Analysis of FLV packaging format

 FLV（Flash Video） yes Adobe A popular streaming media format designed and developed by the company , Because of its lightweight video file size 、 Simple package and so on , Make it very suitable for application on the Internet . Besides ,FLV have access to Flash Player Play it , and Flash Player Plug ins have been installed in most browsers around the world , This makes it possible to play through the web FLV The video is very easy . At present, mainstream video websites such as Youku , Tudou.com , LETV and other websites without exception use FLV Format .FLV The file suffix of encapsulation format is usually “.flv”.
　　 On the whole ,FLV Including file header （File Header） And the body （File Body） Two parts , The file body consists of a series of Tag form . So a FLV The file is as shown in the figure 1-1 structure .

among , Every Tag It also includes Previous Tag Size Field , That's the previous one Tag Size .Tag The type of can be video 、 Audio and Script, Every Tag Only one of the above three types of data can be included . chart 1-2 It shows FLV Detailed structure of the document . 

 

inputFlv: function* () {
      yield 9;
      var tmp = new ArrayBuffer(4);
      var tmp8 = new Uint8Array(tmp);
      var tmp32 = new Uint32Array(tmp);
      while (true) {
        tmp8[3] = 0;
        var t = yield 15;
        var type = t[4];
        tmp8[0] = t[7];
        tmp8[1] = t[6];
        tmp8[2] = t[5];
        var length = tmp32[0];
        tmp8[0] = t[10];
        tmp8[1] = t[9];
        tmp8[2] = t[8];
        var ts = tmp32[0];
        if (ts === 0xFFFFFF) {
          tmp8[3] = t[11];
          ts = tmp32[0];
        }
        var payload = yield length;
        switch (type) {
          case 8:
            this.opt.hasAudio && buffer.push({
              ts,
              payload,
              decoder: audioDecoder,
              type: 0
            });
            break;
          case 9:
            if (this.opt.useWCS) {
              wcsVideoDecoder.decode(payload, ts);
            } else {
              buffer.push({
                ts,
                payload,
                decoder: videoDecoder,
                type: payload[0] >> 4
              });
            }
            break;
        }
      }
    },