控制Firefox中视频/音频流的音量增益 [英] Control volume gain for Video/Audio stream in Firefox

问题描述

当我使用网络音频API创建节点时（源码 - >音频文件）增益 - >目的地）

记录文件的输出只有Audio，因为目的节点的返回流是Audio stream，只能引用这个文档
< a href =https://developer.mozilla.org/en-US/docs/Web/API/MediaStreamAudioDestinationNode =nofollow> https://developer.mozilla.org/zh-CN/docs/Web/ API / MediaStreamAudioDestinationNode

任何有关在目标输出中获取音频/视频流的建议，只能记录音频/视频而不是音频。 b

  var mediastream; 
 
 var ctx = new AudioContext（）; 
 
 var mediaStreamSource = ctx.createMediaStreamSource（mediaStream）; 
 
 var destination = ctx.createMediaStreamDestination（）; 
 
 ObjectStore.VolumeGainNode = ctx.createGain（）; 
 ObjectStore.VolumeGainNode.gain.value = 0.5; 
 
 mediaStreamSource.connect（ObjectStore.VolumeGainNode）; 
 
 ObjectStore.VolumeGainNode.connect（destination）; 
 
 mediaStream = destination.stream; 
  

解决方案

您可以使用流来修改音轨中的音轨。 .addTrack 和 stream.removeTrack ，以及使用新MediaStream（[tracks]）组合新流。 。

这可以让你解决你的问题，用你的增益控制的音轨取代gUM音轨：

  var constraints = {video：true，audio：true}; 
 
 var start =（）=> （e => console.error（e））;或者，如果使用了一个或多个控制字符串， 
 
 var modifyGain =（stream，gainValue）=> {
 var audioTrack = stream.getAudioTracks（）[0]; 
 var ctx = new AudioContext（）; 
 var src = ctx.createMediaStreamSource（new MediaStream（[audioTrack]））; 
 var dst = ctx.createMediaStreamDestination（）; 
 var gainNode = ctx.createGain（）; 
 gainNode.gain.value = gainValue; 
 [src，gainNode，dst] .reduce（（a，b）=>& a.connect（b））; 
 stream.removeTrack（audioTrack）; 
 stream.addTrack（dst.stream.getAudioTracks（）[0]）; 
}; 
  

下面是小提琴（Firefox 44或更新版本）： https://jsfiddle.net/7wd2z8rz/

再次使用MediaRecorder： https://jsfiddle.net/j33xmkcq/

I'm trying to record Video/Audio files using MediaRecorder API for Firefox.

When I'm using web Audio API for creating the nodes (source -> Gain -> Destination)

The output of the recorded file is only Audio as the return stream from the destination node is Audio stream only referring to this documentation https://developer.mozilla.org/en-US/docs/Web/API/MediaStreamAudioDestinationNode

Any suggestion for getting Audio/video stream in the destination output to record audio/video not audio only.

    var mediastream;

    var ctx = new AudioContext();

    var mediaStreamSource = ctx.createMediaStreamSource(mediaStream); 

    var destination = ctx.createMediaStreamDestination();

    ObjectStore.VolumeGainNode = ctx.createGain();
    ObjectStore.VolumeGainNode.gain.value = 0.5;

    mediaStreamSource.connect(ObjectStore.VolumeGainNode);

    ObjectStore.VolumeGainNode.connect(destination);

    mediaStream = destination.stream;

解决方案

You need a stream composed of the gUM video track and your gain-modified audio track.

Following the standard, Firefox lets you modify tracks in a stream using stream.addTrack and stream.removeTrack, as well as compose new streams out of tracks with new MediaStream([tracks]).

This lets you solve your problem by replacing the gUM audio track with your gain-manipulated one:

var constraints = { video: true, audio: true };

var start = () => navigator.mediaDevices.getUserMedia(constraints)
  .then(stream => modifyGain(video.srcObject = stream, 0.5))
  .catch(e => console.error(e));

var modifyGain = (stream, gainValue) => {
    var audioTrack = stream.getAudioTracks()[0];
    var ctx = new AudioContext();
    var src = ctx.createMediaStreamSource(new MediaStream([audioTrack]));
    var dst = ctx.createMediaStreamDestination();
    var gainNode = ctx.createGain();
    gainNode.gain.value = gainValue;
    [src, gainNode, dst].reduce((a, b) => a && a.connect(b));
    stream.removeTrack(audioTrack);
    stream.addTrack(dst.stream.getAudioTracks()[0]);
};

Here's the fiddle (Firefox 44 or newer): https://jsfiddle.net/7wd2z8rz/

Again with MediaRecorder: https://jsfiddle.net/j33xmkcq/

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