libavcodec/flashsv.c

   1 /*
   2  * Flash Screen Video decoder
   3  * Copyright (C) 2004 Alex Beregszaszi
   4  * Copyright (C) 2006 Benjamin Larsson
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 /**
  24  * @file libavcodec/flashsv.c
  25  * Flash Screen Video decoder
  26  * @author Alex Beregszaszi
  27  * @author Benjamin Larsson
  28  */
  29
  30 /* Bitstream description
  31  * The picture is divided into blocks that are zlib compressed.
  32  *
  33  * The decoder is fed complete frames, the frameheader contains:
  34  * 4bits of block width
  35  * 12bits of frame width
  36  * 4bits of block height
  37  * 12bits of frame height
  38  *
  39  * Directly after the header are the compressed blocks. The blocks
  40  * have their compressed size represented with 16bits in the beginnig.
  41  * If the size = 0 then the block is unchanged from the previous frame.
  42  * All blocks are decompressed until the buffer is consumed.
  43  *
  44  * Encoding ideas, a basic encoder would just use a fixed block size.
  45  * Block sizes can be multipels of 16, from 16 to 256. The blocks don't
  46  * have to be quadratic. A brute force search with a set of diffrent
  47  * block sizes should give a better result then to just use a fixed size.
  48  */
  49
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52
  53 #include "avcodec.h"
  54 #include "get_bits.h"
  55
  56 #include <zlib.h>
  57
  58 typedef struct FlashSVContext {
  59     AVCodecContext *avctx;
  60     AVFrame frame;
  61     int image_width, image_height;
  62     int block_width, block_height;
  63     uint8_t* tmpblock;
  64     int block_size;
  65     z_stream zstream;
  66 } FlashSVContext;
  67
  68
  69 static void copy_region(uint8_t *sptr, uint8_t *dptr,
  70         int dx, int dy, int h, int w, int stride)
  71 {
  72     int i;
  73
  74     for (i = dx+h; i > dx; i--)
  75     {
  76         memcpy(dptr+(i*stride)+dy*3, sptr, w*3);
  77         sptr += w*3;
  78     }
  79 }
  80
  81
  82 static av_cold int flashsv_decode_init(AVCodecContext *avctx)
  83 {
  84     FlashSVContext *s = avctx->priv_data;
  85     int zret; // Zlib return code
  86
  87     s->avctx = avctx;
  88     s->zstream.zalloc = Z_NULL;
  89     s->zstream.zfree = Z_NULL;
  90     s->zstream.opaque = Z_NULL;
  91     zret = inflateInit(&(s->zstream));
  92     if (zret != Z_OK) {
  93         av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
  94         return 1;
  95     }
  96     avctx->pix_fmt = PIX_FMT_BGR24;
  97     s->frame.data[0] = NULL;
  98
  99     return 0;
 100 }
 101
 102
 103 static int flashsv_decode_frame(AVCodecContext *avctx,
 104                                     void *data, int *data_size,
 105                                     AVPacket *avpkt)
 106 {
 107     const uint8_t *buf = avpkt->data;
 108     int buf_size = avpkt->size;
 109     FlashSVContext *s = avctx->priv_data;
 110     int h_blocks, v_blocks, h_part, v_part, i, j;
 111     GetBitContext gb;
 112
 113     /* no supplementary picture */
 114     if (buf_size == 0)
 115         return 0;
 116
 117     if(s->frame.data[0])
 118             avctx->release_buffer(avctx, &s->frame);
 119
 120     init_get_bits(&gb, buf, buf_size * 8);
 121
 122     /* start to parse the bitstream */
 123     s->block_width = 16* (get_bits(&gb, 4)+1);
 124     s->image_width =     get_bits(&gb,12);
 125     s->block_height= 16* (get_bits(&gb, 4)+1);
 126     s->image_height=     get_bits(&gb,12);
 127
 128     /* calculate amount of blocks and the size of the border blocks */
 129     h_blocks = s->image_width / s->block_width;
 130     h_part = s->image_width % s->block_width;
 131     v_blocks = s->image_height / s->block_height;
 132     v_part = s->image_height % s->block_height;
 133
 134     /* the block size could change between frames, make sure the buffer
 135      * is large enough, if not, get a larger one */
 136     if(s->block_size < s->block_width*s->block_height) {
 137         if (s->tmpblock != NULL)
 138             av_free(s->tmpblock);
 139         if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) {
 140             av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
 141             return -1;
 142         }
 143     }
 144     s->block_size = s->block_width*s->block_height;
 145
 146     /* init the image size once */
 147     if((avctx->width==0) && (avctx->height==0)){
 148         avctx->width = s->image_width;
 149         avctx->height = s->image_height;
 150     }
 151
 152     /* check for changes of image width and image height */
 153     if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
 154         av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
 155         av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d  vs  ch = %d, cv = %d\n",avctx->height,
 156         avctx->width,s->image_height,s->image_width);
 157         return -1;
 158     }
 159
 160     av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
 161         s->image_width, s->image_height, s->block_width, s->block_height,
 162         h_blocks, v_blocks, h_part, v_part);
 163
 164     s->frame.reference = 1;
 165     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
 166     if(avctx->reget_buffer(avctx, &s->frame) < 0){
 167       av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
 168       return -1;
 169     }
 170
 171     /* loop over all block columns */
 172     for (j = 0; j < v_blocks + (v_part?1:0); j++)
 173     {
 174
 175         int hp = j*s->block_height; // horiz position in frame
 176         int hs = (j<v_blocks)?s->block_height:v_part; // size of block
 177
 178
 179         /* loop over all block rows */
 180         for (i = 0; i < h_blocks + (h_part?1:0); i++)
 181         {
 182             int wp = i*s->block_width; // vert position in frame
 183             int ws = (i<h_blocks)?s->block_width:h_part; // size of block
 184
 185             /* get the size of the compressed zlib chunk */
 186             int size = get_bits(&gb, 16);
 187
 188             if (size == 0) {
 189                 /* no change, don't do anything */
 190             } else {
 191                 /* decompress block */
 192                 int ret = inflateReset(&(s->zstream));
 193                 if (ret != Z_OK)
 194                 {
 195                     av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
 196                     /* return -1; */
 197                 }
 198                 s->zstream.next_in = buf+(get_bits_count(&gb)/8);
 199                 s->zstream.avail_in = size;
 200                 s->zstream.next_out = s->tmpblock;
 201                 s->zstream.avail_out = s->block_size*3;
 202                 ret = inflate(&(s->zstream), Z_FINISH);
 203                 if (ret == Z_DATA_ERROR)
 204                 {
 205                     av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
 206                     inflateSync(&(s->zstream));
 207                     ret = inflate(&(s->zstream), Z_FINISH);
 208                 }
 209
 210                 if ((ret != Z_OK) && (ret != Z_STREAM_END))
 211                 {
 212                     av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
 213                     /* return -1; */
 214                 }
 215                 copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
 216                 skip_bits_long(&gb, 8*size);   /* skip the consumed bits */
 217             }
 218         }
 219     }
 220
 221     *data_size = sizeof(AVFrame);
 222     *(AVFrame*)data = s->frame;
 223
 224     if ((get_bits_count(&gb)/8) != buf_size)
 225         av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
 226             buf_size, (get_bits_count(&gb)/8));
 227
 228     /* report that the buffer was completely consumed */
 229     return buf_size;
 230 }
 231
 232
 233 static av_cold int flashsv_decode_end(AVCodecContext *avctx)
 234 {
 235     FlashSVContext *s = avctx->priv_data;
 236     inflateEnd(&(s->zstream));
 237     /* release the frame if needed */
 238     if (s->frame.data[0])
 239         avctx->release_buffer(avctx, &s->frame);
 240
 241     /* free the tmpblock */
 242     if (s->tmpblock != NULL)
 243         av_free(s->tmpblock);
 244
 245     return 0;
 246 }
 247
 248
 249 AVCodec flashsv_decoder = {
 250     "flashsv",
 251     CODEC_TYPE_VIDEO,
 252     CODEC_ID_FLASHSV,
 253     sizeof(FlashSVContext),
 254     flashsv_decode_init,
 255     NULL,
 256     flashsv_decode_end,
 257     flashsv_decode_frame,
 258     CODEC_CAP_DR1,
 259     .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
 260     .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"),
 261 };