aura.c
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1 /*
2  * Aura 2 decoder
3  *
4  * This file is part of Libav.
5  *
6  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
26 #include "avcodec.h"
27 
28 typedef struct AuraDecodeContext {
32 
34 {
35  AuraDecodeContext *s = avctx->priv_data;
36 
37  s->avctx = avctx;
38  /* width needs to be divisible by 4 for this codec to work */
39  if (avctx->width & 0x3)
40  return -1;
41  avctx->pix_fmt = PIX_FMT_YUV422P;
42 
43  return 0;
44 }
45 
47  void *data, int *data_size,
48  AVPacket *pkt)
49 {
50  AuraDecodeContext *s=avctx->priv_data;
51 
52  uint8_t *Y, *U, *V;
53  uint8_t val;
54  int x, y;
55  const uint8_t *buf = pkt->data;
56 
57  /* prediction error tables (make it clear that they are signed values) */
58  const int8_t *delta_table = (const int8_t*)buf + 16;
59 
60  if (pkt->size != 48 + avctx->height * avctx->width) {
61  av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
62  pkt->size, 48 + avctx->height * avctx->width);
63  return -1;
64  }
65 
66  /* pixel data starts 48 bytes in, after 3x16-byte tables */
67  buf += 48;
68 
69  if(s->frame.data[0])
70  avctx->release_buffer(avctx, &s->frame);
71 
73  s->frame.reference = 0;
74  if(avctx->get_buffer(avctx, &s->frame) < 0) {
75  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
76  return -1;
77  }
78 
79  Y = s->frame.data[0];
80  U = s->frame.data[1];
81  V = s->frame.data[2];
82 
83  /* iterate through each line in the height */
84  for (y = 0; y < avctx->height; y++) {
85  /* reset predictors */
86  val = *buf++;
87  U[0] = val & 0xF0;
88  Y[0] = val << 4;
89  val = *buf++;
90  V[0] = val & 0xF0;
91  Y[1] = Y[0] + delta_table[val & 0xF];
92  Y += 2; U++; V++;
93 
94  /* iterate through the remaining pixel groups (4 pixels/group) */
95  for (x = 1; x < (avctx->width >> 1); x++) {
96  val = *buf++;
97  U[0] = U[-1] + delta_table[val >> 4];
98  Y[0] = Y[-1] + delta_table[val & 0xF];
99  val = *buf++;
100  V[0] = V[-1] + delta_table[val >> 4];
101  Y[1] = Y[ 0] + delta_table[val & 0xF];
102  Y += 2; U++; V++;
103  }
104  Y += s->frame.linesize[0] - avctx->width;
105  U += s->frame.linesize[1] - (avctx->width >> 1);
106  V += s->frame.linesize[2] - (avctx->width >> 1);
107  }
108 
109  *data_size=sizeof(AVFrame);
110  *(AVFrame*)data= s->frame;
111 
112  return pkt->size;
113 }
114 
116 {
117  AuraDecodeContext *s = avctx->priv_data;
118 
119  if (s->frame.data[0])
120  avctx->release_buffer(avctx, &s->frame);
121 
122  return 0;
123 }
124 
126  .name = "aura2",
127  .type = AVMEDIA_TYPE_VIDEO,
128  .id = CODEC_ID_AURA2,
129  .priv_data_size = sizeof(AuraDecodeContext),
133  .capabilities = CODEC_CAP_DR1,
134  .long_name = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),
135 };
136