lavc: add a wrapper for AVCodecContext.get_buffer().
[libav.git] / libavcodec / kgv1dec.c
1 /*
2 * Kega Game Video (KGV1) decoder
3 * Copyright (c) 2010 Daniel Verkamp
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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 * Kega Game Video decoder
25 */
26
27 #include "libavutil/common.h"
28 #include "libavutil/intreadwrite.h"
29 #include "libavutil/imgutils.h"
30 #include "avcodec.h"
31 #include "internal.h"
32
33 typedef struct {
34 AVCodecContext *avctx;
35 AVFrame prev, cur;
36 } KgvContext;
37
38 static void decode_flush(AVCodecContext *avctx)
39 {
40 KgvContext * const c = avctx->priv_data;
41
42 if (c->prev.data[0])
43 avctx->release_buffer(avctx, &c->prev);
44 }
45
46 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
47 {
48 const uint8_t *buf = avpkt->data;
49 const uint8_t *buf_end = buf + avpkt->size;
50 KgvContext * const c = avctx->priv_data;
51 int offsets[8];
52 uint16_t *out, *prev;
53 int outcnt = 0, maxcnt;
54 int w, h, i, res;
55
56 if (avpkt->size < 2)
57 return -1;
58
59 w = (buf[0] + 1) * 8;
60 h = (buf[1] + 1) * 8;
61 buf += 2;
62
63 if (av_image_check_size(w, h, 0, avctx))
64 return -1;
65
66 if (w != avctx->width || h != avctx->height) {
67 if (c->prev.data[0])
68 avctx->release_buffer(avctx, &c->prev);
69 avcodec_set_dimensions(avctx, w, h);
70 }
71
72 maxcnt = w * h;
73
74 c->cur.reference = 3;
75 if ((res = ff_get_buffer(avctx, &c->cur)) < 0)
76 return res;
77 out = (uint16_t *) c->cur.data[0];
78 if (c->prev.data[0]) {
79 prev = (uint16_t *) c->prev.data[0];
80 } else {
81 prev = NULL;
82 }
83
84 for (i = 0; i < 8; i++)
85 offsets[i] = -1;
86
87 while (outcnt < maxcnt && buf_end - 2 > buf) {
88 int code = AV_RL16(buf);
89 buf += 2;
90
91 if (!(code & 0x8000)) {
92 out[outcnt++] = code; // rgb555 pixel coded directly
93 } else {
94 int count;
95 int inp_off;
96 uint16_t *inp;
97
98 if ((code & 0x6000) == 0x6000) {
99 // copy from previous frame
100 int oidx = (code >> 10) & 7;
101 int start;
102
103 count = (code & 0x3FF) + 3;
104
105 if (offsets[oidx] < 0) {
106 if (buf_end - 3 < buf)
107 break;
108 offsets[oidx] = AV_RL24(buf);
109 buf += 3;
110 }
111
112 start = (outcnt + offsets[oidx]) % maxcnt;
113
114 if (maxcnt - start < count)
115 break;
116
117 if (!prev) {
118 av_log(avctx, AV_LOG_ERROR,
119 "Frame reference does not exist\n");
120 break;
121 }
122
123 inp = prev;
124 inp_off = start;
125 } else {
126 // copy from earlier in this frame
127 int offset = (code & 0x1FFF) + 1;
128
129 if (!(code & 0x6000)) {
130 count = 2;
131 } else if ((code & 0x6000) == 0x2000) {
132 count = 3;
133 } else {
134 if (buf_end - 1 < buf)
135 break;
136 count = 4 + *buf++;
137 }
138
139 if (outcnt < offset)
140 break;
141
142 inp = out;
143 inp_off = outcnt - offset;
144 }
145
146 if (maxcnt - outcnt < count)
147 break;
148
149 for (i = inp_off; i < count + inp_off; i++) {
150 out[outcnt++] = inp[i];
151 }
152 }
153 }
154
155 if (outcnt - maxcnt)
156 av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
157
158 *data_size = sizeof(AVFrame);
159 *(AVFrame*)data = c->cur;
160
161 if (c->prev.data[0])
162 avctx->release_buffer(avctx, &c->prev);
163 FFSWAP(AVFrame, c->cur, c->prev);
164
165 return avpkt->size;
166 }
167
168 static av_cold int decode_init(AVCodecContext *avctx)
169 {
170 KgvContext * const c = avctx->priv_data;
171
172 c->avctx = avctx;
173 avctx->pix_fmt = AV_PIX_FMT_RGB555;
174 avctx->flags |= CODEC_FLAG_EMU_EDGE;
175
176 return 0;
177 }
178
179 static av_cold int decode_end(AVCodecContext *avctx)
180 {
181 decode_flush(avctx);
182 return 0;
183 }
184
185 AVCodec ff_kgv1_decoder = {
186 .name = "kgv1",
187 .type = AVMEDIA_TYPE_VIDEO,
188 .id = AV_CODEC_ID_KGV1,
189 .priv_data_size = sizeof(KgvContext),
190 .init = decode_init,
191 .close = decode_end,
192 .decode = decode_frame,
193 .flush = decode_flush,
194 .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),
195 .capabilities = CODEC_CAP_DR1,
196 };