MicStream.cs

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// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

using System.Runtime.InteropServices;
using System.Text;
using UnityEngine;

namespace HoloToolkit.Unity.InputModule
{
    public class MicStream
    {
        // This class replaces Unity's Microphone object.
        // This class is made for HoloLens mic stream selection but should work well on all Windows 10 devices.
        // Choose from one of three possible microphone modes on HoloLens.
        // There is an example of how to use this script in HoloToolkit-Tests\Input\Scripts\MicStreamDemo.cs.

        // Streams: LOW_QUALITY_VOICE is optimized for speech analysis.
        //          COMMUNICATIONS is higher quality voice and is probably preferred.
        //          ROOM_CAPTURE tries to get the sounds of the room more than the voice of the user.
        // This can only be set on initialization.
        public enum StreamCategory { LOW_QUALITY_VOICE, HIGH_QUALITY_VOICE, ROOM_CAPTURE }

        public enum ErrorCodes { ALREADY_RUNNING = -10, NO_AUDIO_DEVICE, NO_INPUT_DEVICE, ALREADY_RECORDING, GRAPH_NOT_EXIST, CHANNEL_COUNT_MISMATCH, FILE_CREATION_PERMISSION_ERROR, NOT_ENOUGH_DATA, NEED_ENABLED_MIC_CAPABILITY };

        const int MAX_PATH = 260; // 260 is maximum path length in windows, to be returned when we MicStopRecording

        [UnmanagedFunctionPointer(CallingConvention.StdCall)] // If included in MicStartStream, this callback will be triggered when audio data is ready. This is not the preferred method for Game Engines and can probably be ignored.
        public delegate void LiveMicCallback();

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicInitializeDefault(int category);

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicInitializeCustomRate(int category, int samplerate);

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicStartStream(bool keepData, bool previewOnDevice, LiveMicCallback micsignal);

        public static int MicStartStream(bool keepData, bool previewOnDevice)
        {
            return MicStartStream(keepData, previewOnDevice, null);
        }

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicStopStream();

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicStartRecording(string filename, bool previewOnDevice);

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern void MicStopRecording(StringBuilder sb);

        public static string MicStopRecording()
        {
            StringBuilder builder = new StringBuilder(MAX_PATH); 
            MicStopRecording(builder);
            return builder.ToString();
        }

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicDestroy();

        [DllImport("MicStreamSelector", ExactSpelling = true)]

        public static extern int MicPause();

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicResume();

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicSetGain(float g);

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        private static extern int MicGetDefaultBufferSize();

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        private static extern int MicGetDefaultNumChannels();

        [DllImport("MicStreamSelector", ExactSpelling = true)]
        public static extern int MicGetFrame(float[] buffer, int length, int numchannels);

        public static bool CheckForErrorOnCall(int returnCode)
        {
            switch (returnCode)
            {
                case (int)ErrorCodes.ALREADY_RECORDING:
                    Debug.LogWarning("WARNING: Tried to start recording when you were already doing so. You need to stop your previous recording before you can start again.");
                    return false;
                case (int)ErrorCodes.ALREADY_RUNNING:
                    Debug.LogWarning("WARNING: Tried to initialize microphone more than once");
                    return false;
                case (int)ErrorCodes.GRAPH_NOT_EXIST:
                    Debug.LogError("ERROR: Tried to do microphone things without a properly initialized microphone. \n Do you have a mic plugged into a functional audio system and did you call MicInitialize() before anything else ??");
                    return false;
                case (int)ErrorCodes.NO_AUDIO_DEVICE:
                    Debug.LogError("ERROR: Tried to start microphone, but you don't appear to have a functional audio device. check your OS audio settings.");
                    return false;
                case (int)ErrorCodes.NO_INPUT_DEVICE:
                    Debug.LogError("ERROR: Tried to start microphone, but you don't have one plugged in, do you?");
                    return false;
                case (int)ErrorCodes.CHANNEL_COUNT_MISMATCH:
                    Debug.LogError("ERROR: Microphone had a channel count mismatch internally on device. Try setting different mono/stereo options in OS mic settings.");
                    return false;
                case (int)ErrorCodes.FILE_CREATION_PERMISSION_ERROR:
                    Debug.LogError("ERROR: Didn't have access to create file in Music library. Make sure permissions to write to Music library are set granted.");
                    return false;
                case (int)ErrorCodes.NOT_ENOUGH_DATA:
                    // usually not an error, means the device hasn't produced enough data yet because it just started running
                    return false;
                case (int)ErrorCodes.NEED_ENABLED_MIC_CAPABILITY:
                    Debug.LogError("ERROR: Seems like you forgot to enable the microphone capabilities in your Unity permissions");
                    return false;
            }
            return true;
        }
    }
}