[FFmpeg-devel] [PATCH 1/2] lavfi/ebur128: add metadata injection.

[Clément Bœsch]

On Sun, Feb 24, 2013 at 11:42:39PM +0100, Stefano Sabatini wrote:
> On date Friday 2013-02-22 00:22:39 +0100, Clément Bœsch encoded:
> > ---
> >  doc/filters.texi        |  5 +++++
> >  libavfilter/f_ebur128.c | 29 +++++++++++++++++++++++++++++
> >  2 files changed, 34 insertions(+)
> > 
> > diff --git a/doc/filters.texi b/doc/filters.texi
> > index a93b433..9fbda34 100644
> > --- a/doc/filters.texi
> > +++ b/doc/filters.texi
> > @@ -6252,6 +6252,11 @@ Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
> >  @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
> >  other integer value between this range is allowed.
> >  
> > + at item metadata
> 
> > +Set metadata injection. Default is @code{0}. If set to @code{1}, the audio will
> > +be divided into 100ms frames, each of them out of the filter containing various
> > +loudness information.
> 
> Set metadata injection. If set to @code{1}, the audio will be segment
> the input into 100ms output frames, each of them containing various
> loudness information in metadata.
> 
> Default is @code{0}.
> ...
> 

Reworded.

> Also you may specify the exact name of the injected metadata keys.
> 

Added.

> > +
> >  @end table
> >  
> >  Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
> > diff --git a/libavfilter/f_ebur128.c b/libavfilter/f_ebur128.c
> > index 66cc133..1d0513d 100644
> > --- a/libavfilter/f_ebur128.c
> > +++ b/libavfilter/f_ebur128.c
> > @@ -33,6 +33,7 @@
> >  #include "libavutil/avassert.h"
> >  #include "libavutil/avstring.h"
> >  #include "libavutil/channel_layout.h"
> > +#include "libavutil/dict.h"
> >  #include "libavutil/xga_font_data.h"
> >  #include "libavutil/opt.h"
> >  #include "libavutil/timestamp.h"
> > @@ -90,6 +91,7 @@ struct rect { int x, y, w, h; };
> >  
> >  typedef struct {
> >      const AVClass *class;           ///< AVClass context for log and options purpose
> > +    int metadata;                   ///< whether or not to inject loudness results in buffers
> >  
> >      /* video  */
> >      int do_video;                   ///< 1 if video output enabled, 0 otherwise
> > @@ -133,6 +135,7 @@ static const AVOption ebur128_options[] = {
> >      { "video", "set video output", OFFSET(do_video), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, V|F },
> >      { "size",  "set video size",   OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "640x480"}, 0, 0, V|F },
> >      { "meter", "set scale meter (+9 to +18)",  OFFSET(meter), AV_OPT_TYPE_INT, {.i64 = 9}, 9, 18, V|F },
> > +    { "metadata", "inject metadata in the filtergraph", OFFSET(metadata), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, V|F },
> 
> flags = A|F?
> 

Right, fixed.

> >      { NULL },
> >  };
> >  
> > @@ -311,6 +314,20 @@ static int config_video_output(AVFilterLink *outlink)
> >      return 0;
> >  }
> >  
> > +static int config_audio_input(AVFilterLink *inlink)
> > +{
> > +    AVFilterContext *ctx = inlink->dst;
> > +    EBUR128Context *ebur128 = ctx->priv;
> > +
> 
> > +    /* force 100ms framing in case of metadata injection: the frames must have
> > +     * a granularity of the window overlap to be accurately exploited */
> > +    if (ebur128->metadata)
> > +        inlink->min_samples =
> > +        inlink->max_samples =
> > +        inlink->partial_buf_size = inlink->sample_rate / 10;
> 
> How do you get 100ms from this relation?
> 

  R samples for 1 second
→ R/10 samples for 1/10 second
→ R/10 samples for 100 ms

-- 
Clément B.
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