I've added documentation for the extension of aphasemeter filter.
Also, I'm not sure that "phasing" is the right word to describe the
detection.
From 1e356929e878a2081add102b77a9560647232ef8 Mon Sep 17 00:00:00 2001
From: Romane Lafon <rom...@nomalab.com>
Date: Wed, 3 Jul 2019 15:15:16 +0200
Subject: [PATCH] avfilter/avf_aphasemeter: Add out of phase and mono detection
Signed-off-by: Romane Lafon <rom...@nomalab.com>
---
doc/filters.texi | 32 +++++++++++
libavfilter/avf_aphasemeter.c | 127 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 155 insertions(+), 4 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 700a76f239..ec8c73d558 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -20656,6 +20656,38 @@ Set color which will be used for drawing median phase. If color is
Enable video output. Default is enabled.
@end table
+@subsection phasing detection
+
+The filter also detects out of phase and mono sequences in stereo streams.
+It logs the sequence start, end and duration when it lasts longer or as long as the minimum set.
+
+The filter accepts the following options for this detection:
+
+@table @option
+@item phasing
+Enable mono and out of phase detection. Default is disabled.
+
+@item tolerance
+Set phase tolerance for mono detection, in amplitude ratio. Default is @code{0}.
+Allowed range is @code{[0, 1]}.
+
+@item angle
+Set angle threshold for out of phase detection, in degree. Default is @code{170}.
+Allowed range is @code{[0, 180]}.
+
+@item duration
+Set mono or out of phase duration until notification, expressed in seconds. Default is @code{2}.
+
+@subsection Examples
+
+@itemize
+@item
+Complete example with @command{ffmpeg} to detect 1 second of mono with 0.001 phase tolerance:
+@example
+ffmpeg -i stereo.wav -af aphasemeter=video=0:phasing=1:duration=1:tolerance=0.001 -f null -
+@end example
+@end itemize
+
@section avectorscope
Convert input audio to a video output, representing the audio vector
diff --git a/libavfilter/avf_aphasemeter.c b/libavfilter/avf_aphasemeter.c
index f497bc9969..77701e5cde 100644
--- a/libavfilter/avf_aphasemeter.c
+++ b/libavfilter/avf_aphasemeter.c
@@ -28,26 +28,41 @@
#include "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
#include "libavutil/parseutils.h"
+#include "libavutil/timestamp.h"
#include "avfilter.h"
#include "formats.h"
#include "audio.h"
#include "video.h"
#include "internal.h"
+#include "stdbool.h"
+#include "float.h"
typedef struct AudioPhaseMeterContext {
const AVClass *class;
AVFrame *out;
int do_video;
+ int do_phasing_detection;
int w, h;
AVRational frame_rate;
int contrast[4];
uint8_t *mpc_str;
uint8_t mpc[4];
int draw_median_phase;
+ int is_mono;
+ int is_out_phase;
+ int start_mono_presence;
+ int start_out_phase_presence;
+ float tolerance;
+ float angle;
+ float phase;
+ float mono_idx[2];
+ float out_phase_idx[2];
+ double duration;
} AudioPhaseMeterContext;
#define OFFSET(x) offsetof(AudioPhaseMeterContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+#define get_duration(index) (index[1] - index[0])
static const AVOption aphasemeter_options[] = {
{ "rate", "set video rate", OFFSET(frame_rate), AV_OPT_TYPE_VIDEO_RATE, {.str="25"}, 0, INT_MAX, FLAGS },
@@ -59,6 +74,10 @@ static const AVOption aphasemeter_options[] = {
{ "bc", "set blue contrast", OFFSET(contrast[2]), AV_OPT_TYPE_INT, {.i64=1}, 0, 255, FLAGS },
{ "mpc", "set median phase color", OFFSET(mpc_str), AV_OPT_TYPE_STRING, {.str = "none"}, 0, 0, FLAGS },
{ "video", "set video output", OFFSET(do_video), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, FLAGS },
+ { "phasing", "set mono and out-of-phase detection output", OFFSET(do_phasing_detection), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, FLAGS },
+ { "tolerance", "set phase tolerance for mono detection", OFFSET(tolerance), AV_OPT_TYPE_FLOAT, {.dbl = 0.}, 0, 1, FLAGS },
+ { "angle", "set angle threshold for out-of-phase detection", OFFSET(angle), AV_OPT_TYPE_FLOAT, {.dbl = 170.}, 90, 180, FLAGS },
+ { "duration", "set minimum mono or out-of-phase duration in seconds", OFFSET(duration), AV_OPT_TYPE_DOUBLE, {.dbl=2.}, 0, 24*60*60, FLAGS },
{ NULL }
};
@@ -140,6 +159,22 @@ static inline int get_x(float phase, int w)
return (phase + 1.) / 2. * (w - 1);
}
+static inline float get_index(AVFilterLink *inlink, AVFrame *in)
+{
+ char *index_str = av_ts2timestr(in->pts, &inlink->time_base);
+ return atof(index_str);
+}
+
+static inline void add_metadata(AVFrame *insamples, const char *key, float value)
+{
+ char buf[128];
+ char str[128];
+
+ snprintf(str, sizeof(str), "%f", value);
+ snprintf(buf, sizeof(buf), "lavfi.aphasemeter.%s", key);
+ av_dict_set(&insamples->metadata, buf, str, 0);
+}
+
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
AVFilterContext *ctx = inlink->dst;
@@ -154,6 +189,10 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
AVFrame *out;
uint8_t *dst;
int i;
+ int mono_measurement;
+ int out_phase_measurement;
+ float tolerance = 1.0f - s->tolerance;
+ float angle = cosf(s->angle/180.0f*M_PI);
if (s->do_video && (!s->out || s->out->width != outlink->w ||
s->out->height != outlink->h)) {
@@ -193,7 +232,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
fphase += phase;
}
fphase /= in->nb_samples;
-
+ s->phase = fphase;
if (s->do_video) {
if (s->draw_median_phase) {
dst = out->data[0] + get_x(fphase, s->w) * 4;
@@ -206,10 +245,64 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
metadata = &in->metadata;
if (metadata) {
- uint8_t value[128];
+ add_metadata(in, "phase", fphase);
+ }
- snprintf(value, sizeof(value), "%f", fphase);
- av_dict_set(metadata, "lavfi.aphasemeter.phase", value, 0);
+ if (s->do_phasing_detection) {
+ mono_measurement = (tolerance - fphase) < FLT_EPSILON;
+ out_phase_measurement = (angle - fphase) > FLT_EPSILON;
+ if (!s->is_mono && mono_measurement) {
+ s->is_mono = 1;
+ s->start_mono_presence = 1;
+ s->mono_idx[0] = get_index(inlink, in);
+ }
+ if (s->is_mono && mono_measurement && s->start_mono_presence) {
+ float mono_duration;
+ s->mono_idx[1] = get_index(inlink, in);
+ mono_duration = get_duration(s->mono_idx);
+ if (mono_duration >= s->duration) {
+ add_metadata(in, "mono_start", s->mono_idx[0]);
+ av_log(s, AV_LOG_INFO, "mono_start: %f\n", s->mono_idx[0]);
+ s->start_mono_presence = 0;
+ }
+ }
+ if (s->is_mono && !mono_measurement) {
+ float mono_duration;
+ s->mono_idx[1] = get_index(inlink, in);
+ mono_duration = get_duration(s->mono_idx);
+ if (mono_duration > s->duration) {
+ add_metadata(in, "mono_end", s->mono_idx[1]);
+ add_metadata(in, "mono_duration", mono_duration);
+ av_log(s, AV_LOG_INFO, "mono_end: %f | mono_duration: %f\n", s->mono_idx[1], mono_duration);
+ }
+ s->is_mono = 0;
+ }
+ if (!s->is_out_phase && out_phase_measurement) {
+ s->out_phase_idx[0] = get_index(inlink, in);
+ s->is_out_phase = 1;
+ s->start_out_phase_presence = 1;
+ }
+ if (s->is_out_phase && out_phase_measurement && s->start_out_phase_presence) {
+ float out_phase_duration;
+ s->out_phase_idx[1] = get_index(inlink, in);
+ out_phase_duration = get_duration(s->out_phase_idx);
+ if (out_phase_duration >= s->duration) {
+ add_metadata(in, "out_phase_start", s->out_phase_idx[0]);
+ av_log(s, AV_LOG_INFO, "out_phase_start: %f\n", s->out_phase_idx[0]);
+ s->start_out_phase_presence = 0;
+ }
+ }
+ if (s->is_out_phase && !out_phase_measurement) {
+ float out_phase_duration;
+ s->out_phase_idx[1] = get_index(inlink, in);
+ out_phase_duration = get_duration(s->out_phase_idx);
+ if (out_phase_duration > s->duration) {
+ add_metadata(in, "out_phase_end", s->out_phase_idx[1]);
+ add_metadata(in, "out_phase_duration", out_phase_duration);
+ av_log(s, AV_LOG_INFO, "out_phase_end: %f | out_phase_duration: %f\n", s->out_phase_idx[1], out_phase_duration);
+ }
+ s->is_out_phase = 0;
+ }
}
if (s->do_video) {
@@ -224,6 +317,32 @@ static av_cold void uninit(AVFilterContext *ctx)
AudioPhaseMeterContext *s = ctx->priv;
int i;
+ if (s->do_phasing_detection) {
+ float tolerance = 1.0f - s->tolerance;
+ float angle = cosf(s->angle/180.0f*M_PI);
+ float mono_duration;
+ float out_phase_duration;
+ AVFilterLink *inlink = ctx->inputs[0];
+
+ if (s->is_mono) {
+ char *index_str = av_ts2timestr(inlink->current_pts, &inlink->time_base);
+ s->mono_idx[1] = atof(index_str);
+ mono_duration = get_duration(s->mono_idx);
+ if (mono_duration > s->duration) {
+ av_log(s, AV_LOG_INFO, "mono_end: %f | mono_duration: %f\n", s->mono_idx[1], mono_duration);
+ }
+ s->is_mono = 0;
+ }
+ if (s->is_out_phase) {
+ char *index_str = av_ts2timestr(inlink->current_pts, &inlink->time_base);
+ s->out_phase_idx[1] = atof(index_str);
+ out_phase_duration = get_duration(s->out_phase_idx);
+ if (out_phase_duration > s->duration) {
+ av_log(s, AV_LOG_INFO, "out_phase_end: %f | out_phase_duration: %f\n", s->out_phase_idx[1], out_phase_duration);
+ }
+ s->is_out_phase = 0;
+ }
+ }
av_frame_free(&s->out);
for (i = 0; i < ctx->nb_outputs; i++)
av_freep(&ctx->output_pads[i].name);
--
2.11.0
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