MmfExCodec
: Multimedia Framework codec plug-in
example
Found in: Examples\MultiMedia\MmfExCodec\
These are the main files contained in the examples. Some extra files may be needed to run the examples, and these will be found in the appropriate examples directory.
//
// main.cpp
// Copyright © 1997-2005 Symbian Software Ltd. All rights reserved.
//
#include <e32base.h>
#include <ecom.h>
#include <ImplementationProxy.h>
#include "MMFExPcm8toPcm16codec.h"
#include "UIDs.hrh"
// __________________________________________________________________________
// Exported proxy for instantiation method resolution
// Define the interface UIDs
const TImplementationProxy ImplementationTable[] =
{
IMPLEMENTATION_PROXY_ENTRY(KExCodecUID, CMMFExPcm8Pcm16Codec::NewL)
};
EXPORT_C const TImplementationProxy* ImplementationGroupProxy(TInt& aTableCount)
{
aTableCount = sizeof(ImplementationTable) / sizeof(TImplementationProxy);
return ImplementationTable;
}
// MMFExPcm8Pcm16Codec.cpp
// Copyright 1997-2005 Symbian Software Ltd. All rights reserved.
//
#include "MMFExPcm8ToPcm16Codec.h"
// Factory function
CMMFCodec* CMMFExPcm8Pcm16Codec::NewL(TAny* )
{
CMMFExPcm8Pcm16Codec* self=new(ELeave) CMMFExPcm8Pcm16Codec();
return self;
}
// Process source buffer and writes converted data to destination buffer
// The codec expands 1 byte to 2 bytes
TCodecProcessResult CMMFExPcm8Pcm16Codec::ProcessL(const CMMFBuffer& aSrc, CMMFBuffer& aDst)
{
TCodecProcessResult result;
result.iStatus = TCodecProcessResult::EProcessIncomplete;
// cast from generic CMMFBuffer to CMMFDataBuffer
iSrc = STATIC_CAST(const CMMFDataBuffer*, &aSrc);
iDst = STATIC_CAST(CMMFDataBuffer*, &aDst);
const TUint dstMaxLen = iDst->Data().MaxLength();
if (!dstMaxLen)
User::Leave(KErrArgument);
//don't scribble Destination (pDst) by only consuming enough source to fill pDst
TUint srcUse = (dstMaxLen - iDst->Position()) / 2;
const TUint srcLen = iSrc->Data().Length();
const TUint sourceRemain = srcLen - iSrc->Position();
//make sure we don't blow source by checking against remaining
//and clipping to minimum remaining if necessary
srcUse = (srcUse<sourceRemain ? srcUse : sourceRemain);
//we need to cast away CONST even on the source, as the TClass needs a TUint8*
TUint8* pSrc = CONST_CAST(TUint8*,iSrc->Data().Ptr());
pSrc += iSrc->Position();
TUint8* pDst = CONST_CAST(TUint8*,iDst->Data().Ptr());
pDst += iDst->Position();
Convert(pSrc, pDst, srcUse );
if ((srcUse * 2) + iDst->Position() < dstMaxLen)
result.iStatus = TCodecProcessResult::EDstNotFilled;
else if (srcUse + iSrc->Position() >= srcLen)
result.iStatus = TCodecProcessResult::EProcessComplete;
result.iSrcBytesProcessed = srcUse;
result.iDstBytesAdded = srcUse * 2;
iDst->Data().SetLength(iDst->Position() + (srcUse * 2));
return result;
}
// Helper to convert signed 8-bit to signed 16-bit
void CMMFExPcm8Pcm16Codec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples)
{
const TInt KAndMask8bit = 0xff;
TInt s16;
while (aSamples--)
{
s16 = (*aSrc++)<<8;
*aDst++ = STATIC_CAST( TInt8, s16&KAndMask8bit);
*aDst++ = STATIC_CAST( TInt8, (s16>>8)&KAndMask8bit);
}
}
// MMFExPcm8Pcm16Codec.h
// Copyright 1997-2005 Symbian Software Ltd. All rights reserved.
//
#ifndef __EXPCM8_PCM16_CODEC_H__
#define __EXPCM8_PCM16_CODEC_H__
#include <mmf\server\mmfcodec.h>
// Declares a MMF plug-in codec that converts
// from PCM8 format to PCM16
class CMMFExPcm8Pcm16Codec : public CMMFCodec
{
public:
// Construction
static CMMFCodec* NewL(TAny* aInitParams);
// Implement CMMFCodec
TCodecProcessResult ProcessL(const CMMFBuffer& aSrc, CMMFBuffer& aDst);
private:
// Helper function
void Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples);
private:
//owned by the Datapath
const CMMFDataBuffer* iSrc;
CMMFDataBuffer* iDst;
};
#endif
UIDs.hrh
#ifndef _MmfExCodecUIDS_H_
#define _MmfExCodecUIDS_H_
#define KPluginDLLUID 0x101F81D6
#define KExCodecUID 0x101F81D7
#endif
bld.inf
PRJ_MMPFILES
MMFExCodec.mmp
// MMFExCodec.mmp
//
// Copyright (c) 1997-2005 Symbian Software Ltd. All rights reserved.
//
TARGET MMFExCodec.dll
TARGETTYPE PLUGIN
// ECom Dll recognition UID followed by the unique UID for this dll
UID 0x10009D8D 0x101F81D6
VENDORID 0x70000001
CAPABILITY ALL -TCB
USERINCLUDE .
SYSTEMINCLUDE \epoc32\include \epoc32\include\ecom
SOURCEPATH .
SOURCE main.cpp
SOURCE MMFExPcm8ToPcm16Codec.cpp
START RESOURCE 101F81D6.rss
TARGETPATH \resource\Plugins
HEADER
END
LIBRARY euser.lib
LIBRARY ECom.lib
101F81D6.rss
#include <mmfPluginInterfaceUIDs.hrh>
#include "RegistryInfo.rh"
#include "UIDs.hrh"
RESOURCE REGISTRY_INFO theInfo
{
dll_uid = KPluginDLLUID;
interfaces =
{
INTERFACE_INFO
{
interface_uid = KMmfUidPluginInterfaceCodec ; // CMMFCodec
implementations =
{
IMPLEMENTATION_INFO
{
implementation_uid = KExCodecUID;
version_no = 1;
display_name = "PCM8 ->PCM16";
default_data = " P8, P16" ;//four CC codes.
opaque_data = "";
}
};
}
};
}
MmfExCodec
demonstrates how to implement a codec plug-in
for the Multimedia Framework. A codec converts media data in one encoding into
another encoding. The example converts audio data encoded with PCM8 into PCM16.
The program is an ECom plug-in that implements the codec interface
CMMFCodec
by the class CMMFExPcm8Pcm16Codec
. When a
client or media format requires a PCM8 to PCM16 codec, the Multimedia Framework
will instantiate a CMMFExPcm8Pcm16Codec
object, and call its
ProcessL()
member function to convert data supplied a source
buffer. As converting PCM8 into PCM16 only requires expanding each byte in the
source buffer into two bytes in the destination buffer,
CMMFExPcm8Pcm16Codec::ProcessL()
is not very complex.