title: Agora Cloud Recording doesn't record mixed in audio files
body: <p>Hi I have been successfully recording an Agora audio call, where one person speaks in a broadcast role, and during the call mixes in a number of audio files.</p>
  <p>All the audio was being recorded until we upgraded to flutter 2 and associated upgraded packages.</p>
  <p>Now all that is recorded is the broadcaster voice, and no mixed in audio.</p>
  <p>The broadcaster and audience members can all hear the mixed in audio within the call  without issue.</p>
  <p>The code (Flutter) is similar to this:</p>
  <p>Mix in Audio into a valid RTC session, with default settings</p>
  <pre><code>    final playing = await session.playAudioFile(path, (){
        state = MessagePlayerState.STOPPED;
        if (!disposing) {
          whenFinished();
        }
      });
  </code></pre>
  <p>The recording options are as follows (My UID is a hardcoded string, that is not the same as any participant UIDs)</p>
  <pre><code>    http.Response response = await http.post(
        Uri.https(AGORA_REST_URL, '$AGORA_REST_API_VERSION/$appId/cloud_recording/resourceid/$resourceId/mode/mix/start'),
        headers: &lt;String, String&gt;{
          HttpHeaders.authorizationHeader: 'Basic $basicAuth',
          HttpHeaders.contentTypeHeader: 'application/json; charset=UTF-8',
        },
        body: jsonEncode(&lt;String, dynamic&gt;{
          'cname': channelName,
          'uid': uid,
          'clientRequest': {
            'recordingConfig':{
              'channelType':0,
              'streamTypes':2, // TODO: Should be a streamTypes of 0 (audio only), but get failures.
              'audioProfile':1,
              'videoStreamType':0,
              'maxIdleTime':120,
              'transcodingConfig':{
                'width':360,
                'height':640,
                'fps':30,
                'bitrate':600,
                'maxResolutionUid':'1',
                'mixedVideoLayout':1
              },
              'recordingFileConfig':{
                'avFileType': ['hls','mp4']
              }
            },
            'storageConfig':{
              'vendor':1,
              'region':3,
              'bucket':AWS_RECORDING_BUCKET, // TODO: Env Var
              'accessKey':AWS_BUCKET_ACCESS_KEY,
              'secretKey':AWS_BUCKET_SECRET_KEY,
            }
          },
        }),
      );
  </code></pre>
  <p>The m3u8 and  ts files are present in the S3 bucket.</p>
  <p>Adjusting the metadata tags in S3 results in a file that plays fine in Safari, but no mixed in audio is heard.</p>
  <p>Converting the file to aac with ffmpeg shows this error</p>
  <pre><code>[hls @ 0x7fd6cc808200] Opening '2838cfc6254e9fec2e3088976f39d7ce_bip_20210618014151427.ts' for reading
  [mpegts @ 0x7fd6cc00a600] Packet corrupt (stream = 0, dts = 1437390).
  size=     480kB time=00:00:30.69 bitrate= 128.1kbits/s speed=1.49e+03x    
  video:0kB audio:470kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 2.093976%
  </code></pre>
  <p>And the result is the same as from the S3 bucket.</p>
  <p>Any help or hints appreciated.</p>