FFmpeg/libavcodec/mpegutils.c

/*
 * Mpeg video formats-related defines and utility functions
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <stdint.h>

#include "libavutil/common.h"
#include "libavutil/frame.h"
#include "libavutil/pixdesc.h"

#include "avcodec.h"
#include "mpegutils.h"

void ff_draw_horiz_band(AVCodecContext *avctx,
                        AVFrame *cur, AVFrame *last,
                        int y, int h, int picture_structure,
                        int first_field, int low_delay)
{
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
    int vshift = desc->log2_chroma_h;
    const int field_pic = picture_structure != PICT_FRAME;
    if (field_pic) {
        h <<= 1;
        y <<= 1;
    }

    h = FFMIN(h, avctx->height - y);

    if (field_pic && first_field &&
        !(avctx->slice_flags & SLICE_FLAG_ALLOW_FIELD))
        return;

    if (avctx->draw_horiz_band) {
        AVFrame *src;
        int offset[AV_NUM_DATA_POINTERS];
        int i;

        if (cur->pict_type == AV_PICTURE_TYPE_B || low_delay ||
           (avctx->slice_flags & SLICE_FLAG_CODED_ORDER))
            src = cur;
        else if (last)
            src = last;
        else
            return;

        if (cur->pict_type == AV_PICTURE_TYPE_B &&
            picture_structure == PICT_FRAME &&
            avctx->codec_id != AV_CODEC_ID_SVQ3) {
            for (i = 0; i < AV_NUM_DATA_POINTERS; i++)
                offset[i] = 0;
        } else {
            offset[0]= y * src->linesize[0];
            offset[1]=
            offset[2]= (y >> vshift) * src->linesize[1];
            for (i = 3; i < AV_NUM_DATA_POINTERS; i++)
                offset[i] = 0;
        }

        emms_c();

        avctx->draw_horiz_band(avctx, src, offset,
                               y, picture_structure, h);
    }
}