libavcodec/flashsvenc.c

   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 libavcodec/flashsvenc.c
  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
  66 typedef 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
  79 static 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
 100 static 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     if (avcodec_check_dimensions(avctx, avctx->width, avctx->height) < 0) {
 112         return -1;
 113     }
 114
 115     // Needed if zlib unused or init aborted before deflateInit
 116     memset(&(s->zstream), 0, sizeof(z_stream));
 117
 118     s->last_key_frame=0;
 119
 120     s->image_width = avctx->width;
 121     s->image_height = avctx->height;
 122
 123     s->tmpblock = av_mallocz(3*256*256);
 124     s->encbuffer = av_mallocz(s->image_width*s->image_height*3);
 125
 126     if (!s->tmpblock || !s->encbuffer) {
 127         av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
 128         return -1;
 129     }
 130
 131     return 0;
 132 }
 133
 134
 135 static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf, int buf_size,
 136      int block_width, int block_height, uint8_t *previous_frame, int* I_frame) {
 137
 138     PutBitContext pb;
 139     int h_blocks, v_blocks, h_part, v_part, i, j;
 140     int buf_pos, res;
 141     int pred_blocks = 0;
 142
 143     init_put_bits(&pb, buf, buf_size*8);
 144
 145     put_bits(&pb, 4, (block_width/16)-1);
 146     put_bits(&pb, 12, s->image_width);
 147     put_bits(&pb, 4, (block_height/16)-1);
 148     put_bits(&pb, 12, s->image_height);
 149     flush_put_bits(&pb);
 150     buf_pos=4;
 151
 152     h_blocks = s->image_width / block_width;
 153     h_part = s->image_width % block_width;
 154     v_blocks = s->image_height / block_height;
 155     v_part = s->image_height % block_height;
 156
 157     /* loop over all block columns */
 158     for (j = 0; j < v_blocks + (v_part?1:0); j++)
 159     {
 160
 161         int hp = j*block_height; // horiz position in frame
 162         int hs = (j<v_blocks)?block_height:v_part; // size of block
 163
 164         /* loop over all block rows */
 165         for (i = 0; i < h_blocks + (h_part?1:0); i++)
 166         {
 167             int wp = i*block_width; // vert position in frame
 168             int ws = (i<h_blocks)?block_width:h_part; // size of block
 169             int ret=Z_OK;
 170             uint8_t *ptr;
 171
 172             ptr = buf+buf_pos;
 173
 174             //copy the block to the temp buffer before compression (if it differs from the previous frame's block)
 175             res = copy_region_enc(p->data[0], s->tmpblock, s->image_height-(hp+hs+1), wp, hs, ws, p->linesize[0], previous_frame);
 176
 177             if (res || *I_frame) {
 178                 unsigned long zsize;
 179                 zsize = 3*block_width*block_height;
 180                 ret = compress2(ptr+2, &zsize, s->tmpblock, 3*ws*hs, 9);
 181
 182
 183                 //ret = deflateReset(&(s->zstream));
 184                 if (ret != Z_OK)
 185                     av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j);
 186
 187                 bytestream_put_be16(&ptr,(unsigned int)zsize);
 188                 buf_pos += zsize+2;
 189                 //av_log(avctx, AV_LOG_ERROR, "buf_pos = %d\n", buf_pos);
 190             } else {
 191                 pred_blocks++;
 192                 bytestream_put_be16(&ptr,0);
 193                 buf_pos += 2;
 194             }
 195         }
 196     }
 197
 198     if (pred_blocks)
 199         *I_frame = 0;
 200     else
 201         *I_frame = 1;
 202
 203     return buf_pos;
 204 }
 205
 206
 207 static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf, int buf_size, void *data)
 208 {
 209     FlashSVContext * const s = avctx->priv_data;
 210     AVFrame *pict = data;
 211     AVFrame * const p = &s->frame;
 212     uint8_t *pfptr;
 213     int res;
 214     int I_frame = 0;
 215     int opt_w, opt_h;
 216
 217     *p = *pict;
 218
 219     /* First frame needs to be a keyframe */
 220     if (avctx->frame_number == 0) {
 221         s->previous_frame = av_mallocz(FFABS(p->linesize[0])*s->image_height);
 222         if (!s->previous_frame) {
 223             av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
 224             return -1;
 225         }
 226         I_frame = 1;
 227     }
 228
 229     if (p->linesize[0] < 0)
 230         pfptr = s->previous_frame - ((s->image_height-1) * p->linesize[0]);
 231     else
 232         pfptr = s->previous_frame;
 233
 234     /* Check the placement of keyframes */
 235     if (avctx->gop_size > 0) {
 236         if (avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
 237             I_frame = 1;
 238         }
 239     }
 240
 241     opt_w=4;
 242     opt_h=4;
 243
 244     if (buf_size < s->image_width*s->image_height*3) {
 245         //Conservative upper bound check for compressed data
 246         av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n", buf_size, s->image_width*s->image_height*3);
 247         return -1;
 248     }
 249
 250     res = encode_bitstream(s, p, buf, buf_size, opt_w*16, opt_h*16, pfptr, &I_frame);
 251
 252     //save the current frame
 253     if(p->linesize[0] > 0)
 254         memcpy(s->previous_frame, p->data[0], s->image_height*p->linesize[0]);
 255     else
 256         memcpy(s->previous_frame, p->data[0] + p->linesize[0] * (s->image_height-1), s->image_height*FFABS(p->linesize[0]));
 257
 258     //mark the frame type so the muxer can mux it correctly
 259     if (I_frame) {
 260         p->pict_type = FF_I_TYPE;
 261         p->key_frame = 1;
 262         s->last_key_frame = avctx->frame_number;
 263         av_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n",avctx->frame_number);
 264     } else {
 265         p->pict_type = FF_P_TYPE;
 266         p->key_frame = 0;
 267     }
 268
 269     avctx->coded_frame = p;
 270
 271     return res;
 272 }
 273
 274 static av_cold int flashsv_encode_end(AVCodecContext *avctx)
 275 {
 276     FlashSVContext *s = avctx->priv_data;
 277
 278     deflateEnd(&(s->zstream));
 279
 280     av_free(s->encbuffer);
 281     av_free(s->previous_frame);
 282     av_free(s->tmpblock);
 283
 284     return 0;
 285 }
 286
 287 AVCodec flashsv_encoder = {
 288     "flashsv",
 289     CODEC_TYPE_VIDEO,
 290     CODEC_ID_FLASHSV,
 291     sizeof(FlashSVContext),
 292     flashsv_encode_init,
 293     flashsv_encode_frame,
 294     flashsv_encode_end,
 295     .pix_fmts = (enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
 296     .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
 297 };
 298