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/*
* Copyright (C) 2007-2008 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
/**
*
* File Name: omxVCM4P2_EncodeVLCZigzag_IntraDCVLC.c
* OpenMAX DL: v1.0.2
* Revision: 9641
* Date: Thursday, February 7, 2008
*
*
*
*
* Description:
* Contains modules for zigzag scanning and VLC encoding
* for intra block.
*
*/
#include "omxtypes.h"
#include "armOMX.h"
#include "omxVC.h"
#include "armVC.h"
#include "armCOMM_Bitstream.h"
#include "armCOMM.h"
#include "armVCM4P2_Huff_Tables_VLC.h"
#include "armVCM4P2_ZigZag_Tables.h"
/**
* Function: omxVCM4P2_EncodeVLCZigzag_IntraDCVLC (6.2.4.5.2)
*
* Description:
* Performs zigzag scan and VLC encoding of AC and DC coefficients for one
* intra block. Two versions of the function (DCVLC and ACVLC) are provided
* in order to support the two different methods of processing DC
* coefficients, as described in [ISO14496-2], subclause 7.4.1.4, "Intra DC
* Coefficient Decoding for the Case of Switched VLC Encoding".
*
* Input Arguments:
*
* ppBitStream - double pointer to the current byte in the bitstream
* pBitOffset - pointer to the bit position in the byte pointed by
* *ppBitStream. Valid within 0 to 7.
* pQDctBlkCoef - pointer to the quantized DCT coefficient
* predDir - AC prediction direction, which is used to decide the zigzag
* scan pattern; takes one of the following values:
* - OMX_VC_NONE - AC prediction not used.
* Performs classical zigzag scan.
* - OMX_VC_HORIZONTAL - Horizontal prediction.
* Performs alternate-vertical zigzag scan.
* - OMX_VC_VERTICAL - Vertical prediction.
* Performs alternate-horizontal zigzag scan.
* pattern - block pattern which is used to decide whether this block is
* encoded
* shortVideoHeader - binary flag indicating presence of
* short_video_header; escape modes 0-3 are used if
* shortVideoHeader==0, and escape mode 4 is used when
* shortVideoHeader==1.
* videoComp - video component type (luminance, chrominance) of the current
* block
*
* Output Arguments:
*
* ppBitStream - *ppBitStream is updated after the block is encoded, so
* that it points to the current byte in the bit stream buffer.
* pBitOffset - *pBitOffset is updated so that it points to the current bit
* position in the byte pointed by *ppBitStream.
*
* Return Value:
*
* OMX_Sts_NoErr - no error
* OMX_Sts_BadArgErr - Bad arguments:
* - At least one of the following pointers is NULL: ppBitStream,
* *ppBitStream, pBitOffset, pQDctBlkCoef.
* - *pBitOffset < 0, or *pBitOffset >7.
* - PredDir is not one of: OMX_VC_NONE, OMX_VC_HORIZONTAL, or
* OMX_VC_VERTICAL.
* - VideoComp is not one component of enum OMXVCM4P2VideoComponent.
*
*/
OMXResult omxVCM4P2_EncodeVLCZigzag_IntraDCVLC(
OMX_U8 **ppBitStream,
OMX_INT *pBitOffset,
const OMX_S16 *pQDctBlkCoef,
OMX_U8 predDir,
OMX_U8 pattern,
OMX_INT shortVideoHeader,
OMXVCM4P2VideoComponent videoComp
)
{
OMX_S16 dcValue, powOfSize;
OMX_U8 DCValueSize, start = 1;
OMX_U16 absDCValue;
/* Argument error checks */
armRetArgErrIf(ppBitStream == NULL, OMX_Sts_BadArgErr);
armRetArgErrIf(*ppBitStream == NULL, OMX_Sts_BadArgErr);
armRetArgErrIf(pBitOffset == NULL, OMX_Sts_BadArgErr);
armRetArgErrIf(pQDctBlkCoef == NULL, OMX_Sts_BadArgErr);
armRetArgErrIf((*pBitOffset < 0) || (*pBitOffset >7), OMX_Sts_BadArgErr);
armRetArgErrIf((videoComp != OMX_VC_LUMINANCE) && (videoComp != OMX_VC_CHROMINANCE), OMX_Sts_BadArgErr);
armRetArgErrIf((predDir != OMX_VC_NONE) && (predDir != OMX_VC_HORIZONTAL) && (predDir != OMX_VC_VERTICAL) , OMX_Sts_BadArgErr);
if (pattern)
{
dcValue = pQDctBlkCoef[0];
absDCValue = armAbs(dcValue);
/* Find the size */
DCValueSize = armLogSize (absDCValue);
absDCValue = armAbs(dcValue);
/* Insert the code into the bitstream */
if (videoComp == OMX_VC_LUMINANCE)
{
armPackVLC32 (ppBitStream, pBitOffset,
armVCM4P2_aIntraDCLumaIndex[DCValueSize]);
}
else if (videoComp == OMX_VC_CHROMINANCE)
{
armPackVLC32 (ppBitStream, pBitOffset,
armVCM4P2_aIntraDCChromaIndex[DCValueSize]);
}
/* Additional code generation in case of negative
dc value the additional */
if (DCValueSize > 0)
{
if (dcValue < 0)
{
/* calulate 2 pow */
powOfSize = (1 << DCValueSize);
absDCValue = absDCValue ^ (powOfSize - 1);
}
armPackBits(ppBitStream, pBitOffset, (OMX_U32)absDCValue, \
DCValueSize);
if (DCValueSize > 8)
{
armPackBits(ppBitStream, pBitOffset, 1, 1);
}
}
}
return armVCM4P2_EncodeVLCZigzag_Intra(
ppBitStream,
pBitOffset,
pQDctBlkCoef,
predDir,
pattern,
shortVideoHeader,
start);
}
/* End of file */
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