree/master/samples/guitar-acoustic';
                var urls            = [
                    dataPath + '/' + 'A3.wav',
                    dataPath + '/' + 'E3.wav',
                    dataPath + '/' + 'Cs3.wav',
                ];
                //var fname = 'second-line-captured.mkv.mp3';
                //var urls            = clipLenSpeeds.map( el => fname );
                //==================================================
                // \\// configures sound parameters
                //==================================================
    
    
                //==================================================
                // //\\ loads and prepares sourceNodes
                //==================================================
                let audioContext    = new AudioContext();
                var sourceNodes     = [];
                var audioBuffers    = [];
    
                Promise.all(
                    clipLenSpeeds.map( ( el, ix ) => 
                        getSample( ix )
                    )
                ).then(
                    ( values ) => {
                        //console.log( 'values from last promise-then:', values );
                        button.removeAttribute( 'disabled' );
                    },
                ).catch( (err) => {
                    console.log( err );
                });
                //==================================================
                // \\// loads and prepares sourceNodes
                //==================================================
    
    
    
                //==================================================
                // //\\ GUI
                //==================================================
                const button            = document.querySelector( '.run' );
                const playbackControl   = document.querySelector( '.playback-rate-control' );
                const playbackValue     = document.querySelector( '.playback-rate-value' );
                button.setAttribute( 'disabled', 'disabled' );
                button.addEventListener( 'click', () => {
                    audioBuffers.forEach( (val,vix) => 
                        startLoopByIx( vix )
                    );
                });
                playbackControl.oninput = function() {
                    playbackValue.innerHTML = playbackControl.value;
                    sourceNodes.forEach( (sn,i) => {
                        sn.playbackRate.value = clipLenSpeeds[i] * playbackControl.value;
                    });
                }
                //==================================================
                // \\// GUI
                //==================================================
                return;
    
    
    
    
    
    
                ///part of the load and initation of audio buffer,
                ///returns promise from the last ".then"
                function getSample( ix )
                {
                    return fetch( urls[ ix ] )
                        .then( response => response.arrayBuffer() )
                        .then( arrayBuffer => audioContext.decodeAudioData( arrayBuffer ) )
                        .then( audioBuffer => {
                            audioBuffers[ ix ] = audioBuffer;
    
                            //if uncommented, this returned value populates
                            //values in Promise.all.then first param,
                            //return audioBuffer;
                        })
                        ;
                }
    
                ///fires up loop belonging to sourceNode[ ix ],
                ///options: either doLoop or one-time play,
                function startLoopByIx( ix )
                {
                    var audioBuffer = audioBuffers[ ix ];
                    var clipLen     = clipLengs[ ix ];
                    var rate        = clipLenSpeeds[ ix ];
                    var pan         = 0; //stereo channels balance
    
                    let sourceNode = audioContext.createBufferSource();
                    let pannerNode = audioContext.createStereoPanner();
    
                    sourceNode.buffer               = audioBuffer;
                    sourceNode.loop                 = doLoop;
                    sourceNode.loopStart            = clipStart;
                    sourceNode.loopEnd              = clipStart + clipLen;
                    sourceNode.playbackRate.value   = rate; //does retuning
                    pannerNode.pan.value            = pan;
    
                    sourceNode.connect( pannerNode );
                    pannerNode.connect( audioContext.destination );
    
                    if( doLoop ) {
                        sourceNode.start( 0, clipStart, );
                    } else {
                        sourceNode.start( 0, clipStart, clipLen );
                    }
                    sourceNodes[ ix ] = sourceNode;
                }
            };
        </script>
      </head>
      <body>
    
        <button class="run">Run samples</button><br>
    
        <h2>Set playback rate</h2>
        <input class="playback-rate-control" type="range" min="0.25" max="3" step="0.05" value="1">
        <span class="playback-rate-value">1.0</span>
    
    
      </body>
    </html>

推荐阅读