[FFmpeg-devel] [PATCH] lavfi/alphaextract: switch to filter_frame API

Clément Bœsch ubitux at gmail.com
Fri Dec 7 02:49:37 CET 2012


On Fri, Dec 07, 2012 at 12:06:08AM +0100, Stefano Sabatini wrote:
> ---
>  libavfilter/vf_alphaextract.c |   26 ++++++++++++++++----------
>  1 file changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/libavfilter/vf_alphaextract.c b/libavfilter/vf_alphaextract.c
> index 35402f6..766cc8c 100644
> --- a/libavfilter/vf_alphaextract.c
> +++ b/libavfilter/vf_alphaextract.c
> @@ -29,6 +29,7 @@
>  #include "avfilter.h"
>  #include "drawutils.h"
>  #include "formats.h"
> +#include "internal.h"
>  #include "video.h"
>  
>  enum { Y, U, V, A };
> @@ -59,16 +60,21 @@ static int config_input(AVFilterLink *inlink)
>      return 0;
>  }
>  
> -static int draw_slice(AVFilterLink *inlink, int y0, int h, int slice_dir)
> +static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *cur_buf)
>  {
>      AlphaExtractContext *extract = inlink->dst->priv;
> -    AVFilterBufferRef *cur_buf = inlink->cur_buf;
> -    AVFilterBufferRef *out_buf = inlink->dst->outputs[0]->out_buf;
> +    AVFilterLink *outlink = inlink->dst->outputs[0];
> +    AVFilterBufferRef *out_buf =
> +        ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
> +
> +    if (!out_buf)
> +        return AVERROR(ENOMEM);

I think you need to unref cur_buf this time.

> +    avfilter_copy_buffer_ref_props(out_buf, cur_buf);
>  
>      if (extract->is_packed_rgb) {
>          int x, y;
>          uint8_t *pin, *pout;
> -        for (y = y0; y < (y0 + h); y++) {
> +        for (y = 0; y < inlink->h; y++) {
>              pin = cur_buf->data[0] + y * cur_buf->linesize[0] + extract->rgba_map[A];
>              pout = out_buf->data[0] + y * out_buf->linesize[0];
>              for (x = 0; x < out_buf->video->w; x++) {
> @@ -79,19 +85,19 @@ static int draw_slice(AVFilterLink *inlink, int y0, int h, int slice_dir)
>          }
>      } else if (cur_buf->linesize[A] == out_buf->linesize[Y]) {
>          const int linesize = cur_buf->linesize[A];
> -        memcpy(out_buf->data[Y] + y0 * linesize,
> -               cur_buf->data[A] + y0 * linesize,
> -               linesize * h);
> +        memcpy(out_buf->data[Y], cur_buf->data[A], linesize * inlink->h);

This code looks better than the previous one. Though there is something
that bugs me, but that's because I don't know the internals enough: can't
the padding between width and linesize be uninitialized data? It will work
but valgrind might complain. Also, second concern, and it's also somehow
unrelated to this patch but: if that padding is very large (like after a
crop filter), won't this be slower than a loop?

>      } else {
>          const int linesize = FFMIN(out_buf->linesize[Y], cur_buf->linesize[A]);
>          int y;
> -        for (y = y0; y < (y0 + h); y++) {
> +        for (y = 0; y < inlink->h; y++) {
>              memcpy(out_buf->data[Y] + y * out_buf->linesize[Y],
>                     cur_buf->data[A] + y * cur_buf->linesize[A],
>                     linesize);

...looks like it should be merged with this better code.

>          }
>      }
> -    return ff_draw_slice(inlink->dst->outputs[0], y0, h, slice_dir);
> +
> +    avfilter_unref_bufferp(&cur_buf);

avfilter_unref_buffer(cur_buf) should be enough but well.

> +    return ff_filter_frame(outlink, out_buf);
>  }
>  
>  static const AVFilterPad alphaextract_inputs[] = {
> @@ -99,7 +105,7 @@ static const AVFilterPad alphaextract_inputs[] = {
>          .name         = "default",
>          .type         = AVMEDIA_TYPE_VIDEO,
>          .config_props = config_input,
> -        .draw_slice   = draw_slice,
> +        .filter_frame = filter_frame,
>          .min_perms    = AV_PERM_READ,
>      },
>      { NULL }

LGTM otherwise, thanks!

-- 
Clément B.
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