diff -r 000000000000 -r bde4ae8d615e os/mm/mmlibs/mmfw/Codecs/Src/MMFCodecCommon/MMFAudioPcm16ToImaAdpcmCodec.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/os/mm/mmlibs/mmfw/Codecs/Src/MMFCodecCommon/MMFAudioPcm16ToImaAdpcmCodec.cpp Fri Jun 15 03:10:57 2012 +0200 @@ -0,0 +1,165 @@ +// Copyright (c) 2003-2009 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: +// + +#include "MMFAudioPcm16ToImaAdpcmCodec.h" + + +EXPORT_C void TMMFAudioPcm16ToImaAdpcmCodec::SetState(const TMMFImaAdpcmCodecState& aState) + { + iState = aState ; + } + +EXPORT_C const TMMFImaAdpcmCodecState& TMMFAudioPcm16ToImaAdpcmCodec::GetState() + { + return iState; + } + +/** +* +* Convert +* @param aSrc +* @param aDst +* @param aSamples +* +*/ +EXPORT_C void TMMFAudioPcm16ToImaAdpcmCodec::Convert(TUint8* aSrc, TUint8* aDst, TInt aSamples) + { + TInt val; // Current input sample value + TInt sign; // Current adpcm sign bit + TInt delta; // Current adpcm output value + TInt diff; // Difference between val and valprev + TInt step; // Stepsize + TInt valpred; // Predicted value + TInt vpdiff; // Current change to valpred + TInt index; // Current step change index + + TInt16* srcPtr=REINTERPRET_CAST(TInt16*, aSrc); + TInt16* src=srcPtr; + + iState.iPredicted = *aSrc++; + iState.iPredicted |= STATIC_CAST(TInt16, ((*aSrc++) << 8)); + + valpred = iState.iPredicted; + index = iState.iIndex; + ASSERT(index >= 0); + step = KStepSizeTable[index]; + + //Write block header + *aDst++ = STATIC_CAST( TUint8, valpred); + *aDst++ = STATIC_CAST( TUint8, valpred >> 8); + *aDst++ = STATIC_CAST( TUint8, index); + *aDst++ = 0; //reserved byte + src++; + aSamples --; + + for (; aSamples > 0; aSamples--) + { + val = *src; + src++; + + step = KStepSizeTable[index]; + + // Step 1 - compute difference with previous value + diff = val - valpred; + sign = (diff < 0) ? 8 : 0; + if ( sign ) diff = (-diff); + + // Step 2 - Divide and clamp + // Note: + // This code *approximately* computes: + // delta = diff*4/step; + // vpdiff = (delta+0.5)*step/4; + // but in shift step bits are dropped. The net result of this is + // that even if you have fast mul/div hardware you cannot put it to + // good use since the fixup would be too expensive. + // + delta = 0; + vpdiff = (step >> 3); + + if ( diff >= step ) + { + delta = 4; + diff -= step; + vpdiff += step; + } + step >>= 1; + if ( diff >= step ) + { + delta |= 2; + diff -= step; + vpdiff += step; + } + step >>= 1; + if ( diff >= step ) + { + delta |= 1; + vpdiff += step; + } + + // Step 3 - Update previous value + if ( sign ) + valpred -= vpdiff; + else + valpred += vpdiff; + + // Step 4 - Clamp previous value to 16 bits + if ( valpred > KClamp - 1 ) + valpred = KClamp - 1; + else if ( valpred < - KClamp ) + valpred = - KClamp; + + // Step 5 - Assemble value, update index and step values + delta |= sign; + + index += KIndexTable[delta]; + if ( index < 0 ) index = 0; + if ( index > 88 ) index = 88; + + // Step 6 - Output value + if (iBufferStep) + iBuffer = delta & 0x0f; + else + *aDst++ = STATIC_CAST( TInt8, ((delta << 4) & 0xf0) | iBuffer); + + iBufferStep = !iBufferStep; + } + + iState.iPredicted = STATIC_CAST(TInt16, valpred); + iState.iIndex = STATIC_CAST(TUint8, index); + } + +// IMA-ADPCM step variation table +const TInt TMMFAudioPcm16ToImaAdpcmCodec::KIndexTable[] = + { + -1, -1, -1, -1, 2, 4, 6, 8, + -1, -1, -1, -1, 2, 4, 6, 8 + }; + +const TInt TMMFAudioPcm16ToImaAdpcmCodec::KStepSizeTable[] = + { + 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, + 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, + 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, + 130, 143, 157, 173, 190, 209, 230, 253, 279, 307, + 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, + 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, + 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358, + 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, + 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 + }; + + + +