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af_apad.c
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1 /*
2  * Copyright (c) 2012 Michael Niedermayer
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 /**
22  * @file
23  * audio pad filter.
24  *
25  * Based on af_aresample.c
26  */
27 
28 #include "libavutil/avstring.h"
30 #include "libavutil/opt.h"
31 #include "libavutil/samplefmt.h"
32 #include "libavutil/avassert.h"
33 #include "avfilter.h"
34 #include "audio.h"
35 #include "internal.h"
36 
37 typedef struct {
38  const AVClass *class;
39  int64_t next_pts;
40 
42  int64_t pad_len;
43  int64_t whole_len;
44 } APadContext;
45 
46 #define OFFSET(x) offsetof(APadContext, x)
47 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
48 
49 static const AVOption apad_options[] = {
50  { "packet_size", "set silence packet size", OFFSET(packet_size), AV_OPT_TYPE_INT, { .i64 = 4096 }, 0, INT_MAX, A },
51  { "pad_len", "number of samples of silence to add", OFFSET(pad_len), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT64_MAX, A },
52  { "whole_len", "target number of samples in the audio stream", OFFSET(whole_len), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT64_MAX, A },
53  { NULL }
54 };
55 
57 
58 static av_cold int init(AVFilterContext *ctx)
59 {
60  APadContext *apad = ctx->priv;
61 
62  apad->next_pts = AV_NOPTS_VALUE;
63  if (apad->whole_len && apad->pad_len) {
64  av_log(ctx, AV_LOG_ERROR, "Both whole and pad length are set, this is not possible\n");
65  return AVERROR(EINVAL);
66  }
67 
68  return 0;
69 }
70 
71 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
72 {
73  AVFilterContext *ctx = inlink->dst;
74  APadContext *apad = ctx->priv;
75 
76  if (apad->whole_len)
77  apad->whole_len -= frame->nb_samples;
78 
79  apad->next_pts = frame->pts + av_rescale_q(frame->nb_samples, (AVRational){1, inlink->sample_rate}, inlink->time_base);
80  return ff_filter_frame(ctx->outputs[0], frame);
81 }
82 
83 static int request_frame(AVFilterLink *outlink)
84 {
85  AVFilterContext *ctx = outlink->src;
86  APadContext *apad = ctx->priv;
87  int ret;
88 
89  ret = ff_request_frame(ctx->inputs[0]);
90 
91  if (ret == AVERROR_EOF && !ctx->is_disabled) {
92  int n_out = apad->packet_size;
93  AVFrame *outsamplesref;
94 
95  if (apad->whole_len > 0) {
96  apad->pad_len = apad->whole_len;
97  apad->whole_len = 0;
98  }
99  if (apad->pad_len > 0) {
100  n_out = FFMIN(n_out, apad->pad_len);
101  apad->pad_len -= n_out;
102  }
103 
104  if(!n_out)
105  return AVERROR_EOF;
106 
107  outsamplesref = ff_get_audio_buffer(outlink, n_out);
108  if (!outsamplesref)
109  return AVERROR(ENOMEM);
110 
111  av_assert0(outsamplesref->sample_rate == outlink->sample_rate);
112  av_assert0(outsamplesref->nb_samples == n_out);
113 
114  av_samples_set_silence(outsamplesref->extended_data, 0,
115  n_out,
116  av_frame_get_channels(outsamplesref),
117  outsamplesref->format);
118 
119  outsamplesref->pts = apad->next_pts;
120  if (apad->next_pts != AV_NOPTS_VALUE)
121  apad->next_pts += av_rescale_q(n_out, (AVRational){1, outlink->sample_rate}, outlink->time_base);
122 
123  return ff_filter_frame(outlink, outsamplesref);
124  }
125  return ret;
126 }
127 
128 static const AVFilterPad apad_inputs[] = {
129  {
130  .name = "default",
131  .type = AVMEDIA_TYPE_AUDIO,
132  .filter_frame = filter_frame,
133  },
134  { NULL }
135 };
136 
137 static const AVFilterPad apad_outputs[] = {
138  {
139  .name = "default",
140  .request_frame = request_frame,
141  .type = AVMEDIA_TYPE_AUDIO,
142  },
143  { NULL }
144 };
145 
147  .name = "apad",
148  .description = NULL_IF_CONFIG_SMALL("Pad audio with silence."),
149  .init = init,
150  .priv_size = sizeof(APadContext),
151  .inputs = apad_inputs,
152  .outputs = apad_outputs,
153  .priv_class = &apad_class,
155 };