mp4descriptor.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"

MP4Descriptor::MP4Descriptor(u_int8_t tag) {
	m_tag = tag;
	m_pParentAtom = NULL;
	m_start = 0;
	m_size = 0;
	m_readMutatePoint = 0;
}

MP4Descriptor::~MP4Descriptor() 
{
	for (u_int32_t i = 0; i < m_pProperties.Size(); i++) {
		delete m_pProperties[i];
	}
}

void MP4Descriptor::AddProperty(MP4Property* pProperty) 
{
	ASSERT(pProperty);
	m_pProperties.Add(pProperty);
	pProperty->SetParentAtom(m_pParentAtom);
}

bool MP4Descriptor::FindContainedProperty(const char *name,
	MP4Property** ppProperty, u_int32_t* pIndex)
{
	u_int32_t numProperties = m_pProperties.Size();

	for (u_int32_t i = 0; i < numProperties; i++) {
		if (m_pProperties[i]->FindProperty(name, ppProperty, pIndex)) { 
			return true;
		}
	}
	return false;
}

void MP4Descriptor::Generate()
{
	// generate properties
	for (u_int32_t i = 0; i < m_pProperties.Size(); i++) {
		m_pProperties[i]->Generate();
	}
}

void MP4Descriptor::Read(MP4File* pFile)
{
	ReadHeader(pFile);

	ReadProperties(pFile, 0, m_readMutatePoint);

	Mutate();

	ReadProperties(pFile, m_readMutatePoint);

	// flush any leftover read bits
	pFile->FlushReadBits();
}

void MP4Descriptor::ReadHeader(MP4File* pFile)
{
	VERBOSE_READ(pFile->GetVerbosity(),
		printf("ReadDescriptor: pos = 0x"X64"\n", 
			pFile->GetPosition()));

	// read tag and length
	u_int8_t tag = pFile->ReadUInt8();
	if (m_tag) {
		ASSERT(tag == m_tag);
	} else {
		m_tag = tag;
	}
	m_size = pFile->ReadMpegLength();
	m_start = pFile->GetPosition();

	VERBOSE_READ(pFile->GetVerbosity(),
		printf("ReadDescriptor: tag 0x%02x data size %u (0x%x)\n", 
			m_tag, m_size, m_size));
}

void MP4Descriptor::ReadProperties(MP4File* pFile, 
	u_int32_t propStartIndex, u_int32_t propCount)
{
	u_int32_t numProperties = MIN(propCount, 
		m_pProperties.Size() - propStartIndex);

	for (u_int32_t i = propStartIndex; 
	  i < propStartIndex + numProperties; i++) {

		MP4Property* pProperty = m_pProperties[i];

		int32_t remaining = m_size - (pFile->GetPosition() - m_start);

		if (pProperty->GetType() == DescriptorProperty) {
		   	if (remaining > 0) {
				// place a limit on how far this sub-descriptor looks
				((MP4DescriptorProperty*)pProperty)->SetSizeLimit(remaining);
				pProperty->Read(pFile);
			} // else do nothing, empty descriptor
		} else {
			// non-descriptor property
			if (remaining >= 0) {
				pProperty->Read(pFile);

				if (pProperty->GetType() == TableProperty) {
					VERBOSE_READ_TABLE(pFile->GetVerbosity(), 
						printf("Read: "); pProperty->Dump(stdout, 0, true));
				} else {
					VERBOSE_READ(pFile->GetVerbosity(), 
						printf("Read: "); pProperty->Dump(stdout, 0, true));
				}
			} else {
				VERBOSE_ERROR(pFile->GetVerbosity(),
					printf("Overran descriptor, tag %u data size %u property %u\n",
					m_tag, m_size, i));
				throw new MP4Error("overran descriptor",
					 "MP4Descriptor::ReadProperties");
			}
		} 
	}
}

void MP4Descriptor::Write(MP4File* pFile)
{
	// call virtual function to adapt properties before writing
	Mutate();

	u_int32_t numProperties = m_pProperties.Size();

	if (numProperties == 0) {
		WARNING(numProperties == 0);
		return;
	}

	// write tag and length placeholder
	pFile->WriteUInt8(m_tag);
	u_int64_t lengthPos = pFile->GetPosition();
	pFile->WriteMpegLength(0);
	u_int64_t startPos = pFile->GetPosition();

	for (u_int32_t i = 0; i < numProperties; i++) {
		m_pProperties[i]->Write(pFile);
	}

	// align with byte boundary (rarely necessary)
	pFile->PadWriteBits();

	// go back and write correct length
	u_int64_t endPos = pFile->GetPosition();
	pFile->SetPosition(lengthPos);
	pFile->WriteMpegLength(endPos - startPos);
	pFile->SetPosition(endPos);
}

void MP4Descriptor::WriteToMemory(MP4File* pFile,
	u_int8_t** ppBytes, u_int64_t* pNumBytes)
{
	// use memory buffer to save descriptor in memory
	// instead of going directly to disk

	pFile->EnableMemoryBuffer();

	Write(pFile);

	pFile->DisableMemoryBuffer(ppBytes, pNumBytes);
}

void MP4Descriptor::Dump(FILE* pFile, u_int8_t indent, bool dumpImplicits)
{
	// call virtual function to adapt properties before dumping
	Mutate();

	u_int32_t numProperties = m_pProperties.Size();

	if (numProperties == 0) {
		WARNING(numProperties == 0);
		return;
	}
	for (u_int32_t i = 0; i < numProperties; i++) {
		m_pProperties[i]->Dump(pFile, indent, dumpImplicits);
	}
}

u_int8_t MP4Descriptor::GetDepth() 
{
	if (m_pParentAtom) {
		return m_pParentAtom->GetDepth();
	}
	return 0;
}