9

The desktopCapturer api example shows how to write a screen capture stream to a <video> element.

// In the renderer process.
var desktopCapturer = require('electron').desktopCapturer;

desktopCapturer.getSources({types: ['window', 'screen']}, function(error, sources) {
  if (error) throw error;
  for (var i = 0; i < sources.length; ++i) {
    if (sources[i].name == "Electron") {
      navigator.webkitGetUserMedia({
        audio: false,
        video: {
          mandatory: {
            chromeMediaSource: 'desktop',
            chromeMediaSourceId: sources[i].id,
            minWidth: 1280,
            maxWidth: 1280,
            minHeight: 720,
            maxHeight: 720
          }
        }
      }, gotStream, getUserMediaError);
      return;
    }
  }
});

function gotStream(stream) {
  document.querySelector('video').src = URL.createObjectURL(stream);
}

function getUserMediaError(e) {
  console.log('getUserMediaError');
}

I tried to replace the gotStream function with the following:

function gotStream(stream) {
  var fs = require('fs');
  fs.writeFileSync('vid.mp4', stream);
}

This creates a text file with [object MediaStream] as the contents.

How can I record this stream and save to a file on disk?

4

3 回答 3

14

我在 Demian 的 MediaRecorder 链接以及其他相关问题的帮助下回答了我自己的问题。

下面是magnemite的摘录，经过一些小的简化，并从 TypeScript 转换为 JavaScript ES5，以便大多数读者更好地理解。

var fs = require('fs');
var electron = require('electron');

var SECRET_KEY = 'Magnemite';

var recorder;
var blobs = [];

function startRecording() {
    var title = document.title;
    document.title = SECRET_KEY;

    electron.desktopCapturer.getSources({ types: ['window', 'screen'] }, function(error, sources) {
        if (error) throw error;
        for (let i = 0; i < sources.length; i++) {
            let src = sources[i];
            if (src.name === SECRET_KEY) {
                document.title = title;

                navigator.webkitGetUserMedia({
                    audio: false,
                    video: {
                        mandatory: {
                            chromeMediaSource: 'desktop',
                            chromeMediaSourceId: src.id,
                            minWidth: 800,
                            maxWidth: 1280,
                            minHeight: 600,
                            maxHeight: 720
                        }
                    }
                }, handleStream, handleUserMediaError);
                return;
            }
        }
    });
}

function handleStream(stream) {
    recorder = new MediaRecorder(stream);
    blobs = [];
    recorder.ondataavailable = function(event) {
        blobs.push(event.data);
    };
    recorder.start();
}

function stopRecording() {
    recorder.stop();
    toArrayBuffer(new Blob(blobs, {type: 'video/webm'}), function(ab) {
        var buffer = toBuffer(ab);
        var file = `./videos/example.webm`;
        fs.writeFile(file, buffer, function(err) {
            if (err) {
                console.error('Failed to save video ' + err);
            } else {
                console.log('Saved video: ' + file);
            }
        });
    });
}

function handleUserMediaError(e) {
    console.error('handleUserMediaError', e);
}

function toArrayBuffer(blob, cb) {
    let fileReader = new FileReader();
    fileReader.onload = function() {
        let arrayBuffer = this.result;
        cb(arrayBuffer);
    };
    fileReader.readAsArrayBuffer(blob);
}

function toBuffer(ab) {
    return Buffer.from(ab);
}

// Record for 7 seconds and save to disk
startRecording();
setTimeout(function() { stopRecording() }, 7000);

这将记录当前电子窗口 7 秒并保存到磁盘。

于 2017-01-03T16:17:45.237 回答
2

看看MediaRecorder API

您应该将该流转换为二进制块。

于 2016-12-15T15:05:22.553 回答
1

desktopCapturer 示例展示了如何获取Blob. 然后，您需要将 转换Blob为fs.writeFile. 以下是简短而有效的：

fs.writeFile(filepath, Buffer.from(await blob.arrayBuffer()), ...);
于 2020-10-16T15:41:44.683 回答