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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"
  30. #include "libavutil/channel_layout.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.  
  42.     int packet_size;
  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.  
  57. AVFILTER_DEFINE_CLASS(apad);
  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.  
  147. AVFilter avfilter_af_apad = {
  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,
  155.     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
  156. };
  157.