如何获取字幕当前显示的文字

Question

我想通过console.log提取外部网站（如youtube.com）暂停视频帧上的字幕文本。

假定外部网站通过 webvtt 或类似文件提供字幕。

由于字幕文本可能是 DOM 的一部分，能否在浏览器的 Developer Console 中使用 JavaScript 代码来提取文本并在之后通过 console.log() 显示它检测它暂停的时间？

Answer 1

您可以访问视频的 .textTracks, from which you'll be able to access its activeCues from where you can get their text 值：

initTrack();
video.addEventListener('pause', e => {
 const track = [ ...video.textTracks ]
   .find( track => track.mode === "showing" );
 const texts = [...track.activeCues].map( cue => cue.text );
 console.log( texts.join('\n') );
});


// just to make a VTT accessible in Snippet
function initTrack() {
  const track = document.querySelector("track");
  let vttText = `WEBVTT`;
  for( let i=0; i<35; i++ ) {
    const t1 = (i + '').padStart(2 , '0');
    const t2 = ((i+1) + '').padStart(2 , '0');
    vttText += `
      00:00:${t1}.000 --> 00:00:${t2}.000
      Test${i}`
  }
  const vttBlob = new Blob([vttText], {
    type: 'text/plain'
  });
  track.src = URL.createObjectURL(vttBlob);
}

video { max-height: 150px;  }
::cue { font-size: 30px }

<div>
  <video id="video" controls>
    <source src="https://upload.wikimedia.org/wikipedia/commons/a/a4/BBH_gravitational_lensing_of_gw150914.webm">
    <track default kind="captions" label="English" srclang="en"/>
  </video>
</div>

如果你想在它播放的时候这样做，那么你可以监听 cuechange 事件：

initTrack();
video.addEventListener("loadedmetadata", (evt) => {
  const track = [...video.textTracks]
    .find(track => track.mode === "showing");
  track.oncuechange = (evt) => {
    const texts = [...track.activeCues].map(cue => cue.text);
    console.log(texts.join("\n"));
  };
});

// just to make a VTT accessible in Snippet
function initTrack() {
  const track = document.querySelector("track");
  let vttText = `WEBVTT`;
  for (let i = 0; i < 35; i++) {
    const t1 = (i + '').padStart(2, '0');
    const t2 = ((i + 1) + '').padStart(2, '0');
    vttText += `
      00:00:${t1}.000 --> 00:00:${t2}.000
      Test${i}`
  }
  const vttBlob = new Blob([vttText], {
    type: 'text/plain'
  });
  track.src = URL.createObjectURL(vttBlob);
}

video {
  max-height: 150px;
}

::cue {
  font-size: 30px
}

<div>
  <video id="video" controls>
    <source src="https://upload.wikimedia.org/wikipedia/commons/a/a4/BBH_gravitational_lensing_of_gw150914.webm">
    <track default kind="captions" label="English" srclang="en"/>
  </video>
</div>

如何获取字幕当前显示的文字

How to get subtitles' currently displayed text

javascript

html

html5-video

webvtt