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

Paul B Mahol onemda at gmail.com
Fri Feb 1 17:19:35 CET 2013


On 2/1/13, Rudolf Polzer <divverent at xonotic.org> wrote:
> The showspectrum filter gets multiple channel (any count) support. Most
> ideas here are from durandal_1707.
>
> Screenshots (temporary URL):
> http://rm.sudo.rm-f.org/~xonotic/temp/ffmpeg-showspectrum/screenshots/
>
> New options:
>
> - combined=1: old ffplay-like combined view of all channels
> - intensity=1: sox-like intensity spectrum
> - logscale=1: sox-like logarithmic scale
> - saturation=<float>: saturation modifier

If there are no objections i will commit this but with different
logic in options and updated doxy:

mode: combined, separate
???: intensity
scale: logarithmic, square root
saturation is same as before

Feel free to propose something better.

>
> Signed-off-by: Rudolf Polzer <divverent at xonotic.org>
> ---
>  Changelog                      |   1 +
>  doc/filters.texi               |   4 +
>  libavfilter/avf_showspectrum.c | 215
> ++++++++++++++++++++++++++++++++++-------
>  3 files changed, 186 insertions(+), 34 deletions(-)
>
> diff --git a/Changelog b/Changelog
> index c509c4c..8d9befc 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -10,6 +10,7 @@ version <next>:
>  - EVRC decoder
>  - audio fade filter
>  - filtering audio with unknown channel layout
> +- showspectrum now with separate channel display and multichannel
> (configurable)
>
>
>  version 1.1:
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 21e2cff..73674cb 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -5709,6 +5709,10 @@ Specify the video size for the output. Default value
> is @code{640x480}.
>  @item slide
>  Specify if the spectrum should slide along the window. Default value is
>  @code{0}.
> + at item compat
> +Specify if the old mode, where up to 2 channels are displayed in same row,
> +should be used. Default value is
> + at code{0}.
>  @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 977fca9..41f7a8e 100644
> --- a/libavfilter/avf_showspectrum.c
> +++ b/libavfilter/avf_showspectrum.c
> @@ -37,14 +37,20 @@ typedef struct {
>      int w, h;
>      AVFilterBufferRef *outpicref;
>      int req_fullfilled;
> +    int nb_display_channels;
>      int sliding;                ///< 1 if sliding mode, 0 otherwise
> +    int combined;               ///< use combined channel display mode
> +    int intensity_colors;       ///< use intensity-based coloring
> +    int logscale;               ///< use logarithmic 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 +60,30 @@ static const AVOption showspectrum_options[] = {
>      { "size", "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str =
> "640x480"}, 0, 0, FLAGS },
>      { "s",    "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str =
> "640x480"}, 0, 0, FLAGS },
>      { "slide", "set sliding mode", OFFSET(sliding), AV_OPT_TYPE_INT, {.i64
> = 0}, 0, 1, FLAGS },
> +    { "combined", "set combined mode", OFFSET(combined), AV_OPT_TYPE_INT,
> {.i64 = 0}, 0, 1, FLAGS },
> +    { "intensity", "set intensity based coloring",
> OFFSET(intensity_colors), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },
> +    { "logscale", "set logarithmic scale", OFFSET(logscale),
> AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },
> +    { "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 +101,12 @@ 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 +119,7 @@ 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 +149,22 @@ 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->combined ? outlink->h : outlink->h /
> inlink->channels;
> +
>      /* 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 +174,25 @@ 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 +218,10 @@ 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 +262,160 @@ 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->combined ? outlink->h : outlink->h /
> showspectrum->nb_display_channels;
> +
>          /* 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;
> +            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 */
> +            if (showspectrum->combined) {
> +                // reduce range by channel count
> +                yf = 256.0f / showspectrum->nb_display_channels;
> +                if (showspectrum->intensity_colors) {
> +                    uf = yf;
> +                    vf = yf;
> +                } else {
> +                    /* adjust saturation for mixed UV coloring */
> +                    /* this factor is correct for infinite channels, an
> approximation otherwise */
> +                    uf = yf * M_PI;
> +                    vf = yf * M_PI;
> +                }
>              } else {
> -                p += showspectrum->xpos * 3;
> +                // full range
> +                yf = 256.0f;
> +                uf = 256.0f;
> +                vf = 256.0f;
> +            }
> +
> +            /* decide channel colors */
> +            if (!showspectrum->intensity_colors) {
> +                if (showspectrum->nb_display_channels >= 2) {
> +                    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->combined ? y : ch * h + y;
> +                float *out = &showspectrum->combine_buffer[3 * row];
> +
> +                /* get magnitude */
> +                float a = w * MAGNITUDE(y, ch);
> +
> +                /* apply scale */
> +                if (showspectrum->logscale)
> +                    a = 1 - log(FFMAX(FFMIN(1, a), 1e-6)) / log(1e-6); //
> zero = -120dBFS
> +                else
> +                    a = sqrt(a);
> +
> +                if (showspectrum->intensity_colors) {
> +                    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;
> +                }
>              }
> +        }
>
> -            a = FFMIN(a, 255);
> -            b = FFMIN(b, 255);
> -            p[0] = a;
> -            p[1] = b;
> -            p[2] = (a + b) / 2;
> +        /* 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 },
> --
> 1.8.1.1
>
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