atom_stz2.cpp

完整的RTP RTSP代码库

/*
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is MPEG4IP.
 * 
 * The Initial Developer of the Original Code is Cisco Systems Inc.
 * Portions created by Cisco Systems Inc. are
 * Copyright (C) Cisco Systems Inc. 2001.  All Rights Reserved.
 * 
 * Contributor(s): 
 *		Dave Mackie		[e-mail]
 */

#include "mp4common.h"

/*
 * This is used for the 4 bit sample size below.  We need the sampleCount
 * to be correct for the number of samples, but the table size needs to
 * be correct to read and write it.
 */

class MP4HalfSizeTableProperty : public MP4TableProperty
{
public:
  MP4HalfSizeTableProperty(char *name, MP4IntegerProperty *pCountProperty) :
    MP4TableProperty(name, pCountProperty) {};

  // The count is half the actual size
  u_int32_t GetCount() {
    return (m_pCountProperty->GetValue() + 1)/ 2;
  };
  void SetCount(u_int32_t count) {
    m_pCountProperty->SetValue(count * 2);
  };
};


MP4Stz2Atom::MP4Stz2Atom() 
	: MP4Atom("stz2") 
{
	AddVersionAndFlags(); /* 0, 1 */

	AddReserved("reserved", 3); /* 2 */

	AddProperty( /* 3 */
		new MP4Integer8Property("fieldSize")); 

	MP4Integer32Property* pCount = 
		new MP4Integer32Property("sampleCount"); 
	AddProperty(pCount); /* 4 */

}

void MP4Stz2Atom::Read() 
{
	ReadProperties(0, 4);

	uint8_t fieldSize = 
	  ((MP4Integer8Property *)m_pProperties[3])->GetValue();
	//	uint32_t sampleCount = 0;

	MP4Integer32Property* pCount = 
	  (MP4Integer32Property *)m_pProperties[4]; 

	MP4TableProperty *pTable;
	if (fieldSize != 4) {
	  pTable = new MP4TableProperty("entries", pCount);
	} else {
	  // 4 bit field size uses a special table.
	  pTable = new MP4HalfSizeTableProperty("entries", pCount);
	}

	AddProperty(pTable);

	if (fieldSize == 16) {
	  pTable->AddProperty( /* 5/0 */
			      new MP4Integer16Property("entrySize"));
	} else {
	  pTable->AddProperty( /* 5/0 */
			      new MP4Integer8Property("entrySize"));
	}
	  
	ReadProperties(4);

	Skip();	// to end of atom
}