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.
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 av_cold 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 // Needed if zlib unused or init aborted before deflateInit
112 memset(&(s->zstream), 0, sizeof(z_stream));
116 s->image_width = avctx->width;
117 s->image_height = avctx->height;
119 s->tmpblock = av_mallocz(3*256*256);
120 s->encbuffer = av_mallocz(s->image_width*s->image_height*3);
122 if (!s->tmpblock || !s->encbuffer) {
123 av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
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) {
135 int h_blocks, v_blocks, h_part, v_part, i, j;
139 init_put_bits(&pb, buf, buf_size*8);
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);
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;
153 /* loop over all block columns */
154 for (j = 0; j < v_blocks + (v_part?1:0); j++)
157 int hp = j*block_height; // horiz position in frame
158 int hs = (j<v_blocks)?block_height:v_part; // size of block
160 /* loop over all block rows */
161 for (i = 0; i < h_blocks + (h_part?1:0); i++)
163 int wp = i*block_width; // vert position in frame
164 int ws = (i<h_blocks)?block_width:h_part; // size of block
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);
173 if (res || *I_frame) {
175 zsize = 3*block_width*block_height;
176 ret = compress2(ptr+2, &zsize, s->tmpblock, 3*ws*hs, 9);
179 //ret = deflateReset(&(s->zstream));
181 av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j);
183 bytestream_put_be16(&ptr,(unsigned int)zsize);
185 //av_log(avctx, AV_LOG_ERROR, "buf_pos = %d\n", buf_pos);
188 bytestream_put_be16(&ptr,0);
203 static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf, int buf_size, void *data)
205 FlashSVContext * const s = avctx->priv_data;
206 AVFrame *pict = data;
207 AVFrame * const p = &s->frame;
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");
225 if (p->linesize[0] < 0)
226 pfptr = s->previous_frame - ((s->image_height-1) * p->linesize[0]);
228 pfptr = s->previous_frame;
230 /* Check the placement of keyframes */
231 if (avctx->gop_size > 0) {
232 if (avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
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);
246 res = encode_bitstream(s, p, buf, buf_size, opt_w*16, opt_h*16, pfptr, &I_frame);
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]);
252 memcpy(s->previous_frame, p->data[0] + p->linesize[0] * (s->image_height-1), s->image_height*FFABS(p->linesize[0]));
254 //mark the frame type so the muxer can mux it correctly
256 p->pict_type = FF_I_TYPE;
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);
261 p->pict_type = FF_P_TYPE;
265 avctx->coded_frame = p;
270 static av_cold int flashsv_encode_end(AVCodecContext *avctx)
272 FlashSVContext *s = avctx->priv_data;
274 deflateEnd(&(s->zstream));
276 av_free(s->encbuffer);
277 av_free(s->previous_frame);
278 av_free(s->tmpblock);
283 AVCodec flashsv_encoder = {
287 sizeof(FlashSVContext),
289 flashsv_encode_frame,
291 .pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
292 .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"),