media/libstagefright/codecs/on2/h264dec/source/h264bsd_nal_unit.c

/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * 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.
 */

/*------------------------------------------------------------------------------

    Table of contents

     1. Include headers
     2. External compiler flags
     3. Module defines
     4. Local function prototypes
     5. Functions
          h264bsdDecodeNalUnit

------------------------------------------------------------------------------*/

/*------------------------------------------------------------------------------
    1. Include headers
------------------------------------------------------------------------------*/

#include "h264bsd_nal_unit.h"
#include "h264bsd_util.h"

/*------------------------------------------------------------------------------
    2. External compiler flags
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
    3. Module defines
------------------------------------------------------------------------------*/

/*------------------------------------------------------------------------------
    4. Local function prototypes
------------------------------------------------------------------------------*/

/*------------------------------------------------------------------------------

    Function name: h264bsdDecodeNalUnit

        Functional description:
            Decode NAL unit header information

        Inputs:
            pStrmData       pointer to stream data structure

        Outputs:
            pNalUnit        NAL unit header information is stored here

        Returns:
            HANTRO_OK       success
            HANTRO_NOK      invalid NAL unit header information

------------------------------------------------------------------------------*/

u32 h264bsdDecodeNalUnit(strmData_t *pStrmData, nalUnit_t *pNalUnit)
{

/* Variables */

    u32 tmp;

/* Code */

    ASSERT(pStrmData);
    ASSERT(pNalUnit);
    ASSERT(pStrmData->bitPosInWord == 0);

    /* forbidden_zero_bit (not checked to be zero, errors ignored) */
    tmp = h264bsdGetBits(pStrmData, 1);
    /* Assuming that NAL unit starts from byte boundary ­> don't have to check
     * following 7 bits for END_OF_STREAM */
    if (tmp == END_OF_STREAM)
        return(HANTRO_NOK);

    tmp = h264bsdGetBits(pStrmData, 2);
    pNalUnit->nalRefIdc = tmp;

    tmp = h264bsdGetBits(pStrmData, 5);
    pNalUnit->nalUnitType = (nalUnitType_e)tmp;

    /* data partitioning NAL units not supported */
    if ( (tmp == 2) || (tmp == 3) || (tmp == 4) )
    {
        return(HANTRO_NOK);
    }

    /* nal_ref_idc shall not be zero for these nal_unit_types */
    if ( ( (tmp == NAL_SEQ_PARAM_SET) || (tmp == NAL_PIC_PARAM_SET) ||
           (tmp == NAL_CODED_SLICE_IDR) ) && (pNalUnit->nalRefIdc == 0) )
    {
        return(HANTRO_NOK);
    }
    /* nal_ref_idc shall be zero for these nal_unit_types */
    else if ( ( (tmp == NAL_SEI) || (tmp == NAL_ACCESS_UNIT_DELIMITER) ||
                (tmp == NAL_END_OF_SEQUENCE) || (tmp == NAL_END_OF_STREAM) ||
                (tmp == NAL_FILLER_DATA) ) && (pNalUnit->nalRefIdc != 0) )
    {
        return(HANTRO_NOK);
    }

    return(HANTRO_OK);

}