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 
00036 /*
00037  * Encoding ideas: A basic encoder would just use a fixed block size.
00038  * Block sizes can be multiples of 16, from 16 to 256. The blocks don't
00039  * have to be quadratic. A brute force search with a set of different
00040  * block sizes should give a better result than to just use a fixed size.
00041  *
00042  * TODO:
00043  * Don't reencode the frame in brute force mode if the frame is a dupe.
00044  * Speed up. Make the difference check faster.
00045  */
00046 
00047 #include <stdio.h>
00048 #include <stdlib.h>
00049 #include <zlib.h>
00050 
00051 #include "avcodec.h"
00052 #include "put_bits.h"
00053 #include "bytestream.h"
00054 
00055 
00056 typedef struct FlashSVContext {
00057     AVCodecContext *avctx;
00058     uint8_t        *previous_frame;
00059     AVFrame         frame;
00060     int             image_width, image_height;
00061     int             block_width, block_height;
00062     uint8_t        *tmpblock;
00063     uint8_t        *encbuffer;
00064     int             block_size;
00065     z_stream        zstream;
00066     int             last_key_frame;
00067 } FlashSVContext;
00068 
00069 static int copy_region_enc(uint8_t *sptr, uint8_t *dptr, int dx, int dy,
00070                            int h, int w, int stride, uint8_t *pfptr)
00071 {
00072     int i, j;
00073     uint8_t *nsptr;
00074     uint8_t *npfptr;
00075     int diff = 0;
00076 
00077     for (i = dx + h; i > dx; i--) {
00078         nsptr  = sptr  + i * stride + dy * 3;
00079         npfptr = pfptr + i * stride + dy * 3;
00080         for (j = 0; j < w * 3; j++) {
00081             diff    |= npfptr[j] ^ nsptr[j];
00082             dptr[j]  = nsptr[j];
00083         }
00084         dptr += w * 3;
00085     }
00086     if (diff)
00087         return 1;
00088     return 0;
00089 }
00090 
00091 static av_cold int flashsv_encode_init(AVCodecContext *avctx)
00092 {
00093     FlashSVContext *s = avctx->priv_data;
00094 
00095     s->avctx = avctx;
00096 
00097     if (avctx->width > 4095 || avctx->height > 4095) {
00098         av_log(avctx, AV_LOG_ERROR,
00099                "Input dimensions too large, input must be max 4096x4096 !\n");
00100         return AVERROR_INVALIDDATA;
00101     }
00102 
00103     // Needed if zlib unused or init aborted before deflateInit
00104     memset(&s->zstream, 0, sizeof(z_stream));
00105 
00106     s->last_key_frame = 0;
00107 
00108     s->image_width  = avctx->width;
00109     s->image_height = avctx->height;
00110 
00111     s->tmpblock  = av_mallocz(3 * 256 * 256);
00112     s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);
00113 
00114     if (!s->tmpblock || !s->encbuffer) {
00115         av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
00116         return AVERROR(ENOMEM);
00117     }
00118 
00119     return 0;
00120 }
00121 
00122 
00123 static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf,
00124                             int buf_size, int block_width, int block_height,
00125                             uint8_t *previous_frame, int *I_frame)
00126 {
00127 
00128     PutBitContext pb;
00129     int h_blocks, v_blocks, h_part, v_part, i, j;
00130     int buf_pos, res;
00131     int pred_blocks = 0;
00132 
00133     init_put_bits(&pb, buf, buf_size * 8);
00134 
00135     put_bits(&pb,  4, block_width / 16 - 1);
00136     put_bits(&pb, 12, s->image_width);
00137     put_bits(&pb,  4, block_height / 16 - 1);
00138     put_bits(&pb, 12, s->image_height);
00139     flush_put_bits(&pb);
00140     buf_pos = 4;
00141 
00142     h_blocks = s->image_width  / block_width;
00143     h_part   = s->image_width  % block_width;
00144     v_blocks = s->image_height / block_height;
00145     v_part   = s->image_height % block_height;
00146 
00147     /* loop over all block columns */
00148     for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
00149 
00150         int y_pos = j * block_height; // vertical position in frame
00151         int cur_blk_height = (j < v_blocks) ? block_height : v_part;
00152 
00153         /* loop over all block rows */
00154         for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
00155             int x_pos = i * block_width; // horizontal position in frame
00156             int cur_blk_width = (i < h_blocks) ? block_width : h_part;
00157             int ret = Z_OK;
00158             uint8_t *ptr = buf + buf_pos;
00159 
00160             /* copy the block to the temp buffer before compression
00161              * (if it differs from the previous frame's block) */
00162             res = copy_region_enc(p->data[0], s->tmpblock,
00163                                   s->image_height - (y_pos + cur_blk_height + 1),
00164                                   x_pos, cur_blk_height, cur_blk_width,
00165                                   p->linesize[0], previous_frame);
00166 
00167             if (res || *I_frame) {
00168                 unsigned long zsize = 3 * block_width * block_height;
00169                 ret = compress2(ptr + 2, &zsize, s->tmpblock,
00170                                 3 * cur_blk_width * cur_blk_height, 9);
00171 
00172                 //ret = deflateReset(&s->zstream);
00173                 if (ret != Z_OK)
00174                     av_log(s->avctx, AV_LOG_ERROR,
00175                            "error while compressing block %dx%d\n", i, j);
00176 
00177                 bytestream_put_be16(&ptr, zsize);
00178                 buf_pos += zsize + 2;
00179                 av_dlog(s->avctx, "buf_pos = %d\n", buf_pos);
00180             } else {
00181                 pred_blocks++;
00182                 bytestream_put_be16(&ptr, 0);
00183                 buf_pos += 2;
00184             }
00185         }
00186     }
00187 
00188     if (pred_blocks)
00189         *I_frame = 0;
00190     else
00191         *I_frame = 1;
00192 
00193     return buf_pos;
00194 }
00195 
00196 
00197 static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf,
00198                                 int buf_size, void *data)
00199 {
00200     FlashSVContext * const s = avctx->priv_data;
00201     AVFrame *pict = data;
00202     AVFrame * const p = &s->frame;
00203     uint8_t *pfptr;
00204     int res;
00205     int I_frame = 0;
00206     int opt_w = 4, opt_h = 4;
00207 
00208     *p = *pict;
00209 
00210     /* First frame needs to be a keyframe */
00211     if (avctx->frame_number == 0) {
00212         s->previous_frame = av_mallocz(FFABS(p->linesize[0]) * s->image_height);
00213         if (!s->previous_frame) {
00214             av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
00215             return AVERROR(ENOMEM);
00216         }
00217         I_frame = 1;
00218     }
00219 
00220     if (p->linesize[0] < 0)
00221         pfptr = s->previous_frame - (s->image_height - 1) * p->linesize[0];
00222     else
00223         pfptr = s->previous_frame;
00224 
00225     /* Check the placement of keyframes */
00226     if (avctx->gop_size > 0 &&
00227         avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
00228         I_frame = 1;
00229     }
00230 
00231     if (buf_size < s->image_width * s->image_height * 3) {
00232         //Conservative upper bound check for compressed data
00233         av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n",
00234                buf_size, s->image_width * s->image_height * 3);
00235         return -1;
00236     }
00237 
00238     res = encode_bitstream(s, p, buf, buf_size, opt_w * 16, opt_h * 16,
00239                            pfptr, &I_frame);
00240 
00241     //save the current frame
00242     if (p->linesize[0] > 0)
00243         memcpy(s->previous_frame, p->data[0], s->image_height * p->linesize[0]);
00244     else
00245         memcpy(s->previous_frame,
00246                p->data[0] + p->linesize[0] * (s->image_height - 1),
00247                s->image_height * FFABS(p->linesize[0]));
00248 
00249     //mark the frame type so the muxer can mux it correctly
00250     if (I_frame) {
00251         p->pict_type      = AV_PICTURE_TYPE_I;
00252         p->key_frame      = 1;
00253         s->last_key_frame = avctx->frame_number;
00254         av_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);
00255     } else {
00256         p->pict_type = AV_PICTURE_TYPE_P;
00257         p->key_frame = 0;
00258     }
00259 
00260     avctx->coded_frame = p;
00261 
00262     return res;
00263 }
00264 
00265 static av_cold int flashsv_encode_end(AVCodecContext *avctx)
00266 {
00267     FlashSVContext *s = avctx->priv_data;
00268 
00269     deflateEnd(&s->zstream);
00270 
00271     av_free(s->encbuffer);
00272     av_free(s->previous_frame);
00273     av_free(s->tmpblock);
00274 
00275     return 0;
00276 }
00277 
00278 AVCodec ff_flashsv_encoder = {
00279     .name           = "flashsv",
00280     .type           = AVMEDIA_TYPE_VIDEO,
00281     .id             = CODEC_ID_FLASHSV,
00282     .priv_data_size = sizeof(FlashSVContext),
00283     .init           = flashsv_encode_init,
00284     .encode         = flashsv_encode_frame,
00285     .close          = flashsv_encode_end,
00286     .pix_fmts       = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
00287     .long_name      = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
00288 };
00289