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 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 "bitstream.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                                     const uint8_t *buf, int buf_size)
 106 {
 107     FlashSVContext *s = avctx->priv_data;
 108     int h_blocks, v_blocks, h_part, v_part, i, j;
 109     GetBitContext gb;
 110
 111     /* no supplementary picture */
 112     if (buf_size == 0)
 113         return 0;
 114
 115     if(s->frame.data[0])
 116             avctx->release_buffer(avctx, &s->frame);
 117
 118     init_get_bits(&gb, buf, buf_size * 8);
 119
 120     /* start to parse the bitstream */
 121     s->block_width = 16* (get_bits(&gb, 4)+1);
 122     s->image_width =     get_bits(&gb,12);
 123     s->block_height= 16* (get_bits(&gb, 4)+1);
 124     s->image_height=     get_bits(&gb,12);
 125
 126     /* calculate amount of blocks and the size of the border blocks */
 127     h_blocks = s->image_width / s->block_width;
 128     h_part = s->image_width % s->block_width;
 129     v_blocks = s->image_height / s->block_height;
 130     v_part = s->image_height % s->block_height;
 131
 132     /* the block size could change between frames, make sure the buffer
 133      * is large enough, if not, get a larger one */
 134     if(s->block_size < s->block_width*s->block_height) {
 135         if (s->tmpblock != NULL)
 136             av_free(s->tmpblock);
 137         if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) {
 138             av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n");
 139             return -1;
 140         }
 141     }
 142     s->block_size = s->block_width*s->block_height;
 143
 144     /* init the image size once */
 145     if((avctx->width==0) && (avctx->height==0)){
 146         avctx->width = s->image_width;
 147         avctx->height = s->image_height;
 148     }
 149
 150     /* check for changes of image width and image height */
 151     if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) {
 152         av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n");
 153         av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d  vs  ch = %d, cv = %d\n",avctx->height,
 154         avctx->width,s->image_height,s->image_width);
 155         return -1;
 156     }
 157
 158     av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n",
 159         s->image_width, s->image_height, s->block_width, s->block_height,
 160         h_blocks, v_blocks, h_part, v_part);
 161
 162     s->frame.reference = 1;
 163     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
 164     if (avctx->get_buffer(avctx, &s->frame) < 0) {
 165         av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 166         return -1;
 167     }
 168
 169     /* loop over all block columns */
 170     for (j = 0; j < v_blocks + (v_part?1:0); j++)
 171     {
 172
 173         int hp = j*s->block_height; // horiz position in frame
 174         int hs = (j<v_blocks)?s->block_height:v_part; // size of block
 175
 176
 177         /* loop over all block rows */
 178         for (i = 0; i < h_blocks + (h_part?1:0); i++)
 179         {
 180             int wp = i*s->block_width; // vert position in frame
 181             int ws = (i<h_blocks)?s->block_width:h_part; // size of block
 182
 183             /* get the size of the compressed zlib chunk */
 184             int size = get_bits(&gb, 16);
 185
 186             if (size == 0) {
 187                 /* no change, don't do anything */
 188             } else {
 189                 /* decompress block */
 190                 int ret = inflateReset(&(s->zstream));
 191                 if (ret != Z_OK)
 192                 {
 193                     av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j);
 194                     /* return -1; */
 195                 }
 196                 s->zstream.next_in = buf+(get_bits_count(&gb)/8);
 197                 s->zstream.avail_in = size;
 198                 s->zstream.next_out = s->tmpblock;
 199                 s->zstream.avail_out = s->block_size*3;
 200                 ret = inflate(&(s->zstream), Z_FINISH);
 201                 if (ret == Z_DATA_ERROR)
 202                 {
 203                     av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n");
 204                     inflateSync(&(s->zstream));
 205                     ret = inflate(&(s->zstream), Z_FINISH);
 206                 }
 207
 208                 if ((ret != Z_OK) && (ret != Z_STREAM_END))
 209                 {
 210                     av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret);
 211                     /* return -1; */
 212                 }
 213                 copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]);
 214                 skip_bits(&gb, 8*size);   /* skip the consumed bits */
 215             }
 216         }
 217     }
 218
 219     *data_size = sizeof(AVFrame);
 220     *(AVFrame*)data = s->frame;
 221
 222     if ((get_bits_count(&gb)/8) != buf_size)
 223         av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n",
 224             buf_size, (get_bits_count(&gb)/8));
 225
 226     /* report that the buffer was completely consumed */
 227     return buf_size;
 228 }
 229
 230
 231 static av_cold int flashsv_decode_end(AVCodecContext *avctx)
 232 {
 233     FlashSVContext *s = avctx->priv_data;
 234     inflateEnd(&(s->zstream));
 235     /* release the frame if needed */
 236     if (s->frame.data[0])
 237         avctx->release_buffer(avctx, &s->frame);
 238
 239     /* free the tmpblock */
 240     if (s->tmpblock != NULL)
 241         av_free(s->tmpblock);
 242
 243     return 0;
 244 }
 245
 246
 247 AVCodec flashsv_decoder = {
 248     "flashsv",
 249     CODEC_TYPE_VIDEO,
 250     CODEC_ID_FLASHSV,
 251     sizeof(FlashSVContext),
 252     flashsv_decode_init,
 253     NULL,
 254     flashsv_decode_end,
 255     flashsv_decode_frame,
 256     CODEC_CAP_DR1,
 257     .pix_fmts = (enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
 258     .long_name = "Flash Screen Video v1",
 259 };