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"
29#include "libavutil/channel_layout.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
37typedef struct {
38    const AVClass *class;
39    int64_t next_pts;
40
41    int packet_size;
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
49static 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
56AVFILTER_DEFINE_CLASS(apad);
57
58static 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
71static 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
83static 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
128static const AVFilterPad apad_inputs[] = {
129    {
130        .name         = "default",
131        .type         = AVMEDIA_TYPE_AUDIO,
132        .filter_frame = filter_frame,
133    },
134    { NULL }
135};
136
137static const AVFilterPad apad_outputs[] = {
138    {
139        .name          = "default",
140        .request_frame = request_frame,
141        .type          = AVMEDIA_TYPE_AUDIO,
142    },
143    { NULL }
144};
145
146AVFilter ff_af_apad = {
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,
154    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
155};
156