# All files / src/demux sample-aes.js

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     /**
     * SAMPLE-AES decrypter
    */

    import Decrypter from '../crypt/decrypter';

    class SampleAesDecrypter {
      constructor (observer, config, decryptdata, discardEPB) {
        this.decryptdata = decryptdata;
        this.discardEPB = discardEPB;
        this.decrypter = new Decrypter(observer, config, { removePKCS7Padding: false });
      }

      decryptBuffer (encryptedData, callback) {
        this.decrypter.decrypt(encryptedData, this.decryptdata.key.buffer, this.decryptdata.iv.buffer, callback);
      }

      // AAC - encrypt all full 16 bytes blocks starting from offset 16
      decryptAacSample (samples, sampleIndex, callback, sync) {
        let curUnit = samples[sampleIndex].unit;
        let encryptedData = curUnit.subarray(16, curUnit.length - curUnit.length % 16);
        let encryptedBuffer = encryptedData.buffer.slice(
          encryptedData.byteOffset,
          encryptedData.byteOffset + encryptedData.length);

        let localthis = this;
        this.decryptBuffer(encryptedBuffer, function (decryptedData) {
          decryptedData = new Uint8Array(decryptedData);
          curUnit.set(decryptedData, 16);

          if (!sync) {
            localthis.decryptAacSamples(samples, sampleIndex + 1, callback);
          }
        });
      }

      decryptAacSamples (samples, sampleIndex, callback) {
        for (;; sampleIndex++) {
          if (sampleIndex >= samples.length) {
            callback();
            return;
          }

          if (samples[sampleIndex].unit.length < 32) {
            continue;
          }

          let sync = this.decrypter.isSync();

          this.decryptAacSample(samples, sampleIndex, callback, sync);

          if (!sync) {
            return;
          }
        }
      }

      // AVC - encrypt one 16 bytes block out of ten, starting from offset 32
      getAvcEncryptedData (decodedData) {
        let encryptedDataLen = Math.floor((decodedData.length - 48) / 160) * 16 + 16;
        let encryptedData = new Int8Array(encryptedDataLen);
        let outputPos = 0;
        for (let inputPos = 32; inputPos <= decodedData.length - 16; inputPos += 160, outputPos += 16) {
          encryptedData.set(decodedData.subarray(inputPos, inputPos + 16), outputPos);
        }

        return encryptedData;
      }

      getAvcDecryptedUnit (decodedData, decryptedData) {
        decryptedData = new Uint8Array(decryptedData);
        let inputPos = 0;
        for (let outputPos = 32; outputPos <= decodedData.length - 16; outputPos += 160, inputPos += 16) {
          decodedData.set(decryptedData.subarray(inputPos, inputPos + 16), outputPos);
        }

        return decodedData;
      }

      decryptAvcSample (samples, sampleIndex, unitIndex, callback, curUnit, sync) {
        let decodedData = this.discardEPB(curUnit.data);
        let encryptedData = this.getAvcEncryptedData(decodedData);
        let localthis = this;

        this.decryptBuffer(encryptedData.buffer, function (decryptedData) {
          curUnit.data = localthis.getAvcDecryptedUnit(decodedData, decryptedData);

          if (!sync) {
            localthis.decryptAvcSamples(samples, sampleIndex, unitIndex + 1, callback);
          }
        });
      }

      decryptAvcSamples (samples, sampleIndex, unitIndex, callback) {
        for (;; sampleIndex++, unitIndex = 0) {
          if (sampleIndex >= samples.length) {
            callback();
            return;
          }

          let curUnits = samples[sampleIndex].units;
          for (;; unitIndex++) {
            if (unitIndex >= curUnits.length) {
              break;
            }

            let curUnit = curUnits[unitIndex];
            if (curUnit.length <= 48 || (curUnit.type !== 1 && curUnit.type !== 5)) {
              continue;
            }

            let sync = this.decrypter.isSync();

            this.decryptAvcSample(samples, sampleIndex, unitIndex, callback, curUnit, sync);

            if (!sync) {
              return;
            }
          }
        }
      }
    }

    export default SampleAesDecrypter;