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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, int dx, int dy,
00080                            int h, int w, int stride, uint8_t *pfptr)
00081 {
00082     int i, j;
00083     uint8_t *nsptr;
00084     uint8_t *npfptr;
00085     int diff = 0;
00086 
00087     for (i = dx + h; i > dx; i--) {
00088         nsptr  = sptr  + (i * stride) + dy * 3;
00089         npfptr = pfptr + (i * stride) + dy * 3;
00090         for (j = 0; j < w * 3; j++) {
00091             diff    |= npfptr[j] ^ nsptr[j];
00092             dptr[j]  = nsptr[j];
00093         }
00094         dptr += w * 3;
00095     }
00096     if (diff)
00097         return 1;
00098     return 0;
00099 }
00100 
00101 static av_cold int flashsv_encode_init(AVCodecContext *avctx)
00102 {
00103     FlashSVContext *s = avctx->priv_data;
00104 
00105     s->avctx = avctx;
00106 
00107     if ((avctx->width > 4095) || (avctx->height > 4095)) {
00108         av_log(avctx, AV_LOG_ERROR, "Input dimensions too large, input must be max 4096x4096 !\n");
00109         return AVERROR_INVALIDDATA;
00110     }
00111 
00112     // Needed if zlib unused or init aborted before deflateInit
00113     memset(&(s->zstream), 0, sizeof(z_stream));
00114 
00115     s->last_key_frame = 0;
00116 
00117     s->image_width  = avctx->width;
00118     s->image_height = avctx->height;
00119 
00120     s->tmpblock  = av_mallocz(3 * 256 * 256);
00121     s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);
00122 
00123     if (!s->tmpblock || !s->encbuffer) {
00124         av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
00125         return AVERROR(ENOMEM);
00126     }
00127 
00128     return 0;
00129 }
00130 
00131 
00132 static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf,
00133                             int buf_size, int block_width, int block_height,
00134                             uint8_t *previous_frame, int *I_frame)
00135 {
00136 
00137     PutBitContext pb;
00138     int h_blocks, v_blocks, h_part, v_part, i, j;
00139     int buf_pos, res;
00140     int pred_blocks = 0;
00141 
00142     init_put_bits(&pb, buf, buf_size * 8);
00143 
00144     put_bits(&pb,  4, (block_width / 16) - 1);
00145     put_bits(&pb, 12, s->image_width);
00146     put_bits(&pb,  4, (block_height / 16) - 1);
00147     put_bits(&pb, 12, s->image_height);
00148     flush_put_bits(&pb);
00149     buf_pos = 4;
00150 
00151     h_blocks = s->image_width  / block_width;
00152     h_part   = s->image_width  % block_width;
00153     v_blocks = s->image_height / block_height;
00154     v_part   = s->image_height % block_height;
00155 
00156     /* loop over all block columns */
00157     for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
00158 
00159         int hp = j * block_height; // horiz position in frame
00160         int hs = (j < v_blocks) ? block_height : v_part; // size of block
00161 
00162         /* loop over all block rows */
00163         for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
00164             int wp  = i * block_width; // vert position in frame
00165             int ws  = (i < h_blocks) ? block_width : h_part; // size of block
00166             int ret = Z_OK;
00167             uint8_t *ptr;
00168 
00169             ptr = buf + buf_pos;
00170 
00171             /* copy the block to the temp buffer before compression
00172              * (if it differs from the previous frame's block) */
00173             res = copy_region_enc(p->data[0], s->tmpblock,
00174                                   s->image_height - (hp + hs + 1),
00175                                   wp, hs, ws, p->linesize[0], previous_frame);
00176 
00177             if (res || *I_frame) {
00178                 unsigned long zsize;
00179                 zsize = 3 * block_width * block_height;
00180                 ret   = compress2(ptr + 2, &zsize, s->tmpblock, 3 * ws * hs, 9);
00181 
00182 
00183                 //ret = deflateReset(&(s->zstream));
00184                 if (ret != Z_OK)
00185                     av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j);
00186 
00187                 bytestream_put_be16(&ptr, (unsigned int) zsize);
00188                 buf_pos += zsize + 2;
00189                 //av_log(avctx, AV_LOG_ERROR, "buf_pos = %d\n", buf_pos);
00190             } else {
00191                 pred_blocks++;
00192                 bytestream_put_be16(&ptr, 0);
00193                 buf_pos += 2;
00194             }
00195         }
00196     }
00197 
00198     if (pred_blocks)
00199         *I_frame = 0;
00200     else
00201         *I_frame = 1;
00202 
00203     return buf_pos;
00204 }
00205 
00206 
00207 static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf,
00208                                 int buf_size, void *data)
00209 {
00210     FlashSVContext * const s = avctx->priv_data;
00211     AVFrame *pict = data;
00212     AVFrame * const p = &s->frame;
00213     uint8_t *pfptr;
00214     int res;
00215     int I_frame = 0;
00216     int opt_w, opt_h;
00217 
00218     *p = *pict;
00219 
00220     /* First frame needs to be a keyframe */
00221     if (avctx->frame_number == 0) {
00222         s->previous_frame = av_mallocz(FFABS(p->linesize[0]) * s->image_height);
00223         if (!s->previous_frame) {
00224             av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
00225             return AVERROR(ENOMEM);
00226         }
00227         I_frame = 1;
00228     }
00229 
00230     if (p->linesize[0] < 0)
00231         pfptr = s->previous_frame - ((s->image_height - 1) * p->linesize[0]);
00232     else
00233         pfptr = s->previous_frame;
00234 
00235     /* Check the placement of keyframes */
00236     if (avctx->gop_size > 0) {
00237         if (avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
00238             I_frame = 1;
00239         }
00240     }
00241 
00242     opt_w = 4;
00243     opt_h = 4;
00244 
00245     if (buf_size < s->image_width*s->image_height*3) {
00246         //Conservative upper bound check for compressed data
00247         av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n",
00248                buf_size, s->image_width * s->image_height * 3);
00249         return -1;
00250     }
00251 
00252     res = encode_bitstream(s, p, buf, buf_size, opt_w * 16, opt_h * 16, pfptr, &I_frame);
00253 
00254     //save the current frame
00255     if (p->linesize[0] > 0)
00256         memcpy(s->previous_frame, p->data[0], s->image_height * p->linesize[0]);
00257     else
00258         memcpy(s->previous_frame, p->data[0] + p->linesize[0] * (s->image_height - 1),
00259                s->image_height * FFABS(p->linesize[0]));
00260 
00261     //mark the frame type so the muxer can mux it correctly
00262     if (I_frame) {
00263         p->pict_type = AV_PICTURE_TYPE_I;
00264         p->key_frame = 1;
00265         s->last_key_frame = avctx->frame_number;
00266         av_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n", avctx->frame_number);
00267     } else {
00268         p->pict_type = AV_PICTURE_TYPE_P;
00269         p->key_frame = 0;
00270     }
00271 
00272     avctx->coded_frame = p;
00273 
00274     return res;
00275 }
00276 
00277 static av_cold int flashsv_encode_end(AVCodecContext *avctx)
00278 {
00279     FlashSVContext *s = avctx->priv_data;
00280 
00281     deflateEnd(&(s->zstream));
00282 
00283     av_free(s->encbuffer);
00284     av_free(s->previous_frame);
00285     av_free(s->tmpblock);
00286 
00287     return 0;
00288 }
00289 
00290 AVCodec ff_flashsv_encoder = {
00291     .name           = "flashsv",
00292     .type           = AVMEDIA_TYPE_VIDEO,
00293     .id             = CODEC_ID_FLASHSV,
00294     .priv_data_size = sizeof(FlashSVContext),
00295     .init           = flashsv_encode_init,
00296     .encode         = flashsv_encode_frame,
00297     .close          = flashsv_encode_end,
00298     .pix_fmts       = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
00299     .long_name      = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
00300 };
00301 

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