AquesTalk Unityプラグイン。バッファサイズは固定(手抜き)。

AquesTalk.cs

using System;
using System.Runtime.InteropServices;

public class AquesTalk : MonoBehaviour {
        [DllImport ("AquesTalkPlugin")]
        private static extern int AquesTalk2Synthe(string koe, int speed, IntPtr data, int size);

        private float[] buffer = new float[1 * 1024 * 1024];

        void Synthe(string koe) {
                GCHandle handle = GCHandle.Alloc (buffer, GCHandleType.Pinned);
                int size = AquesTalk2Synthe (koe, 100, handle.AddrOfPinnedObject (), buffer.Length);
                handle.Free ();

                float[] data = new float[size];
                Buffer.BlockCopy (buffer, 0, data, 0, sizeof(float) * size);

                AudioClip audioClip = AudioClip.Create ("AquesTalk", size, 1, 8000, false, false);
                audioClip.SetData (data, 0);

                audio.clip = audioClip;
                audio.Play ();
        }
}

Plugin.cpp

#include <algorithm>
#include <AquesTalk2Eva/AquesTalk2.h>

extern "C" {

int AquesTalk2Synthe(const char *koe, int speed, float *data, int size) {
    int wavSize;
    unsigned char* wav = AquesTalk2_Synthe_Utf8(koe, speed, &wavSize, NULL);

    for (int i = 0; i < std::min(size, (wavSize - 44) / 2); i++) {
        short sample = *(wav + 44 + i * 2) + *(wav + 44 + i * 2 + 1) * 256;
        *(data + i) = (float)sample / 32768.0;
    }
    
    AquesTalk2_FreeWave(wav);
    
    return (wavSize - 44) / 2;
}

}