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flashsvenc.c
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1 /*
2  * Flash Screen Video encoder
3  * Copyright (C) 2004 Alex Beregszaszi
4  * Copyright (C) 2006 Benjamin Larsson
5  *
6  * This file is part of FFmpeg.
7  *
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.
12  *
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.
17  *
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
21  */
22 
23 /* Encoding development sponsored by http://fh-campuswien.ac.at */
24 
25 /**
26  * @file
27  * Flash Screen Video encoder
28  * @author Alex Beregszaszi
29  * @author Benjamin Larsson
30  *
31  * A description of the bitstream format for Flash Screen Video version 1/2
32  * is part of the SWF File Format Specification (version 10), which can be
33  * downloaded from http://www.adobe.com/devnet/swf.html.
34  */
35 
36 /*
37  * Encoding ideas: A basic encoder would just use a fixed block size.
38  * Block sizes can be multiples of 16, from 16 to 256. The blocks don't
39  * have to be quadratic. A brute force search with a set of different
40  * block sizes should give a better result than to just use a fixed size.
41  *
42  * TODO:
43  * Don't reencode the frame in brute force mode if the frame is a dupe.
44  * Speed up. Make the difference check faster.
45  */
46 
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <zlib.h>
50 
51 #include "avcodec.h"
52 #include "internal.h"
53 #include "put_bits.h"
54 #include "bytestream.h"
55 
56 
57 typedef struct FlashSVContext {
64  int block_size;
65  z_stream zstream;
68 
69 static int copy_region_enc(uint8_t *sptr, uint8_t *dptr, int dx, int dy,
70  int h, int w, int stride, uint8_t *pfptr)
71 {
72  int i, j;
73  uint8_t *nsptr;
74  uint8_t *npfptr;
75  int diff = 0;
76 
77  for (i = dx + h; i > dx; i--) {
78  nsptr = sptr + i * stride + dy * 3;
79  npfptr = pfptr + i * stride + dy * 3;
80  for (j = 0; j < w * 3; j++) {
81  diff |= npfptr[j] ^ nsptr[j];
82  dptr[j] = nsptr[j];
83  }
84  dptr += w * 3;
85  }
86  if (diff)
87  return 1;
88  return 0;
89 }
90 
92 {
93  FlashSVContext *s = avctx->priv_data;
94 
95  deflateEnd(&s->zstream);
96 
97  av_freep(&s->encbuffer);
99  av_freep(&s->tmpblock);
100 
101  av_frame_free(&avctx->coded_frame);
102 
103  return 0;
104 }
105 
107 {
108  FlashSVContext *s = avctx->priv_data;
109 
110  s->avctx = avctx;
111 
112  if (avctx->width > 4095 || avctx->height > 4095) {
113  av_log(avctx, AV_LOG_ERROR,
114  "Input dimensions too large, input must be max 4096x4096 !\n");
115  return AVERROR_INVALIDDATA;
116  }
117 
118  // Needed if zlib unused or init aborted before deflateInit
119  memset(&s->zstream, 0, sizeof(z_stream));
120 
121  s->last_key_frame = 0;
122 
123  s->image_width = avctx->width;
124  s->image_height = avctx->height;
125 
126  s->tmpblock = av_mallocz(3 * 256 * 256);
127  s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);
128 
129  if (!s->tmpblock || !s->encbuffer) {
130  av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
131  return AVERROR(ENOMEM);
132  }
133 
134  avctx->coded_frame = av_frame_alloc();
135  if (!avctx->coded_frame) {
136  flashsv_encode_end(avctx);
137  return AVERROR(ENOMEM);
138  }
139 
140  return 0;
141 }
142 
143 
145  int buf_size, int block_width, int block_height,
146  uint8_t *previous_frame, int *I_frame)
147 {
148 
149  PutBitContext pb;
150  int h_blocks, v_blocks, h_part, v_part, i, j;
151  int buf_pos, res;
152  int pred_blocks = 0;
153 
154  init_put_bits(&pb, buf, buf_size);
155 
156  put_bits(&pb, 4, block_width / 16 - 1);
157  put_bits(&pb, 12, s->image_width);
158  put_bits(&pb, 4, block_height / 16 - 1);
159  put_bits(&pb, 12, s->image_height);
160  flush_put_bits(&pb);
161  buf_pos = 4;
162 
163  h_blocks = s->image_width / block_width;
164  h_part = s->image_width % block_width;
165  v_blocks = s->image_height / block_height;
166  v_part = s->image_height % block_height;
167 
168  /* loop over all block columns */
169  for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
170 
171  int y_pos = j * block_height; // vertical position in frame
172  int cur_blk_height = (j < v_blocks) ? block_height : v_part;
173 
174  /* loop over all block rows */
175  for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
176  int x_pos = i * block_width; // horizontal position in frame
177  int cur_blk_width = (i < h_blocks) ? block_width : h_part;
178  int ret = Z_OK;
179  uint8_t *ptr = buf + buf_pos;
180 
181  /* copy the block to the temp buffer before compression
182  * (if it differs from the previous frame's block) */
183  res = copy_region_enc(p->data[0], s->tmpblock,
184  s->image_height - (y_pos + cur_blk_height + 1),
185  x_pos, cur_blk_height, cur_blk_width,
186  p->linesize[0], previous_frame);
187 
188  if (res || *I_frame) {
189  unsigned long zsize = 3 * block_width * block_height;
190  ret = compress2(ptr + 2, &zsize, s->tmpblock,
191  3 * cur_blk_width * cur_blk_height, 9);
192 
193  //ret = deflateReset(&s->zstream);
194  if (ret != Z_OK)
196  "error while compressing block %dx%d\n", i, j);
197 
198  bytestream_put_be16(&ptr, zsize);
199  buf_pos += zsize + 2;
200  ff_dlog(s->avctx, "buf_pos = %d\n", buf_pos);
201  } else {
202  pred_blocks++;
203  bytestream_put_be16(&ptr, 0);
204  buf_pos += 2;
205  }
206  }
207  }
208 
209  if (pred_blocks)
210  *I_frame = 0;
211  else
212  *I_frame = 1;
213 
214  return buf_pos;
215 }
216 
217 
219  const AVFrame *pict, int *got_packet)
220 {
221  FlashSVContext * const s = avctx->priv_data;
222  const AVFrame * const p = pict;
223  uint8_t *pfptr;
224  int res;
225  int I_frame = 0;
226  int opt_w = 4, opt_h = 4;
227 
228  /* First frame needs to be a keyframe */
229  if (avctx->frame_number == 0) {
231  if (!s->previous_frame) {
232  av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
233  return AVERROR(ENOMEM);
234  }
235  I_frame = 1;
236  }
237 
238  if (p->linesize[0] < 0)
239  pfptr = s->previous_frame - (s->image_height - 1) * p->linesize[0];
240  else
241  pfptr = s->previous_frame;
242 
243  /* Check the placement of keyframes */
244  if (avctx->gop_size > 0 &&
245  avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
246  I_frame = 1;
247  }
248 
249  if ((res = ff_alloc_packet2(avctx, pkt, s->image_width * s->image_height * 3)) < 0)
250  return res;
251 
252  pkt->size = encode_bitstream(s, p, pkt->data, pkt->size, opt_w * 16, opt_h * 16,
253  pfptr, &I_frame);
254 
255  //save the current frame
256  if (p->linesize[0] > 0)
257  memcpy(s->previous_frame, p->data[0], s->image_height * p->linesize[0]);
258  else
259  memcpy(s->previous_frame,
260  p->data[0] + p->linesize[0] * (s->image_height - 1),
261  s->image_height * FFABS(p->linesize[0]));
262 
263  //mark the frame type so the muxer can mux it correctly
264  if (I_frame) {
266  avctx->coded_frame->key_frame = 1;
267  s->last_key_frame = avctx->frame_number;
268  ff_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);
269  } else {
271  avctx->coded_frame->key_frame = 0;
272  }
273 
274  if (avctx->coded_frame->key_frame)
275  pkt->flags |= AV_PKT_FLAG_KEY;
276  *got_packet = 1;
277 
278  return 0;
279 }
280 
282  .name = "flashsv",
283  .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
284  .type = AVMEDIA_TYPE_VIDEO,
285  .id = AV_CODEC_ID_FLASHSV,
286  .priv_data_size = sizeof(FlashSVContext),
288  .encode2 = flashsv_encode_frame,
289  .close = flashsv_encode_end,
290  .pix_fmts = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },
291 };