135 lines
5.3 KiB
C#
135 lines
5.3 KiB
C#
//////////////////////////////////////////////////////////////////////////////////
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// //
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// Copyright © 2005-2020 nzsjb //
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// //
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// This Program is free software; you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation; either version 2, or (at your option) //
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// any later version. //
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// //
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// This Program is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License for more details. //
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// //
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// You should have received a copy of the GNU General Public License //
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// along with GNU Make; see the file COPYING. If not, write to //
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// the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. //
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// http://www.gnu.org/copyleft/gpl.html //
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// //
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//////////////////////////////////////////////////////////////////////////////////
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using System;
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namespace DVBServices
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{
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/// <summary>
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/// The class that describes a basic MPEG2 section header.
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/// </summary>
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public class Mpeg2BasicHeader
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{
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/// <summary>
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/// Get the table identification.
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/// </summary>
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public int TableID { get { return (tableID); } }
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/// <summary>
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/// Get the section length.
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/// </summary>
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public int SectionLength { get { return (sectionLength); } }
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/// <summary>
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/// Return true if the section is private data; false otherwise.
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/// </summary>
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public bool PrivateIndicator { get { return (privateIndicator); } }
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/// <summary>
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/// Return true if the sysntax indicator is set; false otherwise.
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/// </summary>
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public bool SyntaxIndicator { get { return (syntaxIndicator); } }
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/// <summary>
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/// Get the index of the next byte in the MPEG2 section following the header.
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/// </summary>
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/// <exception cref="InvalidOperationException">
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/// The header has not been processed.
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/// </exception>
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public virtual int Index
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{
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get
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{
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if (lastIndex == -1)
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throw (new InvalidOperationException("Mpeg2BasicHeader: Index requested before block processed"));
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return (lastIndex);
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}
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}
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private int tableID;
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private int sectionLength;
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private bool privateIndicator;
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private bool syntaxIndicator;
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private int lastIndex = -1;
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private int dataLength;
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// MPEG basic header layout is as follows
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//
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// tableID byte uimsbf
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//
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// section syntax ind 1 bit bslbf
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// private indicator 1 bit bslbf
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// reserved 2 bits bslbf
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// section length 12 bits uimsbf
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/// <summary>
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/// Initialize a new instance of the Mpeg2BasicHeader class.
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/// </summary>
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public Mpeg2BasicHeader() { }
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/// <summary>
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/// Parse the header.
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/// </summary>
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/// <param name="byteData">The MPEG2 section containing the header.</param>
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public virtual void Process(byte[] byteData)
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{
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lastIndex = 0;
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dataLength = byteData.Length;
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try
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{
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tableID = (int)byteData[lastIndex];
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lastIndex++;
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syntaxIndicator = (byteData[lastIndex] & 0x80) != 0;
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privateIndicator = (byteData[lastIndex] & 0x40) != 0;
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sectionLength = ((byteData[lastIndex] & 0x0f) * 256) + (int)byteData[lastIndex + 1];
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lastIndex += 2;
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Validate();
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}
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catch (IndexOutOfRangeException)
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{
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throw (new ArgumentOutOfRangeException("MPEG2 basic header is short"));
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}
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}
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/// <summary>
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/// Validate the header fields.
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/// </summary>
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/// <exception cref="ArgumentOutOfRangeException">
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/// A header field is not valid.
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/// </exception>
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public virtual void Validate()
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{
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if (dataLength > 4096)
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throw (new ArgumentOutOfRangeException("MPEG2 Section data length wrong"));
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if (sectionLength < 1 || sectionLength > dataLength - 3)
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throw (new ArgumentOutOfRangeException("MPEG2 Section length wrong"));
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}
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/// <summary>
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/// Log the header fields.
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/// </summary>
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public virtual void LogMessage() { }
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}
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}
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