2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
4 * This file is part of Libav.
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.
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.
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
27 #include "libavutil/log.h"
28 #include "libavutil/mem.h"
29 #include "libavutil/opt.h"
31 typedef struct NoiseContext {
37 static int noise(AVBSFContext *ctx, AVPacket *out)
39 NoiseContext *s = ctx->priv_data;
41 int amount = s->amount > 0 ? s->amount : (s->state % 10001 + 1);
44 ret = ff_bsf_get_packet(ctx, &in);
48 ret = av_new_packet(out, in->size);
52 ret = av_packet_copy_props(out, in);
56 memcpy(out->data, in->data, in->size);
58 for (i = 0; i < out->size; i++) {
59 s->state += out->data[i] + 1;
60 if (s->state % amount == 0)
61 out->data[i] = s->state;
70 #define OFFSET(x) offsetof(NoiseContext, x)
71 static const AVOption options[] = {
72 { "amount", NULL, OFFSET(amount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX },
76 static const AVClass noise_class = {
77 .class_name = "noise",
78 .item_name = av_default_item_name,
80 .version = LIBAVUTIL_VERSION_INT,
83 const AVBitStreamFilter ff_noise_bsf = {
85 .priv_data_size = sizeof(int),
86 .priv_class = &noise_class,