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aura.c
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1 /*
2  * Aura 2 decoder
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 /**
22  * @file
23  * Aura 2 decoder
24  */
25 
26 #include "avcodec.h"
27 #include "internal.h"
28 #include "libavutil/internal.h"
29 
30 typedef struct AuraDecodeContext {
34 
36 {
37  AuraDecodeContext *s = avctx->priv_data;
38 
39  s->avctx = avctx;
40  /* width needs to be divisible by 4 for this codec to work */
41  if (avctx->width & 0x3)
42  return -1;
43  avctx->pix_fmt = AV_PIX_FMT_YUV422P;
45 
46  return 0;
47 }
48 
50  void *data, int *got_frame,
51  AVPacket *pkt)
52 {
53  AuraDecodeContext *s = avctx->priv_data;
54  uint8_t *Y, *U, *V;
55  uint8_t val;
56  int x, y;
57  const uint8_t *buf = pkt->data;
58 
59  /* prediction error tables (make it clear that they are signed values) */
60  const int8_t *delta_table = (const int8_t*)buf + 16;
61 
62  if (pkt->size != 48 + avctx->height * avctx->width) {
63  av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
64  pkt->size, 48 + avctx->height * avctx->width);
65  return -1;
66  }
67 
68  /* pixel data starts 48 bytes in, after 3x16-byte tables */
69  buf += 48;
70 
71  if (s->frame.data[0])
72  avctx->release_buffer(avctx, &s->frame);
73 
75  s->frame.reference = 0;
76  if (ff_get_buffer(avctx, &s->frame) < 0) {
77  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
78  return -1;
79  }
80 
81  Y = s->frame.data[0];
82  U = s->frame.data[1];
83  V = s->frame.data[2];
84 
85  /* iterate through each line in the height */
86  for (y = 0; y < avctx->height; y++) {
87  /* reset predictors */
88  val = *buf++;
89  U[0] = val & 0xF0;
90  Y[0] = val << 4;
91  val = *buf++;
92  V[0] = val & 0xF0;
93  Y[1] = Y[0] + delta_table[val & 0xF];
94  Y += 2; U++; V++;
95 
96  /* iterate through the remaining pixel groups (4 pixels/group) */
97  for (x = 1; x < (avctx->width >> 1); x++) {
98  val = *buf++;
99  U[0] = U[-1] + delta_table[val >> 4];
100  Y[0] = Y[-1] + delta_table[val & 0xF];
101  val = *buf++;
102  V[0] = V[-1] + delta_table[val >> 4];
103  Y[1] = Y[ 0] + delta_table[val & 0xF];
104  Y += 2; U++; V++;
105  }
106  Y += s->frame.linesize[0] - avctx->width;
107  U += s->frame.linesize[1] - (avctx->width >> 1);
108  V += s->frame.linesize[2] - (avctx->width >> 1);
109  }
110 
111  *got_frame = 1;
112  *(AVFrame*)data = s->frame;
113 
114  return pkt->size;
115 }
116 
118 {
119  AuraDecodeContext *s = avctx->priv_data;
120 
121  if (s->frame.data[0])
122  avctx->release_buffer(avctx, &s->frame);
123 
124  return 0;
125 }
126 
128  .name = "aura2",
129  .type = AVMEDIA_TYPE_VIDEO,
130  .id = AV_CODEC_ID_AURA2,
131  .priv_data_size = sizeof(AuraDecodeContext),
135  .capabilities = CODEC_CAP_DR1,
136  .long_name = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),
137 };