[FFmpeg-devel] [PATCH] lavfi/select: add support to branch option

[Nicolas George]

Le primidi 21 germinal, an CCXXI, Stefano Sabatini a écrit :
> Updated, with some non-trivial fixes raised by splice.
> -- 
> FFmpeg = Formidable and Free Mythic Picky Exploitable Gymnast

> >From e2985e730f1483fa55521b32b4ecc8c2926f56ae Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab at gmail.com>
> Date: Mon, 8 Apr 2013 12:58:56 +0200
> Subject: [PATCH] lavfi/select: add support to branch option
> 
> TODO: bump micro, add docs
> ---
>  libavfilter/f_select.c |   33 +++++++++++++++++++++++++++++----
>  1 file changed, 29 insertions(+), 4 deletions(-)

No docs?

> 
> diff --git a/libavfilter/f_select.c b/libavfilter/f_select.c
> index 351b7f8..adae0be 100644
> --- a/libavfilter/f_select.c
> +++ b/libavfilter/f_select.c
> @@ -135,7 +135,8 @@ typedef struct {
>      double prev_mafd;               ///< previous MAFD                             (scene detect only)
>  #endif
>      AVFrame *prev_picref; ///< previous frame                            (scene detect only)
> -    double select;
> +    double select, select_branch;
> +    int branch;
>  } SelectContext;
>  
>  #define OFFSET(x) offsetof(SelectContext, x)
> @@ -143,9 +144,13 @@ typedef struct {
>  static const AVOption options[] = {
>      { "expr", "set selection expression", OFFSET(expr_str), AV_OPT_TYPE_STRING, {.str = "1"}, 0, 0, FLAGS },
>      { "e",    "set selection expression", OFFSET(expr_str), AV_OPT_TYPE_STRING, {.str = "1"}, 0, 0, FLAGS },
> +    { "branch", "enable alternative output", OFFSET(branch), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },
> +    { "b",      "enable alternative output", OFFSET(branch), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },
>      {NULL},
>  };
>  
> +static int request_frame(AVFilterLink *outlink);
> +
>  static av_cold int init(AVFilterContext *ctx, const char *args, const AVClass *class)
>  {
>      SelectContext *select = ctx->priv;
> @@ -158,6 +163,17 @@ static av_cold int init(AVFilterContext *ctx, const char *args, const AVClass *c
>      }
>      select->do_scene_detect = !!strstr(select->expr_str, "scene");
>  
> +    if (select->branch) {
> +        AVFilterPad pad = { 0 };
> +
> +        pad.type = ctx->filter->inputs[0].type;
> +        pad.name = av_strdup("branch");
> +        pad.request_frame = request_frame;
> +        if (!pad.name)
> +            return AVERROR(ENOMEM);
> +        ff_insert_outpad(ctx, 1, &pad);
> +    }
> +
>      return 0;
>  }
>  
> @@ -337,8 +353,12 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
>      SelectContext *select = inlink->dst->priv;
>  
>      select->select = select_frame(inlink->dst, frame);
> -    if (select->select)
> +    if (select->select) {
>          return ff_filter_frame(inlink->dst->outputs[0], frame);
> +    } else if (select->branch) {
> +        select->select_branch = 1;
> +        return ff_filter_frame(inlink->dst->outputs[1], frame);
> +    }

If I understand correctly, that means: if the expression returns true, send
to the normal output, if the expression returns 0, [-discard-] {+send to the
"branch" output+}. Is that it?

That looks a bit ad-hoc. What about: outputs=n, and send to output number
floor(expr)?

>  
>      av_frame_free(&frame);
>      return 0;
> @@ -349,13 +369,15 @@ static int request_frame(AVFilterLink *outlink)
>      AVFilterContext *ctx = outlink->src;
>      SelectContext *select = ctx->priv;
>      AVFilterLink *inlink = outlink->src->inputs[0];
> -    select->select = 0;
> +    int branch = outlink == ctx->outputs[1];
> +
> +    select->select = select->select_branch = 0;
>  
>      do {
>          int ret = ff_request_frame(inlink);
>          if (ret < 0)
>              return ret;
> -    } while (!select->select);
> +    } while (!select->select || (branch && !select->select_branch));
>  
>      return 0;
>  }
> @@ -367,6 +389,9 @@ static av_cold void uninit(AVFilterContext *ctx)
>      av_expr_free(select->expr);
>      select->expr = NULL;
>  
> +    if (select->branch)
> +        av_freep(&ctx->output_pads[1].name);
> +
>  #if CONFIG_AVCODEC
>      if (select->do_scene_detect) {
>          av_frame_free(&select->prev_picref);

Regards,

-- 
  Nicolas George
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