static int vaapi_mpeg4_start_frame(AVCodecContext *avctx, av_unused const uint8_t *buffer, av_unused uint32_t size)

{

    Mpeg4DecContext *ctx = avctx->priv_data;

    MpegEncContext * const s = &ctx->m;

    struct vaapi_context * const vactx = avctx->hwaccel_context;

    VAPictureParameterBufferMPEG4 *pic_param;

    VAIQMatrixBufferMPEG4 *iq_matrix;

    int i;



    av_dlog(avctx, "vaapi_mpeg4_start_frame()\n");



    vactx->slice_param_size = sizeof(VASliceParameterBufferMPEG4);



    /* Fill in VAPictureParameterBufferMPEG4 */

    pic_param = ff_vaapi_alloc_pic_param(vactx, sizeof(VAPictureParameterBufferMPEG4));

    if (!pic_param)

        return -1;

    pic_param->vop_width                                = s->width;

    pic_param->vop_height                               = s->height;

    pic_param->forward_reference_picture                = VA_INVALID_ID;

    pic_param->backward_reference_picture               = VA_INVALID_ID;

    pic_param->vol_fields.value                         = 0; /* reset all bits */

    pic_param->vol_fields.bits.short_video_header       = avctx->codec->id == AV_CODEC_ID_H263;

    pic_param->vol_fields.bits.chroma_format            = CHROMA_420;

    pic_param->vol_fields.bits.interlaced               = !s->progressive_sequence;

    pic_param->vol_fields.bits.obmc_disable             = 1;

    pic_param->vol_fields.bits.sprite_enable            = ctx->vol_sprite_usage;

    pic_param->vol_fields.bits.sprite_warping_accuracy  = s->sprite_warping_accuracy;

    pic_param->vol_fields.bits.quant_type               = s->mpeg_quant;

    pic_param->vol_fields.bits.quarter_sample           = s->quarter_sample;

    pic_param->vol_fields.bits.data_partitioned         = s->data_partitioning;

    pic_param->vol_fields.bits.reversible_vlc           = ctx->rvlc;

    pic_param->vol_fields.bits.resync_marker_disable    = !ctx->resync_marker;

    pic_param->no_of_sprite_warping_points              = ctx->num_sprite_warping_points;

    for (i = 0; i < ctx->num_sprite_warping_points && i < 3; i++) {

        pic_param->sprite_trajectory_du[i]              = ctx->sprite_traj[i][0];

        pic_param->sprite_trajectory_dv[i]              = ctx->sprite_traj[i][1];

    }

    pic_param->quant_precision                          = s->quant_precision;

    pic_param->vop_fields.value                         = 0; /* reset all bits */

    pic_param->vop_fields.bits.vop_coding_type          = s->pict_type - AV_PICTURE_TYPE_I;

    pic_param->vop_fields.bits.backward_reference_vop_coding_type = s->pict_type == AV_PICTURE_TYPE_B ? s->next_picture.f.pict_type - AV_PICTURE_TYPE_I : 0;

    pic_param->vop_fields.bits.vop_rounding_type        = s->no_rounding;

    pic_param->vop_fields.bits.intra_dc_vlc_thr         = mpeg4_get_intra_dc_vlc_thr(ctx);

    pic_param->vop_fields.bits.top_field_first          = s->top_field_first;

    pic_param->vop_fields.bits.alternate_vertical_scan_flag = s->alternate_scan;

    pic_param->vop_fcode_forward                        = s->f_code;

    pic_param->vop_fcode_backward                       = s->b_code;

    pic_param->vop_time_increment_resolution            = avctx->time_base.den;

    pic_param->num_macroblocks_in_gob                   = s->mb_width * ff_h263_get_gob_height(s);

    pic_param->num_gobs_in_vop                          = (s->mb_width * s->mb_height) / pic_param->num_macroblocks_in_gob;

    pic_param->TRB                                      = s->pb_time;

    pic_param->TRD                                      = s->pp_time;



    if (s->pict_type == AV_PICTURE_TYPE_B)

        pic_param->backward_reference_picture = ff_vaapi_get_surface_id(&s->next_picture.f);

    if (s->pict_type != AV_PICTURE_TYPE_I)

        pic_param->forward_reference_picture  = ff_vaapi_get_surface_id(&s->last_picture.f);



    /* Fill in VAIQMatrixBufferMPEG4 */

    /* Only the first inverse quantisation method uses the weighting matrices */

    if (pic_param->vol_fields.bits.quant_type) {

        iq_matrix = ff_vaapi_alloc_iq_matrix(vactx, sizeof(VAIQMatrixBufferMPEG4));

        if (!iq_matrix)

            return -1;

        iq_matrix->load_intra_quant_mat         = 1;

        iq_matrix->load_non_intra_quant_mat     = 1;



        for (i = 0; i < 64; i++) {

            int n = s->dsp.idct_permutation[ff_zigzag_direct[i]];

            iq_matrix->intra_quant_mat[i]       = s->intra_matrix[n];

            iq_matrix->non_intra_quant_mat[i]   = s->inter_matrix[n];

        }

    }

    return 0;

}
