android-cloud-H5/screenIos/decoder.js

var isFinish = false;
var isSwitchSharpness = false;
var h264Queue = [];
var ret;

var maxWidth = 1080;
var maxHeight = 1920;
var globalYuvPtr = undefined;
var golbalYuvData;//全局，只分配一次
var renderCount = 0;

function doSomeInit() {
  var allocSize = maxWidth * maxHeight * 3;
  golbalYuvData = new Uint8Array(allocSize);
}

self.Module = {
  onRuntimeInitialized: function () {
    isFinish = true;
    doSomeInit();
    ret = Module._openDecoder();

    if (!ret) {
      console.log("打开编码器成功");
    }
  }
};

self.importScripts("ffmpeghelper.js");

self.addEventListener('message', function (e) {
  var msg = e.data;
  if (msg.type == "rawData") {
    var buffer = e.data.data;

    if (buffer[0] !== 0xff) { // 音频解码
      if (isSwitchSharpness) {
        var type = buffer[4] & 0x1f;
        if (type == 7 || type == 8) {
          console.log("视频类型:" + type);
          isSwitchSharpness = false;
          h264Queue.push(buffer);
        }
      } else {
        h264Queue.push(buffer);
      }

    }
  }

  if (msg.type == "switchSharpness") { // 分辨率切换实现
    isSwitchSharpness = true;
    closeDecoder();
    var ret = Module._openDecoder();//再次开启解码器
    var timeFlag = setInterval(decodeVideo, 1);
    console.log("切换解码器成功");
  }
}, false);

function PrintfLog(str) {
  var curTime = new Date().getTime();
  var objData = {
    cmd: 0,
    data: str,
    time: curTime
  };
  self.postMessage(objData);
}

function doRequestIFrame() {
  var objData = {
    cmd: 5,
  };
  self.postMessage(objData);
}


function decodeVideo() {
  if (h264Queue.length > 0 && isFinish) {
    decodeH264(h264Queue.shift());
  }
}


var timeFlag = setInterval(decodeVideo, 1);

//实现C 端到js yuv数据赋值, 并分配给opengl 渲染
/*yuvData, 存放yuv数据的数组
* inputYuvPtr C++ 
*/
function dispatchYuvData(yuvData, inputYuvPtr, videoWidth, videoHeight, copyLen) {
  for (i = 0; i < copyLen; i++) {
    yuvData[i] = Module.HEAPU8[(inputYuvPtr) + i];
  }

  var curTime = new Date().getTime();
  var objData = {
    cmd: 1,
    data: yuvData,
    time: curTime,
    width: videoWidth,
    height: videoHeight
  };
  self.postMessage(objData);
}

function decodeH264(data) {
  var frameWidth = 0;
  var frameHeight = 0;
  var inputPtr = Module._malloc(data.length); //输入数据

  for (i = 0; i < data.length; i++) {
    Module.HEAPU8[(inputPtr) + i] = data[i]; //转换为堆数据
  }

  var time = new Date().getTime();
  var allocSize = maxWidth * maxHeight * 3 / 2;
  if (globalYuvPtr == undefined) {
    globalYuvPtr = Module._malloc(allocSize);
  }

  var ret = Module._feedData(inputPtr, data.length, globalYuvPtr);

  if (ret >= 0)//解码成功才考虑渲染
  {
    frameWidth = Module._getVideoWidth();//拿到解码器宽、高
    frameHeight = Module._getVideoHeight();
    var curCost = new Date().getTime() - time;
    var copyLen = frameWidth * frameHeight * 3 / 2;//只拷贝必须的长度

    if (renderCount > 1)//第一帧因为画面时全绿色的不渲染
    {
      dispatchYuvData(golbalYuvData, globalYuvPtr, frameWidth, frameHeight, copyLen);
    } else {
      renderCount++;
    }
  }

  Module._free(inputPtr);
}


function closeDecoder() {
  clearInterval(timeFlag);//关闭原有定时器
  Module._closeDecoder();
  renderCount = 0;

  if (globalYuvPtr != undefined) {
    Module._free(globalYuvPtr);
    globalYuvPtr = undefined;
  }
  console.log("此时buffer长度: %d", h264Queue.length);
  while (h264Queue.lengh > 0) {
    h264Queue.shift();
  }
}