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 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 58typedef 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 69static 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 82static 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 103static 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 if (buf_size < 4) 117 return -1; 118 119 init_get_bits(&gb, buf, buf_size * 8); 120 121 /* start to parse the bitstream */ 122 s->block_width = 16* (get_bits(&gb, 4)+1); 123 s->image_width = get_bits(&gb,12); 124 s->block_height= 16* (get_bits(&gb, 4)+1); 125 s->image_height= get_bits(&gb,12); 126 127 /* calculate amount of blocks and the size of the border blocks */ 128 h_blocks = s->image_width / s->block_width; 129 h_part = s->image_width % s->block_width; 130 v_blocks = s->image_height / s->block_height; 131 v_part = s->image_height % s->block_height; 132 133 /* the block size could change between frames, make sure the buffer 134 * is large enough, if not, get a larger one */ 135 if(s->block_size < s->block_width*s->block_height) { 136 if (s->tmpblock != NULL) 137 av_free(s->tmpblock); 138 if ((s->tmpblock = av_malloc(3*s->block_width*s->block_height)) == NULL) { 139 av_log(avctx, AV_LOG_ERROR, "Can't allocate decompression buffer.\n"); 140 return -1; 141 } 142 } 143 s->block_size = s->block_width*s->block_height; 144 145 /* init the image size once */ 146 if((avctx->width==0) && (avctx->height==0)){ 147 avctx->width = s->image_width; 148 avctx->height = s->image_height; 149 } 150 151 /* check for changes of image width and image height */ 152 if ((avctx->width != s->image_width) || (avctx->height != s->image_height)) { 153 av_log(avctx, AV_LOG_ERROR, "Frame width or height differs from first frames!\n"); 154 av_log(avctx, AV_LOG_ERROR, "fh = %d, fv %d vs ch = %d, cv = %d\n",avctx->height, 155 avctx->width,s->image_height,s->image_width); 156 return -1; 157 } 158 159 av_log(avctx, AV_LOG_DEBUG, "image: %dx%d block: %dx%d num: %dx%d part: %dx%d\n", 160 s->image_width, s->image_height, s->block_width, s->block_height, 161 h_blocks, v_blocks, h_part, v_part); 162 163 s->frame.reference = 1; 164 s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE; 165 if(avctx->reget_buffer(avctx, &s->frame) < 0){ 166 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n"); 167 return -1; 168 } 169 170 /* loop over all block columns */ 171 for (j = 0; j < v_blocks + (v_part?1:0); j++) 172 { 173 174 int hp = j*s->block_height; // horiz position in frame 175 int hs = (j<v_blocks)?s->block_height:v_part; // size of block 176 177 178 /* loop over all block rows */ 179 for (i = 0; i < h_blocks + (h_part?1:0); i++) 180 { 181 int wp = i*s->block_width; // vert position in frame 182 int ws = (i<h_blocks)?s->block_width:h_part; // size of block 183 184 /* get the size of the compressed zlib chunk */ 185 int size = get_bits(&gb, 16); 186 if (8 * size > get_bits_left(&gb)) { 187 avctx->release_buffer(avctx, &s->frame); 188 s->frame.data[0] = NULL; 189 return -1; 190 } 191 192 if (size == 0) { 193 /* no change, don't do anything */ 194 } else { 195 /* decompress block */ 196 int ret = inflateReset(&(s->zstream)); 197 if (ret != Z_OK) 198 { 199 av_log(avctx, AV_LOG_ERROR, "error in decompression (reset) of block %dx%d\n", i, j); 200 /* return -1; */ 201 } 202 s->zstream.next_in = buf+(get_bits_count(&gb)/8); 203 s->zstream.avail_in = size; 204 s->zstream.next_out = s->tmpblock; 205 s->zstream.avail_out = s->block_size*3; 206 ret = inflate(&(s->zstream), Z_FINISH); 207 if (ret == Z_DATA_ERROR) 208 { 209 av_log(avctx, AV_LOG_ERROR, "Zlib resync occurred\n"); 210 inflateSync(&(s->zstream)); 211 ret = inflate(&(s->zstream), Z_FINISH); 212 } 213 214 if ((ret != Z_OK) && (ret != Z_STREAM_END)) 215 { 216 av_log(avctx, AV_LOG_ERROR, "error in decompression of block %dx%d: %d\n", i, j, ret); 217 /* return -1; */ 218 } 219 copy_region(s->tmpblock, s->frame.data[0], s->image_height-(hp+hs+1), wp, hs, ws, s->frame.linesize[0]); 220 skip_bits_long(&gb, 8*size); /* skip the consumed bits */ 221 } 222 } 223 } 224 225 *data_size = sizeof(AVFrame); 226 *(AVFrame*)data = s->frame; 227 228 if ((get_bits_count(&gb)/8) != buf_size) 229 av_log(avctx, AV_LOG_ERROR, "buffer not fully consumed (%d != %d)\n", 230 buf_size, (get_bits_count(&gb)/8)); 231 232 /* report that the buffer was completely consumed */ 233 return buf_size; 234} 235 236 237static av_cold int flashsv_decode_end(AVCodecContext *avctx) 238{ 239 FlashSVContext *s = avctx->priv_data; 240 inflateEnd(&(s->zstream)); 241 /* release the frame if needed */ 242 if (s->frame.data[0]) 243 avctx->release_buffer(avctx, &s->frame); 244 245 /* free the tmpblock */ 246 if (s->tmpblock != NULL) 247 av_free(s->tmpblock); 248 249 return 0; 250} 251 252 253AVCodec flashsv_decoder = { 254 "flashsv", 255 AVMEDIA_TYPE_VIDEO, 256 CODEC_ID_FLASHSV, 257 sizeof(FlashSVContext), 258 flashsv_decode_init, 259 NULL, 260 flashsv_decode_end, 261 flashsv_decode_frame, 262 CODEC_CAP_DR1, 263 .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE}, 264 .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"), 265}; 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