[FFmpeg-devel] [PATCH] lavfi: add tdiff filter

[Michael Niedermayer]

On Sat, Nov 22, 2014 at 11:44:29PM +0100, Stefano Sabatini wrote:
> TODO: bump minor
> ---
>  Changelog                |   1 +
>  doc/filters.texi         |   4 ++
>  libavfilter/Makefile     |   1 +
>  libavfilter/allfilters.c |   1 +
>  libavfilter/vf_tdiff.c   | 131 +++++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 138 insertions(+)
>  create mode 100644 libavfilter/vf_tdiff.c
> 
> diff --git a/Changelog b/Changelog
> index 5f38aea..41fdf18 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -15,6 +15,7 @@ version <next>:
>  - ffserver supports codec private options
>  - creating DASH compatible fragmented MP4, MPEG-DASH segmenting muxer
>  - WebP muxer with animated WebP support
> +- tdiff filter
>  
>  
>  version 2.4:
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 8c16c7a..9882da7 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -8394,6 +8394,10 @@ Useful for enlarging pixel art images without reducing sharpness.
>  @section swapuv
>  Swap U & V plane.
>  
> + at section tdiff
> +
> +Show difference between consecutive frames.
> +
>  @section telecine
>  
>  Apply telecine process to the video.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 2c56e38..3217c99 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -97,6 +97,7 @@ OBJS-$(CONFIG_BLACKDETECT_FILTER)            += vf_blackdetect.o
>  OBJS-$(CONFIG_BLACKFRAME_FILTER)             += vf_blackframe.o
>  OBJS-$(CONFIG_BLEND_FILTER)                  += vf_blend.o dualinput.o framesync.o
>  OBJS-$(CONFIG_BOXBLUR_FILTER)                += vf_boxblur.o

> +OBJS-$(CONFIG_CDIFF_FILTER)                  += vf_cdiff.o
[...]
> --- /dev/null
> +++ b/libavfilter/vf_tdiff.c

the name doesnt match


[...]
> +
> +static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
> +{
> +    TDiffContext *tdiff = inlink->dst->priv;
> +    AVFilterLink *outlink = inlink->dst->outputs[0];
> +
> +    if (tdiff->prev_frame) {
> +        int i, j;
> +
> +        AVFrame *diff = ff_get_video_buffer(outlink, outlink->w, outlink->h);
> +        av_frame_copy_props(frame, diff);
> +        if (!diff) {
> +            av_frame_free(&frame);
> +            return AVERROR(ENOMEM);
> +        }
> +
> +        /* compute difference with previous frame */
> +        for (i = 0; i < frame->height; i++) {
> +            uint8_t *pdiff = diff             ->data[0] + i * diff             ->linesize[0];
> +            uint8_t *pprev = tdiff->prev_frame->data[0] + i * tdiff->prev_frame->linesize[0];
> +            uint8_t *pthis = frame            ->data[0] + i * frame            ->linesize[0];
> +            for (j = 0; j < frame->width; j++) {
> +                *pdiff++ = abs(*pthis++ - *pprev++);

a difference that leaves the sign intact might be interresting too
like 128 + *pthis++ - *pprev++ or something like that


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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