noise_bsf.c
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1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of Libav.
5  *
6  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "avcodec.h"
22 
23 
24 static int noise(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
25  uint8_t **poutbuf, int *poutbuf_size,
26  const uint8_t *buf, int buf_size, int keyframe){
27  unsigned int *state= bsfc->priv_data;
28  int amount= args ? atoi(args) : (*state % 10001+1);
29  int i;
30 
31  *poutbuf= av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
32 
33  memcpy(*poutbuf, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
34  for(i=0; i<buf_size; i++){
35  (*state) += (*poutbuf)[i] + 1;
36  if(*state % amount == 0)
37  (*poutbuf)[i] = *state;
38  }
39  return 1;
40 }
41 
43  "noise",
44  sizeof(int),
45  noise,
46 };