mp4dpars.c

Intel提供的在Sitsang等嵌入式开发平台上使用Linux操作系统

/******************************************************************************
//               INTEL CORPORATION PROPRIETARY INFORMATION
//  This software is supplied under the terms of a license agreement or
//  nondisclosure agreement with Intel Corporation and may not be copied
//  or disclosed except in accordance with the terms of that agreement.
//        Copyright (c) 2003 Intel Corporation. All Rights Reserved.
//
//  Description:    Stream syntax parsing functions of MPEG-4 video decoder
//                  sample code for Intel(R) Integrated Performance Primitives.
//  Functions List:
//		parse_mb_mpeg4()
//		parse_gov_mpeg4()
//		parse_vop_header_mpeg4()
//      parse_voandvol_header_mpeg4()
******************************************************************************/

#include "sampmp4.h"

/******************************************************************************
// Name:            parse_mb_mpeg4
// Description:     parsing the MB header which is stored in the vop_infor
// Input Arguments: 
//      stream_buf  - Pointer to the source compressed video bitstream
//      vop_infor   - Pointer to the vop information struct
//      vop_type    - Current vop coding type
//
//  Output Arguments:
//      stream_buf  - Pointer to the updated source video stream after the MB
//                    header is decoded   
//      vop_infor   - Pointer to the updated vop information struct
//
//  Returns:    
//      SAMPLE_STATUS_NOERR     If succeeds
//      SAMPLE_STATUS_ERR       If stream parsing error occurs
******************************************************************************/
sample_status parse_mb_mpeg4
(sample_bitstream *stream_buf, mp4_dec_vop_infor *vop_infor, int vop_type)
{
    Ipp32u  code    = 0;
    int     dquant  = 0;
    int     vlc_end = 0;
    const mp4_tree_node *cur_node = NULL;

    vop_infor->cbpy = 0;
    vop_infor->cbpc = 0;

    /* PVOP */
    if (IVOP != vop_type) {
        /* 1 bit not_coded */
        vop_infor->mb_not_coded = get_bits_mpeg4(stream_buf, 1);
        if (vop_infor->mb_not_coded) {
            vop_infor->mb_type = IPP_VIDEO_INTER;
            return SAMPLE_STATUS_NOERR;
        }

        /* mcbpc vlc: B.1.2, Table B-7, ISO/IEC 14496-2:2001(E) */
        cur_node = mcbpc_pvop_vlc_tbl;
        do {
            code = get_bits_mpeg4(stream_buf, 1);
            if (0 == code) {
                if (0 == cur_node->c0_end) {
                    cur_node = cur_node->next0_node_symbol + mcbpc_pvop_vlc_tbl;
                } else {
                    vop_infor->cbpc    = (cur_node->next0_node_symbol) & 0x3;
                    vop_infor->mb_type = (cur_node->next0_node_symbol) >> 2;
                    vlc_end = 1;
                }
            } else {
                if (0 == cur_node->c1_end) {
                    cur_node = cur_node->next1_node_symbol + mcbpc_pvop_vlc_tbl;
                } else {
                    vop_infor->cbpc    = (cur_node->next1_node_symbol) & 0x3;
                    vop_infor->mb_type = (cur_node->next1_node_symbol) >> 2;
                    vlc_end = 1;
                }
            }
        } while (!vlc_end);
    } else { /* IVOP */        
        /* mcbpc vlc: B.1.2, Table B-6, ISO/IEC 14496-2:2001(E) */
        do {
            /* prefetch 9 bits */
            code = get_bits_mpeg4(stream_buf, 9);
            if (64 <= code) {
                vop_infor->mb_type = IPP_VIDEO_INTRA;
                vop_infor->cbpc = code >> 6;
                
                if (4 <= vop_infor->cbpc) {
                    vop_infor->cbpc = 0;
                    rewind_buffer_mpeg4(stream_buf, 8);
                } else {
                    rewind_buffer_mpeg4(stream_buf, 6);
                }
            } else {
                if (1 == code) {                
                    vop_infor->mb_type = MPEG4_MB_STUFF;
                } else {
                    vop_infor->mb_type = IPP_VIDEO_INTRA_Q;                    
                    vop_infor->cbpc = code >> 3;

                    if (4 <= vop_infor->cbpc) {
                        vop_infor->cbpc = 0;
                        rewind_buffer_mpeg4(stream_buf, 5);
                    } else {
                        rewind_buffer_mpeg4(stream_buf, 3);
                    }
                }
            }
        } while (MPEG4_MB_STUFF == vop_infor->mb_type);
    }
    
    /* 1 bit ac_pred_flag */
    if ((IPP_VIDEO_INTRA == vop_infor->mb_type) ||
        (IPP_VIDEO_INTRA_Q == vop_infor->mb_type)) {
        vop_infor->ac_pred_flag = get_bits_mpeg4(stream_buf, 1);
    }
    
    /* cbpy vlc: B.1.2, Table B-8, ISO/IEC 14496-2:2001(E) */
    /* prefetch 4 bits */
    code = get_bits_mpeg4(stream_buf, 4);
    if ((12 > code) && (2 < code)) {
        vop_infor->cbpy = cbpy4_intra_tbl[code];
    } else if (12 <= code) {
        vop_infor->cbpy = cbpy4_intra_tbl[12];
        rewind_buffer_mpeg4(stream_buf, 2);
    } else if (2 == code) {
        code = get_bits_mpeg4(stream_buf, 1);
        vop_infor->cbpy = 2 - code;
    } else if (1 == code) {
        code = get_bits_mpeg4(stream_buf, 1);
        vop_infor->cbpy = 8 >> code;
    } else {
        code = get_bits_mpeg4(stream_buf, 2);
        if (2 > code) {
            return SAMPLE_STATUS_ERR;
        } else {
            vop_infor->cbpy = 3 * code;
        }
    }
    /* inter-MB */
    if ((IPP_VIDEO_INTRA != vop_infor->mb_type) &&
        (IPP_VIDEO_INTRA_Q != vop_infor->mb_type)) {
        vop_infor->cbpy = 15 - vop_infor->cbpy;
    }

    /* dquant */
    if ((IPP_VIDEO_INTER_Q == vop_infor->mb_type) ||
        (IPP_VIDEO_INTRA_Q == vop_infor->mb_type))
    {
        /* Get 2 bit dquant in intra_Q or inter_Q type */
        dquant = (int)get_bits_mpeg4(stream_buf, 2);
        if (2 <= dquant) {
            dquant  = - 1 + dquant;
        } else {
            dquant  = - 1 - dquant;
        }
        code = vop_infor->cur_qp + dquant;
        CLIP_VIDEO_I(code, 1, 31);
        vop_infor->cur_qp = (Ipp8u)code;
    }
    return SAMPLE_STATUS_NOERR;
}

/******************************************************************************
// Name:            parse_gov_mpeg4
// Description:     Parse group of video object plane from bitstream
// Input Arguments: 
//      stream_buf  - Pointer to the source compressed video bitstream
//      dec_state   - Pointer to the general state structure of MPEG-4 decoder
//
//  Output Arguments:
//      stream_buf  - Pointer to the updated source video stream after the VO 
//                    and VOL header is decoded   
//      dec_state   - Pointer to the updated general state structure of MPEG-4
//                    decoder
//
//  Returns:    
//      SAMPLE_STATUS_NOERR     If succeeds
//      SAMPLE_STATUS_ERR       If stream parsing error occurs
******************************************************************************/
sample_status parse_gov_mpeg4
(sample_bitstream *stream_buf, mp4_dec_state *dec_state)
{

    /* 5 bit time_code_hours */
    dec_state->hour   = get_bits_mpeg4(stream_buf, 5);
    /* 6 bit time_code_minutes */
    dec_state->minute = get_bits_mpeg4(stream_buf, 6);
    /* marker_bit */
    ASSERT_MARKER_BIT(stream_buf);
    /* 6 bit time_code_seconds */
    dec_state->second = get_bits_mpeg4(stream_buf, 6);

    dec_state->modulo_base_disp = dec_state->hour * 3600
        + dec_state->minute * 60 + dec_state->second;
    dec_state->modulo_base_decd = dec_state->modulo_base_disp;

    /* 1 bit closed_gov */
    dec_state->closed_gov  = get_bits_mpeg4(stream_buf, 1);
    /* 1 bit broken_link */
    dec_state->broken_link = get_bits_mpeg4(stream_buf, 1);
    
    return SAMPLE_STATUS_NOERR;
}


/******************************************************************************
// Name:            parse_vop_header_mpeg4
// Description:     Parse video object plane header from bitstream
// Input Arguments: 
//      stream_buf  - Pointer to the source compressed video bitstream
//      dec_state   - Pointer to the general state struct of MPEG-4 decoder
//      vop_infor   - Pointer to the vop information struct
//
//  Output Arguments:
//      stream_buf  - Pointer to the updated source video stream after the VOP
//                    header is decoded
//      dec_state   - Pointer to the updated general state struct of MPEG-4
//                    decoder
//      vop_infor   - Pointer to the updated vop information struct
//
//  Returns:
//      SAMPLE_STATUS_NOERR             If succeeds
//      SAMPLE_STATUS_ERR               If stream parsing error occurs
//      SAMPLE_STATUS_NOTSUPPORTED_ERR  If stream syntax is not supported by
//                                      current sample decoder
******************************************************************************/
sample_status parse_vop_header_mpeg4
(sample_bitstream  *stream_buf, mp4_dec_state *dec_state,
 mp4_dec_vop_infor *vop_infor)
{
    Ipp32u  code;
    int     modulo_inc, delta_base, cur_time_sec;   
    
    /* 2 bit vop_coding_type */
    dec_state->vop_coding_type = get_bits_mpeg4(stream_buf, 2);
    if ((IVOP != dec_state->vop_coding_type) && (PVOP
        != dec_state->vop_coding_type)) {
        return SAMPLE_STATUS_NOTSUPPORTED_ERR;
    }

    /* modulo_time_base */
    modulo_inc = 0;
    do {
        code = get_bits_mpeg4(stream_buf, 1);
        if (code) {
            modulo_inc++;
        }
    } while (0 != code);
    delta_base = dec_state->modulo_base_decd;
    cur_time_sec = modulo_inc + delta_base;

    /* marker_bit */
    ASSERT_MARKER_BIT(stream_buf);

    /* numbits_time_incr bit vop_time_increment */
    vop_infor->vop_time_inc = get_bits_mpeg4(stream_buf,
        dec_state->numbits_time_incr);

    dec_state->modulo_base_disp = dec_state->modulo_base_decd;      
    dec_state->modulo_base_decd = cur_time_sec;
    dec_state->cur_frame_no = cur_time_sec * dec_state->clock_rate + 
        vop_infor->vop_time_inc;

    /* marker_bit */
    ASSERT_MARKER_BIT(stream_buf);

    /* 1 bit vop_coded */
    dec_state->vop_coded = get_bits_mpeg4(stream_buf, 1);
    if (0 == dec_state->vop_coded) {
        return SAMPLE_STATUS_NOERR;
    }

    /* 1 bit vop_rounding_type */
    if (PVOP == dec_state->vop_coding_type) {
        dec_state->rounding = get_bits_mpeg4(stream_buf, 1);
    } else {
        dec_state->rounding = 0;
    }

    /* 3 bit intra_dc_vlc_thr */
    dec_state->intra_dc_thr = get_bits_mpeg4(stream_buf, 3);

    /* 5 bit vop_quant */
    /* not_8_bit is not supported, so the quant_precision is always 5 */
    dec_state->vop_quant = (Ipp8u)get_bits_mpeg4(stream_buf, 5);

    /* 3 bit vop_fcode_forward */
    if (IVOP == dec_state->vop_coding_type) {
        vop_infor->fcode_fwd = 1;        
    } else {
        vop_infor->fcode_fwd = get_bits_mpeg4(stream_buf, 3);
    }

    /* turns into motion_shape_texture() */
    return SAMPLE_STATUS_NOERR;
}


/******************************************************************************
// Name:            parse_voandvol_header_mpeg4
// Description:     Parse visual object and visual object layer header from 
//                  bitstream
// Input Arguments: 
//      stream_buf  - Pointer to the source compressed video bitstream
//      dec_state   - Pointer to the general state structure of MPEG-4 decoder
//
//  Output Arguments:
//      stream_buf  - Pointer to the updated source video stream after the VO