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 libavcodec/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 "libavutil/intreadwrite.h"
  36 #include "avcodec.h"
  37
  38
  39 #define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
  40
  41 typedef struct Rl2Context {
  42     AVCodecContext *avctx;
  43     AVFrame frame;
  44
  45     unsigned short video_base; ///< initial drawing offset
  46     unsigned int clr_count;    ///< number of used colors (currently unused)
  47     unsigned char* back_frame; ///< background frame
  48     unsigned int palette[AVPALETTE_COUNT];
  49 } Rl2Context;
  50
  51 /**
  52  * Run Length Decode a single 320x200 frame
  53  * @param s rl2 context
  54  * @param buf input buffer
  55  * @param size input buffer size
  56  * @param out ouput buffer
  57  * @param stride stride of the output buffer
  58  * @param video_base offset of the rle data inside the frame
  59  */
  60 static void rl2_rle_decode(Rl2Context *s,const unsigned char* in,int size,
  61                                unsigned char* out,int stride,int video_base){
  62     int base_x = video_base % s->avctx->width;
  63     int base_y = video_base / s->avctx->width;
  64     int stride_adj = stride - s->avctx->width;
  65     int i;
  66     const unsigned char* back_frame = s->back_frame;
  67     const unsigned char* in_end = in + size;
  68     const unsigned char* out_end = out + stride * s->avctx->height;
  69     unsigned char* line_end = out + s->avctx->width;
  70
  71     /** copy start of the background frame */
  72     for(i=0;i<=base_y;i++){
  73         if(s->back_frame)
  74             memcpy(out,back_frame,s->avctx->width);
  75         out += stride;
  76         back_frame += s->avctx->width;
  77     }
  78     back_frame += base_x - s->avctx->width;
  79     line_end = out - stride_adj;
  80     out += base_x - stride;
  81
  82     /** decode the variable part of the frame */
  83     while(in < in_end){
  84         unsigned char val = *in++;
  85         int len = 1;
  86         if(val >= 0x80){
  87             if(in >= in_end)
  88                 break;
  89             len = *in++;
  90             if(!len)
  91                 break;
  92         }
  93
  94         if(len >= out_end - out)
  95             break;
  96
  97         if(s->back_frame)
  98             val |= 0x80;
  99         else
 100             val &= ~0x80;
 101
 102         while(len--){
 103             *out++ = (val == 0x80)? *back_frame:val;
 104             back_frame++;
 105             if(out == line_end){
 106                  out += stride_adj;
 107                  line_end += stride;
 108                  if(len >= out_end - out)
 109                      break;
 110             }
 111         }
 112     }
 113
 114     /** copy the rest from the background frame */
 115     if(s->back_frame){
 116         while(out < out_end){
 117             memcpy(out, back_frame, line_end - out);
 118             back_frame += line_end - out;
 119             out = line_end + stride_adj;
 120             line_end += stride;
 121         }
 122     }
 123 }
 124
 125
 126 /**
 127  * Initialize the decoder
 128  * @param avctx decoder context
 129  * @return 0 success, -1 on error
 130  */
 131 static av_cold int rl2_decode_init(AVCodecContext *avctx)
 132 {
 133     Rl2Context *s = avctx->priv_data;
 134     int back_size;
 135     int i;
 136     s->avctx = avctx;
 137     avctx->pix_fmt = PIX_FMT_PAL8;
 138
 139     /** parse extra data */
 140     if(!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE){
 141         av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
 142         return -1;
 143     }
 144
 145     /** get frame_offset */
 146     s->video_base = AV_RL16(&avctx->extradata[0]);
 147     s->clr_count = AV_RL32(&avctx->extradata[2]);
 148
 149     if(s->video_base >= avctx->width * avctx->height){
 150         av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
 151         return -1;
 152     }
 153
 154     /** initialize palette */
 155     for(i=0;i<AVPALETTE_COUNT;i++)
 156         s->palette[i] = AV_RB24(&avctx->extradata[6 + i * 3]);
 157
 158     /** decode background frame if present */
 159     back_size = avctx->extradata_size - EXTRADATA1_SIZE;
 160
 161     if(back_size > 0){
 162         unsigned char* back_frame = av_mallocz(avctx->width*avctx->height);
 163         if(!back_frame)
 164             return -1;
 165         rl2_rle_decode(s,avctx->extradata + EXTRADATA1_SIZE,back_size,
 166                            back_frame,avctx->width,0);
 167         s->back_frame = back_frame;
 168     }
 169     return 0;
 170 }
 171
 172
 173 /**
 174  * Decode a single frame
 175  * @param avctx decoder context
 176  * @param data decoded frame
 177  * @param data_size size of the decoded frame
 178  * @param buf input buffer
 179  * @param buf_size input buffer size
 180  * @return 0 success, -1 on error
 181  */
 182 static int rl2_decode_frame(AVCodecContext *avctx,
 183                               void *data, int *data_size,
 184                               AVPacket *avpkt)
 185 {
 186     const uint8_t *buf = avpkt->data;
 187     int buf_size = avpkt->size;
 188     Rl2Context *s = avctx->priv_data;
 189
 190     if(s->frame.data[0])
 191         avctx->release_buffer(avctx, &s->frame);
 192
 193     /** get buffer */
 194     s->frame.reference= 0;
 195     if(avctx->get_buffer(avctx, &s->frame)) {
 196         av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 197         return -1;
 198     }
 199
 200     /** run length decode */
 201     rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);
 202
 203     /** make the palette available on the way out */
 204     memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
 205
 206     *data_size = sizeof(AVFrame);
 207     *(AVFrame*)data = s->frame;
 208
 209     /** report that the buffer was completely consumed */
 210     return buf_size;
 211 }
 212
 213
 214 /**
 215  * Uninit decoder
 216  * @param avctx decoder context
 217  * @return 0 success, -1 on error
 218  */
 219 static av_cold int rl2_decode_end(AVCodecContext *avctx)
 220 {
 221     Rl2Context *s = avctx->priv_data;
 222
 223     if(s->frame.data[0])
 224         avctx->release_buffer(avctx, &s->frame);
 225
 226     av_free(s->back_frame);
 227
 228     return 0;
 229 }
 230
 231
 232 AVCodec rl2_decoder = {
 233     "rl2",
 234     CODEC_TYPE_VIDEO,
 235     CODEC_ID_RL2,
 236     sizeof(Rl2Context),
 237     rl2_decode_init,
 238     NULL,
 239     rl2_decode_end,
 240     rl2_decode_frame,
 241     CODEC_CAP_DR1,
 242     .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
 243 };
 244