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 "bitstream.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 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_long(&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 231static 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 247AVCodec 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 = NULL_IF_CONFIG_SMALL("Flash Screen Video v1"), 259}; 260