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/*
* Copyright (c) 2018 Paul B Mahol
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <float.h>
#include "libavutil/ffmath.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#include "audio.h"
#include "avfilter.h"
#include "internal.h"
#define BINS 32768
typedef struct ChannelStats {
uint64_t nb_samples;
uint64_t blknum;
float peak;
float sum;
uint32_t peaks[BINS+1];
uint32_t rms[BINS+1];
} ChannelStats;
typedef struct DRMeterContext {
const AVClass *class;
ChannelStats *chstats;
int nb_channels;
int64_t tc_samples;
double time_constant;
} DRMeterContext;
#define OFFSET(x) offsetof(DRMeterContext, x)
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption drmeter_options[] = {
{ "length", "set the window length", OFFSET(time_constant), AV_OPT_TYPE_DOUBLE, {.dbl=3}, .01, 10, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(drmeter);
static int config_output(AVFilterLink *outlink)
{
DRMeterContext *s = outlink->src->priv;
s->chstats = av_calloc(outlink->ch_layout.nb_channels, sizeof(*s->chstats));
if (!s->chstats)
return AVERROR(ENOMEM);
s->nb_channels = outlink->ch_layout.nb_channels;
s->tc_samples = lrint(s->time_constant * outlink->sample_rate);
return 0;
}
static void finish_block(ChannelStats *p)
{
int peak_bin, rms_bin;
float peak, rms;
rms = sqrtf(2.f * p->sum / p->nb_samples);
peak = p->peak;
rms_bin = av_clip(lrintf(rms * BINS), 0, BINS);
peak_bin = av_clip(lrintf(peak * BINS), 0, BINS);
p->rms[rms_bin]++;
p->peaks[peak_bin]++;
p->peak = 0;
p->sum = 0;
p->nb_samples = 0;
p->blknum++;
}
static void update_stat(DRMeterContext *s, ChannelStats *p, float sample)
{
p->peak = fmaxf(fabsf(sample), p->peak);
p->sum += sample * sample;
p->nb_samples++;
if (p->nb_samples >= s->tc_samples)
finish_block(p);
}
static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
{
DRMeterContext *s = inlink->dst->priv;
const int channels = s->nb_channels;
switch (inlink->format) {
case AV_SAMPLE_FMT_FLTP:
for (int c = 0; c < channels; c++) {
ChannelStats *p = &s->chstats[c];
const float *src = (const float *)buf->extended_data[c];
for (int i = 0; i < buf->nb_samples; i++, src++)
update_stat(s, p, *src);
}
break;
case AV_SAMPLE_FMT_FLT: {
const float *src = (const float *)buf->extended_data[0];
for (int i = 0; i < buf->nb_samples; i++) {
for (int c = 0; c < channels; c++, src++)
update_stat(s, &s->chstats[c], *src);
}}
break;
}
return ff_filter_frame(inlink->dst->outputs[0], buf);
}
#define SQR(a) ((a)*(a))
static void print_stats(AVFilterContext *ctx)
{
DRMeterContext *s = ctx->priv;
float dr = 0.f;
for (int ch = 0; ch < s->nb_channels; ch++) {
ChannelStats *p = &s->chstats[ch];
float chdr, secondpeak, rmssum = 0.f;
int first = 0, last = lrintf(0.2f * p->blknum);
int peak_bin = BINS;
if (!p->nb_samples) {
av_log(ctx, AV_LOG_INFO, "No data, dynamic range not meassurable\n");
return;
}
if (p->nb_samples)
finish_block(p);
for (int i = BINS; i >= 0; i--) {
if (p->peaks[i]) {
if (first || p->peaks[i] > 1) {
peak_bin = i;
break;
}
first = 1;
}
}
secondpeak = peak_bin / (float)BINS;
for (int64_t i = BINS, j = 0; i >= 0 && j < last; i--) {
if (p->rms[i]) {
rmssum += SQR(i / (float)BINS) * p->rms[i];
j += p->rms[i];
}
}
chdr = 20.f * log10f(secondpeak / sqrtf(rmssum / (float)last));
dr += chdr;
av_log(ctx, AV_LOG_INFO, "Channel %d: DR: %g\n", ch + 1, chdr);
}
av_log(ctx, AV_LOG_INFO, "Overall DR: %g\n", dr / s->nb_channels);
}
static av_cold void uninit(AVFilterContext *ctx)
{
DRMeterContext *s = ctx->priv;
if (s->nb_channels)
print_stats(ctx);
av_freep(&s->chstats);
}
static const AVFilterPad drmeter_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.filter_frame = filter_frame,
},
};
static const AVFilterPad drmeter_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.config_props = config_output,
},
};
const AVFilter ff_af_drmeter = {
.name = "drmeter",
.description = NULL_IF_CONFIG_SMALL("Measure audio dynamic range."),
.priv_size = sizeof(DRMeterContext),
.priv_class = &drmeter_class,
.uninit = uninit,
.flags = AVFILTER_FLAG_METADATA_ONLY,
FILTER_INPUTS(drmeter_inputs),
FILTER_OUTPUTS(drmeter_outputs),
FILTER_SAMPLEFMTS(AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_FLT),
};
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