1/* 2 * Flash Screen Video encoder 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/* Encoding development sponsored by http://fh-campuswien.ac.at */ 24 25/** 26 * @file 27 * Flash Screen Video encoder 28 * @author Alex Beregszaszi 29 * @author Benjamin Larsson 30 */ 31 32/* Bitstream description 33 * The picture is divided into blocks that are zlib-compressed. 34 * 35 * The decoder is fed complete frames, the frameheader contains: 36 * 4bits of block width 37 * 12bits of frame width 38 * 4bits of block height 39 * 12bits of frame height 40 * 41 * Directly after the header are the compressed blocks. The blocks 42 * have their compressed size represented with 16bits in the beginig. 43 * If the size = 0 then the block is unchanged from the previous frame. 44 * All blocks are decompressed until the buffer is consumed. 45 * 46 * Encoding ideas, a basic encoder would just use a fixed block size. 47 * Block sizes can be multipels of 16, from 16 to 256. The blocks don't 48 * have to be quadratic. A brute force search with a set of different 49 * block sizes should give a better result than to just use a fixed size. 50 */ 51 52/* TODO: 53 * Don't reencode the frame in brute force mode if the frame is a dupe. Speed up. 54 * Make the difference check faster. 55 */ 56 57#include <stdio.h> 58#include <stdlib.h> 59#include <zlib.h> 60 61#include "avcodec.h" 62#include "put_bits.h" 63#include "bytestream.h" 64 65 66typedef struct FlashSVContext { 67 AVCodecContext *avctx; 68 uint8_t *previous_frame; 69 AVFrame frame; 70 int image_width, image_height; 71 int block_width, block_height; 72 uint8_t* tmpblock; 73 uint8_t* encbuffer; 74 int block_size; 75 z_stream zstream; 76 int last_key_frame; 77} FlashSVContext; 78 79static int copy_region_enc(uint8_t *sptr, uint8_t *dptr, 80 int dx, int dy, int h, int w, int stride, uint8_t *pfptr) { 81 int i,j; 82 uint8_t *nsptr; 83 uint8_t *npfptr; 84 int diff = 0; 85 86 for (i = dx+h; i > dx; i--) { 87 nsptr = sptr+(i*stride)+dy*3; 88 npfptr = pfptr+(i*stride)+dy*3; 89 for (j=0 ; j<w*3 ; j++) { 90 diff |=npfptr[j]^nsptr[j]; 91 dptr[j] = nsptr[j]; 92 } 93 dptr += w*3; 94 } 95 if (diff) 96 return 1; 97 return 0; 98} 99 100static av_cold int flashsv_encode_init(AVCodecContext *avctx) 101{ 102 FlashSVContext *s = avctx->priv_data; 103 104 s->avctx = avctx; 105 106 if ((avctx->width > 4095) || (avctx->height > 4095)) { 107 av_log(avctx, AV_LOG_ERROR, "Input dimensions too large, input must be max 4096x4096 !\n"); 108 return -1; 109 } 110 111 // Needed if zlib unused or init aborted before deflateInit 112 memset(&(s->zstream), 0, sizeof(z_stream)); 113 114 s->last_key_frame=0; 115 116 s->image_width = avctx->width; 117 s->image_height = avctx->height; 118 119 s->tmpblock = av_mallocz(3*256*256); 120 s->encbuffer = av_mallocz(s->image_width*s->image_height*3); 121 122 if (!s->tmpblock || !s->encbuffer) { 123 av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n"); 124 return -1; 125 } 126 127 return 0; 128} 129 130 131static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf, int buf_size, 132 int block_width, int block_height, uint8_t *previous_frame, int* I_frame) { 133 134 PutBitContext pb; 135 int h_blocks, v_blocks, h_part, v_part, i, j; 136 int buf_pos, res; 137 int pred_blocks = 0; 138 139 init_put_bits(&pb, buf, buf_size*8); 140 141 put_bits(&pb, 4, (block_width/16)-1); 142 put_bits(&pb, 12, s->image_width); 143 put_bits(&pb, 4, (block_height/16)-1); 144 put_bits(&pb, 12, s->image_height); 145 flush_put_bits(&pb); 146 buf_pos=4; 147 148 h_blocks = s->image_width / block_width; 149 h_part = s->image_width % block_width; 150 v_blocks = s->image_height / block_height; 151 v_part = s->image_height % block_height; 152 153 /* loop over all block columns */ 154 for (j = 0; j < v_blocks + (v_part?1:0); j++) 155 { 156 157 int hp = j*block_height; // horiz position in frame 158 int hs = (j<v_blocks)?block_height:v_part; // size of block 159 160 /* loop over all block rows */ 161 for (i = 0; i < h_blocks + (h_part?1:0); i++) 162 { 163 int wp = i*block_width; // vert position in frame 164 int ws = (i<h_blocks)?block_width:h_part; // size of block 165 int ret=Z_OK; 166 uint8_t *ptr; 167 168 ptr = buf+buf_pos; 169 170 //copy the block to the temp buffer before compression (if it differs from the previous frame's block) 171 res = copy_region_enc(p->data[0], s->tmpblock, s->image_height-(hp+hs+1), wp, hs, ws, p->linesize[0], previous_frame); 172 173 if (res || *I_frame) { 174 unsigned long zsize; 175 zsize = 3*block_width*block_height; 176 ret = compress2(ptr+2, &zsize, s->tmpblock, 3*ws*hs, 9); 177 178 179 //ret = deflateReset(&(s->zstream)); 180 if (ret != Z_OK) 181 av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j); 182 183 bytestream_put_be16(&ptr,(unsigned int)zsize); 184 buf_pos += zsize+2; 185 //av_log(avctx, AV_LOG_ERROR, "buf_pos = %d\n", buf_pos); 186 } else { 187 pred_blocks++; 188 bytestream_put_be16(&ptr,0); 189 buf_pos += 2; 190 } 191 } 192 } 193 194 if (pred_blocks) 195 *I_frame = 0; 196 else 197 *I_frame = 1; 198 199 return buf_pos; 200} 201 202 203static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf, int buf_size, void *data) 204{ 205 FlashSVContext * const s = avctx->priv_data; 206 AVFrame *pict = data; 207 AVFrame * const p = &s->frame; 208 uint8_t *pfptr; 209 int res; 210 int I_frame = 0; 211 int opt_w, opt_h; 212 213 *p = *pict; 214 215 /* First frame needs to be a keyframe */ 216 if (avctx->frame_number == 0) { 217 s->previous_frame = av_mallocz(FFABS(p->linesize[0])*s->image_height); 218 if (!s->previous_frame) { 219 av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n"); 220 return -1; 221 } 222 I_frame = 1; 223 } 224 225 if (p->linesize[0] < 0) 226 pfptr = s->previous_frame - ((s->image_height-1) * p->linesize[0]); 227 else 228 pfptr = s->previous_frame; 229 230 /* Check the placement of keyframes */ 231 if (avctx->gop_size > 0) { 232 if (avctx->frame_number >= s->last_key_frame + avctx->gop_size) { 233 I_frame = 1; 234 } 235 } 236 237 opt_w=4; 238 opt_h=4; 239 240 if (buf_size < s->image_width*s->image_height*3) { 241 //Conservative upper bound check for compressed data 242 av_log(avctx, AV_LOG_ERROR, "buf_size %d < %d\n", buf_size, s->image_width*s->image_height*3); 243 return -1; 244 } 245 246 res = encode_bitstream(s, p, buf, buf_size, opt_w*16, opt_h*16, pfptr, &I_frame); 247 248 //save the current frame 249 if(p->linesize[0] > 0) 250 memcpy(s->previous_frame, p->data[0], s->image_height*p->linesize[0]); 251 else 252 memcpy(s->previous_frame, p->data[0] + p->linesize[0] * (s->image_height-1), s->image_height*FFABS(p->linesize[0])); 253 254 //mark the frame type so the muxer can mux it correctly 255 if (I_frame) { 256 p->pict_type = FF_I_TYPE; 257 p->key_frame = 1; 258 s->last_key_frame = avctx->frame_number; 259 av_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n",avctx->frame_number); 260 } else { 261 p->pict_type = FF_P_TYPE; 262 p->key_frame = 0; 263 } 264 265 avctx->coded_frame = p; 266 267 return res; 268} 269 270static av_cold int flashsv_encode_end(AVCodecContext *avctx) 271{ 272 FlashSVContext *s = avctx->priv_data; 273 274 deflateEnd(&(s->zstream)); 275 276 av_free(s->encbuffer); 277 av_free(s->previous_frame); 278 av_free(s->tmpblock); 279 280 return 0; 281} 282 283AVCodec flashsv_encoder = { 284 "flashsv", 285 AVMEDIA_TYPE_VIDEO, 286 CODEC_ID_FLASHSV, 287 sizeof(FlashSVContext), 288 flashsv_encode_init, 289 flashsv_encode_frame, 290 flashsv_encode_end, 291 .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE}, 292 .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"), 293}; 294 295