Passing buffer through Lambda

Serverless Framework
1

Im trying to pass some audio data, natively passed to Lambda as Buffer:

{
    "contentType": "audio/mpeg",
    "slots": {},
    "sessionAttributes": {},
    "message": "Sorry, I'm not able to assist at this time",
    "dialogState": "Failed",
    "inputTranscript": "",
    "audioStream": {
        "type": "Buffer",
        "data": [
            73,
            68,
            51,
            4,
            ...,
            170
        ]
    }
}

So my Lambda callback looks like this:

  callback(null, {
    headers: {
      'Content-Type': 'audio/mpeg', //also tried with html/text
      "Access-Control-Allow-Origin" : "*",
    },
    body: data.audioStream.toString('base64'),
    statusCode: 200
  });

Unfortunately on client site i’m receving some malformed data:
console.log(atob(data));

ID3#TSSELavf57.56.101ÿó`Ä@ùµAvʐÄ,aÁÀ@FP´1(ïʈ`ƒ¾\aÁÐÿù@@?ÁÀ@?X>ø>ÿYø>õð@?ê|à

oŸ·»a¨÷Yìõèl¯ßá
‡ýCm߁K##ÓHbPàŸ?¿ðŠ‡ª‡ŸþÚBÛ

Where is the problem?

2

Hi…I found a really simple solution I think it is worth to share, since it took me a few time to find this minimal working code.
If you have a common form, that send data with content type application/x-www-form-urlencoded, just flag “Lambda proxy integration”, then you will find encoded form data in event.body which can be parsed with Node.js querystring native module.