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canopus.c
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1 /*
2  * Canopus common routines
3  * Copyright (c) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include <stdint.h>
23 
24 #include "libavutil/rational.h"
25 
26 #include "avcodec.h"
27 #include "bytestream.h"
28 #include "canopus.h"
29 
31  const uint8_t *src, size_t size)
32 {
33  GetByteContext gbc;
34  int par_x, par_y, field_order;
35 
36  bytestream2_init(&gbc, src, size);
37 
38  /* Parse aspect ratio. */
39  bytestream2_skip(&gbc, 8); // unknown, 16 bits 1
40  par_x = bytestream2_get_le32(&gbc);
41  par_y = bytestream2_get_le32(&gbc);
42  if (par_x && par_y)
44  &avctx->sample_aspect_ratio.den,
45  par_x, par_y, 255);
46 
47  /* Short INFO tag (used in CLLC) has only AR data. */
48  if (size == 0x18)
49  return 0;
50 
51  bytestream2_skip(&gbc, 16); // unknown RDRT tag
52 
53  /* Parse FIEL tag. */
54  bytestream2_skip(&gbc, 8); // 'FIEL' and 4 bytes 0
55  field_order = bytestream2_get_le32(&gbc);
56  switch (field_order) {
57  case 0: avctx->field_order = AV_FIELD_TT; break;
58  case 1: avctx->field_order = AV_FIELD_BB; break;
59  case 2: avctx->field_order = AV_FIELD_PROGRESSIVE; break;
60  }
61 
62  return 0;
63 }
int ff_canopus_parse_info_tag(AVCodecContext *avctx, const uint8_t *src, size_t size)
Definition: canopus.c:30
int num
Numerator.
Definition: rational.h:59
AVRational sample_aspect_ratio
sample aspect ratio (0 if unknown) That is the width of a pixel divided by the height of the pixel...
Definition: avcodec.h:1866
static av_always_inline void bytestream2_init(GetByteContext *g, const uint8_t *buf, int buf_size)
Definition: bytestream.h:133
#define src
Definition: vp8dsp.c:254
uint8_t
ptrdiff_t size
Definition: opengl_enc.c:101
int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max)
Reduce a fraction.
Definition: rational.c:35
static av_always_inline void bytestream2_skip(GetByteContext *g, unsigned int size)
Definition: bytestream.h:164
Libavcodec external API header.
main external API structure.
Definition: avcodec.h:1488
Utilties for rational number calculation.
int den
Denominator.
Definition: rational.h:60
enum AVFieldOrder field_order
Field order.
Definition: avcodec.h:2140