[FFmpeg-devel] [PATCH] avfilter/avf_showspectrum: add log scale for frequency plot
Paul B Mahol
onemda at gmail.com
Sun Apr 28 23:57:41 EEST 2019
Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
doc/filters.texi | 26 ++++
libavfilter/avf_showspectrum.c | 239 ++++++++++++++++++++++++---------
2 files changed, 200 insertions(+), 65 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 14c33ecf90..7cc3937b40 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -22226,6 +22226,19 @@ logarithmic
Default value is @samp{sqrt}.
+ at item fscale
+Specify frequency scale.
+
+It accepts the following values:
+ at table @samp
+ at item lin
+linear
+ at item log
+logarithmic
+ at end table
+
+Default value is @samp{lin}.
+
@item saturation
Set saturation modifier for displayed colors. Negative values provide
alternative color scheme. @code{0} is no saturation at all.
@@ -22398,6 +22411,19 @@ logarithmic
@end table
Default value is @samp{log}.
+ at item fscale
+Specify frequency scale.
+
+It accepts the following values:
+ at table @samp
+ at item lin
+linear
+ at item log
+logarithmic
+ at end table
+
+Default value is @samp{lin}.
+
@item saturation
Set saturation modifier for displayed colors. Negative values provide
alternative color scheme. @code{0} is no saturation at all.
diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
index e8d3f1ec8d..b0b4e406ea 100644
--- a/libavfilter/avf_showspectrum.c
+++ b/libavfilter/avf_showspectrum.c
@@ -45,6 +45,7 @@
enum DisplayMode { COMBINED, SEPARATE, NB_MODES };
enum DataMode { D_MAGNITUDE, D_PHASE, NB_DMODES };
+enum FrequencyScale { F_LINEAR, F_LOG, NB_FSCALES };
enum DisplayScale { LINEAR, SQRT, CBRT, LOG, FOURTHRT, FIFTHRT, NB_SCALES };
enum ColorMode { CHANNEL, INTENSITY, RAINBOW, MORELAND, NEBULAE, FIRE, FIERY, FRUIT, COOL, MAGMA, GREEN, VIRIDIS, PLASMA, CIVIDIS, TERRAIN, NB_CLMODES };
enum SlideMode { REPLACE, SCROLL, FULLFRAME, RSCROLL, NB_SLIDES };
@@ -65,6 +66,7 @@ typedef struct ShowSpectrumContext {
int mode; ///< channel display mode
int color_mode; ///< display color scheme
int scale;
+ int fscale;
float saturation; ///< color saturation multiplier
float rotation; ///< color rotation
int start, stop; ///< zoom mode
@@ -95,6 +97,7 @@ typedef struct ShowSpectrumContext {
int single_pic;
int legend;
int start_x, start_y;
+ int (*plot_channel)(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs);
} ShowSpectrumContext;
#define OFFSET(x) offsetof(ShowSpectrumContext, x)
@@ -134,6 +137,9 @@ static const AVOption showspectrum_options[] = {
{ "log", "logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=LOG}, 0, 0, FLAGS, "scale" },
{ "4thrt","4th root", 0, AV_OPT_TYPE_CONST, {.i64=FOURTHRT}, 0, 0, FLAGS, "scale" },
{ "5thrt","5th root", 0, AV_OPT_TYPE_CONST, {.i64=FIFTHRT}, 0, 0, FLAGS, "scale" },
+ { "fscale", "set frequency scale", OFFSET(fscale), AV_OPT_TYPE_INT, {.i64=F_LINEAR}, 0, NB_FSCALES-1, FLAGS, "fscale" },
+ { "lin", "linear", 0, AV_OPT_TYPE_CONST, {.i64=F_LINEAR}, 0, 0, FLAGS, "fscale" },
+ { "log", "logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=F_LOG}, 0, 0, FLAGS, "fscale" },
{ "saturation", "color saturation multiplier", OFFSET(saturation), AV_OPT_TYPE_FLOAT, {.dbl = 1}, -10, 10, FLAGS },
{ "win_func", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64 = WFUNC_HANNING}, 0, NB_WFUNC-1, FLAGS, "win_func" },
{ "rect", "Rectangular", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_RECT}, 0, 0, FLAGS, "win_func" },
@@ -623,6 +629,56 @@ static char *get_time(AVFilterContext *ctx, float seconds, int x)
return units;
}
+static float log_scale(const float value, const float min, const float max)
+{
+ if (value < min)
+ return min;
+ if (value > max)
+ return max;
+
+ {
+ const float b = logf(max / min) / (max - min);
+ const float a = max / expf(max * b);
+
+ return expf(value * b) * a;
+ }
+}
+
+static float get_log_hz(const int bin, const int num_bins, const float sample_rate)
+{
+ const float max_freq = sample_rate / 2;
+ const float hz_per_bin = max_freq / num_bins;
+ const float freq = hz_per_bin * bin;
+ const float scaled_freq = log_scale(freq + 1, 20, max_freq) - 1;
+
+ return num_bins * scaled_freq / max_freq;
+}
+
+static float inv_log_scale(const float value, const float min, const float max)
+{
+ if (value < min)
+ return min;
+ if (value > max)
+ return max;
+
+ {
+ const float b = logf(max / min) / (max - min);
+ const float a = max / expf(max * b);
+
+ return logf(value / a) / b;
+ }
+}
+
+static float bin_pos(const int bin, const int num_bins, const float sample_rate)
+{
+ const float max_freq = sample_rate / 2;
+ const float hz_per_bin = max_freq / num_bins;
+ const float freq = hz_per_bin * bin;
+ const float scaled_freq = inv_log_scale(freq + 1, 20, max_freq) - 1;
+
+ return num_bins * scaled_freq / max_freq;
+}
+
static int draw_legend(AVFilterContext *ctx, int samples)
{
ShowSpectrumContext *s = ctx->priv;
@@ -691,7 +747,8 @@ static int draw_legend(AVFilterContext *ctx, int samples)
}
for (y = 0; y < h; y += 40) {
float range = s->stop ? s->stop - s->start : inlink->sample_rate / 2;
- float hertz = s->start + y * range / (float)(1 << (int)ceil(log2(h)));
+ float bin = s->fscale == F_LINEAR ? y : get_log_hz(y, h, inlink->sample_rate);
+ float hertz = s->start + bin * range / (float)(1 << (int)ceil(log2(h)));
char *units;
if (hertz == 0)
@@ -746,7 +803,8 @@ static int draw_legend(AVFilterContext *ctx, int samples)
}
for (x = 0; x < w - 79; x += 80) {
float range = s->stop ? s->stop - s->start : inlink->sample_rate / 2;
- float hertz = s->start + x * range / (float)(1 << (int)ceil(log2(w)));
+ float bin = s->fscale == F_LINEAR ? x : get_log_hz(x, w, inlink->sample_rate);
+ float hertz = s->start + bin * range / (float)(1 << (int)ceil(log2(w)));
char *units;
if (hertz == 0)
@@ -812,6 +870,110 @@ static int draw_legend(AVFilterContext *ctx, int samples)
return 0;
}
+static float get_value(AVFilterContext *ctx, int ch, int y)
+{
+ ShowSpectrumContext *s = ctx->priv;
+ float *magnitudes = s->magnitudes[ch];
+ float *phases = s->phases[ch];
+ float a;
+
+ switch (s->data) {
+ case D_MAGNITUDE:
+ /* get magnitude */
+ a = magnitudes[y];
+ break;
+ case D_PHASE:
+ /* get phase */
+ a = phases[y];
+ break;
+ default:
+ av_assert0(0);
+ }
+
+ /* apply scale */
+ switch (s->scale) {
+ case LINEAR:
+ a = av_clipf(a, 0, 1);
+ break;
+ case SQRT:
+ a = av_clipf(sqrt(a), 0, 1);
+ break;
+ case CBRT:
+ a = av_clipf(cbrt(a), 0, 1);
+ break;
+ case FOURTHRT:
+ a = av_clipf(sqrt(sqrt(a)), 0, 1);
+ break;
+ case FIFTHRT:
+ a = av_clipf(pow(a, 0.20), 0, 1);
+ break;
+ case LOG:
+ a = 1 + log10(av_clipd(a, 1e-6, 1)) / 6; // zero = -120dBFS
+ break;
+ default:
+ av_assert0(0);
+ }
+
+ return a;
+}
+
+static int plot_channel_lin(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+ ShowSpectrumContext *s = ctx->priv;
+ const int h = s->orientation == VERTICAL ? s->channel_height : s->channel_width;
+ const int ch = jobnr;
+ float yf, uf, vf;
+ int y;
+
+ /* decide color range */
+ color_range(s, ch, &yf, &uf, &vf);
+
+ /* draw the channel */
+ for (y = 0; y < h; y++) {
+ int row = (s->mode == COMBINED) ? y : ch * h + y;
+ float *out = &s->color_buffer[ch][3 * row];
+ float a = get_value(ctx, ch, y);
+
+ pick_color(s, yf, uf, vf, a, out);
+ }
+
+ return 0;
+}
+
+static int plot_channel_log(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+ ShowSpectrumContext *s = ctx->priv;
+ AVFilterLink *inlink = ctx->inputs[0];
+ const int h = s->orientation == VERTICAL ? s->channel_height : s->channel_width;
+ const int ch = jobnr;
+ float y, yf, uf, vf;
+ int yy = 0;
+
+ /* decide color range */
+ color_range(s, ch, &yf, &uf, &vf);
+
+ /* draw the channel */
+ for (y = 0; y < h && yy < h; yy++) {
+ float pos0 = bin_pos(yy+0, h, inlink->sample_rate);
+ float pos1 = bin_pos(yy+1, h, inlink->sample_rate);
+ float delta = pos1 - pos0;
+ float a0, a1;
+
+ a0 = get_value(ctx, ch, yy+0);
+ a1 = get_value(ctx, ch, yy+1);
+ for (float j = pos0; j < pos1 && y + j - pos0 < h; j++) {
+ float row = (s->mode == COMBINED) ? y + j - pos0 : ch * h + y + j - pos0;
+ float *out = &s->color_buffer[ch][3 * lrintf(row)];
+ float lerpfrac = (j - pos0) / delta;
+
+ pick_color(s, yf, uf, vf, lerpfrac * a1 + (1.f-lerpfrac) * a0, out);
+ }
+ y += delta;
+ }
+
+ return 0;
+}
+
static int config_output(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
@@ -820,6 +982,12 @@ static int config_output(AVFilterLink *outlink)
int i, fft_bits, h, w;
float overlap;
+ switch (s->fscale) {
+ case F_LINEAR: s->plot_channel = plot_channel_lin; break;
+ case F_LOG: s->plot_channel = plot_channel_log; break;
+ default: return AVERROR_BUG;
+ }
+
s->stop = FFMIN(s->stop, inlink->sample_rate / 2);
if (s->stop && s->stop <= s->start) {
av_log(ctx, AV_LOG_ERROR, "Stop frequency should be greater than start.\n");
@@ -1099,68 +1267,6 @@ static void clear_combine_buffer(ShowSpectrumContext *s, int size)
}
}
-static int plot_channel(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
-{
- ShowSpectrumContext *s = ctx->priv;
- const int h = s->orientation == VERTICAL ? s->channel_height : s->channel_width;
- const int ch = jobnr;
- float *magnitudes = s->magnitudes[ch];
- float *phases = s->phases[ch];
- float yf, uf, vf;
- int y;
-
- /* decide color range */
- color_range(s, ch, &yf, &uf, &vf);
-
- /* draw the channel */
- for (y = 0; y < h; y++) {
- int row = (s->mode == COMBINED) ? y : ch * h + y;
- float *out = &s->color_buffer[ch][3 * row];
- float a;
-
- switch (s->data) {
- case D_MAGNITUDE:
- /* get magnitude */
- a = magnitudes[y];
- break;
- case D_PHASE:
- /* get phase */
- a = phases[y];
- break;
- default:
- av_assert0(0);
- }
-
- /* apply scale */
- switch (s->scale) {
- case LINEAR:
- a = av_clipf(a, 0, 1);
- break;
- case SQRT:
- a = av_clipf(sqrt(a), 0, 1);
- break;
- case CBRT:
- a = av_clipf(cbrt(a), 0, 1);
- break;
- case FOURTHRT:
- a = av_clipf(sqrt(sqrt(a)), 0, 1);
- break;
- case FIFTHRT:
- a = av_clipf(pow(a, 0.20), 0, 1);
- break;
- case LOG:
- a = 1 + log10(av_clipd(a, 1e-6, 1)) / 6; // zero = -120dBFS
- break;
- default:
- av_assert0(0);
- }
-
- pick_color(s, yf, uf, vf, a, out);
- }
-
- return 0;
-}
-
static int plot_spectrum_column(AVFilterLink *inlink, AVFrame *insamples)
{
AVFilterContext *ctx = inlink->dst;
@@ -1173,7 +1279,7 @@ static int plot_spectrum_column(AVFilterLink *inlink, AVFrame *insamples)
/* initialize buffer for combining to black */
clear_combine_buffer(s, z);
- ctx->internal->execute(ctx, plot_channel, NULL, NULL, s->nb_display_channels);
+ ctx->internal->execute(ctx, s->plot_channel, NULL, NULL, s->nb_display_channels);
for (y = 0; y < z * 3; y++) {
for (x = 0; x < s->nb_display_channels; x++) {
@@ -1447,6 +1553,9 @@ static const AVOption showspectrumpic_options[] = {
{ "log", "logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=LOG}, 0, 0, FLAGS, "scale" },
{ "4thrt","4th root", 0, AV_OPT_TYPE_CONST, {.i64=FOURTHRT}, 0, 0, FLAGS, "scale" },
{ "5thrt","5th root", 0, AV_OPT_TYPE_CONST, {.i64=FIFTHRT}, 0, 0, FLAGS, "scale" },
+ { "fscale", "set frequency scale", OFFSET(fscale), AV_OPT_TYPE_INT, {.i64=F_LINEAR}, 0, NB_FSCALES-1, FLAGS, "fscale" },
+ { "lin", "linear", 0, AV_OPT_TYPE_CONST, {.i64=F_LINEAR}, 0, 0, FLAGS, "fscale" },
+ { "log", "logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=F_LOG}, 0, 0, FLAGS, "fscale" },
{ "saturation", "color saturation multiplier", OFFSET(saturation), AV_OPT_TYPE_FLOAT, {.dbl = 1}, -10, 10, FLAGS },
{ "win_func", "set window function", OFFSET(win_func), AV_OPT_TYPE_INT, {.i64 = WFUNC_HANNING}, 0, NB_WFUNC-1, FLAGS, "win_func" },
{ "rect", "Rectangular", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_RECT}, 0, 0, FLAGS, "win_func" },
--
2.17.1
More information about the ffmpeg-devel
mailing list