Joe Horn 的啟示錄

Jan 04

[C#] 取得 wav 檔案格式

前陣子，在工作上剛好需要對 wav 檔案格式進行判定，可是 NAudio 製作出來的格式用來作判斷又有錯誤，所以土法煉鋼寫了一個小 class：

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.IO;

    public class Wave
    {
        public struct Format
        {
            public String FileName = String.Empty;
            public Boolean PCM = false;
            public uint Channel = 0;
            public uint SampleRate = 0;
            public uint BitsPerSample = 0;
            public uint ByteRate = 0;
            public uint BlockAlign = 0;
        };

        private Format _fmt;

        private void fillUp()
        {
            _fmt.ByteRate = _fmt.Channel * _fmt.SampleRate * _fmt.BitsPerSample / 8;
            _fmt.BlockAlign = _fmt.Channel * _fmt.BitsPerSample / 8;
        }

        public Format getType(String fileName)
        {
            _fmt.FileName = fileName;

            try
            {
                FileStream fs = File.OpenRead(@fileName);
                Byte[] readTmp = new Byte[36];

                fs.Read(readTmp, 0, 36);
                fs.close();

                if (BitConverter.ToUInt16(readTmp, 20) == 1)
                {
                    _fmt.PCM = true;
                }

                _fmt.Channel = BitConverter.ToUInt16(readTmp, 22);
                _fmt.SampleRate = BitConverter.ToUInt32(readTmp, 24);
                _fmt.BitsPerSample = BitConverter.ToUInt16(readTmp, 34);

                fillUp();
            }
            catch (Exception e)
            {
                Console.WriteLine("Wave.getType(fileName) Error : " + e.ToString());
            }
            return _fmt;
        }
    }