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libavcodec/flashsvenc.c

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00001 /*
00002  * Flash Screen Video encoder
00003  * Copyright (C) 2004 Alex Beregszaszi
00004  * Copyright (C) 2006 Benjamin Larsson
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 /* Encoding development sponsored by http://fh-campuswien.ac.at */
00024 
00032 /* Bitstream description
00033  * The picture is divided into blocks that are zlib-compressed.
00034  *
00035  * The decoder is fed complete frames, the frameheader contains:
00036  * 4bits of block width
00037  * 12bits of frame width
00038  * 4bits of block height
00039  * 12bits of frame height
00040  *
00041  * Directly after the header are the compressed blocks. The blocks
00042  * have their compressed size represented with 16bits in the beginig.
00043  * If the size = 0 then the block is unchanged from the previous frame.
00044  * All blocks are decompressed until the buffer is consumed.
00045  *
00046  * Encoding ideas, a basic encoder would just use a fixed block size.
00047  * Block sizes can be multipels of 16, from 16 to 256. The blocks don't
00048  * have to be quadratic. A brute force search with a set of different
00049  * block sizes should give a better result than to just use a fixed size.
00050  */
00051 
00052 /* TODO:
00053  * Don't reencode the frame in brute force mode if the frame is a dupe. Speed up.
00054  * Make the difference check faster.
00055  */
00056 
00057 #include <stdio.h>
00058 #include <stdlib.h>
00059 #include <zlib.h>
00060 
00061 #include "avcodec.h"
00062 #include "put_bits.h"
00063 #include "bytestream.h"
00064 
00065 
00066 typedef struct FlashSVContext {
00067     AVCodecContext *avctx;
00068     uint8_t *previous_frame;
00069     AVFrame frame;
00070     int image_width, image_height;
00071     int block_width, block_height;
00072     uint8_t* tmpblock;
00073     uint8_t* encbuffer;
00074     int block_size;
00075     z_stream zstream;
00076     int last_key_frame;
00077 } FlashSVContext;
00078 
00079 static int copy_region_enc(uint8_t *sptr, uint8_t *dptr,
00080         int dx, int dy, int h, int w, int stride, uint8_t *pfptr) {
00081     int i,j;
00082     uint8_t *nsptr;
00083     uint8_t *npfptr;
00084     int diff = 0;
00085 
00086     for (i = dx+h; i > dx; i--) {
00087         nsptr = sptr+(i*stride)+dy*3;
00088         npfptr = pfptr+(i*stride)+dy*3;
00089         for (j=0 ; j<w*3 ; j++) {
00090             diff |=npfptr[j]^nsptr[j];
00091             dptr[j] = nsptr[j];
00092         }
00093         dptr += w*3;
00094     }
00095     if (diff)
00096         return 1;
00097     return 0;
00098 }
00099 
00100 static av_cold int flashsv_encode_init(AVCodecContext *avctx)
00101 {
00102     FlashSVContext *s = avctx->priv_data;
00103 
00104     s->avctx = avctx;
00105 
00106     if ((avctx->width > 4095) || (avctx->height > 4095)) {
00107         av_log(avctx, AV_LOG_ERROR, "Input dimensions too large, input must be max 4096x4096 !\n");
00108         return -1;
00109     }
00110 
00111     // Needed if zlib unused or init aborted before deflateInit
00112     memset(&(s->zstream), 0, sizeof(z_stream));
00113 
00114     s->last_key_frame=0;
00115 
00116     s->image_width = avctx->width;
00117     s->image_height = avctx->height;
00118 
00119     s->tmpblock = av_mallocz(3*256*256);
00120     s->encbuffer = av_mallocz(s->image_width*s->image_height*3);
00121 
00122     if (!s->tmpblock || !s->encbuffer) {
00123         av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
00124         return -1;
00125     }
00126 
00127     return 0;
00128 }
00129 
00130 
00131 static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf, int buf_size,
00132      int block_width, int block_height, uint8_t *previous_frame, int* I_frame) {
00133 
00134     PutBitContext pb;
00135     int h_blocks, v_blocks, h_part, v_part, i, j;
00136     int buf_pos, res;
00137     int pred_blocks = 0;
00138 
00139     init_put_bits(&pb, buf, buf_size*8);
00140 
00141     put_bits(&pb, 4, (block_width/16)-1);
00142     put_bits(&pb, 12, s->image_width);
00143     put_bits(&pb, 4, (block_height/16)-1);
00144     put_bits(&pb, 12, s->image_height);
00145     flush_put_bits(&pb);
00146     buf_pos=4;
00147 
00148     h_blocks = s->image_width / block_width;
00149     h_part = s->image_width % block_width;
00150     v_blocks = s->image_height / block_height;
00151     v_part = s->image_height % block_height;
00152 
00153     /* loop over all block columns */
00154     for (j = 0; j < v_blocks + (v_part?1:0); j++)
00155     {
00156 
00157         int hp = j*block_height; // horiz position in frame
00158         int hs = (j<v_blocks)?block_height:v_part; // size of block
00159 
00160         /* loop over all block rows */
00161         for (i = 0; i < h_blocks + (h_part?1:0); i++)
00162         {
00163             int wp = i*block_width; // vert position in frame
00164             int ws = (i<h_blocks)?block_width:h_part; // size of block
00165             int ret=Z_OK;
00166             uint8_t *ptr;
00167 
00168             ptr = buf+buf_pos;
00169 
00170             //copy the block to the temp buffer before compression (if it differs from the previous frame's block)
00171             res = copy_region_enc(p->data[0], s->tmpblock, s->image_height-(hp+hs+1), wp, hs, ws, p->linesize[0], previous_frame);
00172 
00173             if (res || *I_frame) {
00174                 unsigned long zsize;
00175                 zsize = 3*block_width*block_height;
00176                 ret = compress2(ptr+2, &zsize, s->tmpblock, 3*ws*hs, 9);
00177 
00178 
00179                 //ret = deflateReset(&(s->zstream));
00180                 if (ret != Z_OK)
00181                     av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j);
00182 
00183                 bytestream_put_be16(&ptr,(unsigned int)zsize);
00184                 buf_pos += zsize+2;
00185                 //av_log(avctx, AV_LOG_ERROR, "buf_pos = %d\n", buf_pos);
00186             } else {
00187                 pred_blocks++;
00188                 bytestream_put_be16(&ptr,0);
00189                 buf_pos += 2;
00190             }
00191         }
00192     }
00193 
00194     if (pred_blocks)
00195         *I_frame = 0;
00196     else
00197         *I_frame = 1;
00198 
00199     return buf_pos;
00200 }
00201 
00202 
00203 static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf, int buf_size, void *data)
00204 {
00205     FlashSVContext * const s = avctx->priv_data;
00206     AVFrame *pict = data;
00207     AVFrame * const p = &s->frame;
00208     uint8_t *pfptr;
00209     int res;
00210     int I_frame = 0;
00211     int opt_w, opt_h;
00212 
00213     *p = *pict;
00214 
00215     /* First frame needs to be a keyframe */
00216     if (avctx->frame_number == 0) {
00217         s->previous_frame = av_mallocz(FFABS(p->linesize[0])*s->image_height);
00218         if (!s->previous_frame) {
00219             av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
00220             return -1;
00221         }
00222         I_frame = 1;
00223     }
00224 
00225     if (p->linesize[0] < 0)
00226         pfptr = s->previous_frame - ((s->image_height-1) * p->linesize[0]);
00227     else
00228         pfptr = s->previous_frame;
00229 
00230     /* Check the placement of keyframes */
00231     if (avctx->gop_size > 0) {
00232         if (avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
00233             I_frame = 1;
00234         }
00235     }
00236 
00237     opt_w=4;
00238     opt_h=4;
00239 
00240     if (buf_size < s->image_width*s->image_height*3) {
00241         //Conservative upper bound check for compressed data
00242         av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n", buf_size, s->image_width*s->image_height*3);
00243         return -1;
00244     }
00245 
00246     res = encode_bitstream(s, p, buf, buf_size, opt_w*16, opt_h*16, pfptr, &I_frame);
00247 
00248     //save the current frame
00249     if(p->linesize[0] > 0)
00250         memcpy(s->previous_frame, p->data[0], s->image_height*p->linesize[0]);
00251     else
00252         memcpy(s->previous_frame, p->data[0] + p->linesize[0] * (s->image_height-1), s->image_height*FFABS(p->linesize[0]));
00253 
00254     //mark the frame type so the muxer can mux it correctly
00255     if (I_frame) {
00256         p->pict_type = FF_I_TYPE;
00257         p->key_frame = 1;
00258         s->last_key_frame = avctx->frame_number;
00259         av_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n",avctx->frame_number);
00260     } else {
00261         p->pict_type = FF_P_TYPE;
00262         p->key_frame = 0;
00263     }
00264 
00265     avctx->coded_frame = p;
00266 
00267     return res;
00268 }
00269 
00270 static av_cold int flashsv_encode_end(AVCodecContext *avctx)
00271 {
00272     FlashSVContext *s = avctx->priv_data;
00273 
00274     deflateEnd(&(s->zstream));
00275 
00276     av_free(s->encbuffer);
00277     av_free(s->previous_frame);
00278     av_free(s->tmpblock);
00279 
00280     return 0;
00281 }
00282 
00283 AVCodec flashsv_encoder = {
00284     "flashsv",
00285     AVMEDIA_TYPE_VIDEO,
00286     CODEC_ID_FLASHSV,
00287     sizeof(FlashSVContext),
00288     flashsv_encode_init,
00289     flashsv_encode_frame,
00290     flashsv_encode_end,
00291     .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
00292     .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
00293 };
00294 

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