/VmcController/MCEState/DirectShow/DvrmsMetadata.cs

// Stephen Toub

// stoub@microsoft.com



using System;

using System.IO;

using System.Text;

using System.Collections;

using System.Collections.Generic;

using System.Runtime.InteropServices;

using Microsoft.DirectShow;



namespace Microsoft.DirectShow.Metadata

{

    /// <summary>

    /// Metadata editor for DVR-MS files.

    /// </summary>

    public sealed class DvrmsMetadata: IDisposable

	{

		IStreamBufferRecordingAttribute _editor;



		/// <summary>Initializes the editor.</summary>

		/// <param name="filepath">The path to the file.</param>

		public DvrmsMetadata(string filepath)

		{

			IFileSourceFilter sourceFilter = (IFileSourceFilter)ClassId.CoCreateInstance(ClassId.RecordingAttributes);

			sourceFilter.Load(filepath, null);

			_editor = (IStreamBufferRecordingAttribute)sourceFilter;

		}



		/// <summary>Gets all of the attributes on a file.</summary>

		/// <returns>A collection of the attributes from the file.</returns>

        public Dictionary<string, MetadataItem> GetAttributes()

		{

			if (_editor == null) throw new ObjectDisposedException(GetType().Name);



            Dictionary<string, MetadataItem> propsRetrieved = new Dictionary<string, MetadataItem>();

			object obj = _editor.EnumAttributes();



			// Get the number of attributes

			ushort attributeCount = _editor.GetAttributeCount(0);



			// Get each attribute by index

			for(ushort i = 0; i < attributeCount; i++)

			{

				MetadataItemType attributeType;

				StringBuilder attributeName = null;

				byte[] attributeValue = null;

				ushort attributeNameLength = 0;

				ushort attributeValueLength = 0;



				// Get the lengths of the name and the value, then use them to create buffers to receive them

				uint reserved = 0;

				_editor.GetAttributeByIndex(i, ref reserved, attributeName, ref attributeNameLength,

					out attributeType, attributeValue, ref attributeValueLength);

				attributeName = new StringBuilder(attributeNameLength);

				attributeValue = new byte[attributeValueLength];



				// Get the name and value

				_editor.GetAttributeByIndex(i, ref reserved, attributeName, ref attributeNameLength,

					out attributeType, attributeValue, ref attributeValueLength);



				// If we got a name, parse the value and add the metadata item

				if (attributeName != null && attributeName.Length > 0)

				{

					object val = ParseAttributeValue(attributeType, attributeValue);

					string key = attributeName.ToString().TrimEnd('\0');

					propsRetrieved[key] = new MetadataItem(key, val, attributeType);

				}

			}



			// Return the parsed items

			return propsRetrieved;

		}



        /// <summary>Gets the value of the specified attribute.</summary>

        /// <param name="itemType">The type of the attribute.</param>

        /// <param name="valueData">The byte array to be parsed.</param>

        private static object ParseAttributeValue(MetadataItemType itemType, byte[] valueData)

        {

            if (!Enum.IsDefined(typeof(MetadataItemType), itemType))

                throw new ArgumentOutOfRangeException("itemType");

            if (valueData == null) throw new ArgumentNullException("valueData");



            // Convert the attribute value to a byte array based on the item type.

            switch (itemType)

            {

                case MetadataItemType.String:

                    StringBuilder sb = new StringBuilder(valueData.Length);

                    for (int i = 0; i < valueData.Length - 2; i += 2)

                    {

                        sb.Append(Convert.ToString(BitConverter.ToChar(valueData, i)));

                    }

                    string result = sb.ToString();

                    if (result.EndsWith("\\0")) result = result.Substring(0, result.Length - 2);

                    return result;

                case MetadataItemType.Boolean: return BitConverter.ToBoolean(valueData, 0);

                case MetadataItemType.Dword: return BitConverter.ToInt32(valueData, 0);

                case MetadataItemType.Qword: return BitConverter.ToInt64(valueData, 0);

                case MetadataItemType.Word: return BitConverter.ToInt16(valueData, 0);

                case MetadataItemType.Guid: return new Guid(valueData);

                case MetadataItemType.Binary: return valueData;

                default: throw new ArgumentOutOfRangeException("itemType");

            }

        }



        /// <summary>

        /// Releases unmanaged and - optionally - managed resources

        /// </summary>

        public void Dispose()

        {

            Dispose(true);

            GC.SuppressFinalize(this);

        }



        /// <summary>

        /// Releases unmanaged and - optionally - managed resources

        /// </summary>

        /// <param name="disposeManagedObjs"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>

        void Dispose(bool disposeManagedObjs)

		{

            if (disposeManagedObjs && _editor != null)

			{

				while(Marshal.ReleaseComObject(_editor) > 0);

				_editor = null;

			}

		}



        /// <summary>

        /// Releases unmanaged resources and performs other cleanup operations before the

        /// <see cref="DvrmsMetadata"/> is reclaimed by garbage collection.

        /// </summary>

        ~DvrmsMetadata()

        {

            Dispose(false);

        }



		[ComImport]

		[Guid("16CA4E03-FE69-4705-BD41-5B7DFC0C95F3")]

		[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]

		private interface IStreamBufferRecordingAttribute

		{

			/// <summary>Sets an attribute on a recording object. If an attribute of the same name already exists, overwrites the old.</summary>

			/// <param name="ulReserved">Reserved. Set this parameter to zero.</param>

			/// <param name="pszAttributeName">Wide-character string that contains the name of the attribute.</param>

			/// <param name="StreamBufferAttributeType">Defines the data type of the attribute data.</param>

			/// <param name="pbAttribute">Pointer to a buffer that contains the attribute data.</param>

			/// <param name="cbAttributeLength">The size of the buffer specified in pbAttribute.</param>

			void SetAttribute(

				[In] uint ulReserved, 

				[In, MarshalAs(UnmanagedType.LPWStr)] string pszAttributeName,

				[In] MetadataItemType StreamBufferAttributeType,

				[In, MarshalAs(UnmanagedType.LPArray)] byte [] pbAttribute,

				[In] ushort cbAttributeLength);



			/// <summary>Returns the number of attributes that are currently defined for this stream buffer file.</summary>

			/// <param name="ulReserved">Reserved. Set this parameter to zero.</param>

			/// <returns>Number of attributes that are currently defined for this stream buffer file.</returns>

			ushort GetAttributeCount([In] uint ulReserved);



			/// <summary>Given a name, returns the attribute data.</summary>

			/// <param name="pszAttributeName">Wide-character string that contains the name of the attribute.</param>

			/// <param name="pulReserved">Reserved. Set this parameter to zero.</param>

			/// <param name="pStreamBufferAttributeType">

			/// Pointer to a variable that receives a member of the STREAMBUFFER_ATTR_DATATYPE enumeration. 

			/// This value indicates the data type that you should use to interpret the attribute, which is 

			/// returned in the pbAttribute parameter.

			/// </param>

			/// <param name="pbAttribute">

			/// Pointer to a buffer that receives the attribute, as an array of bytes. Specify the size of the buffer in the 

			/// pcbLength parameter. To find out the required size for the array, set pbAttribute to NULL and check the 

			/// value that is returned in pcbLength.

			/// </param>

			/// <param name="pcbLength">

			/// On input, specifies the size of the buffer given in pbAttribute, in bytes. On output, 

			/// contains the number of bytes that were copied to the buffer.

			/// </param>

			void GetAttributeByName(

				[In, MarshalAs(UnmanagedType.LPWStr)] string pszAttributeName,

				[In] ref uint pulReserved,

				[Out] out MetadataItemType pStreamBufferAttributeType,

				[Out, MarshalAs(UnmanagedType.LPArray)] byte[] pbAttribute,

				[In, Out] ref ushort pcbLength);



			/// <summary>The GetAttributeByIndex method retrieves an attribute, specified by index number.</summary>

			/// <param name="wIndex">Zero-based index of the attribute to retrieve.</param>

			/// <param name="pulReserved">Reserved. Set this parameter to zero.</param>

			/// <param name="pszAttributeName">Pointer to a buffer that receives the name of the attribute, as a null-terminated wide-character string.</param>

			/// <param name="pcchNameLength">On input, specifies the size of the buffer given in pszAttributeName, in wide characters.</param>

			/// <param name="pStreamBufferAttributeType">Pointer to a variable that receives a member of the STREAMBUFFER_ATTR_DATATYPE enumeration.</param>

			/// <param name="pbAttribute">Pointer to a buffer that receives the attribute, as an array of bytes.</param>

			/// <param name="pcbLength">On input, specifies the size of the buffer given in pbAttribute, in bytes.</param>

			void GetAttributeByIndex (

				[In] ushort wIndex,

				[In, Out] ref uint pulReserved,

				[Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszAttributeName,

				[In, Out] ref ushort pcchNameLength,

				[Out] out MetadataItemType pStreamBufferAttributeType,

				[Out, MarshalAs(UnmanagedType.LPArray)] byte [] pbAttribute,

				[In, Out] ref ushort pcbLength);



			/// <summary>The EnumAttributes method enumerates the existing attributes of the stream buffer file.</summary>

			/// <returns>Address of a variable that receives an IEnumStreamBufferRecordingAttrib interface pointer.</returns>

			[return: MarshalAs(UnmanagedType.Interface)]

			object EnumAttributes();

		}



    }



    /// <summary>The type of a metadata attribute value.</summary>

    public enum MetadataItemType

    {

        /// <summary>DWORD</summary>

        Dword = 0,

        /// <summary>String</summary>

        String = 1,

        /// <summary>Binary</summary>

        Binary = 2,

        /// <summary>Boolean</summary>

        Boolean = 3,

        /// <summary>QWORD</summary>

        Qword = 4,

        /// <summary>WORD</summary>

        Word = 5,

        /// <summary>Guid</summary>

        Guid = 6,

    }



    /// <summary>Represents a metadata attribute.</summary>

    public class MetadataItem : ICloneable

    {

        /// <summary>The name of the attribute.</summary>

        private string _name;

        /// <summary>The value of the attribute.</summary>

        private object _value;

        /// <summary>The type of the attribute value.</summary>

        private MetadataItemType _type;



        /// <summary>Initializes the metadata item.</summary>

        /// <param name="name">The name of the attribute.</param>

        /// <param name="value">The value of the attribute.</param>

        /// <param name="type">The type of the attribute value.</param>

        internal MetadataItem(string name, object value, MetadataItemType type)

        {

            Name = name;

            Value = value;

            Type = type;

        }



        /// <summary>Gets or sets the name of the attribute.</summary>

        public string Name { get { return _name; } set { _name = value; } }

        /// <summary>Gets or sets the value of the attribute.</summary>

        public object Value { get { return _value; } set { _value = value; } }

        /// <summary>Gets or sets the type of the attribute value.</summary>

        public MetadataItemType Type { get { return _type; } set { _type = value; } }



        /// <summary>Clones the attribute item.</summary>

        /// <returns>A shallow copy of the attribute.</returns>

        public MetadataItem Clone() { return (MetadataItem)MemberwiseClone(); }



        /// <summary>Clones the attribute item.</summary>

        /// <returns>A shallow copy of the attribute.</returns>

        object ICloneable.Clone() { return Clone(); }

    }



}