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