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
23 #include "bsf.h"
24 #include "bsf_internal.h"
25
26 #include "libavutil/log.h"
27 #include "libavutil/opt.h"
28
29 typedef struct NoiseContext {
30 const AVClass *class;
31 int amount;
32 int dropamount;
33 unsigned int state;
34 } NoiseContext;
35
noise(AVBSFContext * ctx,AVPacket * pkt)36 static int noise(AVBSFContext *ctx, AVPacket *pkt)
37 {
38 NoiseContext *s = ctx->priv_data;
39 int amount = s->amount > 0 ? s->amount : (s->state % 10001 + 1);
40 int i, ret;
41
42 if (amount <= 0)
43 return AVERROR(EINVAL);
44
45 ret = ff_bsf_get_packet_ref(ctx, pkt);
46 if (ret < 0)
47 return ret;
48
49 if (s->dropamount > 0 && s->state % s->dropamount == 0) {
50 s->state++;
51 av_packet_unref(pkt);
52 return AVERROR(EAGAIN);
53 }
54
55 ret = av_packet_make_writable(pkt);
56 if (ret < 0) {
57 av_packet_unref(pkt);
58 return ret;
59 }
60
61 for (i = 0; i < pkt->size; i++) {
62 s->state += pkt->data[i] + 1;
63 if (s->state % amount == 0)
64 pkt->data[i] = s->state;
65 }
66
67 return 0;
68 }
69
70 #define OFFSET(x) offsetof(NoiseContext, x)
71 #define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_BSF_PARAM)
72 static const AVOption options[] = {
73 { "amount", NULL, OFFSET(amount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
74 { "dropamount", NULL, OFFSET(dropamount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
75 { NULL },
76 };
77
78 static const AVClass noise_class = {
79 .class_name = "noise",
80 .item_name = av_default_item_name,
81 .option = options,
82 .version = LIBAVUTIL_VERSION_INT,
83 };
84
85 const AVBitStreamFilter ff_noise_bsf = {
86 .name = "noise",
87 .priv_data_size = sizeof(NoiseContext),
88 .priv_class = &noise_class,
89 .filter = noise,
90 };
91