Error for MULAW push stream on Windows

Hello,

I am trying to stream Twilio audio (MULAW) to Speech to Text service similar to #446 but I’m running C# on Windows.

I have GStreamer installed and using 1.11.0 of Microsoft.CognitiveServices.Speech

• OS: Windows
• Hardware - x64
• Programming language: C#

private SpeechRecognizer _recognizer;
        private PushAudioInputStream _inputStream;
        private AudioConfig _audioInput;

public async Task Start()
        {
            var config = SpeechConfig.FromSubscription(_projectSettings.AzureSpeechServiceSubscriptionKey, _projectSettings.AzureSpeechServiceRegionName);
            
            var audioFormat = AudioStreamFormat.GetCompressedFormat(AudioStreamContainerFormat.MULAW);

            _inputStream = AudioInputStream.CreatePushStream(audioFormat);
            _audioInput = AudioConfig.FromStreamInput(_inputStream);

            _recognizer = new SpeechRecognizer(config, _audioInput);
            _recognizer.SessionStarted += RecognizerStarted;
            _recognizer.Recognized += RecognizerRecognized;
            _recognizer.Canceled += RecognizerCancelled;

            await _recognizer.StartContinuousRecognitionAsync();
        }

I am taking the raw Twilio stream (media.payload see here) base64 decoding it and feeding it directly into the push stream with no buffer

public async Task Transcribe(byte[] audioBytes) { _inputStream.Write(audioBytes); }

I get the following error:

Message: The stream is of a different type than handled by this element. DebugInfo: riff-read.c(262): gst_riff_parse_file_header (): /GstPipeline:pipeline/GstWavParse:wavparse: Stream is no RIFF stream: 0x7a6f7afe SessionId: 3aeeac302e6f410a9411751dd25512c8

Please let me know if my setup is incorrect as I could find no examples with a stream to pushstream scenario

[garethkelly]

@twilio-jyoung - no problem Ive updated repo here

[garethkelly]

Hi @twilio-jyoung

I was able to get it working (credit to Joris Kalz from Microsoft who gave me the solution) Using the following two files:

https://www.codeproject.com/Articles/14237/Using-the-G711-standard MuLawDecoder.cs MuLawEncoder.cs

Let me know if you need me to upload my feature branch with full example.

Its a lot of code - and not even sure what it does 😃 so it would really be better if Microsoft supported MULAW/8000 format or Twilio was able to support streaming in WAV/PCM (was told this was on long term road map)