omxacaac_unpackadtsframeheader.c

The OpenMAX DL (Development Layer) APIs contain a comprehensive set of audio, video, signal processi

/**
 * 
 * File Name:  omxACAAC_UnpackADTSFrameHeader.c
 * OpenMAX DL: v1.0.2
 * Revision:   10586
 * Date:       Wednesday, March 5, 2008
 * 
 * (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
 * 
 * 
 *
 * Description:
 * This file contains module for parsing ADTS header information from AAC bitstream
 *
 */
 
#include "omxtypes.h"
#include "armOMX.h"
#include "omxAC.h"

#include "armCOMM.h"
#include "armCOMM_Bitstream.h"

/**
 * Function:  omxACAAC_UnpackADTSFrameHeader   (3.2.3.1.2)
 *
 * Description:
 * Unpacks the ADTS frame header from the input bit stream and copies the 
 * contents into an ADTS header data structure.  If the ADTS protection bit is 
 * asserted (pADTSFrameHeader->protectionBit==0) then the 16-bit CRC word is 
 * copied into pADTSFrameHeader->CRCWord. The first byte is stored in 
 * pADTSFrameHeader->CRCWord[15:8], and the second byte is stored in 
 * pADTSFrameHeader >CRCWord[7:0]. This function does not test for header 
 * corruption. 
 *
 * Reference: [ISO14496-3], Table 1.A.6 
 *
 * Input Arguments:
 *   
 *   ppBitStream - double pointer to the current byte in the input stream 
 *   pADTSFrameHeader - pointer an uninitialized OMXACCADTSHeader structure 
 *
 * Output Arguments:
 *   
 *   ppBitStream - double pointer to the current byte after unpacking the 
 *            ADTS frame header. 
 *   pADTSFrameHeader - pointer to the updated OMXAACADTSFrameHeader 
 *            structure.  All ADTS header structure members are updated by the 
 *            function to reflect the contents of the ADTS header in the input 
 *            stream.  The structure member CRCWord is updated only if 
 *            protectionBit==1. 
 *
 * Return Value:
 *    
 *    OMX_Sts_NoErr - no error 
 *    OMX_Sts_BadArgErr - bad arguments.  
 *    -    At least one of the following pointers is NULL : 
 *            -  ppBitStream, 
 *            - *ppBitStream, 
 *            -  pADTSFrameHeader
 *
 */
 
OMXResult omxACAAC_UnpackADTSFrameHeader(
     const OMX_U8 **ppBitStream,
     OMXAACADTSFrameHeader *pADTSFrameHeader
 )
{
        
    OMX_INT offset = 0, *pOffset;

    /* Argument Check */
    armRetArgErrIf(ppBitStream      == NULL, OMX_Sts_BadArgErr);
    armRetArgErrIf(*ppBitStream     == NULL, OMX_Sts_BadArgErr);
    armRetArgErrIf(pADTSFrameHeader == NULL, OMX_Sts_BadArgErr);

    /* Processing */
    pOffset = &offset;
           
    /* ADTS Fixed Header */
    armByteAlign(ppBitStream, pOffset);
    armSkipBits(ppBitStream, pOffset, 12);/*Syncword*/
    
    pADTSFrameHeader->id            = (OMX_INT)armGetBits(ppBitStream, pOffset, 1);
    pADTSFrameHeader->layer         = (OMX_INT)armGetBits(ppBitStream, pOffset, 2);
    pADTSFrameHeader->protectionBit = (OMX_INT)armGetBits(ppBitStream, pOffset, 1);
    
    pADTSFrameHeader->profile           = (OMX_INT)armGetBits(ppBitStream, pOffset, 2);
    pADTSFrameHeader->samplingRateIndex = (OMX_INT)armGetBits(ppBitStream, pOffset, 4);
    pADTSFrameHeader->privateBit        = (OMX_INT)armGetBits(ppBitStream, pOffset, 1);

    pADTSFrameHeader->chConfig     = (OMX_INT)armGetBits(ppBitStream, pOffset, 3);
    pADTSFrameHeader->originalCopy = (OMX_INT)armGetBits(ppBitStream, pOffset, 1);
    pADTSFrameHeader->home         = (OMX_INT)armGetBits(ppBitStream, pOffset, 1);
    
    /* ADTS Variable Header */
    pADTSFrameHeader->cpRightIdBit    = (OMX_INT)armGetBits(ppBitStream, pOffset, 1);
    pADTSFrameHeader->cpRightIdStart  = (OMX_INT)armGetBits(ppBitStream, pOffset, 1);
    pADTSFrameHeader->frameLen        = (OMX_INT)armGetBits(ppBitStream, pOffset, 13);
    pADTSFrameHeader->ADTSBufFullness = (OMX_INT)armGetBits(ppBitStream, pOffset, 11);
    pADTSFrameHeader->numRawBlock     = (OMX_INT)armGetBits(ppBitStream, pOffset, 2);

    /* ADTS Error Check */    
    if(pADTSFrameHeader->protectionBit == 0)
    {
        /* Read CRC Word */
        pADTSFrameHeader->CRCWord = (OMX_INT)armGetBits(ppBitStream, pOffset, 16);
    }
    
    
    return  OMX_Sts_NoErr;
        
}
/* End of File */