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af_asetnsamples.c
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1 /*
2  * Copyright (c) 2012 Andrey Utkin
3  * Copyright (c) 2012 Stefano Sabatini
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 /**
23  * @file
24  * Filter that changes number of samples on single output operation
25  */
26 
27 #include "libavutil/audio_fifo.h"
28 #include "libavutil/avassert.h"
30 #include "libavutil/opt.h"
31 #include "avfilter.h"
32 #include "audio.h"
33 #include "internal.h"
34 #include "formats.h"
35 
36 typedef struct {
37  const AVClass *class;
38  int nb_out_samples; ///< how many samples to output
39  AVAudioFifo *fifo; ///< samples are queued here
40  int64_t next_out_pts;
41  int pad;
42 } ASNSContext;
43 
44 #define OFFSET(x) offsetof(ASNSContext, x)
45 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
46 
47 static const AVOption asetnsamples_options[] = {
48  { "nb_out_samples", "set the number of per-frame output samples", OFFSET(nb_out_samples), AV_OPT_TYPE_INT, {.i64=1024}, 1, INT_MAX, FLAGS },
49  { "n", "set the number of per-frame output samples", OFFSET(nb_out_samples), AV_OPT_TYPE_INT, {.i64=1024}, 1, INT_MAX, FLAGS },
50  { "pad", "pad last frame with zeros", OFFSET(pad), AV_OPT_TYPE_INT, {.i64=1}, 0, 1, FLAGS },
51  { "p", "pad last frame with zeros", OFFSET(pad), AV_OPT_TYPE_INT, {.i64=1}, 0, 1, FLAGS },
52  { NULL }
53 };
54 
55 AVFILTER_DEFINE_CLASS(asetnsamples);
56 
57 static av_cold int init(AVFilterContext *ctx)
58 {
59  ASNSContext *asns = ctx->priv;
60 
62  av_log(ctx, AV_LOG_VERBOSE, "nb_out_samples:%d pad:%d\n", asns->nb_out_samples, asns->pad);
63 
64  return 0;
65 }
66 
67 static av_cold void uninit(AVFilterContext *ctx)
68 {
69  ASNSContext *asns = ctx->priv;
70  av_audio_fifo_free(asns->fifo);
71 }
72 
73 static int config_props_output(AVFilterLink *outlink)
74 {
75  ASNSContext *asns = outlink->src->priv;
77 
78  asns->fifo = av_audio_fifo_alloc(outlink->format, nb_channels, asns->nb_out_samples);
79  if (!asns->fifo)
80  return AVERROR(ENOMEM);
81  outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
82 
83  return 0;
84 }
85 
86 static int push_samples(AVFilterLink *outlink)
87 {
88  ASNSContext *asns = outlink->src->priv;
89  AVFrame *outsamples = NULL;
90  int ret, nb_out_samples, nb_pad_samples;
91 
92  if (asns->pad) {
93  nb_out_samples = av_audio_fifo_size(asns->fifo) ? asns->nb_out_samples : 0;
94  nb_pad_samples = nb_out_samples - FFMIN(nb_out_samples, av_audio_fifo_size(asns->fifo));
95  } else {
96  nb_out_samples = FFMIN(asns->nb_out_samples, av_audio_fifo_size(asns->fifo));
97  nb_pad_samples = 0;
98  }
99 
100  if (!nb_out_samples)
101  return 0;
102 
103  outsamples = ff_get_audio_buffer(outlink, nb_out_samples);
104  if (!outsamples)
105  return AVERROR(ENOMEM);
106 
107  av_audio_fifo_read(asns->fifo,
108  (void **)outsamples->extended_data, nb_out_samples);
109 
110  if (nb_pad_samples)
111  av_samples_set_silence(outsamples->extended_data, nb_out_samples - nb_pad_samples,
112  nb_pad_samples, av_get_channel_layout_nb_channels(outlink->channel_layout),
113  outlink->format);
114  outsamples->nb_samples = nb_out_samples;
115  outsamples->channel_layout = outlink->channel_layout;
116  outsamples->sample_rate = outlink->sample_rate;
117  outsamples->pts = asns->next_out_pts;
118 
119  if (asns->next_out_pts != AV_NOPTS_VALUE)
120  asns->next_out_pts += nb_out_samples;
121 
122  ret = ff_filter_frame(outlink, outsamples);
123  if (ret < 0)
124  return ret;
125  return nb_out_samples;
126 }
127 
128 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
129 {
130  AVFilterContext *ctx = inlink->dst;
131  ASNSContext *asns = ctx->priv;
132  AVFilterLink *outlink = ctx->outputs[0];
133  int ret;
134  int nb_samples = insamples->nb_samples;
135 
136  if (av_audio_fifo_space(asns->fifo) < nb_samples) {
137  av_log(ctx, AV_LOG_DEBUG, "No space for %d samples, stretching audio fifo\n", nb_samples);
138  ret = av_audio_fifo_realloc(asns->fifo, av_audio_fifo_size(asns->fifo) + nb_samples);
139  if (ret < 0) {
140  av_log(ctx, AV_LOG_ERROR,
141  "Stretching audio fifo failed, discarded %d samples\n", nb_samples);
142  return -1;
143  }
144  }
145  av_audio_fifo_write(asns->fifo, (void **)insamples->extended_data, nb_samples);
146  if (asns->next_out_pts == AV_NOPTS_VALUE)
147  asns->next_out_pts = insamples->pts;
148  av_frame_free(&insamples);
149 
150  while (av_audio_fifo_size(asns->fifo) >= asns->nb_out_samples)
151  push_samples(outlink);
152  return 0;
153 }
154 
155 static int request_frame(AVFilterLink *outlink)
156 {
157  AVFilterLink *inlink = outlink->src->inputs[0];
158  int ret;
159 
160  ret = ff_request_frame(inlink);
161  if (ret == AVERROR_EOF) {
162  ret = push_samples(outlink);
163  return ret < 0 ? ret : ret > 0 ? 0 : AVERROR_EOF;
164  }
165 
166  return ret;
167 }
168 
170  {
171  .name = "default",
172  .type = AVMEDIA_TYPE_AUDIO,
173  .filter_frame = filter_frame,
174  .needs_writable = 1,
175  },
176  { NULL }
177 };
178 
180  {
181  .name = "default",
182  .type = AVMEDIA_TYPE_AUDIO,
183  .request_frame = request_frame,
184  .config_props = config_props_output,
185  },
186  { NULL }
187 };
188 
190  .name = "asetnsamples",
191  .description = NULL_IF_CONFIG_SMALL("Set the number of samples for each output audio frames."),
192  .priv_size = sizeof(ASNSContext),
193  .init = init,
194  .uninit = uninit,
195  .inputs = asetnsamples_inputs,
196  .outputs = asetnsamples_outputs,
197  .priv_class = &asetnsamples_class,
198 };