slicetype_decision.c

X264的纯C语言的的原码

            }
            if( p1 > p0+1 )
                i_bcost = i_bcost * 9 / 8; // arbitray penalty for I-blocks in and after B-frames
        }
    }

    return i_bcost;
}
#undef TRY_BIDIR
#undef SAVE_MVS

int x264_slicetype_frame_cost( x264_t *h, x264_mb_analysis_t *a,
                               x264_frame_t **frames, int p0, int p1, int b )
{
    int i_score = 0;
    int dist_scale_factor = 128;
    int *row_satd = frames[b]->i_row_satds[b-p0][p1-b];

    /* Check whether we already evaluated this frame
     * If we have tried this frame as P, then we have also tried
     * the preceding frames as B. (is this still true?) */
    if( frames[b]->i_cost_est[b-p0][p1-b] >= 0 )
        return frames[b]->i_cost_est[b-p0][p1-b];

    /* Init MVs so that we don't have to check edge conditions when loading predictors. */
    /* FIXME: not needed every time */
    memset( frames[b]->mv[0], 0, h->sps->i_mb_height * h->sps->i_mb_width * 2*sizeof(int16_t) );
    if( b != p1 )
        memset( frames[b]->mv[1], 0, h->sps->i_mb_height * h->sps->i_mb_width * 2*sizeof(int16_t) );

    if( b == p1 )
        frames[b]->i_intra_mbs[b-p0] = 0;
    if( p1 != p0 )
        dist_scale_factor = ( ((b-p0) << 8) + ((p1-p0) >> 1) ) / (p1-p0);

    /* the edge mbs seem to reduce the predictive quality of the
     * whole frame's score, but are needed for a spatial distribution. */
    if( h->param.rc.i_vbv_buffer_size )
    {
        for( h->mb.i_mb_y = 0; h->mb.i_mb_y < h->sps->i_mb_height; h->mb.i_mb_y++ )
        {
            row_satd[ h->mb.i_mb_y ] = 0;
            for( h->mb.i_mb_x = 0; h->mb.i_mb_x < h->sps->i_mb_width; h->mb.i_mb_x++ )
            {
                int i_mb_cost = x264_slicetype_mb_cost( h, a, frames, p0, p1, b, dist_scale_factor );
                row_satd[ h->mb.i_mb_y ] += i_mb_cost;
                if( h->mb.i_mb_y > 0 && h->mb.i_mb_y < h->sps->i_mb_height - 1 &&
                    h->mb.i_mb_x > 0 && h->mb.i_mb_x < h->sps->i_mb_width - 1 )
                {
                    i_score += i_mb_cost;
                }
            }
        }
    }
    else
    {
        for( h->mb.i_mb_y = 1; h->mb.i_mb_y < h->sps->i_mb_height - 1; h->mb.i_mb_y++ )
            for( h->mb.i_mb_x = 1; h->mb.i_mb_x < h->sps->i_mb_width - 1; h->mb.i_mb_x++ )
                i_score += x264_slicetype_mb_cost( h, a, frames, p0, p1, b, dist_scale_factor );
    }

    if( b != p1 )
        i_score = i_score * 100 / (120 + h->param.i_bframe_bias);

    frames[b]->i_cost_est[b-p0][p1-b] = i_score;
//  fprintf( stderr, "frm %d %c(%d,%d): %6d I:%d  \n", frames[b]->i_frame,
//           (p1==0?'I':b<p1?'B':'P'), b-p0, p1-b, i_score, frames[b]->i_intra_mbs[b-p0] );
///    x264_cpu_restore( h->param.cpu );
    return i_score;
}
void x264_slicetype_analyse( x264_t *h )
{
    x264_mb_analysis_t a;
    x264_frame_t *frames[X264_BFRAME_MAX+3] = { NULL, };
    int num_frames;
    int keyint_limit;
    int j;
    int i_mb_count = (h->sps->i_mb_width - 2) * (h->sps->i_mb_height - 2);
    int cost1p0, cost2p0, cost1b1, cost2p1;

    if( !h->frames.last_nonb )
        return;
    frames[0] = h->frames.last_nonb;
    for( j = 0; h->frames.next[j]; j++ )
        frames[j+1] = h->frames.next[j];
    keyint_limit = h->param.i_keyint_max - frames[0]->i_frame + h->frames.i_last_idr - 1;
    num_frames = X264_MIN( j, keyint_limit );
    if( num_frames == 0 )
        return;
    if( num_frames == 1 )
    {
no_b_frames:
        frames[1]->i_type = X264_TYPE_P;
        return;
    }

    x264_lowres_context_init( h, &a );

    cost2p1 = x264_slicetype_frame_cost( h, &a, frames, 0, 2, 2 );
    if( frames[2]->i_intra_mbs[2] > i_mb_count / 2 )
        goto no_b_frames;

    cost1b1 = x264_slicetype_frame_cost( h, &a, frames, 0, 2, 1 );
    cost1p0 = x264_slicetype_frame_cost( h, &a, frames, 0, 1, 1 );
    cost2p0 = x264_slicetype_frame_cost( h, &a, frames, 1, 2, 2 );
//  fprintf( stderr, "PP: %d + %d <=> BP: %d + %d \n",
//           cost1p0, cost2p0, cost1b1, cost2p1 );
    if( cost1p0 + cost2p0 < cost1b1 + cost2p1 )
        goto no_b_frames;

// arbitrary and untuned
#define INTER_THRESH 300
#define P_SENS_BIAS (50 - h->param.i_bframe_bias)
    frames[1]->i_type = X264_TYPE_B;

    for( j = 2; j <= X264_MIN( h->param.i_bframe, num_frames-1 ); j++ )
    {
        int pthresh = X264_MAX(INTER_THRESH - P_SENS_BIAS * (j-1), INTER_THRESH/10);
        int pcost = x264_slicetype_frame_cost( h, &a, frames, 0, j+1, j+1 );
//      fprintf( stderr, "frm%d+%d: %d <=> %d, I:%d/%d \n",
//               frames[0]->i_frame, j-1, pthresh, pcost/i_mb_count,
//               frames[j+1]->i_intra_mbs[j+1], i_mb_count );
        if( pcost > pthresh*i_mb_count || frames[j+1]->i_intra_mbs[j+1] > i_mb_count/3 )
        {
            frames[j]->i_type = X264_TYPE_P;
            break;
        }
        else
            frames[j]->i_type = X264_TYPE_B;
    }
}

void x264_slicetype_decide( x264_t *h )
{
    x264_frame_t *frm;
    int bframes;
    int i;

    if( h->frames.next[0] == NULL )
        return;

    if( h->param.rc.b_stat_read )
    {
        /* Use the frame types from the first pass */
        for( i = 0; h->frames.next[i] != NULL; i++ )
            h->frames.next[i]->i_type =
                x264_ratecontrol_slice_type( h, h->frames.next[i]->i_frame );
    }
    else if( h->param.i_bframe && h->param.b_bframe_adaptive )
        x264_slicetype_analyse( h );

    for( bframes = 0;; bframes++ )
    {
        frm = h->frames.next[bframes];

        /* Limit GOP size */
        if( frm->i_frame - h->frames.i_last_idr >= h->param.i_keyint_max )
        {
            if( frm->i_type == X264_TYPE_AUTO )
                frm->i_type = X264_TYPE_IDR;
            if( frm->i_type != X264_TYPE_IDR )
                x264_log( h, X264_LOG_WARNING, "specified frame type (%d) is not compatible with keyframe interval\n", frm->i_type );
        }
        if( frm->i_type == X264_TYPE_IDR )
        {
            /* Close GOP */
            if( bframes > 0 )
            {
                bframes--;
                h->frames.next[bframes]->i_type = X264_TYPE_P;
            }
            else
            {
                h->i_frame_num = 0;
            }
        }

        if( bframes == h->param.i_bframe
            || h->frames.next[bframes+1] == NULL )
        {
            if( IS_X264_TYPE_B( frm->i_type ) )
                x264_log( h, X264_LOG_WARNING, "specified frame type is not compatible with max B-frames\n" );
            if( frm->i_type == X264_TYPE_AUTO
                || IS_X264_TYPE_B( frm->i_type ) )
                frm->i_type = X264_TYPE_P;
        }

        if( frm->i_type != X264_TYPE_AUTO && frm->i_type != X264_TYPE_B && frm->i_type != X264_TYPE_BREF )
            break;

        frm->i_type = X264_TYPE_B;
    }
}

int x264_rc_analyse_slice( x264_t *h )
{
    x264_mb_analysis_t a;
    x264_frame_t *frames[X264_BFRAME_MAX+2] = { NULL, };
    int p0=0, p1, b;
    int cost;

    x264_lowres_context_init( h, &a );

    if( IS_X264_TYPE_I(h->fenc->i_type) )
    {
        p1 = b = 0;
    }
    else if( X264_TYPE_P == h->fenc->i_type )
    {
        p1 = 0;
        while( h->frames.current[p1] && IS_X264_TYPE_B( h->frames.current[p1]->i_type ) )
            p1++;
        p1++;
        b = p1;
    }
    else //B
    {
        p1 = (h->fref1[0]->i_poc - h->fref0[0]->i_poc)/2;
        b  = (h->fref1[0]->i_poc - h->fenc->i_poc)/2;
        frames[p1] = h->fref1[0];
    }
    frames[p0] = h->fref0[0];
    frames[b] = h->fenc;

    cost = x264_slicetype_frame_cost( h, &a, frames, p0, p1, b );
    h->fenc->i_row_satd = h->fenc->i_row_satds[b-p0][p1-b];
    h->fdec->i_row_satd = h->fdec->i_row_satds[b-p0][p1-b];
    h->fdec->i_satd = cost;
    memcpy( h->fdec->i_row_satd, h->fenc->i_row_satd, h->sps->i_mb_height * sizeof(int) );
    return cost;
}