AudioContext给音频提高音量

b站有些视频音量设为100%时,不够响,可以用AudioContext API进行突破限制

复制代码

/**
 * 带平滑过渡的增益控制
 * @param {HTMLMediaElement} mediaElement - video/audio 元素
 * @param {number} gainValue - 目标增益值
 * @param {number} duration - 过渡时间（秒），默认 0.1秒
 */
async function adjustMediaGainSmooth(mediaElement, gainValue, duration = 0.1) {
  const targetGain = Math.max(0, Math.min(20, gainValue));

  if (!mediaElement._audioCtx) {
    const AudioContext = window.AudioContext || window.webkitAudioContext;
    mediaElement._audioCtx = new AudioContext();
    mediaElement._gainNode = mediaElement._audioCtx.createGain();
    mediaElement._source = mediaElement._audioCtx.createMediaElementSource(mediaElement);

    mediaElement._source.connect(mediaElement._gainNode);
    mediaElement._gainNode.connect(mediaElement._audioCtx.destination);
  }

  if (mediaElement._audioCtx.state === 'suspended') {
    await mediaElement._audioCtx.resume();
  }

  const now = mediaElement._audioCtx.currentTime;
  const currentGain = mediaElement._gainNode.gain.value;

  // 取消之前的调度，从当前值平滑过渡到目标值
  mediaElement._gainNode.gain.cancelScheduledValues(now);
  mediaElement._gainNode.gain.setValueAtTime(currentGain, now);
  mediaElement._gainNode.gain.linearRampToValueAtTime(targetGain, now + duration);

  return targetGain;
}

// 使用：1秒内平滑过渡到 10 倍音量
await adjustMediaGainSmooth(document.querySelector("#bilibili-player video"), 20, 1.0);

/**

* 带平滑过渡的增益控制

* @param {HTMLMediaElement} mediaElement - video/audio 元素

* @param {number} gainValue - 目标增益值

* @param {number} duration - 过渡时间（秒），默认 0.1秒

async function adjustMediaGainSmooth(mediaElement, gainValue, duration = 0.1) {

const targetGain = Math.max(0, Math.min(20, gainValue));

if (!mediaElement._audioCtx) {

const AudioContext = window.AudioContext || window.webkitAudioContext;

mediaElement._audioCtx = new AudioContext();

mediaElement._gainNode = mediaElement._audioCtx.createGain();

mediaElement._source = mediaElement._audioCtx.createMediaElementSource(mediaElement);

mediaElement._source.connect(mediaElement._gainNode);

mediaElement._gainNode.connect(mediaElement._audioCtx.destination);

}

if (mediaElement._audioCtx.state === 'suspended') {

await mediaElement._audioCtx.resume();

}

const now = mediaElement._audioCtx.currentTime;

const currentGain = mediaElement._gainNode.gain.value;

// 取消之前的调度，从当前值平滑过渡到目标值

mediaElement._gainNode.gain.cancelScheduledValues(now);

mediaElement._gainNode.gain.setValueAtTime(currentGain, now);

mediaElement._gainNode.gain.linearRampToValueAtTime(targetGain, now + duration);

return targetGain;

}

// 使用：1秒内平滑过渡到 10 倍音量

await adjustMediaGainSmooth(document.querySelector("#bilibili-player video"), 20, 1.0);