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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 /**
23  * @file
24  * audio pad filter.
25  *
26  * Based on af_aresample.c
27  */
28 
29 #include "libavutil/avstring.h"
31 #include "libavutil/opt.h"
32 #include "libavutil/samplefmt.h"
33 #include "libavutil/avassert.h"
34 #include "avfilter.h"
35 #include "audio.h"
36 #include "internal.h"
37 
38 typedef struct {
39  const AVClass *class;
40  int64_t next_pts;
41 
43  int64_t pad_len;
44  int64_t whole_len;
45 } APadContext;
46 
47 #define OFFSET(x) offsetof(APadContext, x)
48 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
49 
50 static const AVOption apad_options[] = {
51  { "packet_size", "set silence packet size", OFFSET(packet_size), AV_OPT_TYPE_INT, { .i64 = 4096 }, 0, INT_MAX, A },
52  { "pad_len", "number of samples of silence to add", OFFSET(pad_len), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT64_MAX, A },
53  { "whole_len", "target number of samples in the audio stream", OFFSET(whole_len), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT64_MAX, A },
54  { NULL }
55 };
56 
58 
59 static av_cold int init(AVFilterContext *ctx)
60 {
61  APadContext *apad = ctx->priv;
62 
63  apad->next_pts = AV_NOPTS_VALUE;
64  if (apad->whole_len && apad->pad_len) {
65  av_log(ctx, AV_LOG_ERROR, "Both whole and pad length are set, this is not possible\n");
66  return AVERROR(EINVAL);
67  }
68 
69  return 0;
70 }
71 
72 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
73 {
74  AVFilterContext *ctx = inlink->dst;
75  APadContext *apad = ctx->priv;
76 
77  if (apad->whole_len)
78  apad->whole_len -= frame->nb_samples;
79 
80  apad->next_pts = frame->pts + av_rescale_q(frame->nb_samples, (AVRational){1, inlink->sample_rate}, inlink->time_base);
81  return ff_filter_frame(ctx->outputs[0], frame);
82 }
83 
84 static int request_frame(AVFilterLink *outlink)
85 {
86  AVFilterContext *ctx = outlink->src;
87  APadContext *apad = ctx->priv;
88  int ret;
89 
90  ret = ff_request_frame(ctx->inputs[0]);
91 
92  if (ret == AVERROR_EOF && !ctx->is_disabled) {
93  int n_out = apad->packet_size;
94  AVFrame *outsamplesref;
95 
96  if (apad->whole_len > 0) {
97  apad->pad_len = apad->whole_len;
98  apad->whole_len = 0;
99  }
100  if (apad->pad_len > 0) {
101  n_out = FFMIN(n_out, apad->pad_len);
102  apad->pad_len -= n_out;
103  }
104 
105  if(!n_out)
106  return AVERROR_EOF;
107 
108  outsamplesref = ff_get_audio_buffer(outlink, n_out);
109  if (!outsamplesref)
110  return AVERROR(ENOMEM);
111 
112  av_assert0(outsamplesref->sample_rate == outlink->sample_rate);
113  av_assert0(outsamplesref->nb_samples == n_out);
114 
115  av_samples_set_silence(outsamplesref->extended_data, 0,
116  n_out,
117  av_frame_get_channels(outsamplesref),
118  outsamplesref->format);
119 
120  outsamplesref->pts = apad->next_pts;
121  if (apad->next_pts != AV_NOPTS_VALUE)
122  apad->next_pts += av_rescale_q(n_out, (AVRational){1, outlink->sample_rate}, outlink->time_base);
123 
124  return ff_filter_frame(outlink, outsamplesref);
125  }
126  return ret;
127 }
128 
129 static const AVFilterPad apad_inputs[] = {
130  {
131  .name = "default",
132  .type = AVMEDIA_TYPE_AUDIO,
133  .filter_frame = filter_frame,
134  },
135  { NULL }
136 };
137 
138 static const AVFilterPad apad_outputs[] = {
139  {
140  .name = "default",
141  .request_frame = request_frame,
142  .type = AVMEDIA_TYPE_AUDIO,
143  },
144  { NULL }
145 };
146 
148  .name = "apad",
149  .description = NULL_IF_CONFIG_SMALL("Pad audio with silence."),
150  .init = init,
151  .priv_size = sizeof(APadContext),
152  .inputs = apad_inputs,
153  .outputs = apad_outputs,
154  .priv_class = &apad_class,
156 };