1 /*
2 * Copyright (c) 2018 Paul B Mahol
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 #include <float.h>
22
23 #include "libavutil/ffmath.h"
24 #include "libavutil/opt.h"
25 #include "audio.h"
26 #include "avfilter.h"
27 #include "internal.h"
28
29 #define BINS 32768
30
31 typedef struct ChannelStats {
32 uint64_t nb_samples;
33 uint64_t blknum;
34 float peak;
35 float sum;
36 uint32_t peaks[BINS+1];
37 uint32_t rms[BINS+1];
38 } ChannelStats;
39
40 typedef struct DRMeterContext {
41 const AVClass *class;
42 ChannelStats *chstats;
43 int nb_channels;
44 uint64_t tc_samples;
45 double time_constant;
46 } DRMeterContext;
47
48 #define OFFSET(x) offsetof(DRMeterContext, x)
49 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
50
51 static const AVOption drmeter_options[] = {
52 { "length", "set the window length", OFFSET(time_constant), AV_OPT_TYPE_DOUBLE, {.dbl=3}, .01, 10, FLAGS },
53 { NULL }
54 };
55
56 AVFILTER_DEFINE_CLASS(drmeter);
57
config_output(AVFilterLink * outlink)58 static int config_output(AVFilterLink *outlink)
59 {
60 DRMeterContext *s = outlink->src->priv;
61
62 s->chstats = av_calloc(sizeof(*s->chstats), outlink->ch_layout.nb_channels);
63 if (!s->chstats)
64 return AVERROR(ENOMEM);
65 s->nb_channels = outlink->ch_layout.nb_channels;
66 s->tc_samples = s->time_constant * outlink->sample_rate + .5;
67
68 return 0;
69 }
70
finish_block(ChannelStats * p)71 static void finish_block(ChannelStats *p)
72 {
73 int peak_bin, rms_bin;
74 float peak, rms;
75
76 rms = sqrt(2 * p->sum / p->nb_samples);
77 peak = p->peak;
78 rms_bin = av_clip(lrintf(rms * BINS), 0, BINS);
79 peak_bin = av_clip(lrintf(peak * BINS), 0, BINS);
80 p->rms[rms_bin]++;
81 p->peaks[peak_bin]++;
82
83 p->peak = 0;
84 p->sum = 0;
85 p->nb_samples = 0;
86 p->blknum++;
87 }
88
update_stat(DRMeterContext * s,ChannelStats * p,float sample)89 static void update_stat(DRMeterContext *s, ChannelStats *p, float sample)
90 {
91 if (p->nb_samples >= s->tc_samples) {
92 finish_block(p);
93 }
94
95 p->peak = FFMAX(FFABS(sample), p->peak);
96 p->sum += sample * sample;
97 p->nb_samples++;
98 }
99
filter_frame(AVFilterLink * inlink,AVFrame * buf)100 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
101 {
102 DRMeterContext *s = inlink->dst->priv;
103 const int channels = s->nb_channels;
104 int i, c;
105
106 switch (inlink->format) {
107 case AV_SAMPLE_FMT_FLTP:
108 for (c = 0; c < channels; c++) {
109 ChannelStats *p = &s->chstats[c];
110 const float *src = (const float *)buf->extended_data[c];
111
112 for (i = 0; i < buf->nb_samples; i++, src++)
113 update_stat(s, p, *src);
114 }
115 break;
116 case AV_SAMPLE_FMT_FLT: {
117 const float *src = (const float *)buf->extended_data[0];
118
119 for (i = 0; i < buf->nb_samples; i++) {
120 for (c = 0; c < channels; c++, src++)
121 update_stat(s, &s->chstats[c], *src);
122 }}
123 break;
124 }
125
126 return ff_filter_frame(inlink->dst->outputs[0], buf);
127 }
128
129 #define SQR(a) ((a)*(a))
130
print_stats(AVFilterContext * ctx)131 static void print_stats(AVFilterContext *ctx)
132 {
133 DRMeterContext *s = ctx->priv;
134 float dr = 0;
135 int ch;
136
137 for (ch = 0; ch < s->nb_channels; ch++) {
138 ChannelStats *p = &s->chstats[ch];
139 float chdr, secondpeak, rmssum = 0;
140 int i, j, first = 0;
141
142 if (!p->nb_samples) {
143 av_log(ctx, AV_LOG_INFO, "No data, dynamic range not meassurable\n");
144 return;
145 }
146
147 finish_block(p);
148
149 for (i = 0; i <= BINS; i++) {
150 if (p->peaks[BINS - i]) {
151 if (first)
152 break;
153 first = 1;
154 }
155 }
156
157 secondpeak = (BINS - i) / (double)BINS;
158
159 for (i = BINS, j = 0; i >= 0 && j < 0.2 * p->blknum; i--) {
160 if (p->rms[i]) {
161 rmssum += SQR(i / (double)BINS);
162 j += p->rms[i];
163 }
164 }
165
166 chdr = 20 * log10(secondpeak / sqrt(rmssum / (0.2 * p->blknum)));
167 dr += chdr;
168 av_log(ctx, AV_LOG_INFO, "Channel %d: DR: %g\n", ch + 1, chdr);
169 }
170
171 av_log(ctx, AV_LOG_INFO, "Overall DR: %g\n", dr / s->nb_channels);
172 }
173
uninit(AVFilterContext * ctx)174 static av_cold void uninit(AVFilterContext *ctx)
175 {
176 DRMeterContext *s = ctx->priv;
177
178 if (s->nb_channels)
179 print_stats(ctx);
180 av_freep(&s->chstats);
181 }
182
183 static const AVFilterPad drmeter_inputs[] = {
184 {
185 .name = "default",
186 .type = AVMEDIA_TYPE_AUDIO,
187 .filter_frame = filter_frame,
188 },
189 };
190
191 static const AVFilterPad drmeter_outputs[] = {
192 {
193 .name = "default",
194 .type = AVMEDIA_TYPE_AUDIO,
195 .config_props = config_output,
196 },
197 };
198
199 const AVFilter ff_af_drmeter = {
200 .name = "drmeter",
201 .description = NULL_IF_CONFIG_SMALL("Measure audio dynamic range."),
202 .priv_size = sizeof(DRMeterContext),
203 .priv_class = &drmeter_class,
204 .uninit = uninit,
205 .flags = AVFILTER_FLAG_METADATA_ONLY,
206 FILTER_INPUTS(drmeter_inputs),
207 FILTER_OUTPUTS(drmeter_outputs),
208 FILTER_SAMPLEFMTS(AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_FLT),
209 };
210