using System.Collections;
using System.Data;
using System.Text;
using System.Runtime.InteropServices;
using System;

namespace RtpAudio
{

    #region//編解碼動態(tài)庫引用
    public static class Codec
    {
        /// <summary>
        /// 語音編碼初始化操作
        /// </summary>
        /// <param name="quality"></param>
        [DllImport("speexCodec.dll", EntryPoint = "encoder_init")]
        public extern static void encoder_init(int quality);

        /// <summary>
        ///語音編碼的釋放
        /// </summary>
        [DllImport("speexCodec.dll", EntryPoint = "encoder_dispose")]
        public extern static void encoder_dispose();

        /// <summary>
        ///語音編碼的執(zhí)行過程
        /// </summary>
        /// <param name="data">要進行編碼的數(shù)據(jù)</param>
        /// <param name="output">編碼之后的數(shù)據(jù)</param>
        /// <returns></returns>
        [DllImport("speexCodec.dll", EntryPoint = "encoder_encode")]
        public extern static int encoder_encode(short[] data, byte[] output);

        /// <summary>
        ///解碼初始化
        /// </summary>
        [DllImport("speexCodec.dll", EntryPoint = "decoder_init")]
        public extern static void decoder_init();

        /// <summary>
        ///語音解碼釋放 
        /// </summary>
        [DllImport("speexCodec.dll", EntryPoint = "decoder_dispose")]
        public extern static void decoder_dispose();

        /// <summary>
        ///語音解碼
        /// </summary>
        /// <param name="nbBytes">解碼的字節(jié)數(shù)</param>
        /// <param name="data">要進行解碼的語音數(shù)據(jù)</param>
        /// <param name="output">解碼后輸出的語音數(shù)據(jù)</param>
        [DllImport("speexCodec.dll", EntryPoint = "decoder_decode")]
        public extern static void decoder_decode(int nbBytes, byte[] data, short[] output);
    }
    #endregion

    #region// 編碼
    public class SpeexEncoder : IDisposable
    {
        const int FrameSize = 160;

        private bool _init = false;

        public void Dispose()
        {
            Codec.encoder_dispose();
            _init = false;
        }

        /// <summary>
        /// 初始化結構保存數(shù)據(jù)，quality的值可以取 8表示 15kbps
        /// </summary>
        /// <param name="quality"></param>
        public void SetQuality(int quality)
        {
            if (_init)
                Codec.encoder_dispose();
            Codec.encoder_init(quality);
            _init = true;
        }

        //在開始捕獲后，每隔 1 秒（緩沖區(qū)設置為可以保存最長 10 秒的音頻，超過的話最早的內容會被覆蓋）讀出當前的音頻流，
        //然后送給 SpeexEncoder 編碼
        /// <summary>
        ///數(shù)據(jù)編碼
        /// </summary>
        /// <param name="data">要進行編碼的數(shù)據(jù)</param>
        /// <returns></returns>
        public byte[] Encode(byte[] data)
        {
            if (!_init)
                throw new NotSupportedException("尚未設置編碼器比特率。");
            //data的長度必須為 160 *2 的整數(shù)倍
            if (data.Length % (FrameSize * 2) != 0)  //將要進行 語音編碼的數(shù)據(jù) 切分為多個 320字節(jié)的單元
                throw new ArgumentException("數(shù)據(jù)無效。", "data");
            int nbBytes;
            short[] input = new short[FrameSize]; //一會要進行語音編碼數(shù)據(jù)
            byte[] buffer = new byte[200];
            byte[] output = new byte[0];

            for (int i = 0; i < data.Length / (FrameSize * 2); i++) //將 data數(shù)組 劃分為 多個 320 單元
            {
                for (int j = 0; j < input.Length; j++)
                    input[j] = (short)(data[i * FrameSize * 2 + j * 2] + data[i * FrameSize * 2 + j * 2 + 1] * 0x100);

                nbBytes = Codec.encoder_encode(input, buffer); //針對 每 320 字節(jié)即編碼， 編碼之后的數(shù)據(jù)長度

                Array.Resize<byte>(ref output, output.Length + nbBytes + sizeof(int));
                Array.Copy(buffer, 0, output, output.Length - nbBytes, nbBytes);
                for (int j = 0; j < sizeof(int); j++)
                {
                    output[output.Length - nbBytes - sizeof(int) + j] = (byte)(nbBytes % 0x100);
                    nbBytes /= 0x100;
                }
            }
            return output;
        }
    }
    #endregion

    #region//解碼
    public class SpeexDecoder : IDisposable
    {
        public const int FrameSize = 160;

        private bool _init = false;

        /// <summary>
        ///解碼釋放
        /// </summary>
        public void Dispose()
        {
            if (_init)
                Codec.decoder_dispose();
        }

       
        
        /// <summary>
        ///解碼語音數(shù)據(jù)
        /// </summary>
        /// <param name="data">要解碼的語音數(shù)據(jù)</param>
        /// <returns>解碼之后的語音數(shù)組</returns>
        public byte[] Decode(byte[] data)
        {
            if (!_init)
                Codec.decoder_init(); //解碼初始化
            int nbBytes, index = 0;

            byte[] input; // input數(shù)組為一暫存數(shù)組
            short[] buffer = new short[FrameSize];
            byte[] output = new byte[0];

            while (index < data.Length)
            {
                nbBytes = 0;
                //每段的前四字節(jié)存儲的是 該段數(shù)據(jù)的長度值
                index += sizeof(int);
                for (int i = 1; i <= sizeof(int); i++)
                    nbBytes = nbBytes * 0x100 + data[index - i]; 

                input = new byte[nbBytes]; //讀出對應的解碼段的長度

                Array.Copy(data, index, input, 0, input.Length);// 將接收的編碼語音數(shù)據(jù)拷貝到  input數(shù)組中去

                index += input.Length;

                //解碼之后的數(shù)據(jù)在 buffer中
                Codec.decoder_decode(nbBytes, input, buffer); //對數(shù)據(jù)進行解碼,解碼后語音數(shù)據(jù)即還原了

                Array.Resize<byte>(ref output, output.Length + FrameSize * 2);

                for (int i = 0; i < FrameSize; i++)
                {
                    output[output.Length - FrameSize * 2 + i * 2] = (byte)(buffer[i] % 0x100);
                    output[output.Length - FrameSize * 2 + i * 2 + 1] = (byte)(buffer[i] / 0x100);
                }
            }
            return output;
        }
    }
    #endregion

}