FFmpeg
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 "bsf.h"
26 
27 #include "libavutil/log.h"
28 #include "libavutil/mem.h"
29 #include "libavutil/opt.h"
30 
31 typedef struct NoiseContext {
32  const AVClass *class;
33  int amount;
35  unsigned int state;
36 } NoiseContext;
37 
39 {
40  NoiseContext *s = ctx->priv_data;
41  int amount = s->amount > 0 ? s->amount : (s->state % 10001 + 1);
42  int i, ret = 0;
43 
44  if (amount <= 0)
45  return AVERROR(EINVAL);
46 
47  ret = ff_bsf_get_packet_ref(ctx, pkt);
48  if (ret < 0)
49  return ret;
50 
51  if (s->dropamount > 0 && s->state % s->dropamount == 0) {
52  s->state++;
53  av_packet_unref(pkt);
54  return AVERROR(EAGAIN);
55  }
56 
57  ret = av_packet_make_writable(pkt);
58  if (ret < 0)
59  goto fail;
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 fail:
67  if (ret < 0)
68  av_packet_unref(pkt);
69 
70  return ret;
71 }
72 
73 #define OFFSET(x) offsetof(NoiseContext, x)
74 #define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_BSF_PARAM)
75 static const AVOption options[] = {
76  { "amount", NULL, OFFSET(amount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
77  { "dropamount", NULL, OFFSET(dropamount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
78  { NULL },
79 };
80 
81 static const AVClass noise_class = {
82  .class_name = "noise",
83  .item_name = av_default_item_name,
84  .option = options,
85  .version = LIBAVUTIL_VERSION_INT,
86 };
87 
89  .name = "noise",
90  .priv_data_size = sizeof(NoiseContext),
91  .priv_class = &noise_class,
92  .filter = noise,
93 };
#define NULL
Definition: coverity.c:32
static const AVClass noise_class
Definition: noise_bsf.c:81
AVOption.
Definition: opt.h:246
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
Memory handling functions.
The bitstream filter state.
Definition: avcodec.h:5774
int size
Definition: avcodec.h:1481
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:191
static AVPacket pkt
void * priv_data
Opaque filter-specific private data.
Definition: avcodec.h:5795
#define OFFSET(x)
Definition: noise_bsf.c:73
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:72
static const AVOption options[]
Definition: noise_bsf.c:75
AVOptions.
const char * name
Definition: avcodec.h:5824
uint8_t * data
Definition: avcodec.h:1480
int av_packet_make_writable(AVPacket *pkt)
Create a writable reference for the data described by a given packet, avoiding data copy if possible...
Definition: avpacket.c:682
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
filter_frame For filters that do not use the this method is called when a frame is pushed to the filter s input It can be called at any time except in a reentrant way If the input frame is enough to produce then the filter should push the output frames on the output link immediately As an exception to the previous rule if the input frame is enough to produce several output frames then the filter needs output only at least one per link The additional frames can be left buffered in the filter
#define fail()
Definition: checkasm.h:122
#define FLAGS
Definition: noise_bsf.c:74
AVFormatContext * ctx
Definition: movenc.c:48
#define s(width, name)
Definition: cbs_vp9.c:257
Libavcodec external API header.
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:599
unsigned int state
Definition: noise_bsf.c:35
Describe the class of an AVClass context structure.
Definition: log.h:67
static int noise(AVBSFContext *ctx, AVPacket *pkt)
Definition: noise_bsf.c:38
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
This structure stores compressed data.
Definition: avcodec.h:1457
int ff_bsf_get_packet_ref(AVBSFContext *ctx, AVPacket *pkt)
Called by bitstream filters to get packet for filtering.
Definition: bsf.c:239
int dropamount
Definition: noise_bsf.c:34
const AVBitStreamFilter ff_noise_bsf
Definition: noise_bsf.c:88