[FFmpeg-devel] [PATCH 1/5] lavfi: remplace passthrough_filter_frame with a flag.

Michael Niedermayer michaelni at gmx.at
Sat May 11 17:17:48 CEST 2013


On Sat, May 11, 2013 at 04:50:36PM +0200, Stefano Sabatini wrote:
> On date Saturday 2013-05-11 15:19:06 +0200, Stefano Sabatini encoded:
> > On date Friday 2013-05-10 17:49:46 +0200, Clément Bœsch encoded:
> > > On Thu, May 09, 2013 at 01:53:23AM +0200, Clément Bœsch wrote:
> > > > With the introduction of AVFilterContext->is_disabled, we can simplify
> > > > the custom passthrough mode in filters.
> > > > ---
> > > >  libavfilter/af_apad.c    |  3 +--
> > > >  libavfilter/avfilter.c   |  6 +++---
> > > >  libavfilter/avfilter.h   | 19 ++++++-------------
> > > >  libavfilter/version.h    |  4 ++--
> > > >  libavfilter/vf_overlay.c | 25 ++++---------------------
> > > >  5 files changed, 16 insertions(+), 41 deletions(-)
> > > > 
> > > 
> > > New version attached.
> > > 
> > > -- 
> > > Clément B.
> > 
> > > From b0c4e23be426386a2fb6a1a974a5fff751c58e2d Mon Sep 17 00:00:00 2001
> > > From: =?UTF-8?q?Cl=C3=A9ment=20B=C5=93sch?= <ubitux at gmail.com>
> > > Date: Thu, 9 May 2013 01:04:41 +0200
> > > Subject: [PATCH 1/5] lavfi: replace passthrough_filter_frame with a flag.
> > > 
> > > With the introduction of AVFilterContext->is_disabled, we can simplify
> > > the custom passthrough mode in filters.
> > > 
> > > This commit is technically a compat break, but the timeline was
> > > introduced very recently.
> > > ---
> > >  libavfilter/af_apad.c              |  3 +--
> > >  libavfilter/af_volume.c            |  2 +-
> > >  libavfilter/avfilter.c             |  6 +++---
> > >  libavfilter/avfilter.h             | 26 ++++++++++++--------------
> > >  libavfilter/version.h              |  4 ++--
> > >  libavfilter/vf_boxblur.c           |  2 +-
> > >  libavfilter/vf_colorbalance.c      |  2 +-
> > >  libavfilter/vf_colorchannelmixer.c |  2 +-
> > >  libavfilter/vf_colormatrix.c       |  2 +-
> > >  libavfilter/vf_cropdetect.c        |  2 +-
> > >  libavfilter/vf_curves.c            |  2 +-
> > >  libavfilter/vf_delogo.c            |  2 +-
> > >  libavfilter/vf_drawbox.c           |  2 +-
> > >  libavfilter/vf_edgedetect.c        |  2 +-
> > >  libavfilter/vf_gradfun.c           |  2 +-
> > >  libavfilter/vf_histeq.c            |  2 +-
> > >  libavfilter/vf_hue.c               |  2 +-
> > >  libavfilter/vf_lut.c               |  2 +-
> > >  libavfilter/vf_noise.c             |  2 +-
> > >  libavfilter/vf_overlay.c           | 25 ++++---------------------
> > >  libavfilter/vf_pp.c                |  2 +-
> > >  libavfilter/vf_removelogo.c        |  2 +-
> > >  libavfilter/vf_smartblur.c         |  2 +-
> > >  libavfilter/vf_unsharp.c           |  2 +-
> > >  24 files changed, 41 insertions(+), 61 deletions(-)
> > > 
> > > diff --git a/libavfilter/af_apad.c b/libavfilter/af_apad.c
> > > index 265b76a..c863792 100644
> > > --- a/libavfilter/af_apad.c
> > > +++ b/libavfilter/af_apad.c
> > > @@ -131,7 +131,6 @@ static const AVFilterPad apad_inputs[] = {
> > >          .name         = "default",
> > >          .type         = AVMEDIA_TYPE_AUDIO,
> > >          .filter_frame = filter_frame,
> > > -        .passthrough_filter_frame = filter_frame,
> > >      },
> > >      { NULL },
> > >  };
> > > @@ -153,5 +152,5 @@ AVFilter avfilter_af_apad = {
> > >      .inputs        = apad_inputs,
> > >      .outputs       = apad_outputs,
> > >      .priv_class    = &apad_class,
> > > -    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE,
> > > +    .flags         = AVFILTER_FLAG_INTERNAL_TIMELINE,
> > >  };
> > > diff --git a/libavfilter/af_volume.c b/libavfilter/af_volume.c
> > > index b7aec8d..79054af 100644
> > > --- a/libavfilter/af_volume.c
> > > +++ b/libavfilter/af_volume.c
> > > @@ -296,5 +296,5 @@ AVFilter avfilter_af_volume = {
> > >      .init           = init,
> > >      .inputs         = avfilter_af_volume_inputs,
> > >      .outputs        = avfilter_af_volume_outputs,
> > > -    .flags          = AVFILTER_FLAG_SUPPORT_TIMELINE,
> > > +    .flags          = AVFILTER_FLAG_GENERIC_TIMELINE,
> > >  };
> > > diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
> > > index 3f94dde..6676a58 100644
> > > --- a/libavfilter/avfilter.c
> > > +++ b/libavfilter/avfilter.c
> > > @@ -995,9 +995,9 @@ static int ff_filter_frame_framed(AVFilterLink *link, AVFrame *frame)
> > >          dstctx->var_values[VAR_POS] = pos == -1 ? NAN : pos;
> > >  
> > >          dstctx->is_disabled = !av_expr_eval(dstctx->enable, dstctx->var_values, NULL);
> > > -        if (dstctx->is_disabled)
> > > -            filter_frame = dst->passthrough_filter_frame ? dst->passthrough_filter_frame
> > > -                                                         : default_filter_frame;
> > > +        if (dstctx->is_disabled &&
> > > +            (dstctx->filter->flags & AVFILTER_FLAG_GENERIC_TIMELINE))
> > > +            filter_frame = default_filter_frame;
> > >      }
> > >      ret = filter_frame(link, out);
> > >      link->frame_count++;
> > > diff --git a/libavfilter/avfilter.h b/libavfilter/avfilter.h
> > > index a79c86c..8695a36 100644
> > > --- a/libavfilter/avfilter.h
> > > +++ b/libavfilter/avfilter.h
> > > @@ -385,19 +385,6 @@ struct AVFilterPad {
> > >      int needs_fifo;
> > >  
> > >      int needs_writable;
> > > -
> > > -    /**
> > > -     * Passthrough filtering callback.
> > > -     *
> > > -     * If a filter supports timeline editing (in case
> > > -     * AVFILTER_FLAG_SUPPORT_TIMELINE is enabled) then it can implement a
> > > -     * custom passthrough callback to update its local context (for example to
> > > -     * keep a frame reference, or simply send the filter to a custom outlink).
> > > -     * The filter must not do any change to the frame in this callback.
> > > -     *
> > > -     * Input pads only.
> > > -     */
> > > -    int (*passthrough_filter_frame)(AVFilterLink *link, AVFrame *frame);
> > >  };
> > >  #endif
> > >  
> > > @@ -446,7 +433,18 @@ enum AVMediaType avfilter_pad_get_type(const AVFilterPad *pads, int pad_idx);
> > >   * to enable or disable a filter in the timeline. Filters supporting this
> > >   * option have this flag set.
> > >   */
> > > -#define AVFILTER_FLAG_SUPPORT_TIMELINE      (1 << 16)
> > 
> > > +#define AVFILTER_FLAG_GENERIC_TIMELINE      (1 << 16)
> > > +/**
> > 
> > > + * Same as AVFILTER_FLAG_GENERIC_TIMELINE, except that the filter will have its
> > > + * inpad->filter_frame() callback(s) naturally called (and will use
> > > + * AVFilterContext->is_disabled internally).
> > 
> > "naturally" ... "internally" ... "generic" are pretty vague terms and
> > the result is confusing. Can you specify the meaning of "generic" and
> > "internal" in a more precise way (and possibly to find some less vague
> > terms may help).
> 
> This is my attempt. I just replaced "generic" with "default" since
> default_filter_frame() is used, "internal" may be replaced by "auto"
> or "automatic" but I'm not really satisfied with that as well, since
> the user may guess that this is "automatically" executed by the
> framework (rather than by the filter code).
> 
> Other alternatives to "generic":
> external framework default
> 
> Other alternatives to "internal":
> callback
> 
> 
> /**
>  * Some filters support a generic "enable" expression option that can be used
>  * to enable or disable a filter in the timeline. Filters supporting this
>  * option have this flag set. When the enable expression is false, the
>  * default no-op filter_frame() function is called in place of the
>  * filter_frame() callback defined on each input pad, thus the frame
>  * is passed unchanged to the next filters.
>  */
> #define AVFILTER_FLAG_SUPPORT_TIMELINE_DEFAULT   (1 << 16)
> 
> /**
>  * Same as AVFILTER_FLAG_SUPPORT_TIMELINE_DEFAULT, except that the filter will have its
>  * filter_frame() callback(s) called as usual even when the enable
>  * expression is false. The filter will disable filtering
>  * within the filter_frame() callback(s) itself, for example executing
>  * code depending on the AVFilterContext->is_disabled value.
>  */
> #define AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL     (1 << 17)

why do you need 2 flags ?

if enabled filter_frame() is called
if disabled passthrough_filter_frame() is called

if a filter wants both to go to filter_frame, it can just have both
function pointers point to filter_frame

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Rewriting code that is poorly written but fully understood is good.
Rewriting code that one doesnt understand is a sign that one is less smart
then the original author, trying to rewrite it will not make it better.
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