我正在寻找一种基于浏览器的方式来记录直到静音发生。
在 Firefox 和 Chrome 中可以从麦克风录制 HTML 音频 - 使用 Recordmp3js 见: http://nusofthq.com/blog/recording-mp3-using-only-html5-and-javascript-recordmp3-js/ 以及 github 上的代码:http://github.com/nusofthq/Recordmp3js
我看不出有什么方法可以更改该代码以记录直到静音。
记录直到可以使用 Java 为 native Android 应用程序完成(和调整)静音 - 请参见此处: Android audio capture silence detection
Google Voice Search演示浏览器可以做到这一点 - 但我如何使用 Javascript？ 有什么想法吗？
最佳答案
如果您使用 Web Audio API，请通过调用 navigator.getUserMedia 打开实时麦克风音频捕获，然后使用 createScriptProcessor 创建一个节点，然后为该节点分配一个事件回调:onaudioprocess。在你的回调函数中(下面我使用 script_processor_analysis_node)你可以访问实时音频缓冲区，然后你可以解析它以寻找静音(振幅低的一段时间 [保持接近零])。
正常时域音频曲线见:array_time_domain 每次调用回调 script_processor_analysis_node 时都会重新填充...类似地，对于频域，请参见 array_freq_domain
调低扬声器音量或使用耳机以避免来自麦克风的反馈 -> 扬声器 -> 麦克风 ...
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>capture microphone then show time & frequency domain output</title>
<script type="text/javascript">
var webaudio_tooling_obj = function () {
var audioContext = new AudioContext();
console.log("audio is starting up ...");
var BUFF_SIZE_RENDERER = 16384;
var audioInput = null,
microphone_stream = null,
gain_node = null,
script_processor_node = null,
script_processor_analysis_node = null,
analyser_node = null;
if (!navigator.getUserMedia)
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia ||
navigator.mozGetUserMedia || navigator.msGetUserMedia;
if (navigator.getUserMedia){
navigator.getUserMedia({audio:true},
function(stream) {
start_microphone(stream);
},
function(e) {
alert('Error capturing audio.');
}
);
} else { alert('getUserMedia not supported in this browser.'); }
// ---
function show_some_data(given_typed_array, num_row_to_display, label) {
var size_buffer = given_typed_array.length;
var index = 0;
console.log("__________ " + label);
if (label === "time") {
for (; index < num_row_to_display && index < size_buffer; index += 1) {
var curr_value_time = (given_typed_array[index] / 128) - 1.0;
console.log(curr_value_time);
}
} else if (label === "frequency") {
for (; index < num_row_to_display && index < size_buffer; index += 1) {
console.log(given_typed_array[index]);
}
} else {
throw new Error("ERROR - must pass time or frequency");
}
}
function process_microphone_buffer(event) {
var i, N, inp, microphone_output_buffer;
microphone_output_buffer = event.inputBuffer.getChannelData(0); // just mono - 1 channel for now
}
function start_microphone(stream){
gain_node = audioContext.createGain();
gain_node.connect( audioContext.destination );
microphone_stream = audioContext.createMediaStreamSource(stream);
microphone_stream.connect(gain_node);
script_processor_node = audioContext.createScriptProcessor(BUFF_SIZE_RENDERER, 1, 1);
script_processor_node.onaudioprocess = process_microphone_buffer;
microphone_stream.connect(script_processor_node);
// --- enable volume control for output speakers
document.getElementById('volume').addEventListener('change', function() {
var curr_volume = this.value;
gain_node.gain.value = curr_volume;
console.log("curr_volume ", curr_volume);
});
// --- setup FFT
script_processor_analysis_node = audioContext.createScriptProcessor(2048, 1, 1);
script_processor_analysis_node.connect(gain_node);
analyser_node = audioContext.createAnalyser();
analyser_node.smoothingTimeConstant = 0;
analyser_node.fftSize = 2048;
microphone_stream.connect(analyser_node);
analyser_node.connect(script_processor_analysis_node);
var buffer_length = analyser_node.frequencyBinCount;
var array_freq_domain = new Uint8Array(buffer_length);
var array_time_domain = new Uint8Array(buffer_length);
console.log("buffer_length " + buffer_length);
script_processor_analysis_node.onaudioprocess = function() {
// get the average for the first channel
analyser_node.getByteFrequencyData(array_freq_domain);
analyser_node.getByteTimeDomainData(array_time_domain);
// draw the spectrogram
if (microphone_stream.playbackState == microphone_stream.PLAYING_STATE) {
show_some_data(array_freq_domain, 5, "frequency");
show_some_data(array_time_domain, 5, "time"); // store this to record to aggregate buffer/file
// examine array_time_domain for near zero values over some time period
}
};
}
}(); // webaudio_tooling_obj = function()
</script>
</head>
<body>
<p>Volume</p>
<input id="volume" type="range" min="0" max="1" step="0.1" value="0.5"/>
</body>
</html>
关于javascript - HTML 音频录制到静音？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24515978/