/*

* Copyright (c) 2006 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  Class definition for the MP3 utility functions.

*

*/

//  INCLUDES

#include "MP3AudioControllerUtility.h"

#include "DebugMacros.h"

#include <mmfdatabuffer.h>

// CONSTANTS

const TUint KFlagsOffset            = 4;

const TUint KFramesOffset           = 8;

// Bit rates in bits/sec supported by MPEG2, MPEG1 and MPEG2.5 respectively

const TInt16 cBitRateTable[3][16] =

	{

		{-1,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0},

		{-1,32,40,48,56,64,80,96,112,128,160,192,224,256,320,0},

		{-1,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0},

	};

// Sampling frequencies supported by MPEG2, MPEG1 and MPEG2.5 respectively

const TUint16 cSamplingFrequencyTable[3][4] =

	{

		{22050,24000,16000,0},

		{44100,48000,32000,0},

		{11025,12000,8000,0},

	};

// Maximum MP3 frame size

const TInt KRawMp3MaxFrameSize      = 1441;     // 320kbit/s @ 32kHz = int((144*320000/32000)+1)

// The size of MP3 header, header must include bits for determining frame length

const TInt KRawMp3FrameHeaderSize   = 5;

// ============================ MEMBER FUNCTIONS ===============================

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::CMP3AudioControllerUtility

// C++ default constructor can NOT contain any code, that

// might leave.

// -----------------------------------------------------------------------------

//

CMP3AudioControllerUtility::CMP3AudioControllerUtility()

    {

    }

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::ConstructL

// Symbian 2nd phase constructor can leave.

// -----------------------------------------------------------------------------

//

void CMP3AudioControllerUtility::ConstructL()

    {

	DP0(_L("CMP3AudioControllerUtility::ConstructL"));

    }

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::NewL

// Two-phased constructor.

// -----------------------------------------------------------------------------

//

EXPORT_C CMP3AudioControllerUtility* CMP3AudioControllerUtility::NewL()

	{

	DP0(_L("CMP3AudioControllerUtility::NewL"));

    CMP3AudioControllerUtility* self = new(ELeave) CMP3AudioControllerUtility;

    CleanupStack::PushL(self);

    self->ConstructL();

    CleanupStack::Pop(self);

    return self;

    }

// Destructor

EXPORT_C CMP3AudioControllerUtility::~CMP3AudioControllerUtility()

    {

	iFramesArray.Close();

    }

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::ScanHeaderL

// Used to scan the header information

// -----------------------------------------------------------------------------

//

void CMP3AudioControllerUtility::ScanHeaderL(

	CMMFDataBuffer* aDataBuf)

	{

	DP0(_L("CMP3AudioControllerUtility::ScanHeaderL"));

	iBitRateFrozen = EFalse;

    const TUint8* bufferPtr = aDataBuf->Data().Ptr();

    TInt bufferSize = aDataBuf->Data().Size();

	TInt scannedBuffer = 0;

    if (iLenMetaData == 0)

        {

        iSyncOffset = 0;

        iLenMetaData = ID3HeaderLength(aDataBuf);

        }

    TInt bufferRemaining = bufferSize;

    while (iLenMetaData > 0)

        {

	    if (iLenMetaData >= bufferRemaining)

	        {

	        // this buffer contains all metadata

	        iSyncOffset += bufferRemaining;

	        iLenMetaData -= bufferRemaining;

	        User::Leave(KErrNotReady);

	        }

	    else

	        {

	        iSyncOffset += iLenMetaData;

	        scannedBuffer += iLenMetaData;

	        // be sure to check for following id3 tags

	        bufferRemaining = bufferSize - scannedBuffer;

	        aDataBuf->SetPosition(scannedBuffer);

	        iLenMetaData = ID3HeaderLength(aDataBuf);

    	    }

        }

    TInt seekOffset = 0;

    aDataBuf->SetPosition(scannedBuffer);

	seekOffset = SeekSync(aDataBuf, bufferSize);

    iSyncOffset += seekOffset; // offset to this point from content beginning

    scannedBuffer += seekOffset; // offset to this point in this buffer

    aDataBuf->SetPosition(scannedBuffer);

	if (seekOffset == bufferSize)

		{

        User::Leave(KErrNotReady);

		}

	DP0(_L("CMP3AudioControllerUtility::ScanHeaderL - Calling FrameInfo"));

	TAudioFrameInfo frameInfo;

	TInt frameLen = FrameInfo(bufferPtr+scannedBuffer, bufferSize-scannedBuffer, frameInfo);

	iHeaderOffset = 0;

    iBitRate = 0;

    iDurationUs = 0;

    iSamplingRate = frameInfo.iSamplingRate;

    iBitRate = frameInfo.iBitRate;

    iSamplesPerFrame = frameInfo.iFrameSamples;

    iChannels = frameInfo.iChannels;

	iSamplingRateOut = frameInfo.iSamplingRateOut;

	if (iSamplingRate > 0)

	    {

    	iFrameTimeMs = (iSamplesPerFrame*1000)/iSamplingRate;

	    }

    TInt aNumFrames;

	iFormatIsVBR = ParseFirstFrame(aDataBuf, &aNumFrames);

	iNumFrames = aNumFrames;

	TInt frameBytes = 0;

	TInt avgFrameLen = 0;

	TInt frames = 0;

	TInt scaling=0;

	TInt round=0;

	// We could have used the bitrate found above for CBR MP3 content and not continue to average

	// the bitrate. However, some users can manipulated the file and append other bitrate content.

	// Since it is not too difficult, we can update the bitrate above with an averaged bitrate.

	// If we want to only use the bitate above for cbr, we would set the bitrate frozen flag and

	// on the condition that it's not iFormatIsVBR and the bitrate is non-zero. 

	for (TInt i=1; i<=100; i++)

		{

		if (scannedBuffer > bufferSize)

			{

			break;

			}

		frameLen = FrameInfo(bufferPtr+scannedBuffer, bufferSize-scannedBuffer, frameInfo);

		scannedBuffer += frameLen;

		if (frameLen <= 0)

			{

			break;

			}

		if (i == 10) // ignore the first 10 frames

			{

			frameBytes = frameLen;

			frames = 1;    	        	

			}

		else

			{

			frameBytes += frameLen;

			frames++;    	        	

			}	

		avgFrameLen = frameBytes / frames; // frames is always non-zero here

		scaling = frameBytes*10/frames;

		round = scaling%10;

		if(round > 5)

		    {

		     ++avgFrameLen;

		    }

		}

	iBitRate = (avgFrameLen * 8 * iSamplingRate) / iSamplesPerFrame;

	}

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::SeekSync

// -----------------------------------------------------------------------------

//

TInt CMP3AudioControllerUtility::SeekSync(CMMFDataBuffer* aBuf,	TInt aBufLen)

    {

    const TUint bufStart = aBuf->Position();

    const TUint8* buf = aBuf->Data().Ptr() + bufStart;

    const TInt KMaxFrames = 3;          // number of frames to check

    const TInt KNotFound = aBufLen;     // sync not found position

    TAudioFrameInfo frameInfo;           // frame parameters

    TInt i = 0;

    TInt syncPos = KNotFound;

    TInt maxSeek = KMaxFrames;

    const TUint8* endPtr = buf+aBufLen-bufStart;

    // Seek a valid frame candidate byte by byte until a valid frame

    // is found or all bytes have been checked.

    while (buf < endPtr  &&  syncPos == KNotFound)

	    {

        TInt seekCount = 0;

        const TUint8* framePtr = buf;

        TInt frameBufLen = aBufLen;

        syncPos = i;

		// Check the validity of this frame candidate and the nearest next

        // frames. If they are not OK, syncPos will be set to KNotFound.

        while (framePtr < endPtr  &&  syncPos != KNotFound  && seekCount < maxSeek)

	        {

            TInt length = FrameInfo(framePtr, frameBufLen, frameInfo);

			if (length == 0)

            	{

                syncPos = KNotFound;

				}

            if ((length > 0) && (frameInfo.iBitRate < 0))

            	{

                maxSeek = 1; // free formatcase

				}

            framePtr += length;

            frameBufLen -= length;

            seekCount++;

			// consider SYNC not found if we reach end of buffer before finding 3 SYNC frames

			if ((framePtr >= endPtr) && (seekCount < maxSeek))

				{

				syncPos = KNotFound;

				buf += (aBufLen-1);      // force an exit from while loop

				}

        	}

        buf++; aBufLen--; i++;

    	}

    return syncPos;

    }

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::FrameInfo

// -----------------------------------------------------------------------------

//

TInt CMP3AudioControllerUtility::FrameInfo(

	const TUint8* aBuf,

	TInt aBufLen,

	TAudioFrameInfo& aInfo)

    {

    TInt length = 0;

    TUint temp;

    TUint lTempVal;

	if (aBufLen >= KRawMp3FrameHeaderSize)

	    {

		// Extract header fields to aInfo and check their bit syntax

		// (including the sync word!). If the syntax is not OK the length

		// is set to zero.

		temp = 0;

		temp = aBuf[0] << 24;

		temp |= (aBuf[1] << 16);

		temp |= (aBuf[2] << 8);

		temp |= aBuf[3];

		if (((temp >> 21) & 0x7FF) != 0x7FF)

			{

			return length;

			}

		lTempVal = (temp >> 19) & 0x03;

		switch (lTempVal)

			{

			case 0:

				aInfo.iId = 2;  // MPEG2.5

				aInfo.iFrameSamples = 576;

				break;

			case 1:

				return length;

			case 2:

				aInfo.iId = 0;  // MPEG 2

				aInfo.iFrameSamples = 576;

				break;

			case 3:

				aInfo.iId = 1;  // MPEG 1

				aInfo.iFrameSamples = 1152;

				break;

			}

		lTempVal = (temp >> 17) & 0x03;

		if (lTempVal != 1)

			{

			return length;

			}

		lTempVal = (temp >> 12) & 0x0F;

		aInfo.iBitRate = cBitRateTable[aInfo.iId][lTempVal]*1000;

		if (aInfo.iBitRate == 0)

			{

			return length;

			}

		lTempVal = (temp >> 10) & 0x03;

		if (lTempVal == 3)

			{

			return length;

			}

		else

			{

			aInfo.iSamplingRate = cSamplingFrequencyTable[aInfo.iId][lTempVal];

			}

		aInfo.iPadding = (temp >> 9) & 0x01;

		lTempVal = (temp >> 6) & 0x03;

		aInfo.iMode = lTempVal;

		if (lTempVal == 3)

			{

			aInfo.iChannels = 1;

			}

		else

            {

            aInfo.iChannels = 2;

            }

        aInfo.iSamplingRateOut = aInfo.iSamplingRate;

//        aInfo.iChannelsOut = 2; /* always set to stereo output */

        aInfo.iChannelsOut = aInfo.iChannels;

        aInfo.iFrameSamplesOut = aInfo.iFrameSamples;

		if (aInfo.iBitRate == -1)

			{

			// For free mode operation

			length = KRawMp3MaxFrameSize;

			}

		if (aInfo.iSamplingRate > 0  &&  aInfo.iBitRate > 0)

			{

			length = (144*aInfo.iBitRate)/aInfo.iSamplingRate;

			if (aInfo.iId != 1)

				{

				length >>= 1; /*for MPEG2 and MPEG2.5 */

				}

			if (aInfo.iPadding)

				{

				length++;

				}

			}

		aInfo.iFrameSize = length;

        iChannelsOut = aInfo.iChannelsOut;

    	}

    return length;

    }

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::SetCodecConfigData

// -----------------------------------------------------------------------------

//

void CMP3AudioControllerUtility::SetCodecConfigData(

	RArray<TInt>& aCodecConfig)

    {

//    aCodecConfig[0] = 0; /*(iChannels == 2) ? 0 : 1*/; // don't have decoder downmix stereo to mono

    // the sw codec always outputs 2 ch for mono and stereo,

    // but for mono, we will downmix the 2ch to mono out

    aCodecConfig[0] = (iChannels == 2) ? 0 : 1; // stereo to mono downmix

    aCodecConfig[5] = iSamplingRate;

    aCodecConfig[8] = iSamplesPerFrame;

    }

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::ParseFirstFrame

// -----------------------------------------------------------------------------

//

TBool CMP3AudioControllerUtility::ParseFirstFrame(

	const CMMFDataBuffer* aBuf,

	TInt* aNumFrames)

    {

	_LIT8(KTagXing, "Xing");

	_LIT8(KTagVBRI, "VBRI");

//	const TInt tocPresent = 0x00000001;

//	const TInt bytesPresent = 0x00000002;

	const TInt framesPresent = 0x00000004;

//	const TInt qualityPresent = 0x00000008;

	TBool firstFrameIsVBR = EFalse;

	TPtrC8 searchBuf;

	TInt numFrames = 0;

	// Set search buffer

//	searchBuf.Set(aBuf->Data());

	const TUint8* ptr = aBuf->Data().Ptr();

	TInt pos = aBuf->Position();

	TInt len = aBuf->Data().Size();

	searchBuf.Set(ptr+pos, len-pos);

    TInt startTagXing = searchBuf.Find (KTagXing);

    TInt startTagVBRI = searchBuf.Find (KTagVBRI);

	if (startTagXing != KErrNotFound)

		{

        TInt flags = searchBuf[startTagXing+KFlagsOffset];

        flags = (flags << 8) | searchBuf[startTagXing+KFlagsOffset+1];

		flags = (flags << 8) | searchBuf[startTagXing+KFlagsOffset+2];

		flags = (flags << 8) | searchBuf[startTagXing+KFlagsOffset+3];

	    firstFrameIsVBR = ETrue;

		if (flags & framesPresent)

			{

            numFrames = searchBuf[startTagXing+KFramesOffset];

            numFrames = (numFrames << 8) | searchBuf[startTagXing+KFramesOffset+1];

		    numFrames = (numFrames << 8) | searchBuf[startTagXing+KFramesOffset+2];

		    numFrames = (numFrames << 8) | searchBuf[startTagXing+KFramesOffset+3];

			}

		}

	else if (startTagVBRI != KErrNotFound)

		{

        numFrames = searchBuf[startTagVBRI+14];

        numFrames = (numFrames << 8) | searchBuf[startTagVBRI+14+1];

	    numFrames = (numFrames << 8) | searchBuf[startTagVBRI+14+2];

	    numFrames = (numFrames << 8) | searchBuf[startTagVBRI+14+3];

	    firstFrameIsVBR = ETrue;

		}

	else

		{

	    firstFrameIsVBR = EFalse;

		}

	*aNumFrames = numFrames;

    return firstFrameIsVBR;

    }

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::FrameHeaderSize

// Returns the Frame Header Size for the MP3 file.

// -----------------------------------------------------------------------------

//

TInt CMP3AudioControllerUtility::FrameHeaderSize()

	{

	return KRawMp3FrameHeaderSize;

	}

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::Duration

// -----------------------------------------------------------------------------

//

TInt64 CMP3AudioControllerUtility::Duration()

    {

    if (iFormatIsVBR && (iNumFrames > 0))

        {

		if (iSamplingRateOut > 0)

		    { // numframes may not be present

    		iDurationUs = ((TInt64)iSamplesPerFrame*(TInt64)iNumFrames*(TInt64)1000000)/iSamplingRateOut;

		    }

        }

    else

        {

        CAdvancedAudioUtility::Duration();

        }    

    return iDurationUs;

    }

// -----------------------------------------------------------------------------

// CMP3AudioControllerUtility::BitRate

// -----------------------------------------------------------------------------

//

TInt CMP3AudioControllerUtility::BitRate()

    {

    if (iFormatIsVBR && (iNumFrames > 0))

        {

        Duration(); // for VBR bitrate depends on duration

       	TInt nonAudioBytes = iSyncOffset+iHeaderOffset;

		TInt audioBytes = iClipSize - nonAudioBytes;

        if (iDurationUs > 0)

            {

            iBitRate = 8*(((TInt64)audioBytes*(TInt64)1000000)/iDurationUs);

            }

        }

    else

        {

        CAdvancedAudioUtility::BitRate();

        }    

    return iBitRate;

    }

// ========================== OTHER EXPORTED FUNCTIONS =========================

// End of File