path: root/libavfilter/af_dcshift.c (plain)
blob: 7332c12b19562a14c872cdfbc354862efbdd5523

1	/*
2	* Copyright (c) 2000 Chris Ausbrooks <weed@bucket.pp.ualr.edu>
3	* Copyright (c) 2000 Fabien COELHO <fabien@coelho.net>
4	*
5	* This file is part of FFmpeg.
6	*
7	* FFmpeg is free software; you can redistribute it and/or
8	* modify it under the terms of the GNU Lesser General Public
9	* License as published by the Free Software Foundation; either
10	* version 2.1 of the License, or (at your option) any later version.
11	*
12	* FFmpeg is distributed in the hope that it will be useful,
13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15	* Lesser General Public License for more details.
16	*
17	* You should have received a copy of the GNU Lesser General Public
18	* License along with FFmpeg; if not, write to the Free Software
19	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20	*/
21
22	#include "libavutil/opt.h"
23	#include "libavutil/samplefmt.h"
24	#include "avfilter.h"
25	#include "audio.h"
26	#include "internal.h"
27
28	typedef struct DCShiftContext {
29	const AVClass *class;
30	double dcshift;
31	double limiterthreshhold;
32	double limitergain;
33	} DCShiftContext;
34
35	#define OFFSET(x) offsetof(DCShiftContext, x)
36	#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
37
38	static const AVOption dcshift_options[] = {
39	{ "shift", "set DC shift", OFFSET(dcshift), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -1, 1, A },
40	{ "limitergain", "set limiter gain", OFFSET(limitergain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, 0, 1, A },
41	{ NULL }
42	};
43
44	AVFILTER_DEFINE_CLASS(dcshift);
45
46	static av_cold int init(AVFilterContext *ctx)
47	{
48	DCShiftContext *s = ctx->priv;
49
50	s->limiterthreshhold = INT32_MAX * (1.0 - (fabs(s->dcshift) - s->limitergain));
51
52	return 0;
53	}
54
55	static int query_formats(AVFilterContext *ctx)
56	{
57	AVFilterChannelLayouts *layouts;
58	AVFilterFormats *formats;
59	static const enum AVSampleFormat sample_fmts[] = {
60	AV_SAMPLE_FMT_S32P, AV_SAMPLE_FMT_NONE
61	};
62	int ret;
63
64	layouts = ff_all_channel_counts();
65	if (!layouts)
66	return AVERROR(ENOMEM);
67	ret = ff_set_common_channel_layouts(ctx, layouts);
68	if (ret < 0)
69	return ret;
70
71	formats = ff_make_format_list(sample_fmts);
72	if (!formats)
73	return AVERROR(ENOMEM);
74	ret = ff_set_common_formats(ctx, formats);
75	if (ret < 0)
76	return ret;
77
78	formats = ff_all_samplerates();
79	if (!formats)
80	return AVERROR(ENOMEM);
81	return ff_set_common_samplerates(ctx, formats);
82	}
83
84	static int filter_frame(AVFilterLink *inlink, AVFrame *in)
85	{
86	AVFilterContext *ctx = inlink->dst;
87	AVFilterLink *outlink = ctx->outputs[0];
88	AVFrame *out = ff_get_audio_buffer(inlink, in->nb_samples);
89	DCShiftContext *s = ctx->priv;
90	int i, j;
91	double dcshift = s->dcshift;
92
93	if (!out) {
94	av_frame_free(&in);
95	return AVERROR(ENOMEM);
96	}
97	av_frame_copy_props(out, in);
98
99	if (s->limitergain > 0) {
100	for (i = 0; i < inlink->channels; i++) {
101	const int32_t *src = (int32_t *)in->extended_data[i];
102	int32_t *dst = (int32_t *)out->extended_data[i];
103
104	for (j = 0; j < in->nb_samples; j++) {
105	double d;
106
107	d = src[j];
108
109	if (d > s->limiterthreshhold && dcshift > 0) {
110	d = (d - s->limiterthreshhold) * s->limitergain /
111	(INT32_MAX - s->limiterthreshhold) +
112	s->limiterthreshhold + dcshift;
113	} else if (d < -s->limiterthreshhold && dcshift < 0) {
114	d = (d + s->limiterthreshhold) * s->limitergain /
115	(INT32_MAX - s->limiterthreshhold) -
116	s->limiterthreshhold + dcshift;
117	} else {
118	d = dcshift * INT32_MAX + d;
119	}
120
121	dst[j] = av_clipl_int32(d);
122	}
123	}
124	} else {
125	for (i = 0; i < inlink->channels; i++) {
126	const int32_t *src = (int32_t *)in->extended_data[i];
127	int32_t *dst = (int32_t *)out->extended_data[i];
128
129	for (j = 0; j < in->nb_samples; j++) {
130	double d = dcshift * (INT32_MAX + 1.) + src[j];
131
132	dst[j] = av_clipl_int32(d);
133	}
134	}
135	}
136
137	av_frame_free(&in);
138	return ff_filter_frame(outlink, out);
139	}
140	static const AVFilterPad dcshift_inputs[] = {
141	{
142	.name = "default",
143	.type = AVMEDIA_TYPE_AUDIO,
144	.filter_frame = filter_frame,
145	},
146	{ NULL }
147	};
148
149	static const AVFilterPad dcshift_outputs[] = {
150	{
151	.name = "default",
152	.type = AVMEDIA_TYPE_AUDIO,
153	},
154	{ NULL }
155	};
156
157	AVFilter ff_af_dcshift = {
158	.name = "dcshift",
159	.description = NULL_IF_CONFIG_SMALL("Apply a DC shift to the audio."),
160	.query_formats = query_formats,
161	.priv_size = sizeof(DCShiftContext),
162	.priv_class = &dcshift_class,
163	.init = init,
164	.inputs = dcshift_inputs,
165	.outputs = dcshift_outputs,
166	.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
167	};
168