1/*
2 * Copyright (c) 2013 Nicolas George
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 License
8 * 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
14 * GNU Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
18 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21#include "libavutil/opt.h"
22#include "avfilter.h"
23#include "internal.h"
24
25typedef struct {
26    const AVClass *class;
27    int sample_rate;
28    int rescale_pts;
29} ASetRateContext;
30
31#define CONTEXT ASetRateContext
32#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
33
34#define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \
35    { name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type,          \
36      { .deffield = def }, min, max, FLAGS, __VA_ARGS__ }
37
38#define OPT_INT(name, field, def, min, max, descr, ...) \
39    OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__)
40
41static const AVOption asetrate_options[] = {
42    OPT_INT("sample_rate", sample_rate, 44100, 1, INT_MAX, "set the sample rate"),
43    OPT_INT("r",           sample_rate, 44100, 1, INT_MAX, "set the sample rate"),
44    {NULL},
45};
46
47AVFILTER_DEFINE_CLASS(asetrate);
48
49static av_cold int query_formats(AVFilterContext *ctx)
50{
51    ASetRateContext *sr = ctx->priv;
52    int sample_rates[] = { sr->sample_rate, -1 };
53
54    ff_formats_ref(ff_make_format_list(sample_rates),
55                   &ctx->outputs[0]->in_samplerates);
56    return 0;
57}
58
59static av_cold int config_props(AVFilterLink *outlink)
60{
61    AVFilterContext *ctx = outlink->src;
62    ASetRateContext *sr = ctx->priv;
63    AVFilterLink *inlink = ctx->inputs[0];
64    AVRational intb = ctx->inputs[0]->time_base;
65    int inrate = inlink->sample_rate;
66
67    if (intb.num == 1 && intb.den == inrate) {
68        outlink->time_base.num = 1;
69        outlink->time_base.den = outlink->sample_rate;
70    } else {
71        outlink->time_base = intb;
72        sr->rescale_pts = 1;
73        if (av_q2d(intb) > 1.0 / FFMAX(inrate, outlink->sample_rate))
74            av_log(ctx, AV_LOG_WARNING, "Time base is inaccurate\n");
75    }
76    return 0;
77}
78
79static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
80{
81    AVFilterContext *ctx = inlink->dst;
82    ASetRateContext *sr = ctx->priv;
83    AVFilterLink *outlink = ctx->outputs[0];
84
85    frame->sample_rate = outlink->sample_rate;
86    if (sr->rescale_pts)
87        frame->pts = av_rescale(frame->pts, inlink->sample_rate,
88                                           outlink->sample_rate);
89    return ff_filter_frame(outlink, frame);
90}
91
92static const AVFilterPad asetrate_inputs[] = {
93    {
94        .name         = "default",
95        .type         = AVMEDIA_TYPE_AUDIO,
96        .filter_frame = filter_frame,
97    },
98    { NULL }
99};
100
101static const AVFilterPad asetrate_outputs[] = {
102    {
103        .name         = "default",
104        .type         = AVMEDIA_TYPE_AUDIO,
105        .config_props = config_props,
106    },
107    { NULL }
108};
109
110AVFilter ff_af_asetrate = {
111    .name          = "asetrate",
112    .description   = NULL_IF_CONFIG_SMALL("Change the sample rate without "
113                                          "altering the data."),
114    .query_formats = query_formats,
115    .priv_size     = sizeof(ASetRateContext),
116    .inputs        = asetrate_inputs,
117    .outputs       = asetrate_outputs,
118    .priv_class    = &asetrate_class,
119};
120