[FFmpeg-devel] [PATCH] Add crop filter

[Michael Niedermayer]

On Wed, Oct 07, 2009 at 11:50:19PM +0200, Stefano Sabatini wrote:
> On date Tuesday 2009-10-06 15:01:32 +0200, Michael Niedermayer encoded:
> > On Tue, Oct 06, 2009 at 12:58:41AM +0200, Stefano Sabatini wrote:
[...]
> +static int norm_offset(int x, int max)
> +{
> +    if (x < 0)
> +        x = max + x;
> +    return av_clip(x, 0, max-1);
> +}

using max before its validated and cliped like that does not work
anyway, iam not sure all that cliping is a good idea, i would just
tell the user that his parameters are partly beyond the input image
dimensions and that she should fix that.


[...]
> +static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
> +{
> +    CropContext *crop = link->dst->priv;
> +    AVFilterPicRef *ref2 = avfilter_ref_pic(picref, ~0);
> +    int i;
> +
> +    ref2->w        = crop->w;
> +    ref2->h        = crop->h;
> +    ref2->data[0] += crop->y * ref2->linesize[0];
> +    ref2->data[0] += crop->x * crop->bpp;
> +
> +    for (i = 1; i < 4; i ++) {
> +        if (ref2->data[i]) {
> +            ref2->data[i] += (crop->y >> crop->vsub) * ref2->linesize[i];
> +            ref2->data[i] +=  crop->x >> crop->hsub;
> +        }
> +    }

fails for paletted formats


[...]

also it may be usefull if we had a filter that generated random images in
random pixel formats and random width/height for testing ...

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

Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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