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wnv1.c
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1 /*
2  * Winnov WNV1 codec
3  * Copyright (c) 2005 Konstantin Shishkov
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 /**
23  * @file
24  * Winnov WNV1 codec.
25  */
26 
27 #include "avcodec.h"
28 #include "get_bits.h"
29 #include "internal.h"
30 #include "mathops.h"
31 
32 
33 typedef struct WNV1Context {
34  int shift;
36 } WNV1Context;
37 
38 static const uint16_t code_tab[16][2] = {
39  { 0x1FD, 9 }, { 0xFD, 8 }, { 0x7D, 7 }, { 0x3D, 6 }, { 0x1D, 5 }, { 0x0D, 4 }, { 0x005, 3 },
40  { 0x000, 1 },
41  { 0x004, 3 }, { 0x0C, 4 }, { 0x1C, 5 }, { 0x3C, 6 }, { 0x7C, 7 }, { 0xFC, 8 }, { 0x1FC, 9 }, { 0xFF, 8 }
42 };
43 
44 #define CODE_VLC_BITS 9
45 static VLC code_vlc;
46 
47 /* returns modified base_value */
48 static inline int wnv1_get_code(WNV1Context *w, int base_value)
49 {
50  int v = get_vlc2(&w->gb, code_vlc.table, CODE_VLC_BITS, 1);
51 
52  if (v == 15)
53  return ff_reverse[get_bits(&w->gb, 8 - w->shift)];
54  else
55  return base_value + ((v - 7) << w->shift);
56 }
57 
58 static int decode_frame(AVCodecContext *avctx,
59  void *data, int *got_frame,
60  AVPacket *avpkt)
61 {
62  WNV1Context * const l = avctx->priv_data;
63  const uint8_t *buf = avpkt->data;
64  int buf_size = avpkt->size;
65  AVFrame * const p = data;
66  unsigned char *Y,*U,*V;
67  int i, j, ret;
68  int prev_y = 0, prev_u = 0, prev_v = 0;
69  uint8_t *rbuf;
70 
71  if (buf_size <= 8) {
72  av_log(avctx, AV_LOG_ERROR, "Packet size %d is too small\n", buf_size);
73  return AVERROR_INVALIDDATA;
74  }
75 
76  rbuf = av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
77  if (!rbuf) {
78  av_log(avctx, AV_LOG_ERROR, "Cannot allocate temporary buffer\n");
79  return AVERROR(ENOMEM);
80  }
81  memset(rbuf + buf_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
82 
83  if ((ret = ff_get_buffer(avctx, p, 0)) < 0) {
84  av_free(rbuf);
85  return ret;
86  }
87  p->key_frame = 1;
88 
89  for (i = 8; i < buf_size; i++)
90  rbuf[i] = ff_reverse[buf[i]];
91  init_get_bits(&l->gb, rbuf + 8, (buf_size - 8) * 8);
92 
93  if (buf[2] >> 4 == 6)
94  l->shift = 2;
95  else {
96  l->shift = 8 - (buf[2] >> 4);
97  if (l->shift > 4) {
99  "Unknown WNV1 frame header value %i",
100  buf[2] >> 4);
101  l->shift = 4;
102  }
103  if (l->shift < 1) {
104  avpriv_request_sample(avctx,
105  "Unknown WNV1 frame header value %i",
106  buf[2] >> 4);
107  l->shift = 1;
108  }
109  }
110 
111  Y = p->data[0];
112  U = p->data[1];
113  V = p->data[2];
114  for (j = 0; j < avctx->height; j++) {
115  for (i = 0; i < avctx->width / 2; i++) {
116  Y[i * 2] = wnv1_get_code(l, prev_y);
117  prev_u = U[i] = wnv1_get_code(l, prev_u);
118  prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
119  prev_v = V[i] = wnv1_get_code(l, prev_v);
120  }
121  Y += p->linesize[0];
122  U += p->linesize[1];
123  V += p->linesize[2];
124  }
125 
126 
127  *got_frame = 1;
128  av_free(rbuf);
129 
130  return buf_size;
131 }
132 
134 {
135  static VLC_TYPE code_table[1 << CODE_VLC_BITS][2];
136 
137  avctx->pix_fmt = AV_PIX_FMT_YUV422P;
138 
139  code_vlc.table = code_table;
140  code_vlc.table_allocated = 1 << CODE_VLC_BITS;
141  init_vlc(&code_vlc, CODE_VLC_BITS, 16,
142  &code_tab[0][1], 4, 2,
143  &code_tab[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);
144 
145  return 0;
146 }
147 
149  .name = "wnv1",
150  .long_name = NULL_IF_CONFIG_SMALL("Winnov WNV1"),
151  .type = AVMEDIA_TYPE_VIDEO,
152  .id = AV_CODEC_ID_WNV1,
153  .priv_data_size = sizeof(WNV1Context),
154  .init = decode_init,
155  .decode = decode_frame,
156  .capabilities = CODEC_CAP_DR1,
157 };