AWS Transcribe Medical BadRequestException: Your stream is too big. Reduce the frame size and try your request again.

The highWaterMark value was set to 128 and I reduced it to 64 and it still gives the error:

2023-02-04T17:31:04.829Z	77e692ab-1c41-46b9-99de-4e5fd12363ae	ERROR	Error processing transcribe stream. SessionId:  87997632-5d42-425e-b6ab-6cad9e9f0aff {
    "name": "BadRequestException",
    "$fault": "client",
    "$metadata": {},
    "message": "Your stream is too big. Reduce the frame size and try your request again."
}

The JavaScript demo client is putting the audio file on a Kinesis Video Streams stream and the backend is getting the audio and passing it to Transcribe streaming. I'm doing this to save the audio stream in a file in the backend. In the end, there will be various clients/systems with microphones that will send audio to KVS.

Is there something with that portion that could be resulting in the error?

I can see that all fragments from KVS are being read, the transcription stops after a few TranscriptEvents. I tried changing highWaterMark to 1024, but same error.

Here is the Lambda code that reads audio fragments from KVS and sends them to a combined stream for Transcribe & audio file:

  import Block from 'block-stream2';
  const audioStream = new Block(2);

  const combinedStream = new PassThrough();
  const combinedStreamBlock = new Block(2);
  combinedStream.pipe(combinedStreamBlock);
  combinedStreamBlock.on('data', (chunk) => {
    // send to transcribe
    transcribePassthroughStream.write(chunk);

    // save to tmp file
    writeRecordingStream.write(chunk);
  });

  // audioStream comes from KVS
  audioStream.pipe(combinedStream);