2 * Flash Screen Video encoder
3 * Copyright (C) 2004 Alex Beregszaszi
4 * Copyright (C) 2006 Benjamin Larsson
6 * This file is part of FFmpeg.
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.
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.
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
23 /* Encoding development sponsored by http://fh-campuswien.ac.at */
27 * Flash Screen Video encoder
28 * @author Alex Beregszaszi
29 * @author Benjamin Larsson
32 /* Bitstream description
33 * The picture is divided into blocks that are zlib-compressed.
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
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.
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.
53 * Don't reencode the frame in brute force mode if the frame is a dupe. Speed up.
54 * Make the difference check faster.
62 #include "bitstream.h"
63 #include "bytestream.h"
66 typedef struct FlashSVContext {
67 AVCodecContext *avctx;
68 uint8_t *previous_frame;
70 int image_width, image_height;
71 int block_width, block_height;
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) {
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];
100 static int flashsv_encode_init(AVCodecContext *avctx)
102 FlashSVContext *s = avctx->priv_data;
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");
111 if (avcodec_check_dimensions(avctx, avctx->width, avctx->height) < 0) {
115 // Needed if zlib unused or init aborted before deflateInit
116 memset(&(s->zstream), 0, sizeof(z_stream));
120 s->image_width = avctx->width;
121 s->image_height = avctx->height;
123 s->tmpblock = av_mallocz(3*256*256);
124 s->encbuffer = av_mallocz(s->image_width*s->image_height*3);
126 if (!s->tmpblock || !s->encbuffer) {
127 av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
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) {
139 int h_blocks, v_blocks, h_part, v_part, i, j;
143 init_put_bits(&pb, buf, buf_size*8);
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);
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;
157 /* loop over all block columns */
158 for (j = 0; j < v_blocks + (v_part?1:0); j++)
161 int hp = j*block_height; // horiz position in frame
162 int hs = (j<v_blocks)?block_height:v_part; // size of block
164 /* loop over all block rows */
165 for (i = 0; i < h_blocks + (h_part?1:0); i++)
167 int wp = i*block_width; // vert position in frame
168 int ws = (i<h_blocks)?block_width:h_part; // size of block
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);
177 if (res || *I_frame) {
179 zsize = 3*block_width*block_height;
180 ret = compress2(ptr+2, &zsize, s->tmpblock, 3*ws*hs, 9);
183 //ret = deflateReset(&(s->zstream));
185 av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j);
187 bytestream_put_be16(&ptr,(unsigned int)zsize);
189 //av_log(avctx, AV_LOG_ERROR, "buf_pos = %d\n", buf_pos);
192 bytestream_put_be16(&ptr,0);
207 static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf, int buf_size, void *data)
209 FlashSVContext * const s = avctx->priv_data;
210 AVFrame *pict = data;
211 AVFrame * const p = &s->frame;
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");
229 if (p->linesize[0] < 0)
230 pfptr = s->previous_frame - ((s->image_height-1) * p->linesize[0]);
232 pfptr = s->previous_frame;
234 /* Check the placement of keyframes */
235 if (avctx->gop_size > 0) {
236 if (avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
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);
250 res = encode_bitstream(s, p, buf, buf_size, opt_w*16, opt_h*16, pfptr, &I_frame);
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]);
256 memcpy(s->previous_frame, p->data[0] + p->linesize[0] * (s->image_height-1), s->image_height*FFABS(p->linesize[0]));
258 //mark the frame type so the muxer can mux it correctly
260 p->pict_type = FF_I_TYPE;
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);
265 p->pict_type = FF_P_TYPE;
269 avctx->coded_frame = p;
274 static int flashsv_encode_end(AVCodecContext *avctx)
276 FlashSVContext *s = avctx->priv_data;
278 deflateEnd(&(s->zstream));
280 av_free(s->encbuffer);
281 av_free(s->previous_frame);
282 av_free(s->tmpblock);
287 AVCodec flashsv_encoder = {
291 sizeof(FlashSVContext),
293 flashsv_encode_frame,
295 .pix_fmts = (enum PixelFormat[]){PIX_FMT_BGR24, -1},