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
42typedef 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 */
60static 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 */
132static av_cold int rl2_decode_init(AVCodecContext *avctx)
133{
134    Rl2Context *s = avctx->priv_data;
135    int back_size;
136    int i;
137
138    s->avctx       = avctx;
139    avctx->pix_fmt = AV_PIX_FMT_PAL8;
140
141    /** parse extra data */
142    if (!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE) {
143        av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
144        return AVERROR(EINVAL);
145    }
146
147    /** get frame_offset */
148    s->video_base = AV_RL16(&avctx->extradata[0]);
149    s->clr_count  = AV_RL32(&avctx->extradata[2]);
150
151    if (s->video_base >= avctx->width * avctx->height) {
152        av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
153        return AVERROR_INVALIDDATA;
154    }
155
156    /** initialize palette */
157    for (i = 0; i < AVPALETTE_COUNT; i++)
158        s->palette[i] = 0xFFU << 24 | AV_RB24(&avctx->extradata[6 + i * 3]);
159
160    /** decode background frame if present */
161    back_size = avctx->extradata_size - EXTRADATA1_SIZE;
162
163    if (back_size > 0) {
164        uint8_t *back_frame = av_mallocz(avctx->width*avctx->height);
165        if (!back_frame)
166            return AVERROR(ENOMEM);
167        rl2_rle_decode(s, avctx->extradata + EXTRADATA1_SIZE, back_size,
168                       back_frame, avctx->width, 0);
169        s->back_frame = back_frame;
170    }
171    return 0;
172}
173
174
175static int rl2_decode_frame(AVCodecContext *avctx,
176                            void *data, int *got_frame,
177                            AVPacket *avpkt)
178{
179    AVFrame *frame     = data;
180    const uint8_t *buf = avpkt->data;
181    int ret, buf_size  = avpkt->size;
182    Rl2Context *s = avctx->priv_data;
183
184    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
185        return ret;
186
187    /** run length decode */
188    rl2_rle_decode(s, buf, buf_size, frame->data[0], frame->linesize[0],
189                   s->video_base);
190
191    /** make the palette available on the way out */
192    memcpy(frame->data[1], s->palette, AVPALETTE_SIZE);
193
194    *got_frame = 1;
195
196    /** report that the buffer was completely consumed */
197    return buf_size;
198}
199
200
201/**
202 * Uninit decoder
203 * @param avctx decoder context
204 * @return 0 success, -1 on error
205 */
206static av_cold int rl2_decode_end(AVCodecContext *avctx)
207{
208    Rl2Context *s = avctx->priv_data;
209
210    av_free(s->back_frame);
211
212    return 0;
213}
214
215
216AVCodec ff_rl2_decoder = {
217    .name           = "rl2",
218    .long_name      = NULL_IF_CONFIG_SMALL("RL2 video"),
219    .type           = AVMEDIA_TYPE_VIDEO,
220    .id             = AV_CODEC_ID_RL2,
221    .priv_data_size = sizeof(Rl2Context),
222    .init           = rl2_decode_init,
223    .close          = rl2_decode_end,
224    .decode         = rl2_decode_frame,
225    .capabilities   = CODEC_CAP_DR1,
226};
227