title: Getting error 400 when trying to use Azure Speech Recognition and Flutter
body: <p>I've been given the task to use the Azure Speech Recognition API on a Flutter application. The app is supposed to record the user's voice and send it to the Azure API. I've tried to use the only pub.dev plugin that I could find, but it did not work and the documentation does not have a Flutter example. Since the request returned 200 on Postman and I was able to make it work on a Javascript application, the problem must be my Flutter application, maybe something on the request, since it is returning code 400 (bad request), saying that the request contains invalid data.</p>
  <p>The code below is my request to the API. The file which I'm using to get the bytes is a wav file containing the recorded voice</p>
  <p>Could you help me? Thanks for the attention.</p>
  <pre><code>      var bytes = file.readAsBytesSync();
        var response = await Dio().post(
          &quot;https://brazilsouth.stt.speech.microsoft.com/speech/recognition/conversation/cognitiveservices/v1?language=pt-BR&quot;,
          data: bytes,
          options: Options(
              headers: {
                &quot;Ocp-Apim-Subscription-Key&quot;: &quot;subscriptionKey&quot;,
                &quot;Content-Type&quot;: &quot;audio/wav&quot;
              },
        );
        print(response.statusCode);
  </code></pre>