libavcodec/rl2.c

   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  * RL2 Video Decoder
  24  * @file rl2.c
  25  * @author Sascha Sommer (saschasommer@freenet.de)
  26  * For more information about the RL2 format, visit:
  27  *   http://wiki.multimedia.cx/index.php?title=RL2
  28  */
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34
  35 #include "avcodec.h"
  36
  37
  38 #define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
  39
  40 typedef struct Rl2Context {
  41     AVCodecContext *avctx;
  42     AVFrame frame;
  43
  44     unsigned short video_base; ///< initial drawing offset
  45     unsigned int clr_count;    ///< number of used colors (currently unused)
  46     unsigned char* back_frame; ///< background frame
  47     unsigned int palette[AVPALETTE_COUNT];
  48 } Rl2Context;
  49
  50 /**
  51  * Run Length Decode a single 320x200 frame
  52  * @param s rl2 context
  53  * @param buf input buffer
  54  * @param size input buffer size
  55  * @param out ouput buffer
  56  * @param stride stride of the output buffer
  57  * @param video_base offset of the rle data inside the frame
  58  */
  59 static void rl2_rle_decode(Rl2Context *s,const unsigned char* in,int size,
  60                                unsigned char* out,int stride,int video_base){
  61     int base_x = video_base % s->avctx->width;
  62     int base_y = video_base / s->avctx->width;
  63     int stride_adj = stride - s->avctx->width;
  64     int i;
  65     const unsigned char* back_frame = s->back_frame;
  66     const unsigned char* in_end = in + size;
  67     const unsigned char* out_end = out + stride * s->avctx->height;
  68     unsigned char* line_end = out + s->avctx->width;
  69
  70     /** copy start of the background frame */
  71     for(i=0;i<=base_y;i++){
  72         if(s->back_frame)
  73             memcpy(out,back_frame,s->avctx->width);
  74         out += stride;
  75         back_frame += s->avctx->width;
  76     }
  77     back_frame += base_x - s->avctx->width;
  78     line_end = out - stride_adj;
  79     out += base_x - stride;
  80
  81     /** decode the variable part of the frame */
  82     while(in < in_end){
  83         unsigned char val = *in++;
  84         int len = 1;
  85         if(val >= 0x80){
  86             if(in >= in_end)
  87                 break;
  88             len = *in++;
  89             if(!len)
  90                 break;
  91         }
  92
  93         if(len >= out_end - out)
  94             break;
  95
  96         if(s->back_frame)
  97             val |= 0x80;
  98         else
  99             val &= ~0x80;
 100
 101         while(len--){
 102             *out++ = (val == 0x80)? *back_frame:val;
 103             back_frame++;
 104             if(out == line_end){
 105                  out += stride_adj;
 106                  line_end += stride;
 107                  if(len >= out_end - out)
 108                      break;
 109             }
 110         }
 111     }
 112
 113     /** copy the rest from the background frame */
 114     if(s->back_frame){
 115         while(out < out_end){
 116             memcpy(out, back_frame, line_end - out);
 117             back_frame += line_end - out;
 118             out = line_end + stride_adj;
 119             line_end += stride;
 120         }
 121     }
 122 }
 123
 124
 125 /**
 126  * Initialize the decoder
 127  * @param avctx decoder context
 128  * @return 0 success, -1 on error
 129  */
 130 static av_cold int rl2_decode_init(AVCodecContext *avctx)
 131 {
 132     Rl2Context *s = avctx->priv_data;
 133     int back_size;
 134     int i;
 135     s->avctx = avctx;
 136     avctx->pix_fmt = PIX_FMT_PAL8;
 137
 138     /** parse extra data */
 139     if(!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE){
 140         av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
 141         return -1;
 142     }
 143
 144     /** get frame_offset */
 145     s->video_base = AV_RL16(&avctx->extradata[0]);
 146     s->clr_count = AV_RL32(&avctx->extradata[2]);
 147
 148     if(s->video_base >= avctx->width * avctx->height){
 149         av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
 150         return -1;
 151     }
 152
 153     /** initialize palette */
 154     for(i=0;i<AVPALETTE_COUNT;i++)
 155         s->palette[i] = AV_RB24(&avctx->extradata[6 + i * 3]);
 156
 157     /** decode background frame if present */
 158     back_size = avctx->extradata_size - EXTRADATA1_SIZE;
 159
 160     if(back_size > 0){
 161         unsigned char* back_frame = av_mallocz(avctx->width*avctx->height);
 162         if(!back_frame)
 163             return -1;
 164         rl2_rle_decode(s,avctx->extradata + EXTRADATA1_SIZE,back_size,
 165                            back_frame,avctx->width,0);
 166         s->back_frame = back_frame;
 167     }
 168     return 0;
 169 }
 170
 171
 172 /**
 173  * Decode a single frame
 174  * @param avctx decoder context
 175  * @param data decoded frame
 176  * @param data_size size of the decoded frame
 177  * @param buf input buffer
 178  * @param buf_size input buffer size
 179  * @return 0 success, -1 on error
 180  */
 181 static int rl2_decode_frame(AVCodecContext *avctx,
 182                               void *data, int *data_size,
 183                               const uint8_t *buf, int buf_size)
 184 {
 185     Rl2Context *s = avctx->priv_data;
 186
 187     if(s->frame.data[0])
 188         avctx->release_buffer(avctx, &s->frame);
 189
 190     /** get buffer */
 191     s->frame.reference= 0;
 192     if(avctx->get_buffer(avctx, &s->frame)) {
 193         av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 194         return -1;
 195     }
 196
 197     /** run length decode */
 198     rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);
 199
 200     /** make the palette available on the way out */
 201     memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
 202
 203     *data_size = sizeof(AVFrame);
 204     *(AVFrame*)data = s->frame;
 205
 206     /** report that the buffer was completely consumed */
 207     return buf_size;
 208 }
 209
 210
 211 /**
 212  * Uninit decoder
 213  * @param avctx decoder context
 214  * @return 0 success, -1 on error
 215  */
 216 static av_cold int rl2_decode_end(AVCodecContext *avctx)
 217 {
 218     Rl2Context *s = avctx->priv_data;
 219
 220     if(s->frame.data[0])
 221         avctx->release_buffer(avctx, &s->frame);
 222
 223     av_free(s->back_frame);
 224
 225     return 0;
 226 }
 227
 228
 229 AVCodec rl2_decoder = {
 230     "rl2",
 231     CODEC_TYPE_VIDEO,
 232     CODEC_ID_RL2,
 233     sizeof(Rl2Context),
 234     rl2_decode_init,
 235     NULL,
 236     rl2_decode_end,
 237     rl2_decode_frame,
 238     CODEC_CAP_DR1,
 239     .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
 240 };
 241