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mpegutils.c
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1 /*
2  * Mpeg video formats-related defines and utility functions
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <stdint.h>
22 
23 #include "libavutil/common.h"
24 #include "libavutil/frame.h"
25 #include "libavutil/pixdesc.h"
26 
27 #include "avcodec.h"
28 #include "mpegutils.h"
29 
31  AVFrame *cur, AVFrame *last,
32  int y, int h, int picture_structure,
33  int first_field, int low_delay)
34 {
35  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
36  int vshift = desc->log2_chroma_h;
37  const int field_pic = picture_structure != PICT_FRAME;
38  if (field_pic) {
39  h <<= 1;
40  y <<= 1;
41  }
42 
43  h = FFMIN(h, avctx->height - y);
44 
45  if (field_pic && first_field &&
47  return;
48 
49  if (avctx->draw_horiz_band) {
50  AVFrame *src;
52  int i;
53 
54  if (cur->pict_type == AV_PICTURE_TYPE_B || low_delay ||
56  src = cur;
57  else if (last)
58  src = last;
59  else
60  return;
61 
62  if (cur->pict_type == AV_PICTURE_TYPE_B &&
63  picture_structure == PICT_FRAME &&
64  avctx->codec_id != AV_CODEC_ID_SVQ3) {
65  for (i = 0; i < AV_NUM_DATA_POINTERS; i++)
66  offset[i] = 0;
67  } else {
68  offset[0]= y * src->linesize[0];
69  offset[1]=
70  offset[2]= (y >> vshift) * src->linesize[1];
71  for (i = 3; i < AV_NUM_DATA_POINTERS; i++)
72  offset[i] = 0;
73  }
74 
75  emms_c();
76 
77  avctx->draw_horiz_band(avctx, src, offset,
78  y, picture_structure, h);
79  }
80 }