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     // 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
 131 static 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
 203 static 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
 270 static 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
 283 AVCodec flashsv_encoder = {
 284     "flashsv",
 285     CODEC_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