1 /*
2 * RL2 Video Decoder
3 * Copyright (C) 2008 Sascha Sommer (saschasommer@freenet.de)
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 * RL2 Video Decoder
25 * @author Sascha Sommer (saschasommer@freenet.de)
26 * @see http://wiki.multimedia.cx/index.php?title=RL2
27 */
28
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32
33 #include "libavutil/internal.h"
34 #include "libavutil/intreadwrite.h"
35 #include "libavutil/mem.h"
36 #include "avcodec.h"
37 #include "internal.h"
38
39
40 #define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
41
42 typedef struct Rl2Context {
43 AVCodecContext *avctx;
44
45 uint16_t video_base; ///< initial drawing offset
46 uint32_t clr_count; ///< number of used colors (currently unused)
47 uint8_t *back_frame; ///< background frame
48 uint32_t palette[AVPALETTE_COUNT];
49 } Rl2Context;
50
51 /**
52 * Run Length Decode a single 320x200 frame
53 * @param s rl2 context
54 * @param in input buffer
55 * @param size input buffer size
56 * @param out output buffer
57 * @param stride stride of the output buffer
58 * @param video_base offset of the rle data inside the frame
59 */
rl2_rle_decode(Rl2Context * s,const uint8_t * in,int size,uint8_t * out,int stride,int video_base)60 static void rl2_rle_decode(Rl2Context *s, const uint8_t *in, int size,
61 uint8_t *out, int stride, int video_base)
62 {
63 int base_x = video_base % s->avctx->width;
64 int base_y = video_base / s->avctx->width;
65 int stride_adj = stride - s->avctx->width;
66 int i;
67 const uint8_t *back_frame = s->back_frame;
68 const uint8_t *in_end = in + size;
69 const uint8_t *out_end = out + stride * s->avctx->height;
70 uint8_t *line_end;
71
72 /** copy start of the background frame */
73 for (i = 0; i <= base_y; i++) {
74 if (s->back_frame)
75 memcpy(out, back_frame, s->avctx->width);
76 out += stride;
77 back_frame += s->avctx->width;
78 }
79 back_frame += base_x - s->avctx->width;
80 line_end = out - stride_adj;
81 out += base_x - stride;
82
83 /** decode the variable part of the frame */
84 while (in < in_end) {
85 uint8_t val = *in++;
86 int len = 1;
87 if (val >= 0x80) {
88 if (in >= in_end)
89 break;
90 len = *in++;
91 if (!len)
92 break;
93 }
94
95 if (len >= out_end - out)
96 break;
97
98 if (s->back_frame)
99 val |= 0x80;
100 else
101 val &= ~0x80;
102
103 while (len--) {
104 *out++ = (val == 0x80) ? *back_frame : val;
105 back_frame++;
106 if (out == line_end) {
107 out += stride_adj;
108 line_end += stride;
109 if (len >= out_end - out)
110 break;
111 }
112 }
113 }
114
115 /** copy the rest from the background frame */
116 if (s->back_frame) {
117 while (out < out_end) {
118 memcpy(out, back_frame, line_end - out);
119 back_frame += line_end - out;
120 out = line_end + stride_adj;
121 line_end += stride;
122 }
123 }
124 }
125
126
127 /**
128 * Initialize the decoder
129 * @param avctx decoder context
130 * @return 0 success, -1 on error
131 */
rl2_decode_init(AVCodecContext * avctx)132 static av_cold int rl2_decode_init(AVCodecContext *avctx)
133 {
134 Rl2Context *s = avctx->priv_data;
135 int back_size;
136 int i;
137 int ret;
138
139 s->avctx = avctx;
140 avctx->pix_fmt = AV_PIX_FMT_PAL8;
141
142 ret = ff_set_dimensions(avctx, 320, 200);
143 if (ret < 0)
144 return ret;
145
146 /** parse extra data */
147 if (!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE) {
148 av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
149 return AVERROR(EINVAL);
150 }
151
152 /** get frame_offset */
153 s->video_base = AV_RL16(&avctx->extradata[0]);
154 s->clr_count = AV_RL32(&avctx->extradata[2]);
155
156 if (s->video_base >= avctx->width * avctx->height) {
157 av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
158 return AVERROR_INVALIDDATA;
159 }
160
161 /** initialize palette */
162 for (i = 0; i < AVPALETTE_COUNT; i++)
163 s->palette[i] = 0xFFU << 24 | AV_RB24(&avctx->extradata[6 + i * 3]);
164
165 /** decode background frame if present */
166 back_size = avctx->extradata_size - EXTRADATA1_SIZE;
167
168 if (back_size > 0) {
169 uint8_t *back_frame = av_mallocz(avctx->width*avctx->height);
170 if (!back_frame)
171 return AVERROR(ENOMEM);
172 rl2_rle_decode(s, avctx->extradata + EXTRADATA1_SIZE, back_size,
173 back_frame, avctx->width, 0);
174 s->back_frame = back_frame;
175 }
176 return 0;
177 }
178
179
rl2_decode_frame(AVCodecContext * avctx,void * data,int * got_frame,AVPacket * avpkt)180 static int rl2_decode_frame(AVCodecContext *avctx,
181 void *data, int *got_frame,
182 AVPacket *avpkt)
183 {
184 AVFrame *frame = data;
185 const uint8_t *buf = avpkt->data;
186 int ret, buf_size = avpkt->size;
187 Rl2Context *s = avctx->priv_data;
188
189 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
190 return ret;
191
192 /** run length decode */
193 rl2_rle_decode(s, buf, buf_size, frame->data[0], frame->linesize[0],
194 s->video_base);
195
196 /** make the palette available on the way out */
197 memcpy(frame->data[1], s->palette, AVPALETTE_SIZE);
198
199 *got_frame = 1;
200
201 /** report that the buffer was completely consumed */
202 return buf_size;
203 }
204
205
206 /**
207 * Uninit decoder
208 * @param avctx decoder context
209 * @return 0 success, -1 on error
210 */
rl2_decode_end(AVCodecContext * avctx)211 static av_cold int rl2_decode_end(AVCodecContext *avctx)
212 {
213 Rl2Context *s = avctx->priv_data;
214
215 av_freep(&s->back_frame);
216
217 return 0;
218 }
219
220
221 AVCodec ff_rl2_decoder = {
222 .name = "rl2",
223 .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
224 .type = AVMEDIA_TYPE_VIDEO,
225 .id = AV_CODEC_ID_RL2,
226 .priv_data_size = sizeof(Rl2Context),
227 .init = rl2_decode_init,
228 .close = rl2_decode_end,
229 .decode = rl2_decode_frame,
230 .capabilities = AV_CODEC_CAP_DR1,
231 };
232