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 #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;
44 
45  return 0;
46 }
47 
49  void *data, int *got_frame,
50  AVPacket *pkt)
51 {
52  AuraDecodeContext *s = avctx->priv_data;
53  uint8_t *Y, *U, *V;
54  uint8_t val;
55  int x, y;
56  const uint8_t *buf = pkt->data;
57 
58  /* prediction error tables (make it clear that they are signed values) */
59  const int8_t *delta_table = (const int8_t*)buf + 16;
60 
61  if (pkt->size != 48 + avctx->height * avctx->width) {
62  av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
63  pkt->size, 48 + avctx->height * avctx->width);
64  return -1;
65  }
66 
67  /* pixel data starts 48 bytes in, after 3x16-byte tables */
68  buf += 48;
69 
70  if (s->frame.data[0])
71  avctx->release_buffer(avctx, &s->frame);
72 
74  s->frame.reference = 0;
75  if (ff_get_buffer(avctx, &s->frame) < 0) {
76  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
77  return -1;
78  }
79 
80  Y = s->frame.data[0];
81  U = s->frame.data[1];
82  V = s->frame.data[2];
83 
84  /* iterate through each line in the height */
85  for (y = 0; y < avctx->height; y++) {
86  /* reset predictors */
87  val = *buf++;
88  U[0] = val & 0xF0;
89  Y[0] = val << 4;
90  val = *buf++;
91  V[0] = val & 0xF0;
92  Y[1] = Y[0] + delta_table[val & 0xF];
93  Y += 2; U++; V++;
94 
95  /* iterate through the remaining pixel groups (4 pixels/group) */
96  for (x = 1; x < (avctx->width >> 1); x++) {
97  val = *buf++;
98  U[0] = U[-1] + delta_table[val >> 4];
99  Y[0] = Y[-1] + delta_table[val & 0xF];
100  val = *buf++;
101  V[0] = V[-1] + delta_table[val >> 4];
102  Y[1] = Y[ 0] + delta_table[val & 0xF];
103  Y += 2; U++; V++;
104  }
105  Y += s->frame.linesize[0] - avctx->width;
106  U += s->frame.linesize[1] - (avctx->width >> 1);
107  V += s->frame.linesize[2] - (avctx->width >> 1);
108  }
109 
110  *got_frame = 1;
111  *(AVFrame*)data = s->frame;
112 
113  return pkt->size;
114 }
115 
117 {
118  AuraDecodeContext *s = avctx->priv_data;
119 
120  if (s->frame.data[0])
121  avctx->release_buffer(avctx, &s->frame);
122 
123  return 0;
124 }
125 
127  .name = "aura2",
128  .type = AVMEDIA_TYPE_VIDEO,
129  .id = AV_CODEC_ID_AURA2,
130  .priv_data_size = sizeof(AuraDecodeContext),
134  .capabilities = CODEC_CAP_DR1,
135  .long_name = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),
136 };