[FFmpeg-devel] [PATCH] lavfi/showspectrum: display multiple channels in separate row

Stefano Sabatini stefasab at gmail.com
Mon Feb 4 00:25:45 CET 2013


On date Sunday 2013-02-03 18:49:48 +0000, Paul B Mahol encoded:
> From: Rudolf Polzer <divverent at xonotic.org>
> 
> The showspectrum filter gets multiple channel (any count) support.
> 
> Signed-off-by: Rudolf Polzer <divverent at xonotic.org>
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
>  Changelog                      |   1 +
>  doc/filters.texi               |  15 +++
>  libavfilter/avf_showspectrum.c | 245 +++++++++++++++++++++++++++++++++++------
>  3 files changed, 226 insertions(+), 35 deletions(-)
> 
> diff --git a/Changelog b/Changelog
> index 01bb42e..5ee9200 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -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:
> diff --git a/doc/filters.texi b/doc/filters.texi
> index fdbe3b7..3268233 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -6023,6 +6023,21 @@ 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}.
> + at item mode
> +Specify display mode. Can be either @code{combined}: all channels are
> +displayed in same row, or @code{separate}: all channels are displayed

displayed in the same row

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

in separate rows.

You may use a table here and below, for better rendering.

> + at item color
> +Specify display color mode. Can be either @code{channel}: each channel
> +is displayed in separate color, or @code{intensity}: each channel is

in a separate color

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

the same color scheme.

> + at item scale
> +Specify scale used for calculating intensity color values. Can be either
> + at code{sqrt} or @code{log}. Default value is @code{sqrt}.

> + at item saturation
> +Set saturation modifier for displayed colors. Negative values provide
> +alternative color scheme. @code{0} is no saturation at all.
> +Default value is @code{1}.

Specify the valid range here (also is this a double or an int?). Also
it is not clear how the color scheme is selected.

>  @end table
>  
>  The usage is very similar to the showwaves filter; see the examples in that
> diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
> index d8aed0d..f78189f 100644
> --- a/libavfilter/avf_showspectrum.c
> +++ b/libavfilter/avf_showspectrum.c
> @@ -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 ChDisplayMode { COMBINED, SEPARATE, NB_MODES };

ChDisplay is obfuscated, DisplayMode or ChannelDisplayMode would be
fine.

> +enum ColorMode     { CHANNEL, INTENSITY, NB_CLMODES };
> +enum DisplayScale  { SQRT, LOG, NB_SCALES };
> +
>  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 ChDisplayMode mode;    ///< channel display mode
> +    enum ColorMode clmode;      ///< display color scheme

nit: color_mode is less obfuscated

> +    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 +66,36 @@ 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(clmode), 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}, SQRT, NB_SCALES-1, FLAGS, "scale" },
> +    { "sqrt", "square root", 0, AV_OPT_TYPE_CONST, {.i64=SQRT}, 0, 0, FLAGS, "scale" },
> +    { "log", "logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=LOG}, 0, 0, FLAGS, "scale" },
> +    { "saturation", "color saturation multiplier", OFFSET(saturation), AV_OPT_TYPE_FLOAT, {.dbl = 1}, -10, 10, FLAGS },

Nit: using some empty line to separate unit elements would help
readability.

>      { 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 },z
> +    { 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 +113,12 @@ 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 +131,7 @@ 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 };

any special reason for the switch?

>  
>      /* set input audio formats */
>      formats = ff_make_format_list(sample_fmts);
> @@ -120,19 +161,23 @@ 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 +187,25 @@ 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 +231,10 @@ 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));
> +

nit+++: weird indent

[...]

I leave the rest of the code to you and divverent as long as I don't
think I can find the time to study the math behind it.
-- 
FFmpeg = Fanciful Fundamentalist Magic Ponderous Ecletic Geek


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