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https://github.com/axiomatic-systems/Bento4.git
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123 lines
3.9 KiB
C++
123 lines
3.9 KiB
C++
/*****************************************************************
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| AP4 - Expandable base class
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| Copyright 2002-2008 Axiomatic Systems, LLC
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| This file is part of Bento4/AP4 (MP4 Atom Processing Library).
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| Unless you have obtained Bento4 under a difference license,
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| this version of Bento4 is Bento4|GPL.
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| Bento4|GPL 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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| Bento4|GPL 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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| You should have received a copy of the GNU General Public License
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| along with Bento4|GPL; see the file COPYING. If not, write to the
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| Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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| 02111-1307, USA.
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****************************************************************/
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/*----------------------------------------------------------------------
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| includes
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+---------------------------------------------------------------------*/
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#include "Ap4Debug.h"
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#include "Ap4Descriptor.h"
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#include "Ap4Utils.h"
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#include "Ap4Atom.h"
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/*----------------------------------------------------------------------
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| AP4_Expandable::MinHeaderSize
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+---------------------------------------------------------------------*/
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AP4_Size
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AP4_Expandable::MinHeaderSize(AP4_Size payload_size)
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{
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// compute how many bytes are needed to encode the payload size
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// plus tag
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return 2+(payload_size/128);
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}
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/*----------------------------------------------------------------------
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| AP4_Expandable::AP4_Expandable
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+---------------------------------------------------------------------*/
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AP4_Expandable::AP4_Expandable(AP4_UI32 class_id,
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ClassIdSize class_id_size,
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AP4_Size header_size,
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AP4_Size payload_size) :
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m_ClassId(class_id),
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m_ClassIdSize(class_id_size),
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m_HeaderSize(header_size),
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m_PayloadSize(payload_size)
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{
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AP4_ASSERT(header_size >= 1+1);
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AP4_ASSERT(header_size <= 1+4);
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}
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/*----------------------------------------------------------------------
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| AP4_Expandable::Write
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+---------------------------------------------------------------------*/
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AP4_Result
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AP4_Expandable::Write(AP4_ByteStream& stream)
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{
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AP4_Result result;
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// write the class id
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switch (m_ClassIdSize) {
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case CLASS_ID_SIZE_08:
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result = stream.WriteUI08((AP4_UI08)m_ClassId);
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if (AP4_FAILED(result)) return result;
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break;
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default:
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return AP4_ERROR_INTERNAL;
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}
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// write the size
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AP4_ASSERT(m_HeaderSize-1 <= 8);
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AP4_ASSERT(m_HeaderSize >= 2);
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unsigned int size = m_PayloadSize;
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unsigned char bytes[8];
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// last bytes of the encoded size
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bytes[m_HeaderSize-2] = size&0x7F;
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// leading bytes of the encoded size
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for (int i=m_HeaderSize-3; i>=0; i--) {
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// move to the next 7 bits
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size >>= 7;
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// output a byte with a top bit marker
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bytes[i] = (size&0x7F) | 0x80;
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}
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result = stream.Write(bytes, m_HeaderSize-1);
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if (AP4_FAILED(result)) return result;
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// write the fields
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WriteFields(stream);
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return result;
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}
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/*----------------------------------------------------------------------
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| AP4_Expandable::Inspect
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+---------------------------------------------------------------------*/
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AP4_Result
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AP4_Expandable::Inspect(AP4_AtomInspector& inspector)
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{
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char name[64];
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AP4_FormatString(name, sizeof(name), "#:%02x", m_ClassId);
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inspector.StartDescriptor(name, GetHeaderSize(), GetSize());
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inspector.EndDescriptor();
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return AP4_SUCCESS;
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}
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