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|
/*****************************************************************
|
| AP4 - Expandable base class
|
| Copyright 2002-2008 Axiomatic Systems, LLC
|
|
| This file is part of Bento4/AP4 (MP4 Atom Processing Library).
|
| Unless you have obtained Bento4 under a difference license,
| this version of Bento4 is Bento4|GPL.
| Bento4|GPL is free software; you can redistribute it and/or modify
| it under the terms of the GNU General Public License as published by
| the Free Software Foundation; either version 2, or (at your option)
| any later version.
|
| Bento4|GPL is distributed in the hope that it will be useful,
| but WITHOUT ANY WARRANTY; without even the implied warranty of
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
| GNU General Public License for more details.
|
| You should have received a copy of the GNU General Public License
| along with Bento4|GPL; see the file COPYING. If not, write to the
| Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
| 02111-1307, USA.
|
****************************************************************/
/*----------------------------------------------------------------------
| includes
+---------------------------------------------------------------------*/
#include "Ap4Debug.h"
#include "Ap4Descriptor.h"
#include "Ap4Utils.h"
#include "Ap4Atom.h"
/*----------------------------------------------------------------------
| AP4_Expandable::MinHeaderSize
+---------------------------------------------------------------------*/
AP4_Size
AP4_Expandable::MinHeaderSize(AP4_Size payload_size)
{
// compute how many bytes are needed to encode the payload size
// plus tag
return 2+(payload_size/128);
}
/*----------------------------------------------------------------------
| AP4_Expandable::AP4_Expandable
+---------------------------------------------------------------------*/
AP4_Expandable::AP4_Expandable(AP4_UI32 class_id,
ClassIdSize class_id_size,
AP4_Size header_size,
AP4_Size payload_size) :
m_ClassId(class_id),
m_ClassIdSize(class_id_size),
m_HeaderSize(header_size),
m_PayloadSize(payload_size)
{
AP4_ASSERT(header_size >= 1+1);
AP4_ASSERT(header_size <= 1+4);
}
/*----------------------------------------------------------------------
| AP4_Expandable::Write
+---------------------------------------------------------------------*/
AP4_Result
AP4_Expandable::Write(AP4_ByteStream& stream)
{
AP4_Result result;
// write the class id
switch (m_ClassIdSize) {
case CLASS_ID_SIZE_08:
result = stream.WriteUI08((AP4_UI08)m_ClassId);
if (AP4_FAILED(result)) return result;
break;
default:
return AP4_ERROR_INTERNAL;
}
// write the size
AP4_ASSERT(m_HeaderSize-1 <= 8);
AP4_ASSERT(m_HeaderSize >= 2);
unsigned int size = m_PayloadSize;
unsigned char bytes[8];
// last bytes of the encoded size
bytes[m_HeaderSize-2] = size&0x7F;
// leading bytes of the encoded size
for (int i=m_HeaderSize-3; i>=0; i--) {
// move to the next 7 bits
size >>= 7;
// output a byte with a top bit marker
bytes[i] = (size&0x7F) | 0x80;
}
result = stream.Write(bytes, m_HeaderSize-1);
if (AP4_FAILED(result)) return result;
// write the fields
WriteFields(stream);
return result;
}
/*----------------------------------------------------------------------
| AP4_Expandable::Inspect
+---------------------------------------------------------------------*/
AP4_Result
AP4_Expandable::Inspect(AP4_AtomInspector& inspector)
{
char name[64];
AP4_FormatString(name, sizeof(name), "#:%02x", m_ClassId);
inspector.StartDescriptor(name, GetHeaderSize(), GetSize());
inspector.EndDescriptor();
return AP4_SUCCESS;
}
|
