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avfilter/af_astats: measure noise floor

tags/n4.3
Paul B Mahol 5 years ago
parent
1b59f3f844
commit
87b4fb65a8
2 changed files with 84 additions and 1 deletions
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  1. +5
    -0
      doc/filters.texi
  2. +79
    -1
      libavfilter/af_astats.c

+ 5
- 0
doc/filters.texi View File

@@ -2329,6 +2329,7 @@ RMS_trough
Crest_factor
Flat_factor
Peak_count
Noise_floor
Bit_depth
Dynamic_range
Zero_crossings
@@ -2351,6 +2352,7 @@ RMS_peak
RMS_trough
Flat_factor
Peak_count
Noise_floor
Bit_depth
Number_of_samples
Number_of_NaNs
@@ -2422,6 +2424,9 @@ Flatness (i.e. consecutive samples with the same value) of the signal at its pea
Number of occasions (not the number of samples) that the signal attained either
@var{Min level} or @var{Max level}.

@item Noise floor dB
Minimum local peak measured in dBFS over a short window.

@item Bit depth
Overall bit depth of audio. Number of bits used for each sample.



+ 79
- 1
libavfilter/af_astats.c View File

@@ -27,6 +27,9 @@
#include "avfilter.h"
#include "internal.h"

#define HISTOGRAM_SIZE 8192
#define HISTOGRAM_MAX (HISTOGRAM_SIZE-1)

#define MEASURE_ALL UINT_MAX
#define MEASURE_NONE 0

@@ -52,6 +55,7 @@
#define MEASURE_NUMBER_OF_NANS (1 << 19)
#define MEASURE_NUMBER_OF_INFS (1 << 20)
#define MEASURE_NUMBER_OF_DENORMALS (1 << 21)
#define MEASURE_NOISE_FLOOR (1 << 22)

#define MEASURE_MINMAXPEAK (MEASURE_MIN_LEVEL | MEASURE_MAX_LEVEL | MEASURE_PEAK_LEVEL)

@@ -75,6 +79,11 @@ typedef struct ChannelStats {
uint64_t nb_nans;
uint64_t nb_infs;
uint64_t nb_denormals;
double *win_samples;
unsigned histogram[HISTOGRAM_SIZE];
int win_pos;
int max_index;
double noise_floor;
} ChannelStats;

typedef struct AudioStatsContext {
@@ -122,6 +131,7 @@ static const AVOption astats_options[] = {
{ "Dynamic_range" , "", 0, AV_OPT_TYPE_CONST, {.i64=MEASURE_DYNAMIC_RANGE }, 0, 0, FLAGS, "measure" },
{ "Zero_crossings" , "", 0, AV_OPT_TYPE_CONST, {.i64=MEASURE_ZERO_CROSSINGS }, 0, 0, FLAGS, "measure" },
{ "Zero_crossings_rate" , "", 0, AV_OPT_TYPE_CONST, {.i64=MEASURE_ZERO_CROSSINGS_RATE }, 0, 0, FLAGS, "measure" },
{ "Noise_floor" , "", 0, AV_OPT_TYPE_CONST, {.i64=MEASURE_NOISE_FLOOR }, 0, 0, FLAGS, "measure" },
{ "Number_of_samples" , "", 0, AV_OPT_TYPE_CONST, {.i64=MEASURE_NUMBER_OF_SAMPLES }, 0, 0, FLAGS, "measure" },
{ "Number_of_NaNs" , "", 0, AV_OPT_TYPE_CONST, {.i64=MEASURE_NUMBER_OF_NANS }, 0, 0, FLAGS, "measure" },
{ "Number_of_Infs" , "", 0, AV_OPT_TYPE_CONST, {.i64=MEASURE_NUMBER_OF_INFS }, 0, 0, FLAGS, "measure" },
@@ -197,6 +207,10 @@ static void reset_stats(AudioStatsContext *s)
p->nb_infs = 0;
p->nb_denormals = 0;
p->last = NAN;
p->noise_floor = NAN;
p->win_pos = 0;
memset(p->win_samples, 0, s->tc_samples * sizeof(*p->win_samples));
memset(p->histogram, 0, sizeof(p->histogram));
}
}

@@ -207,9 +221,19 @@ static int config_output(AVFilterLink *outlink)
s->chstats = av_calloc(sizeof(*s->chstats), outlink->channels);
if (!s->chstats)
return AVERROR(ENOMEM);

s->tc_samples = 5 * s->time_constant * outlink->sample_rate + .5;
s->nb_channels = outlink->channels;

for (int i = 0; i < s->nb_channels; i++) {
ChannelStats *p = &s->chstats[i];

p->win_samples = av_calloc(s->tc_samples, sizeof(*p->win_samples));
if (!p->win_samples)
return AVERROR(ENOMEM);
}

s->mult = exp((-1 / s->time_constant / outlink->sample_rate));
s->tc_samples = 5 * s->time_constant * outlink->sample_rate + .5;
s->nb_frames = 0;
s->maxbitdepth = av_get_bytes_per_sample(outlink->format) * 8;
s->is_double = outlink->format == AV_SAMPLE_FMT_DBL ||
@@ -249,6 +273,9 @@ static inline void update_minmax(AudioStatsContext *s, ChannelStats *p, double d

static inline void update_stat(AudioStatsContext *s, ChannelStats *p, double d, double nd, int64_t i)
{
double drop;
int index;

if (d < p->min) {
p->min = d;
p->nmin = nd;
@@ -296,6 +323,38 @@ static inline void update_stat(AudioStatsContext *s, ChannelStats *p, double d,
p->mask |= i;
p->imask &= i;

drop = p->win_samples[p->win_pos];
p->win_samples[p->win_pos] = nd;
index = av_clip(FFABS(nd) * HISTOGRAM_MAX, 0, HISTOGRAM_MAX);
p->max_index = FFMAX(p->max_index, index);
p->histogram[index]++;
if (!isnan(p->noise_floor))
p->histogram[av_clip(FFABS(drop) * HISTOGRAM_MAX, 0, HISTOGRAM_MAX)]--;
p->win_pos++;

while (p->histogram[p->max_index] == 0)
p->max_index--;
if (p->win_pos >= s->tc_samples || !isnan(p->noise_floor)) {
double noise_floor = 1.;

for (int i = p->max_index; i >= 0; i--) {
if (p->histogram[i]) {
noise_floor = i / (double)HISTOGRAM_MAX;
break;
}
}

if (isnan(p->noise_floor)) {
p->noise_floor = noise_floor;
} else {
p->noise_floor = FFMIN(noise_floor, p->noise_floor);
}
}

if (p->win_pos >= s->tc_samples) {
p->win_pos = 0;
}

if (p->nb_samples >= s->tc_samples) {
p->max_sigma_x2 = FFMAX(p->max_sigma_x2, p->avg_sigma_x2);
p->min_sigma_x2 = FFMIN(p->min_sigma_x2, p->avg_sigma_x2);
@@ -349,6 +408,7 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
diff1_sum_x2 = 0,
sigma_x = 0,
sigma_x2 = 0,
noise_floor = 0,
min_sigma_x2 = DBL_MAX,
max_sigma_x2 =-DBL_MAX;
AVRational depth;
@@ -372,6 +432,7 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
max_sigma_x2 = FFMAX(max_sigma_x2, p->max_sigma_x2);
sigma_x += p->sigma_x;
sigma_x2 += p->sigma_x2;
noise_floor = FFMAX(noise_floor, p->noise_floor);
min_count += p->min_count;
max_count += p->max_count;
min_runs += p->min_runs;
@@ -413,6 +474,8 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
set_meta(metadata, c + 1, "Flat_factor", "%f", LINEAR_TO_DB((p->min_runs + p->max_runs) / (p->min_count + p->max_count)));
if (s->measure_perchannel & MEASURE_PEAK_COUNT)
set_meta(metadata, c + 1, "Peak_count", "%f", (float)(p->min_count + p->max_count));
if (s->measure_perchannel & MEASURE_NOISE_FLOOR)
set_meta(metadata, c + 1, "Noise_floor"," %f", LINEAR_TO_DB(p->noise_floor));
if (s->measure_perchannel & MEASURE_BIT_DEPTH) {
bit_depth(s, p->mask, p->imask, &depth);
set_meta(metadata, c + 1, "Bit_depth", "%f", depth.num);
@@ -458,6 +521,8 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
set_meta(metadata, 0, "Overall.Flat_factor", "%f", LINEAR_TO_DB((min_runs + max_runs) / (min_count + max_count)));
if (s->measure_overall & MEASURE_PEAK_COUNT)
set_meta(metadata, 0, "Overall.Peak_count", "%f", (float)(min_count + max_count) / (double)s->nb_channels);
if (s->measure_overall & MEASURE_NOISE_FLOOR)
set_meta(metadata, 0, "Overall.Noise_floor", "%f", LINEAR_TO_DB(noise_floor));
if (s->measure_overall & MEASURE_BIT_DEPTH) {
bit_depth(s, mask, imask, &depth);
set_meta(metadata, 0, "Overall.Bit_depth", "%f", depth.num);
@@ -572,6 +637,7 @@ static void print_stats(AVFilterContext *ctx)
diff1_sum = 0,
sigma_x = 0,
sigma_x2 = 0,
noise_floor = 0,
min_sigma_x2 = DBL_MAX,
max_sigma_x2 =-DBL_MAX;
AVRational depth;
@@ -595,6 +661,7 @@ static void print_stats(AVFilterContext *ctx)
max_sigma_x2 = FFMAX(max_sigma_x2, p->max_sigma_x2);
sigma_x += p->sigma_x;
sigma_x2 += p->sigma_x2;
noise_floor = FFMAX(noise_floor, p->noise_floor);
min_count += p->min_count;
max_count += p->max_count;
min_runs += p->min_runs;
@@ -638,6 +705,8 @@ static void print_stats(AVFilterContext *ctx)
av_log(ctx, AV_LOG_INFO, "Flat factor: %f\n", LINEAR_TO_DB((p->min_runs + p->max_runs) / (p->min_count + p->max_count)));
if (s->measure_perchannel & MEASURE_PEAK_COUNT)
av_log(ctx, AV_LOG_INFO, "Peak count: %"PRId64"\n", p->min_count + p->max_count);
if (s->measure_perchannel & MEASURE_NOISE_FLOOR)
av_log(ctx, AV_LOG_INFO, "Noise floor dB: %f\n", LINEAR_TO_DB(p->noise_floor));
if (s->measure_perchannel & MEASURE_BIT_DEPTH) {
bit_depth(s, p->mask, p->imask, &depth);
av_log(ctx, AV_LOG_INFO, "Bit depth: %u/%u\n", depth.num, depth.den);
@@ -684,6 +753,8 @@ static void print_stats(AVFilterContext *ctx)
av_log(ctx, AV_LOG_INFO, "Flat factor: %f\n", LINEAR_TO_DB((min_runs + max_runs) / (min_count + max_count)));
if (s->measure_overall & MEASURE_PEAK_COUNT)
av_log(ctx, AV_LOG_INFO, "Peak count: %f\n", (min_count + max_count) / (double)s->nb_channels);
if (s->measure_overall & MEASURE_NOISE_FLOOR)
av_log(ctx, AV_LOG_INFO, "Noise floor dB: %f\n", LINEAR_TO_DB(noise_floor));
if (s->measure_overall & MEASURE_BIT_DEPTH) {
bit_depth(s, mask, imask, &depth);
av_log(ctx, AV_LOG_INFO, "Bit depth: %u/%u\n", depth.num, depth.den);
@@ -704,6 +775,13 @@ static av_cold void uninit(AVFilterContext *ctx)

if (s->nb_channels)
print_stats(ctx);
if (s->chstats) {
for (int i = 0; i < s->nb_channels; i++) {
ChannelStats *p = &s->chstats[i];

av_freep(&p->win_samples);
}
}
av_freep(&s->chstats);
}



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