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noise_bsf.c
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1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <stdlib.h>
22 #include <string.h>
23 
24 #include "avcodec.h"
25 #include "libavutil/mem.h"
26 
27 
28 static int noise(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
29  uint8_t **poutbuf, int *poutbuf_size,
30  const uint8_t *buf, int buf_size, int keyframe){
31  unsigned int *state= bsfc->priv_data;
32  int amount= args ? atoi(args) : (*state % 10001+1);
33  int i;
34 
35  if(amount <= 0)
36  return AVERROR(EINVAL);
37 
38  *poutbuf= av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
39 
40  memcpy(*poutbuf, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
41  for(i=0; i<buf_size; i++){
42  (*state) += (*poutbuf)[i] + 1;
43  if(*state % amount == 0)
44  (*poutbuf)[i] = *state;
45  }
46  return 1;
47 }
48 
50  "noise",
51  sizeof(int),
52  noise,
53 };