[FFmpeg-devel] [PATCH] lavfi/showspectrum: add sliding mode.

[Stefano Sabatini]

On date Sunday 2012-10-21 21:02:18 +0200, Clément Bœsch encoded:
> ---
>  doc/filters.texi               |  3 +++
>  libavfilter/avf_showspectrum.c | 17 +++++++++++++----
>  2 files changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 916655a..72bf0a1 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -4675,6 +4675,9 @@ spectrum.
>  
>  The filter accepts the following named parameters:
>  @table @option
> + at item sliding
> +Specify if the spectrum should slide along the window. Default value is
> + at code{0}.

I prefer "slide" for consistency with other similar options
(e.g. "stitch"), also shorter.

>  @item size, s
>  Specify the video size for the output. Default value is @code{640x480}.
>  @end table
> diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
> index 641c27f..55bf260 100644
> --- a/libavfilter/avf_showspectrum.c
> +++ b/libavfilter/avf_showspectrum.c
> @@ -37,6 +37,7 @@ typedef struct {
>      int w, h;
>      AVFilterBufferRef *outpicref;
>      int req_fullfilled;
> +    int sliding;                ///< 1 if sliding mode, 0 otherwise
>      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)
> @@ -52,6 +53,7 @@ typedef struct {
>  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 },
> +    { "sliding", "set sliding mode", OFFSET(sliding), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },
>      { NULL },
>  };
>  
> @@ -247,16 +249,23 @@ static int plot_spectrum_column(AVFilterLink *inlink, AVFilterBufferRef *insampl
>  
>          for (y = 0; y < outlink->h; y++) {
>              // FIXME: bin[0] contains first and last bins
> -            const int pos = showspectrum->xpos * 3 + (outlink->h - y - 1) * outpicref->linesize[0];
> +            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) {
> +                p += showspectrum->xpos * 3;
> +            } else {
> +                memmove(p, p + 3, (outlink->w - 1) * 3);
> +                p += (outlink->w - 1) * 3;
> +            }

Nit+: avoid negative logic when avoidable

> +
>              a = FFMIN(a, 255);
>              b = FFMIN(b, 255);
> -            outpicref->data[0][pos]   = a;
> -            outpicref->data[0][pos+1] = b;
> -            outpicref->data[0][pos+2] = (a + b) / 2;
> +            p[0] = a;
> +            p[1] = b;
> +            p[2] = (a + b) / 2;
>          }
>          outpicref->pts = insamples->pts +
>              av_rescale_q(showspectrum->consumed,

LGTM, also bump micro so people/programs know when the feature was
added, thanks.
-- 
FFmpeg = Forgiving and Freak Meaningless Philosofic Ecletic Game