SpAudioStreamWrapper.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Speech / Src / Internal / SapiInterop / SpAudioStreamWrapper.cs / 1 / SpAudioStreamWrapper.cs
                        
                        
                            //------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
//
// Description: 
//		Maps an audio stream the SAPI ISpStreamFormat 
//
// History: 
//		7/10/2005	[....]		
//-----------------------------------------------------------------

using System; 
using System.IO;
using System.Runtime.InteropServices; 
using System.Runtime.InteropServices.ComTypes; 
using System.Speech.AudioFormat;
using System.Speech.Internal.SapiInterop; 
using System.Speech.Internal.Synthesis;

#pragma warning disable 1634, 1691 // Allows suppression of certain PreSharp messages.
 
using STATSTG = System.Runtime.InteropServices.ComTypes.STATSTG;
 
namespace System.Speech.Internal.SapiInterop 
{
    internal class SpAudioStreamWrapper : SpStreamWrapper, ISpStreamFormat 
    {
        //*******************************************************************
        //
        // Constructors 
        //
        //******************************************************************* 
 
        #region Constructors
 
        internal SpAudioStreamWrapper (Stream stream, SpeechAudioFormatInfo audioFormat) : base (stream)
        {
            // Assume PCM to start with
            _formatType = SAPIGuids.SPDFID_WaveFormatEx; 

            if (audioFormat != null) 
            { 
                WAVEFORMATEX wfx = new WAVEFORMATEX ();
                wfx.wFormatTag = (short) audioFormat.EncodingFormat; 
                wfx.nChannels = (short) audioFormat.ChannelCount;
                wfx.nSamplesPerSec = audioFormat.SamplesPerSecond;
                wfx.nAvgBytesPerSec = audioFormat.AverageBytesPerSecond;
                wfx.nBlockAlign = (short) audioFormat.BlockAlign; 
                wfx.wBitsPerSample = (short) audioFormat.BitsPerSample;
                wfx.cbSize = (short) audioFormat.FormatSpecificData ().Length; 
 
                _wfx = wfx.ToBytes ();
                if (wfx.cbSize == 0) 
                {
                    byte [] wfxTemp = new byte [_wfx.Length + wfx.cbSize];
                    Array.Copy (_wfx, wfxTemp, _wfx.Length);
                    Array.Copy (audioFormat.FormatSpecificData (), 0, wfxTemp, _wfx.Length, wfx.cbSize); 
                    _wfx = wfxTemp;
                } 
            } 
            else
            { 
                try
                {
                    GetStreamOffsets (stream);
                } 
                catch (IOException)
                { 
                    throw new FormatException (SR.Get (SRID.SynthesizerInvalidWaveFile)); 
                }
            } 
        }

        #endregion
 
        //********************************************************************
        // 
        // Public Methods 
        //
        //******************************************************************* 

        #region public Methods

        #region ISpStreamFormat interface implementation 

        void ISpStreamFormat.GetFormat (out Guid guid, out IntPtr format) 
        { 
            guid = _formatType;
            format = Marshal.AllocCoTaskMem (_wfx.Length); 
            Marshal.Copy (_wfx, 0, format, _wfx.Length);
        }

        #endregion 

        #endregion 
 
        //********************************************************************
        // 
        // Internal Properties
        //
        //********************************************************************
 
        #region Internal Methods
 
#pragma warning disable 56518 // The Binary reader cannot be disposed or it would close the underlying stream 

        ///  
        /// Builds the
        /// 
        /// 
        internal void GetStreamOffsets (Stream stream) 
        {
            BinaryReader br = new BinaryReader (stream); 
            // Read the riff Header 
            RIFFHDR riff = new RIFFHDR ();
 
            riff._id = br.ReadUInt32 ();
            riff._len = br.ReadInt32 ();
            riff._type = br.ReadUInt32 ();
 
            if (riff._id != RIFF_MARKER && riff._type != WAVE_MARKER)
            { 
                throw new FormatException (); 
            }
 
            BLOCKHDR block = new BLOCKHDR ();
            block._id = br.ReadUInt32 ();
            block._len = br.ReadInt32 ();
 
            if (block._id != FMT_MARKER)
            { 
                throw new FormatException (); 
            }
 
            // If the format is of type WAVEFORMAT then fake a cbByte with a length of zero
            _wfx = br.ReadBytes (block._len);

            // Hardcode the value of the size for the structure element 
            // as the C# compiler pads the structure to the closest 4 or 8 bytes
            if (block._len == 16) 
            { 
                byte [] wfxTemp = new byte [18];
                Array.Copy (_wfx, wfxTemp, 16); 
                _wfx = wfxTemp;
            }

            while (true) 
            {
                DATAHDR dataHdr = new DATAHDR (); 
 
                // check for the end of file (+8 for the 2 DWORD)
                if (stream.Position + 8 >= stream.Length) 
                {
                    break;
                }
                dataHdr._id = br.ReadUInt32 (); 
                dataHdr._len = br.ReadInt32 ();
 
                // Is this the WAVE data? 
                if (dataHdr._id == DATA_MARKER)
                { 
                    _endOfStreamPosition = stream.Position + dataHdr._len;
                    break;
                }
                else 
                {
                    // Skip this RIFF fragment. 
                    stream.Seek (dataHdr._len, SeekOrigin.Current); 
                }
            } 
        }

#pragma warning restore 56518 // The Binary reader cannot be disposed or it would close the underlying stream
 
        #endregion
 
        //******************************************************************* 
        //
        // Private Types 
        //
        //********************************************************************

        #region Private Types 

        private const UInt32 RIFF_MARKER = 0x46464952; 
        private const UInt32 WAVE_MARKER = 0x45564157; 
        private const UInt32 FMT_MARKER = 0x20746d66;
        private const UInt32 DATA_MARKER = 0x61746164; 

        [StructLayout (LayoutKind.Sequential)]
        private struct RIFFHDR
        { 
            internal UInt32 _id;
            internal Int32 _len;             /* file length less header */ 
            internal UInt32 _type;            /* should be "WAVE" */ 
        }
 
        [StructLayout (LayoutKind.Sequential)]
        private struct BLOCKHDR
        {
            internal UInt32 _id;              /* should be "fmt " or "data" */ 
            internal Int32 _len;             /* block size less header */
        }; 
 
        [StructLayout (LayoutKind.Sequential)]
        private struct DATAHDR 
        {
            internal UInt32 _id;              /* should be "fmt " or "data" */
            internal Int32 _len;              /* block size less header */
        } 

        #endregion 
 
        //*******************************************************************
        // 
        // Private Fields
        //
        //*******************************************************************
 
        #region Private Fields
 
        private byte [] _wfx; 
        private Guid _formatType;
 
        #endregion

    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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