attack
特性为
DynamicsCompressorNode
接口是
k-rate
AudioParam
representing the amount of time, in seconds, required to reduce the gain by 10 dB. It defines how quickly the signal is adapted when its volume is increased.
attack
property's default value is
0.003
and it can be set between
0
and
1
.
var audioCtx = new AudioContext(); var compressor = audioCtx.createDynamicsCompressor(); compressor.attack.value = 0;
注意
: Though the
AudioParam
returned is read-only, the value it represents is not.
The below code demonstrates a simple usage of
createDynamicsCompressor()
to add compression to an audio track. For a more complete example, have a look at our
basic Compressor example
(
view the source code
).
// Create a MediaElementAudioSourceNode
// Feed the HTMLMediaElement into it
var source = audioCtx.createMediaElementSource(myAudio);
// Create a compressor node
var compressor = audioCtx.createDynamicsCompressor();
compressor.threshold.setValueAtTime(-50, audioCtx.currentTime);
compressor.knee.setValueAtTime(40, audioCtx.currentTime);
compressor.ratio.setValueAtTime(12, audioCtx.currentTime);
compressor.attack.setValueAtTime(0, audioCtx.currentTime);
compressor.release.setValueAtTime(0.25, audioCtx.currentTime);
// connect the AudioBufferSourceNode to the destination
source.connect(audioCtx.destination);
button.onclick = function() {
var active = button.getAttribute('data-active');
if(active == 'false') {
button.setAttribute('data-active', 'true');
button.innerHTML = 'Remove compression';
source.disconnect(audioCtx.destination);
source.connect(compressor);
compressor.connect(audioCtx.destination);
} else if(active == 'true') {
button.setAttribute('data-active', 'false');
button.innerHTML = 'Add compression';
source.disconnect(compressor);
compressor.disconnect(audioCtx.destination);
source.connect(audioCtx.destination);
}
}
| 规范 | 状态 | 注释 |
|---|---|---|
|
Web 音频 API
The definition of 'attack' in that specification. |
工作草案 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
attack
|
Chrome 14 | Edge 12 | Firefox 25 | IE 不支持 No | Opera 15 | Safari 6 | WebView Android Yes | Chrome Android 18 | Firefox Android 26 | Opera Android 14 | Safari iOS Yes | Samsung Internet Android 1.0 |
完整支持
不支持
DynamicsCompressorNode
AnalyserNode
AudioBuffer
AudioBufferSourceNode
AudioContext
AudioContextOptions
AudioDestinationNode
AudioListener
AudioNode
AudioNodeOptions
AudioParam
AudioProcessingEvent
AudioScheduledSourceNode
AudioWorklet
AudioWorkletGlobalScope
AudioWorkletNode
AudioWorkletProcessor
BaseAudioContext
BiquadFilterNode
ChannelMergerNode
ChannelSplitterNode
ConstantSourceNode
ConvolverNode
DelayNode
GainNode
IIRFilterNode
MediaElementAudioSourceNode
MediaStreamAudioDestinationNode
MediaStreamAudioSourceNode
OfflineAudioCompletionEvent
OfflineAudioContext
OscillatorNode
PannerNode
PeriodicWave
StereoPannerNode
WaveShaperNode