decodframe.c

/*
 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */


#include "onyxd_int.h"
#include "vp8/common/header.h"
#include "vp8/common/reconintra.h"
#include "vp8/common/reconintra4x4.h"
#include "vp8/common/recon.h"
#include "vp8/common/reconinter.h"
#include "dequantize.h"
#include "detokenize.h"
#include "vp8/common/invtrans.h"
#include "vp8/common/alloccommon.h"
#include "vp8/common/entropymode.h"
#include "vp8/common/quant_common.h"
#include "vpx_scale/vpxscale.h"
#include "vpx_scale/yv12extend.h"
#include "vp8/common/setupintrarecon.h"

#include "decodemv.h"
#include "vp8/common/extend.h"
#include "vp8/common/modecont.h"
#include "vpx_mem/vpx_mem.h"
#include "vp8/common/idct.h"
#include "dequantize.h"
#include "dboolhuff.h"

#include "vp8/common/seg_common.h"

#include <assert.h>
#include <stdio.h>


#ifdef DEC_DEBUG
int dec_debug = 0;
#endif

void vp8cx_init_de_quantizer(VP8D_COMP *pbi)
{
    int i;
    int Q;
    VP8_COMMON *const pc = & pbi->common;

    for (Q = 0; Q < QINDEX_RANGE; Q++)
    {
        pc->Y1dequant[Q][0] = (short)vp8_dc_quant(Q, pc->y1dc_delta_q);
        pc->Y2dequant[Q][0] = (short)vp8_dc2quant(Q, pc->y2dc_delta_q);
        pc->UVdequant[Q][0] = (short)vp8_dc_uv_quant(Q, pc->uvdc_delta_q);

        /* all the ac values = ; */
        for (i = 1; i < 16; i++)
        {
            int rc = vp8_default_zig_zag1d[i];

            pc->Y1dequant[Q][rc] = (short)vp8_ac_yquant(Q);
            pc->Y2dequant[Q][rc] = (short)vp8_ac2quant(Q, pc->y2ac_delta_q);
            pc->UVdequant[Q][rc] = (short)vp8_ac_uv_quant(Q, pc->uvac_delta_q);
        }
    }
}

void mb_init_dequantizer(VP8D_COMP *pbi, MACROBLOCKD *xd)
{
    int i;
    int QIndex;
    VP8_COMMON *const pc = & pbi->common;
    int segment_id = xd->mode_info_context->mbmi.segment_id;

    // Set the Q baseline allowing for any segment level adjustment
    if ( segfeature_active( xd, segment_id, SEG_LVL_ALT_Q ) )
    {
        /* Abs Value */
        if (xd->mb_segment_abs_delta == SEGMENT_ABSDATA)
            QIndex = get_segdata( xd, segment_id, SEG_LVL_ALT_Q );

        /* Delta Value */
        else
        {
            QIndex = pc->base_qindex +
                     get_segdata( xd, segment_id, SEG_LVL_ALT_Q );
            QIndex = (QIndex >= 0) ? ((QIndex <= MAXQ) ? QIndex : MAXQ) : 0;    /* Clamp to valid range */
        }
    }
    else
        QIndex = pc->base_qindex;

    /* Set up the block level dequant pointers */
    for (i = 0; i < 16; i++)
    {
        xd->block[i].dequant = pc->Y1dequant[QIndex];
    }

    for (i = 16; i < 24; i++)
    {
        xd->block[i].dequant = pc->UVdequant[QIndex];
    }

    xd->block[24].dequant = pc->Y2dequant[QIndex];

}

#if CONFIG_RUNTIME_CPU_DETECT
#define RTCD_VTABLE(x) (&(pbi)->common.rtcd.x)
#else
#define RTCD_VTABLE(x) NULL
#endif

/* skip_recon_mb() is Modified: Instead of writing the result to predictor buffer and then copying it
 *  to dst buffer, we can write the result directly to dst buffer. This eliminates unnecessary copy.
 */
static void skip_recon_mb(VP8D_COMP *pbi, MACROBLOCKD *xd)
{
    if (xd->mode_info_context->mbmi.ref_frame == INTRA_FRAME)
    {
        RECON_INVOKE(&pbi->common.rtcd.recon, build_intra_predictors_mbuv_s)(xd);
        RECON_INVOKE(&pbi->common.rtcd.recon,
                     build_intra_predictors_mby_s)(xd);
    }
    else
    {
        vp8_build_inter16x16_predictors_mb(xd, xd->dst.y_buffer,
                                           xd->dst.u_buffer, xd->dst.v_buffer,
                                           xd->dst.y_stride, xd->dst.uv_stride);

        if (xd->mode_info_context->mbmi.second_ref_frame)
        {
            vp8_build_2nd_inter16x16_predictors_mb(xd, xd->dst.y_buffer,
                                                   xd->dst.u_buffer, xd->dst.v_buffer,
                                                   xd->dst.y_stride, xd->dst.uv_stride);
        }
    }
#ifdef DEC_DEBUG
        if (dec_debug) {
          int i, j;
          printf("Generating predictors\n");
          for (i=0;i<16;i++) {
            for (j=0;j<16;j++) printf("%3d ", xd->dst.y_buffer[i*xd->dst.y_stride+j]);
            printf("\n");
          }
        }
#endif

}

extern const int vp8_i8x8_block[4];
static void decode_macroblock(VP8D_COMP *pbi, MACROBLOCKD *xd,
                              unsigned int mb_idx)
{
    int eobtotal = 0;
    MB_PREDICTION_MODE mode;
    int i;
    int tx_type;

    if(pbi->common.frame_type == KEY_FRAME)
    {
        if( pbi->common.txfm_mode==ALLOW_8X8 &&
             (xd->mode_info_context->mbmi.mode == DC_PRED
            ||xd->mode_info_context->mbmi.mode == TM_PRED))
            xd->mode_info_context->mbmi.txfm_size = TX_8X8;
        else
            xd->mode_info_context->mbmi.txfm_size = TX_4X4;
    }
    else
    {
        if( pbi->common.txfm_mode==ONLY_4X4 )
        {
            xd->mode_info_context->mbmi.txfm_size = TX_4X4;
        }
        else if( pbi->common.txfm_mode == ALLOW_8X8 )
        {
            if( xd->mode_info_context->mbmi.mode ==B_PRED
                ||xd->mode_info_context->mbmi.mode ==I8X8_PRED
                ||xd->mode_info_context->mbmi.mode ==SPLITMV)
                xd->mode_info_context->mbmi.txfm_size = TX_4X4;
            else
                xd->mode_info_context->mbmi.txfm_size = TX_8X8;
        }
    }
    tx_type = xd->mode_info_context->mbmi.txfm_size;

    if (xd->mode_info_context->mbmi.mb_skip_coeff)
    {
        vp8_reset_mb_tokens_context(xd);
    }
    else if (!vp8dx_bool_error(xd->current_bc))
    {
        for(i = 0; i < 25; i++)
        {
            xd->block[i].eob = 0;
            xd->eobs[i] = 0;
        }
        if ( tx_type == TX_8X8 )
            eobtotal = vp8_decode_mb_tokens_8x8(pbi, xd);
        else
            eobtotal = vp8_decode_mb_tokens(pbi, xd);
#ifdef DEC_DEBUG
        if (dec_debug) {
            printf("\nTokens (%d)\n", eobtotal);
            for (i =0; i<400; i++) {
                printf("%3d ", xd->qcoeff[i]);
                if (i%16 == 15) printf("\n");
            }
            printf("\n");
        }
#endif
    }

    mode = xd->mode_info_context->mbmi.mode;

    if (eobtotal == 0 && mode != B_PRED && mode != SPLITMV
        && mode != I8X8_PRED
        &&!vp8dx_bool_error(xd->current_bc)
        )
    {
        /* Special case:  Force the loopfilter to skip when eobtotal and
         * mb_skip_coeff are zero.
         * */
        xd->mode_info_context->mbmi.mb_skip_coeff = 1;

        skip_recon_mb(pbi, xd);
        return;
    }

#ifdef DEC_DEBUG
        if (dec_debug) {
          int i, j;
          printf("Generating predictors\n");
          for (i=0;i<16;i++) {
            for (j=0;j<16;j++) printf("%3d ", xd->dst.y_buffer[i*xd->dst.y_stride+j]);
            printf("\n");
          }
        }
#endif

    if (xd->segmentation_enabled)
        mb_init_dequantizer(pbi, xd);

    /* do prediction */
    if (xd->mode_info_context->mbmi.ref_frame == INTRA_FRAME)
    {
        if(mode != I8X8_PRED)
        {
            RECON_INVOKE(&pbi->common.rtcd.recon, build_intra_predictors_mbuv)(xd);
            if (mode != B_PRED)
            {
                RECON_INVOKE(&pbi->common.rtcd.recon,
                    build_intra_predictors_mby)(xd);
            }
#if 0
            // Intra-modes requiring recon data from top-right
            // MB have been temporarily disabled.
            else
            {
                vp8_intra_prediction_down_copy(xd);
            }
#endif
        }
    }
    else
    {
        vp8_build_inter_predictors_mb(xd);
    }

    /* dequantization and idct */
    if (mode == I8X8_PRED)
    {
        for (i = 0; i < 4; i++)
        {
            int ib = vp8_i8x8_block[i];
            const int iblock[4]={0,1,4,5};
            int j;
            int i8x8mode;
            BLOCKD *b;

            b = &xd->block[ib];
            i8x8mode= b->bmi.as_mode.first;
            RECON_INVOKE(RTCD_VTABLE(recon), intra8x8_predict)
                          (b, i8x8mode, b->predictor);

            for(j = 0; j < 4; j++)
            {
                b = &xd->block[ib+iblock[j]];
                if (xd->eobs[ib+iblock[j]] > 1)
                {
                    DEQUANT_INVOKE(&pbi->dequant, idct_add)
                        (b->qcoeff, b->dequant,  b->predictor,
                        *(b->base_dst) + b->dst, 16, b->dst_stride);
                }
                else
                {
                    IDCT_INVOKE(RTCD_VTABLE(idct), idct1_scalar_add)
                        (b->qcoeff[0] * b->dequant[0], b->predictor,
                        *(b->base_dst) + b->dst, 16, b->dst_stride);
                    ((int *)b->qcoeff)[0] = 0;
                }
            }

            b = &xd->block[16+i];
            RECON_INVOKE(RTCD_VTABLE(recon), intra_uv4x4_predict)
                          (b, i8x8mode, b->predictor);
            DEQUANT_INVOKE(&pbi->dequant, idct_add)
                (b->qcoeff, b->dequant,  b->predictor,
                *(b->base_dst) + b->dst, 8, b->dst_stride);
            b = &xd->block[20+i];
            RECON_INVOKE(RTCD_VTABLE(recon), intra_uv4x4_predict)
                          (b, i8x8mode, b->predictor);
            DEQUANT_INVOKE(&pbi->dequant, idct_add)
                (b->qcoeff, b->dequant,  b->predictor,
                *(b->base_dst) + b->dst, 8, b->dst_stride);
        }
    }
    else if (mode == B_PRED)
    {
        for (i = 0; i < 16; i++)
        {
            BLOCKD *b = &xd->block[i];
            int b_mode = xd->mode_info_context->bmi[i].as_mode.first;
#if CONFIG_COMP_INTRA_PRED
            int b_mode2 = xd->mode_info_context->bmi[i].as_mode.second;

            if (b_mode2 == (B_PREDICTION_MODE) (B_DC_PRED - 1))
            {
#endif
            RECON_INVOKE(RTCD_VTABLE(recon), intra4x4_predict)
                          (b, b_mode, b->predictor);
#if CONFIG_COMP_INTRA_PRED
            }
            else
            {
                RECON_INVOKE(RTCD_VTABLE(recon), comp_intra4x4_predict)
                    (b, b_mode, b_mode2, b->predictor);
            }
#endif

            if (xd->eobs[i] > 1)
            {
                DEQUANT_INVOKE(&pbi->dequant, idct_add)
                    (b->qcoeff, b->dequant,  b->predictor,
                    *(b->base_dst) + b->dst, 16, b->dst_stride);
            }
            else
            {
                IDCT_INVOKE(RTCD_VTABLE(idct), idct1_scalar_add)
                    (b->qcoeff[0] * b->dequant[0], b->predictor,
                    *(b->base_dst) + b->dst, 16, b->dst_stride);
                ((int *)b->qcoeff)[0] = 0;
            }
        }
    }
    else if (mode == SPLITMV)
    {
        DEQUANT_INVOKE (&pbi->dequant, idct_add_y_block)
            (xd->qcoeff, xd->block[0].dequant,
            xd->predictor, xd->dst.y_buffer,
            xd->dst.y_stride, xd->eobs);
    }
    else
    {
        BLOCKD *b = &xd->block[24];


        if( tx_type == TX_8X8 )
        {
            DEQUANT_INVOKE(&pbi->dequant, block_2x2)(b);
#ifdef DEC_DEBUG
            if (dec_debug)
            {
                int j;
                printf("DQcoeff Haar\n");
                for (j=0;j<16;j++) {
                    printf("%d ", b->dqcoeff[j]);
                }
                printf("\n");
            }
#endif
            IDCT_INVOKE(RTCD_VTABLE(idct), ihaar2)(&b->dqcoeff[0], b->diff, 8);
            ((int *)b->qcoeff)[0] = 0;//2nd order block are set to 0 after inverse transform
            ((int *)b->qcoeff)[1] = 0;
            ((int *)b->qcoeff)[2] = 0;
            ((int *)b->qcoeff)[3] = 0;
            ((int *)b->qcoeff)[4] = 0;
            ((int *)b->qcoeff)[5] = 0;
            ((int *)b->qcoeff)[6] = 0;
            ((int *)b->qcoeff)[7] = 0;
            DEQUANT_INVOKE (&pbi->dequant, dc_idct_add_y_block_8x8)
                (xd->qcoeff, xd->block[0].dequant,
                xd->predictor, xd->dst.y_buffer,
                xd->dst.y_stride, xd->eobs, xd->block[24].diff, xd);
        }
        else
        {
            DEQUANT_INVOKE(&pbi->dequant, block)(b);
            if (xd->eobs[24] > 1)
            {
                IDCT_INVOKE(RTCD_VTABLE(idct), iwalsh16)(&b->dqcoeff[0], b->diff);
                ((int *)b->qcoeff)[0] = 0;
                ((int *)b->qcoeff)[1] = 0;
                ((int *)b->qcoeff)[2] = 0;
                ((int *)b->qcoeff)[3] = 0;
                ((int *)b->qcoeff)[4] = 0;
                ((int *)b->qcoeff)[5] = 0;
                ((int *)b->qcoeff)[6] = 0;
                ((int *)b->qcoeff)[7] = 0;
            }
            else
            {
                IDCT_INVOKE(RTCD_VTABLE(idct), iwalsh1)(&b->dqcoeff[0], b->diff);
                ((int *)b->qcoeff)[0] = 0;
            }

            DEQUANT_INVOKE (&pbi->dequant, dc_idct_add_y_block)
                (xd->qcoeff, xd->block[0].dequant,
                xd->predictor, xd->dst.y_buffer,
                xd->dst.y_stride, xd->eobs, xd->block[24].diff);
        }
    }

    if( tx_type == TX_8X8 )
        DEQUANT_INVOKE (&pbi->dequant, idct_add_uv_block_8x8)//
            (xd->qcoeff+16*16, xd->block[16].dequant,
            xd->predictor+16*16, xd->dst.u_buffer, xd->dst.v_buffer,
            xd->dst.uv_stride, xd->eobs+16, xd);//
    else if(xd->mode_info_context->mbmi.mode!=I8X8_PRED)
        DEQUANT_INVOKE (&pbi->dequant, idct_add_uv_block)
                (xd->qcoeff+16*16, xd->block[16].dequant,
                xd->predictor+16*16, xd->dst.u_buffer, xd->dst.v_buffer,
                xd->dst.uv_stride, xd->eobs+16);
}


static int get_delta_q(vp8_reader *bc, int prev, int *q_update)
{
    int ret_val = 0;

    if (vp8_read_bit(bc))
    {
        ret_val = vp8_read_literal(bc, 4);

        if (vp8_read_bit(bc))
            ret_val = -ret_val;
    }

    /* Trigger a quantizer update if the delta-q value has changed */
    if (ret_val != prev)
        *q_update = 1;

    return ret_val;
}

#ifdef PACKET_TESTING
#include <stdio.h>
FILE *vpxlog = 0;
#endif

/* Decode a row of Superblocks (2x2 region of MBs) */
static void
decode_sb_row(VP8D_COMP *pbi, VP8_COMMON *pc, int mbrow, MACROBLOCKD *xd)
{
    int i;
    int sb_col;
    int mb_row, mb_col;
    int recon_yoffset, recon_uvoffset;
    int ref_fb_idx = pc->lst_fb_idx;
    int dst_fb_idx = pc->new_fb_idx;
    int recon_y_stride = pc->yv12_fb[ref_fb_idx].y_stride;
    int recon_uv_stride = pc->yv12_fb[ref_fb_idx].uv_stride;
    int row_delta[4] = { 0, +1,  0, -1};
    int col_delta[4] = {+1, -1, +1, +1};
    int sb_cols = (pc->mb_cols + 1)>>1;
    ENTROPY_CONTEXT_PLANES left_context[2];

    // For a SB there are 2 left contexts, each pertaining to a MB row within
    vpx_memset(left_context, 0, sizeof(left_context));

    mb_row = mbrow;
    mb_col = 0;

    for (sb_col=0; sb_col<sb_cols; sb_col++)
    {
        // Process the 4 MBs within the SB in the order:
        // top-left, top-right, bottom-left, bottom-right
        for ( i=0; i<4; i++ )
        {
            int dy = row_delta[i];
            int dx = col_delta[i];
            int offset_extended = dy * xd->mode_info_stride + dx;

            if ((mb_row >= pc->mb_rows) || (mb_col >= pc->mb_cols))
            {
                // MB lies outside frame, skip on to next
                mb_row += dy;
                mb_col += dx;
                xd->mode_info_context += offset_extended;
                continue;
            }

#ifdef DEC_DEBUG
            dec_debug = (pc->current_video_frame==0 && mb_row==0 && mb_col==0);
#endif
            // Copy in the appropriate left context for this MB row
            vpx_memcpy (&pc->left_context,
                        &left_context[i>>1],
                        sizeof(ENTROPY_CONTEXT_PLANES));

            // Set above context pointer
            xd->above_context = pc->above_context + mb_col;

            /* Distance of Mb to the various image edges.
             * These are specified to 8th pel as they are always compared to
             * values that are in 1/8th pel units
             */
            xd->mb_to_top_edge = -((mb_row * 16)) << 3;
            xd->mb_to_bottom_edge = ((pc->mb_rows - 1 - mb_row) * 16) << 3;

            xd->mb_to_left_edge = -((mb_col * 16) << 3);
            xd->mb_to_right_edge = ((pc->mb_cols - 1 - mb_col) * 16) << 3;

            xd->up_available = (mb_row != 0);
            xd->left_available = (mb_col != 0);

            update_blockd_bmi(xd);

            recon_yoffset = (mb_row * recon_y_stride * 16) + (mb_col * 16);
            recon_uvoffset = (mb_row * recon_uv_stride * 8) + (mb_col * 8);

            xd->dst.y_buffer = pc->yv12_fb[dst_fb_idx].y_buffer + recon_yoffset;
            xd->dst.u_buffer = pc->yv12_fb[dst_fb_idx].u_buffer + recon_uvoffset;
            xd->dst.v_buffer = pc->yv12_fb[dst_fb_idx].v_buffer + recon_uvoffset;

            /* Select the appropriate reference frame for this MB */
            if (xd->mode_info_context->mbmi.ref_frame == LAST_FRAME)
                ref_fb_idx = pc->lst_fb_idx;
            else if (xd->mode_info_context->mbmi.ref_frame == GOLDEN_FRAME)
                ref_fb_idx = pc->gld_fb_idx;
            else
                ref_fb_idx = pc->alt_fb_idx;

            xd->pre.y_buffer = pc->yv12_fb[ref_fb_idx].y_buffer +recon_yoffset;
            xd->pre.u_buffer = pc->yv12_fb[ref_fb_idx].u_buffer +recon_uvoffset;
            xd->pre.v_buffer = pc->yv12_fb[ref_fb_idx].v_buffer +recon_uvoffset;

            if (xd->mode_info_context->mbmi.second_ref_frame)
            {
                int second_ref_fb_idx;

                /* Select the appropriate reference frame for this MB */
                if (xd->mode_info_context->mbmi.second_ref_frame == LAST_FRAME)
                    second_ref_fb_idx = pc->lst_fb_idx;
                else if (xd->mode_info_context->mbmi.second_ref_frame ==
                                                                   GOLDEN_FRAME)
                    second_ref_fb_idx = pc->gld_fb_idx;
                else
                    second_ref_fb_idx = pc->alt_fb_idx;

                xd->second_pre.y_buffer =
                       pc->yv12_fb[second_ref_fb_idx].y_buffer + recon_yoffset;
                xd->second_pre.u_buffer =
                       pc->yv12_fb[second_ref_fb_idx].u_buffer + recon_uvoffset;
                xd->second_pre.v_buffer =
                       pc->yv12_fb[second_ref_fb_idx].v_buffer + recon_uvoffset;
            }

            if (xd->mode_info_context->mbmi.ref_frame != INTRA_FRAME)
            {
                /* propagate errors from reference frames */
                xd->corrupted |= pc->yv12_fb[ref_fb_idx].corrupted;
            }

            decode_macroblock(pbi, xd, mb_row * pc->mb_cols + mb_col);

            /* check if the boolean decoder has suffered an error */
            xd->corrupted |= vp8dx_bool_error(xd->current_bc);

            // Store the modified left context for the MB row locally
            vpx_memcpy (&left_context[i>>1],
                        &pc->left_context,
                        sizeof(ENTROPY_CONTEXT_PLANES));

            // skip to next MB
            xd->mode_info_context += offset_extended;
            mb_row += dy;
            mb_col += dx;
        }
    }

    /* skip prediction column */
    xd->mode_info_context += 1 - (pc->mb_cols & 0x1) + xd->mode_info_stride;
}

static unsigned int read_partition_size(const unsigned char *cx_size)
{
    const unsigned int size =
        cx_size[0] + (cx_size[1] << 8) + (cx_size[2] << 16);
    return size;
}

static int read_is_valid(const unsigned char *start,
                         size_t               len,
                         const unsigned char *end)
{
    return (start + len > start && start + len <= end);
}


static void setup_token_decoder(VP8D_COMP *pbi,
                                const unsigned char *cx_data)
{
    VP8_COMMON          *pc = &pbi->common;
    const unsigned char *user_data_end = pbi->Source + pbi->source_sz;
    vp8_reader          *bool_decoder;
    const unsigned char *partition;

    ptrdiff_t            partition_size;
    ptrdiff_t            bytes_left;

    // Dummy read for now
    vp8_read_literal(&pbi->bc, 2);

    // Set up pointers to token partition
    partition = cx_data;
    bool_decoder = &pbi->bc2;
    bytes_left = user_data_end - partition;
    partition_size = bytes_left;

    /* Validate the calculated partition length. If the buffer
     * described by the partition can't be fully read, then restrict
     * it to the portion that can be (for EC mode) or throw an error.
     */
    if (!read_is_valid(partition, partition_size, user_data_end))
    {
        vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
                           "Truncated packet or corrupt partition "
                           "%d length", 1);
    }

    if (vp8dx_start_decode(bool_decoder, partition, partition_size))
        vpx_internal_error(&pc->error, VPX_CODEC_MEM_ERROR,
                           "Failed to allocate bool decoder %d", 1);
}

static void init_frame(VP8D_COMP *pbi)
{
    VP8_COMMON *const pc = & pbi->common;
    MACROBLOCKD *const xd  = & pbi->mb;

    if (pc->frame_type == KEY_FRAME)
    {
        /* Various keyframe initializations */
        vpx_memcpy(pc->fc.mvc, vp8_default_mv_context, sizeof(vp8_default_mv_context));
#if CONFIG_HIGH_PRECISION_MV
        vpx_memcpy(pc->fc.mvc_hp, vp8_default_mv_context_hp,
                   sizeof(vp8_default_mv_context_hp));
#endif

        vp8_init_mbmode_probs(pc);

        vp8_default_coef_probs(pc);
        vp8_kf_default_bmode_probs(pc->kf_bmode_prob);

        // Reset the segment feature data to the default stats:
        // Features disabled, 0, with delta coding (Default state).
        clearall_segfeatures( xd );

        xd->mb_segment_abs_delta = SEGMENT_DELTADATA;

        /* reset the mode ref deltasa for loop filter */
        vpx_memset(xd->ref_lf_deltas, 0, sizeof(xd->ref_lf_deltas));
        vpx_memset(xd->mode_lf_deltas, 0, sizeof(xd->mode_lf_deltas));

        /* All buffers are implicitly updated on key frames. */
        pc->refresh_golden_frame = 1;
        pc->refresh_alt_ref_frame = 1;
        pc->copy_buffer_to_gf = 0;
        pc->copy_buffer_to_arf = 0;

        /* Note that Golden and Altref modes cannot be used on a key frame so
         * ref_frame_sign_bias[] is undefined and meaningless
         */
        pc->ref_frame_sign_bias[GOLDEN_FRAME] = 0;
        pc->ref_frame_sign_bias[ALTREF_FRAME] = 0;

        vpx_memcpy(&pc->lfc, &pc->fc, sizeof(pc->fc));
        vpx_memcpy(&pc->lfc_a, &pc->fc, sizeof(pc->fc));

        vp8_init_mode_contexts(&pbi->common);
        vpx_memcpy( pbi->common.vp8_mode_contexts,
                    pbi->common.mode_context,
                    sizeof(pbi->common.mode_context));
    }
    else
    {

        if (!pc->use_bilinear_mc_filter)
#if CONFIG_ENHANCED_INTERP
            pc->mcomp_filter_type = EIGHTTAP;
#else
            pc->mcomp_filter_type = SIXTAP;
#endif
        else
            pc->mcomp_filter_type = BILINEAR;

        /* To enable choice of different interploation filters */
        if (pc->mcomp_filter_type == SIXTAP)
        {
            xd->subpixel_predict      = SUBPIX_INVOKE(RTCD_VTABLE(subpix), sixtap4x4);
            xd->subpixel_predict8x4   = SUBPIX_INVOKE(RTCD_VTABLE(subpix), sixtap8x4);
            xd->subpixel_predict8x8   = SUBPIX_INVOKE(RTCD_VTABLE(subpix), sixtap8x8);
            xd->subpixel_predict16x16 = SUBPIX_INVOKE(RTCD_VTABLE(subpix), sixtap16x16);
            xd->subpixel_predict_avg  = SUBPIX_INVOKE(RTCD_VTABLE(subpix), sixtap_avg4x4);
            xd->subpixel_predict_avg8x8 = SUBPIX_INVOKE(RTCD_VTABLE(subpix), sixtap_avg8x8);
            xd->subpixel_predict_avg16x16 = SUBPIX_INVOKE(RTCD_VTABLE(subpix), sixtap_avg16x16);
        }
#if CONFIG_ENHANCED_INTERP
        else if (pc->mcomp_filter_type == EIGHTTAP)
        {
            xd->subpixel_predict      = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap4x4);
            xd->subpixel_predict8x4   = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap8x4);
            xd->subpixel_predict8x8   = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap8x8);
            xd->subpixel_predict16x16 = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap16x16);
            xd->subpixel_predict_avg8x8 = SUBPIX_INVOKE(
                RTCD_VTABLE(subpix), eighttap_avg8x8);
            xd->subpixel_predict_avg16x16 = SUBPIX_INVOKE(
                RTCD_VTABLE(subpix), eighttap_avg16x16);
            xd->subpixel_predict_avg  = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap_avg4x4);
        }
        else if (pc->mcomp_filter_type == EIGHTTAP_SHARP)
        {
            xd->subpixel_predict      = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap4x4_sharp);
            xd->subpixel_predict8x4   = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap8x4_sharp);
            xd->subpixel_predict8x8   = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap8x8_sharp);
            xd->subpixel_predict16x16 = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap16x16_sharp);
            xd->subpixel_predict_avg  = SUBPIX_INVOKE(RTCD_VTABLE(subpix), eighttap_avg4x4_sharp);
            xd->subpixel_predict_avg8x8 = SUBPIX_INVOKE(
                RTCD_VTABLE(subpix), eighttap_avg8x8_sharp);
            xd->subpixel_predict_avg16x16 = SUBPIX_INVOKE(
                RTCD_VTABLE(subpix), eighttap_avg16x16_sharp);
        }
#endif
        else
        {
            xd->subpixel_predict      = SUBPIX_INVOKE(RTCD_VTABLE(subpix), bilinear4x4);
            xd->subpixel_predict8x4   = SUBPIX_INVOKE(RTCD_VTABLE(subpix), bilinear8x4);
            xd->subpixel_predict8x8   = SUBPIX_INVOKE(RTCD_VTABLE(subpix), bilinear8x8);
            xd->subpixel_predict16x16 = SUBPIX_INVOKE(RTCD_VTABLE(subpix), bilinear16x16);
            xd->subpixel_predict_avg  = SUBPIX_INVOKE(RTCD_VTABLE(subpix), bilinear_avg4x4);
            xd->subpixel_predict_avg8x8 = SUBPIX_INVOKE(RTCD_VTABLE(subpix), bilinear_avg8x8);
            xd->subpixel_predict_avg16x16 = SUBPIX_INVOKE(RTCD_VTABLE(subpix), bilinear_avg16x16);
        }
    }

    xd->left_context = &pc->left_context;
    xd->mode_info_context = pc->mi;
    xd->frame_type = pc->frame_type;
    xd->mode_info_context->mbmi.mode = DC_PRED;
    xd->mode_info_stride = pc->mode_info_stride;
    xd->corrupted = 0; /* init without corruption */

    xd->fullpixel_mask = 0xffffffff;
    if(pc->full_pixel)
        xd->fullpixel_mask = 0xfffffff8;

}

int vp8_decode_frame(VP8D_COMP *pbi)
{
    vp8_reader *const bc = & pbi->bc;
    VP8_COMMON *const pc = & pbi->common;
    MACROBLOCKD *const xd  = & pbi->mb;
    const unsigned char *data = (const unsigned char *)pbi->Source;
    const unsigned char *data_end = data + pbi->source_sz;
    ptrdiff_t first_partition_length_in_bytes;

    int mb_row;
    int i, j, k, l;
    int corrupt_tokens = 0;

    /* start with no corruption of current frame */
    xd->corrupted = 0;
    pc->yv12_fb[pc->new_fb_idx].corrupted = 0;

    if (data_end - data < 3)
    {
        vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
                           "Truncated packet");
    }
    else
    {
        pc->frame_type = (FRAME_TYPE)(data[0] & 1);
        pc->version = (data[0] >> 1) & 7;
        pc->show_frame = (data[0] >> 4) & 1;
        first_partition_length_in_bytes =
            (data[0] | (data[1] << 8) | (data[2] << 16)) >> 5;

        if ((data + first_partition_length_in_bytes > data_end
            || data + first_partition_length_in_bytes < data))
            vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
                               "Truncated packet or corrupt partition 0 length");

        data += 3;

        vp8_setup_version(pc);

        if (pc->frame_type == KEY_FRAME)
        {
            const int Width = pc->Width;
            const int Height = pc->Height;

            /* vet via sync code */
            /* When error concealment is enabled we should only check the sync
             * code if we have enough bits available
             */
            if (data + 3 < data_end)
            {
                if (data[0] != 0x9d || data[1] != 0x01 || data[2] != 0x2a)
                    vpx_internal_error(&pc->error, VPX_CODEC_UNSUP_BITSTREAM,
                                   "Invalid frame sync code");
            }

            /* If error concealment is enabled we should only parse the new size
             * if we have enough data. Otherwise we will end up with the wrong
             * size.
             */
            if (data + 6 < data_end)
            {
                pc->Width = (data[3] | (data[4] << 8)) & 0x3fff;
                pc->horiz_scale = data[4] >> 6;
                pc->Height = (data[5] | (data[6] << 8)) & 0x3fff;
                pc->vert_scale = data[6] >> 6;
            }
            data += 7;

            if (Width != pc->Width  ||  Height != pc->Height)
            {
                if (pc->Width <= 0)
                {
                    pc->Width = Width;
                    vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
                                       "Invalid frame width");
                }

                if (pc->Height <= 0)
                {
                    pc->Height = Height;
                    vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
                                       "Invalid frame height");
                }

                if (vp8_alloc_frame_buffers(pc, pc->Width, pc->Height))
                    vpx_internal_error(&pc->error, VPX_CODEC_MEM_ERROR,
                                       "Failed to allocate frame buffers");
            }
        }
    }

    if ((!pbi->decoded_key_frame && pc->frame_type != KEY_FRAME) ||
        pc->Width == 0 || pc->Height == 0)
    {
        return -1;
    }

    init_frame(pbi);

    if (vp8dx_start_decode(bc, data, data_end - data))
        vpx_internal_error(&pc->error, VPX_CODEC_MEM_ERROR,
                           "Failed to allocate bool decoder 0");
    if (pc->frame_type == KEY_FRAME) {
        pc->clr_type    = (YUV_TYPE)vp8_read_bit(bc);
        pc->clamp_type  = (CLAMP_TYPE)vp8_read_bit(bc);
    }

    /* Is segmentation enabled */
    xd->segmentation_enabled = (unsigned char)vp8_read_bit(bc);

    if (xd->segmentation_enabled)
    {
        // Read whether or not the segmentation map is being explicitly
        // updated this frame.
        xd->update_mb_segmentation_map = (unsigned char)vp8_read_bit(bc);

        // If so what method will be used.
        if ( xd->update_mb_segmentation_map )
            pc->temporal_update = (unsigned char)vp8_read_bit(bc);

        // Is the segment data being updated
        xd->update_mb_segmentation_data = (unsigned char)vp8_read_bit(bc);

        if (xd->update_mb_segmentation_data)
        {
            int data;

            xd->mb_segment_abs_delta = (unsigned char)vp8_read_bit(bc);

            clearall_segfeatures( xd );

            // For each segmentation...
            for (i = 0; i < MAX_MB_SEGMENTS; i++)
            {
                // For each of the segments features...
                for (j = 0; j < SEG_LVL_MAX; j++)
                {

#if CONFIG_FEATUREUPDATES
                    // feature updated?
                    if (vp8_read_bit(bc))
                    {
                        int active=1;

                        if ( segfeature_active( xd, i, j ))
                            active=vp8_read_bit(bc);

                        // Is the feature enabled
                        if (active)
                        {
                            // Update the feature data and mask
                            enable_segfeature(xd, i, j);

                            data = (signed char)vp8_read_literal(
                                                bc, seg_feature_data_bits(j));

                            // Is the segment data signed..
                            if ( is_segfeature_signed(j) )
                            {
                                if (vp8_read_bit(bc))
                                    data = - data;
                            }
                        }
                        else
                            data = 0;

                        set_segdata(xd, i, j, data);
                    }

#else
                    // Is the feature enabled
                    if (vp8_read_bit(bc))
                    {
                        // Update the feature data and mask
                        enable_segfeature(xd, i, j);

                        data = (signed char)vp8_read_literal(
                                            bc, seg_feature_data_bits(j));

                        // Is the segment data signed..
                        if ( is_segfeature_signed(j) )
                        {
                            if (vp8_read_bit(bc))
                                data = - data;
                        }
                    }
                    else
                        data = 0;

                    set_segdata(xd, i, j, data);
#endif
                }
            }
        }

        if (xd->update_mb_segmentation_map)
        {
            // Which macro block level features are enabled
            vpx_memset(xd->mb_segment_tree_probs, 255,
                       sizeof(xd->mb_segment_tree_probs));
            vpx_memset(pc->segment_pred_probs, 255,
                       sizeof(pc->segment_pred_probs));

            // Read the probs used to decode the segment id for each macro
            // block.
            for (i = 0; i < MB_FEATURE_TREE_PROBS; i++)
            {
                // If not explicitly set value is defaulted to 255 by
                //memset above
                if (vp8_read_bit(bc))
                    xd->mb_segment_tree_probs[i] =
                        (vp8_prob)vp8_read_literal(bc, 8);
            }

            // If predictive coding of segment map is enabled read the
            // prediction probabilities.
            if ( pc->temporal_update )
            {
                // Read the prediction probs needed to decode the segment id
                // when predictive coding enabled
                for (i = 0; i < PREDICTION_PROBS; i++)
                {
                    // If not explicitly set value is defaulted to 255 by
                    // memset above
                    if (vp8_read_bit(bc))
                        pc->segment_pred_probs[i] =
                            (vp8_prob)vp8_read_literal(bc, 8);
                }
            }