[FFmpeg-devel] [PATCH 3/5] libavfilter/ebur128: add gaugetype option

[Paul B Mahol]

On 10/7/18, Daniel Molkentin <daniel at molkentin.de> wrote:
> Allow to show short term instead of momentary. Useful for monitoring
> whilst live mixing.
>
> Signed-off-by: Daniel Molkentin <daniel at molkentin.de>
> Signed-off-by: Conrad Zelck <c.zelck at imail.de>
> ---
>  doc/filters.texi        |  8 +++++++-
>  libavfilter/f_ebur128.c | 18 ++++++++++++++++--
>  2 files changed, 23 insertions(+), 3 deletions(-)

Please use AV_OPT_TYPE_INT in combination of AV_OPT_TYPE_CONST, like
all filters do.

Using strcmp is fragile and ugly.

>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index bd5154f9be..40d9006075 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -19279,7 +19279,8 @@ time graph to observe the loudness evolution. The
> graphic contains the logged
>  message mentioned above, so it is not printed anymore when this option is
> set,
>  unless the verbose logging is set. The main graphing area contains the
>  short-term loudness (3 seconds of analysis), and the gauge on the right is
> for
> -the momentary loudness (400 milliseconds).
> +the momentary loudness (400 milliseconds), but can optionally be configured
> +to instead display short-term loundness (see @var{gaugetype}).
>
>  More information about the Loudness Recommendation EBU R128 on
>  @url{http://tech.ebu.ch/loudness}.
> @@ -19362,6 +19363,11 @@ Set a specific target level (in LUFS) used as
> relative zero in the visualization
>  This parameter is optional and has a default value of -23LUFS as specified
>  by EBU R128. However, material published online may prefer a level of
> -16LUFS
>  (e.g. for use with podcasts or video platforms).
> +
> + at item gaugetype
> +Set the value displayed by the gauge. Valid values are m (momentary) and s
> (short-term).
> +By default the momentary value will be used, but in certain scenarios it
> may be more useful
> +to observe the short term value instead (e.g. live mixing).
>  @end table
>
>  @subsection Examples
> diff --git a/libavfilter/f_ebur128.c b/libavfilter/f_ebur128.c
> index 89bfcb0b3e..66d4c4dec7 100644
> --- a/libavfilter/f_ebur128.c
> +++ b/libavfilter/f_ebur128.c
> @@ -143,6 +143,7 @@ typedef struct EBUR128Context {
>      int dual_mono;                  ///< whether or not to treat single
> channel input files as dual-mono
>      double pan_law;                 ///< pan law value used to calculate
> dual-mono measurements
>      int target;                     ///< target level in LUFS used to set
> relative zero LU in visualization
> +    char *gauge_type;               ///< whether gauge shows momentary or
> short
>  } EBUR128Context;
>
>  enum {
> @@ -170,6 +171,7 @@ static const AVOption ebur128_options[] = {
>      { "dualmono", "treat mono input files as dual-mono", OFFSET(dual_mono),
> AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, A|F },
>      { "panlaw", "set a specific pan law for dual-mono files",
> OFFSET(pan_law), AV_OPT_TYPE_DOUBLE, {.dbl = -3.01029995663978}, -10.0, 0.0,
> A|F },
>      { "target", "set a specific target level in LUFS (-23 to 0)",
> OFFSET(target), AV_OPT_TYPE_INT, {.i64 = -23}, -23, 0, V|F },
> +    { "gaugetype", "sets whether the gauge shows momentrary (m) or
> short-term (s)", OFFSET(gauge_type), AV_OPT_TYPE_STRING, {.str = "m"},
> CHAR_MIN, CHAR_MAX, V|F },
>      { NULL },
>  };
>
> @@ -517,6 +519,11 @@ static av_cold int init(AVFilterContext *ctx)
>          return ret;
>      }
>
> +    if (strcmp(ebur128->gauge_type, "m") && strcmp(ebur128->gauge_type,
> "s")) {
> +        av_log(ctx, AV_LOG_ERROR, "Value for gaugetype can only be 'm' or
> 's'.\n");
> +        return AVERROR(EINVAL);
> +    }
> +
>      /* summary */
>      av_log(ctx, AV_LOG_VERBOSE, "EBU +%d scale\n", ebur128->meter);
>
> @@ -741,9 +748,16 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *insamples)
>              if (ebur128->do_video) {
>                  int x, y, ret;
>                  uint8_t *p;
> +                double gauge_value;
> +
> +                if (!strcmp(ebur128->gauge_type, "m")) {
> +                    gauge_value = loudness_400 - ebur128->target;
> +                } else {
> +                    gauge_value = loudness_3000 - ebur128->target;
> +                }
>
>                  const int y_loudness_lu_graph = lu_to_y(ebur128,
> loudness_3000 - ebur128->target);
> -                const int y_loudness_lu_gauge = lu_to_y(ebur128,
> loudness_400  - ebur128->target);
> +                const int y_loudness_lu_gauge = lu_to_y(ebur128,
> gauge_value);
>
>                  /* draw the graph using the short-term loudness */
>                  p = pic->data[0] + ebur128->graph.y*pic->linesize[0] +
> ebur128->graph.x*3;
> @@ -755,7 +769,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *insamples)
>                      p += pic->linesize[0];
>                  }
>
> -                /* draw the gauge using the momentary loudness */
> +                /* draw the gauge using either momentary or short-term
> loudness */
>                  p = pic->data[0] + ebur128->gauge.y*pic->linesize[0] +
> ebur128->gauge.x*3;
>                  for (y = 0; y < ebur128->gauge.h; y++) {
>                      const uint8_t *c = get_graph_color(ebur128,
> y_loudness_lu_gauge, y);
> --
> 2.17.1
>
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