@@ -12,6 +12,7 @@ version <next>:

 - filtering audio with unknown channel layout

 - allpass, bass, bandpass, bandreject, biquad, equalizer, highpass, lowpass

   and treble audio filter

+- improved showspectrum filter, with multichannel support and sox-like colors

 version 1.1:

@@ -6055,6 +6055,34 @@ Specify the video size for the output. Default value is @code{640x512}.

 @item slide

 Specify if the spectrum should slide along the window. Default value is

 @code{0}.

+@item mode

+Specify display mode. Can be either @code{combined}: all channels are

+displayed in the same row, or @code{separate}: all channels are displayed

+in separate rows. Default value is @code{combined}.

+@item color

+Specify display color mode. Can be either @code{channel}: each channel

+is displayed in a separate color, or @code{intensity}: each channel is

+displayed using the same color scheme. Default value is @code{channel}.

+@item scale

+Specify scale used for calculating intensity color values.

+

+It accepts the following values:

+@table @option

+@item{lin}

+linear

+@item{sqrt}

+square root, default

+@item{cbrt}

+cubic root

+@item{log}

+logarithmic

+@end table

+

+@item saturation

+Set saturation modifier for displayed colors. Negative values provide

+alternative color scheme. @code{0} is no saturation at all.

+Saturation must be in [-10.0, 10.0] range.

+Default value is @code{1}.

 @end table

 The usage is very similar to the showwaves filter; see the examples in that

@@ -27,24 +27,36 @@

 #include <math.h>

 #include "libavcodec/avfft.h"

+#include "libavutil/avassert.h"

 #include "libavutil/channel_layout.h"

 #include "libavutil/opt.h"

 #include "avfilter.h"

 #include "internal.h"

+enum DisplayMode  { COMBINED, SEPARATE, NB_MODES };

+enum DisplayScale { LINEAR, SQRT, CBRT, LOG, NB_SCALES };

+enum ColorMode    { CHANNEL, INTENSITY, NB_CLMODES };

+

 typedef struct {

     const AVClass *class;

     int w, h;

     AVFilterBufferRef *outpicref;

     int req_fullfilled;

+    int nb_display_channels;

+    int channel_height;

     int sliding;                ///< 1 if sliding mode, 0 otherwise

+    enum DisplayMode mode;      ///< channel display mode

+    enum ColorMode color_mode;  ///< display color scheme

+    enum DisplayScale scale;

+    float saturation;           ///< color saturation multiplier

     int xpos;                   ///< x position (current column)

     RDFTContext *rdft;          ///< Real Discrete Fourier Transform context

     int rdft_bits;              ///< number of bits (RDFT window size = 1<<rdft_bits)

-    FFTSample *rdft_data;       ///< bins holder for each (displayed) channels

+    FFTSample **rdft_data;      ///< bins holder for each (displayed) channels

     int filled;                 ///< number of samples (per channel) filled in current rdft_buffer

     int consumed;               ///< number of samples (per channel) consumed from the input frame

     float *window_func_lut;     ///< Window function LUT

+    float *combine_buffer;      ///< color combining buffer (3 * h items)

 } ShowSpectrumContext;

 #define OFFSET(x) offsetof(ShowSpectrumContext, x)

@@ -54,11 +66,38 @@ static const AVOption showspectrum_options[] = {

     { "size", "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "640x512"}, 0, 0, FLAGS },

     { "s",    "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "640x512"}, 0, 0, FLAGS },

     { "slide", "set sliding mode", OFFSET(sliding), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },

+    { "mode", "set channel display mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=COMBINED}, COMBINED, NB_MODES-1, FLAGS, "mode" },

+    { "combined", "combined mode", 0, AV_OPT_TYPE_CONST, {.i64=COMBINED}, 0, 0, FLAGS, "mode" },

+    { "separate", "separate mode", 0, AV_OPT_TYPE_CONST, {.i64=SEPARATE}, 0, 0, FLAGS, "mode" },

+    { "color", "set channel coloring", OFFSET(color_mode), AV_OPT_TYPE_INT, {.i64=CHANNEL}, CHANNEL, NB_CLMODES-1, FLAGS, "color" },

+    { "channel",   "separate color for each channel", 0, AV_OPT_TYPE_CONST, {.i64=CHANNEL},   0, 0, FLAGS, "color" },

+    { "intensity", "intensity based coloring",        0, AV_OPT_TYPE_CONST, {.i64=INTENSITY}, 0, 0, FLAGS, "color" },

+    { "scale", "set display scale", OFFSET(scale), AV_OPT_TYPE_INT, {.i64=SQRT}, LINEAR, NB_SCALES-1, FLAGS, "scale" },

+    { "sqrt", "square root", 0, AV_OPT_TYPE_CONST, {.i64=SQRT},   0, 0, FLAGS, "scale" },

+    { "cbrt", "cubic root",  0, AV_OPT_TYPE_CONST, {.i64=CBRT},   0, 0, FLAGS, "scale" },

+    { "log",  "logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=LOG},    0, 0, FLAGS, "scale" },

+    { "lin",  "linear",      0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0, FLAGS, "scale" },

+    { "saturation", "color saturation multiplier", OFFSET(saturation), AV_OPT_TYPE_FLOAT, {.dbl = 1}, -10, 10, FLAGS },

     { NULL },

 };

 AVFILTER_DEFINE_CLASS(showspectrum);

+typedef struct {

+    float a, y, u, v;

+} intensity_color_table_item;

+static const intensity_color_table_item intensity_color_table[] =

+{

+    { 0, 0, 0, 0 },

+    { 0.13, .03587126228984074, .1573300977624594, -.02548747583751842 },

+    { 0.3, .1857228179456802, .1772436246393981, .1747555484041475 },

+    { 0.6, .2818498058365613, -.1593064119945782, .4713207455460892 },

+    { 0.73, .6583062117554781, -.3716070802232764, .2435275933125293 },

+    { 0.78, 0.763185357582429, -.4307467689263783, .1686649662231043 },

+    { 0.91, .9533636363636364, -.2045454545454546, .03313636363636363 },

+    { 1, 1, 0, 0 }

+};

+

 static av_cold int init(AVFilterContext *ctx, const char *args)

 {

     ShowSpectrumContext *showspectrum = ctx->priv;

@@ -76,8 +115,12 @@ static av_cold int init(AVFilterContext *ctx, const char *args)

 static av_cold void uninit(AVFilterContext *ctx)

 {

     ShowSpectrumContext *showspectrum = ctx->priv;

+    int i;

+    av_freep(&showspectrum->combine_buffer);

     av_rdft_end(showspectrum->rdft);

+    for (i = 0; i < showspectrum->nb_display_channels; i++)

+        av_freep(&showspectrum->rdft_data[i]);

     av_freep(&showspectrum->rdft_data);

     av_freep(&showspectrum->window_func_lut);

     avfilter_unref_bufferp(&showspectrum->outpicref);

@@ -90,7 +133,7 @@ static int query_formats(AVFilterContext *ctx)

     AVFilterLink *inlink = ctx->inputs[0];

     AVFilterLink *outlink = ctx->outputs[0];

     static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16P, AV_SAMPLE_FMT_NONE };

-    static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_RGB24, AV_PIX_FMT_NONE };

+    static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_NONE };

     /* set input audio formats */

     formats = ff_make_format_list(sample_fmts);

@@ -120,19 +163,23 @@ static int query_formats(AVFilterContext *ctx)

 static int config_output(AVFilterLink *outlink)

 {

     AVFilterContext *ctx = outlink->src;

+    AVFilterLink *inlink = ctx->inputs[0];

     ShowSpectrumContext *showspectrum = ctx->priv;

-    int i, rdft_bits, win_size;

+    int i, rdft_bits, win_size, h;

     outlink->w = showspectrum->w;

     outlink->h = showspectrum->h;

+    h = (showspectrum->mode == COMBINED) ? outlink->h : outlink->h / inlink->channels;

+    showspectrum->channel_height = h;

+

     /* RDFT window size (precision) according to the requested output frame height */

-    for (rdft_bits = 1; 1<<rdft_bits < 2*outlink->h; rdft_bits++);

+    for (rdft_bits = 1; 1 << rdft_bits < 2 * h; rdft_bits++);

     win_size = 1 << rdft_bits;

     /* (re-)configuration if the video output changed (or first init) */

     if (rdft_bits != showspectrum->rdft_bits) {

-        size_t rdft_size;

+        size_t rdft_size, rdft_listsize;

         AVFilterBufferRef *outpicref;

         av_rdft_end(showspectrum->rdft);

@@ -142,12 +189,25 @@ static int config_output(AVFilterLink *outlink)

         /* RDFT buffers: x2 for each (display) channel buffer.

          * Note: we use free and malloc instead of a realloc-like function to

          * make sure the buffer is aligned in memory for the FFT functions. */

+        for (i = 0; i < showspectrum->nb_display_channels; i++)

+            av_freep(&showspectrum->rdft_data[i]);

         av_freep(&showspectrum->rdft_data);

-        if (av_size_mult(sizeof(*showspectrum->rdft_data), 2 * win_size, &rdft_size) < 0)

+        showspectrum->nb_display_channels = inlink->channels;

+

+        if (av_size_mult(sizeof(*showspectrum->rdft_data),

+                         showspectrum->nb_display_channels, &rdft_listsize) < 0)

+            return AVERROR(EINVAL);

+        if (av_size_mult(sizeof(**showspectrum->rdft_data),

+                         win_size, &rdft_size) < 0)

             return AVERROR(EINVAL);

-        showspectrum->rdft_data = av_malloc(rdft_size);

+        showspectrum->rdft_data = av_malloc(rdft_listsize);

         if (!showspectrum->rdft_data)

             return AVERROR(ENOMEM);

+        for (i = 0; i < showspectrum->nb_display_channels; i++) {

+            showspectrum->rdft_data[i] = av_malloc(rdft_size);

+            if (!showspectrum->rdft_data[i])

+                return AVERROR(ENOMEM);

+        }

         showspectrum->filled = 0;

         /* pre-calc windowing function (hann here) */

@@ -173,6 +233,10 @@ static int config_output(AVFilterLink *outlink)

     if (showspectrum->xpos >= outlink->w)

         showspectrum->xpos = 0;

+    showspectrum->combine_buffer =

+        av_realloc_f(showspectrum->combine_buffer, outlink->h * 3,

+                     sizeof(*showspectrum->combine_buffer));

+

     av_log(ctx, AV_LOG_VERBOSE, "s:%dx%d RDFT window size:%d\n",

            showspectrum->w, showspectrum->h, win_size);

     return 0;

@@ -213,62 +277,180 @@ static int plot_spectrum_column(AVFilterLink *inlink, AVFilterBufferRef *insampl

     AVFilterLink *outlink = ctx->outputs[0];

     ShowSpectrumContext *showspectrum = ctx->priv;

     AVFilterBufferRef *outpicref = showspectrum->outpicref;

-    const int nb_channels = av_get_channel_layout_nb_channels(insamples->audio->channel_layout);

     /* nb_freq contains the power of two superior or equal to the output image

      * height (or half the RDFT window size) */

     const int nb_freq = 1 << (showspectrum->rdft_bits - 1);

     const int win_size = nb_freq << 1;

+    const double w = 1. / (sqrt(nb_freq) * 32768.);

-    int ch, n, y;

-    FFTSample *data[2];

-    const int nb_display_channels = FFMIN(nb_channels, 2);

+    int ch, plane, n, y;

     const int start = showspectrum->filled;

     const int add_samples = FFMIN(win_size - start, nb_samples);

     /* fill RDFT input with the number of samples available */

-    for (ch = 0; ch < nb_display_channels; ch++) {

+    for (ch = 0; ch < showspectrum->nb_display_channels; ch++) {

         const int16_t *p = (int16_t *)insamples->extended_data[ch];

         p += showspectrum->consumed;

-        data[ch] = showspectrum->rdft_data + win_size * ch; // select channel buffer

         for (n = 0; n < add_samples; n++)

-            data[ch][start + n] = p[n] * showspectrum->window_func_lut[start + n];

+            showspectrum->rdft_data[ch][start + n] = p[n] * showspectrum->window_func_lut[start + n];

     }

     showspectrum->filled += add_samples;

     /* complete RDFT window size? */

     if (showspectrum->filled == win_size) {

+        /* channel height */

+        int h = showspectrum->channel_height;

+

         /* run RDFT on each samples set */

-        for (ch = 0; ch < nb_display_channels; ch++)

-            av_rdft_calc(showspectrum->rdft, data[ch]);

+        for (ch = 0; ch < showspectrum->nb_display_channels; ch++)

+            av_rdft_calc(showspectrum->rdft, showspectrum->rdft_data[ch]);

         /* fill a new spectrum column */

-#define RE(ch) data[ch][2*y + 0]

-#define IM(ch) data[ch][2*y + 1]

-#define MAGNITUDE(re, im) sqrt((re)*(re) + (im)*(im))

+#define RE(y, ch) showspectrum->rdft_data[ch][2 * y + 0]

+#define IM(y, ch) showspectrum->rdft_data[ch][2 * y + 1]

+#define MAGNITUDE(y, ch) hypot(RE(y, ch), IM(y, ch))

+        /* initialize buffer for combining to black */

         for (y = 0; y < outlink->h; y++) {

-            // FIXME: bin[0] contains first and last bins

-            uint8_t *p = outpicref->data[0] + (outlink->h - y - 1) * outpicref->linesize[0];

-            const double w = 1. / sqrt(nb_freq);

-            int a =                           sqrt(w * MAGNITUDE(RE(0), IM(0)));

-            int b = nb_display_channels > 1 ? sqrt(w * MAGNITUDE(RE(1), IM(1))) : a;

-

-            if (showspectrum->sliding) {

-                memmove(p, p + 3, (outlink->w - 1) * 3);

-                p += (outlink->w - 1) * 3;

-            } else {

-                p += showspectrum->xpos * 3;

+            showspectrum->combine_buffer[3 * y    ] = 0;

+            showspectrum->combine_buffer[3 * y + 1] = 127.5;

+            showspectrum->combine_buffer[3 * y + 2] = 127.5;

+        }

+

+        for (ch = 0; ch < showspectrum->nb_display_channels; ch++) {

+            float yf, uf, vf;

+

+            /* decide color range */

+            switch (showspectrum->mode) {

+            case COMBINED:

+                // reduce range by channel count

+                yf = 256.0f / showspectrum->nb_display_channels;

+                switch (showspectrum->color_mode) {

+                case INTENSITY:

+                    uf = yf;

+                    vf = yf;

+                    break;

+                case CHANNEL:

+                    /* adjust saturation for mixed UV coloring */

+                    /* this factor is correct for infinite channels, an approximation otherwise */

+                    uf = yf * M_PI;

+                    vf = yf * M_PI;

+                    break;

+                default:

+                    av_assert0(0);

+                }

+                break;

+            case SEPARATE:

+                // full range

+                yf = 256.0f;

+                uf = 256.0f;

+                vf = 256.0f;

+                break;

+            default:

+                av_assert0(0);

             }

-            a = FFMIN(a, 255);

-            b = FFMIN(b, 255);

-            p[0] = a;

-            p[1] = b;

-            p[2] = (a + b) / 2;

+            if (showspectrum->color_mode == CHANNEL) {

+                if (showspectrum->nb_display_channels > 1) {

+                    uf *= 0.5 * sin((2 * M_PI * ch) / showspectrum->nb_display_channels);

+                    vf *= 0.5 * cos((2 * M_PI * ch) / showspectrum->nb_display_channels);

+                } else {

+                    uf = 0.0f;

+                    vf = 0.0f;

+                }

+            }

+            uf *= showspectrum->saturation;

+            vf *= showspectrum->saturation;

+

+            /* draw the channel */

+            for (y = 0; y < h; y++) {

+                int row = (showspectrum->mode == COMBINED) ? y : ch * h + y;

+                float *out = &showspectrum->combine_buffer[3 * row];

+

+                /* get magnitude */

+                float a = w * MAGNITUDE(y, ch);

+

+                /* apply scale */

+                switch (showspectrum->scale) {

+                case LINEAR:

+                    break;

+                case SQRT:

+                    a = sqrt(a);

+                    break;

+                case CBRT:

+                    a = cbrt(a);

+                    break;

+                case LOG:

+                    a = 1 - log(FFMAX(FFMIN(1, a), 1e-6)) / log(1e-6); // zero = -120dBFS

+                    break;

+                default:

+                    av_assert0(0);

+                }

+

+                if (showspectrum->color_mode == INTENSITY) {

+                    float y, u, v;

+                    int i;

+

+                    for (i = 1; i < sizeof(intensity_color_table) / sizeof(*intensity_color_table) - 1; i++)

+                        if (intensity_color_table[i].a >= a)

+                            break;

+                    // i now is the first item >= the color

+                    // now we know to interpolate between item i - 1 and i

+                    if (a <= intensity_color_table[i - 1].a) {

+                        y = intensity_color_table[i - 1].y;

+                        u = intensity_color_table[i - 1].u;

+                        v = intensity_color_table[i - 1].v;

+                    } else if (a >= intensity_color_table[i].a) {

+                        y = intensity_color_table[i].y;

+                        u = intensity_color_table[i].u;

+                        v = intensity_color_table[i].v;

+                    } else {

+                        float start = intensity_color_table[i - 1].a;

+                        float end = intensity_color_table[i].a;

+                        float lerpfrac = (a - start) / (end - start);

+                        y = intensity_color_table[i - 1].y * (1.0f - lerpfrac)

+                          + intensity_color_table[i].y * lerpfrac;

+                        u = intensity_color_table[i - 1].u * (1.0f - lerpfrac)

+                          + intensity_color_table[i].u * lerpfrac;

+                        v = intensity_color_table[i - 1].v * (1.0f - lerpfrac)

+                          + intensity_color_table[i].v * lerpfrac;

+                    }

+

+                    out[0] += y * yf;

+                    out[1] += u * uf;

+                    out[2] += v * vf;

+                } else {

+                    out[0] += a * yf;

+                    out[1] += a * uf;

+                    out[2] += a * vf;

+                }

+            }

         }

+

+        /* copy to output */

+        if (showspectrum->sliding) {

+            for (plane = 0; plane < 3; plane++) {

+                for (y = 0; y < outlink->h; y++) {

+                    uint8_t *p = outpicref->data[plane] +

+                                 y * outpicref->linesize[plane];

+                    memmove(p, p + 1, outlink->w - 1);

+                }

+            }

+            showspectrum->xpos = outlink->w - 1;

+        }

+        for (plane = 0; plane < 3; plane++) {

+            uint8_t *p = outpicref->data[plane] +

+                         (outlink->h - 1) * outpicref->linesize[plane] +

+                         showspectrum->xpos;

+            for (y = 0; y < outlink->h; y++) {

+                *p = rint(FFMAX(0, FFMIN(showspectrum->combine_buffer[3 * y + plane], 255)));

+                p -= outpicref->linesize[plane];

+            }

+        }

+

         outpicref->pts = insamples->pts +

             av_rescale_q(showspectrum->consumed,

                          (AVRational){ 1, inlink->sample_rate },