[FFmpeg-devel] [PATCH] Add vf_scale.c filter

[Michael Niedermayer]

On Tue, Mar 03, 2009 at 01:13:35AM +0100, Stefano Sabatini wrote:
> On date Friday 2009-02-27 16:44:46 +0100, Michael Niedermayer encoded:
> > On Fri, Feb 27, 2009 at 12:56:08PM +0100, Stefano Sabatini wrote:
> > > Hi all, 
> > > as in subject.
> > 
> > first quick question
> > does
> > crop, expand and slices work? (a single pix_fmt working is enough)
> 
> crop seems to work, but it doesn't work like in mplayer, syntax is
> x:y:w:h, also default is not centered, this should be changed I
> think.
> 
> slices seem to work fine after the Vitor's patch, expand is currently
> not implemented and the padding implementation in ffmpeg.c is
> currently half-broken, 

> so I think we need an expand filter as well.

i agree, we need a working zero memcpy() expand to test other filters.


>  
> > i mean can i take a 320x200 movie crop a 100x100 area out scale
> > that to 200x200 and add a border to make 300x200 _without_ any
> > memcpy() ?
> > just a simple test to make sure no serious bugs are in there
> > 
> > second question are there any features mplayers vf_scale has that lavfi
> > does not?
> 
> Yes, and it shouldn't be hard to implement them (e.g. luma/chroma
> gaussian blur, params etc.), that should be done before or after the
> integration?

before :)


> 
> > also we need support for interlaced scaling though this is better done
> > through some generic wraper filter
> > that is a filter that as arguments has another filtername and its arguments
> > and that then creates 2 such filters and filters the odd and even
> > lines seperately with them
> 
> OK, si there something similar in MPlayer on which to base this?

no, it should be quite trivial though ...



> 
> > [...]
> > 
> > > +        char sws_flags[256];
> > > +        int i = 0;
> > > +        p = strchr(sws_opts, '=');
> > > +        p++;
> > > +        while (*p && *p != ':' && i < sizeof(sws_flags) - 1)
> > > +            sws_flags[i++] = *p++;
> > > +        sws_flags[i] = 0;
> > 
> > sscanf("sws_flags=%255[^:]")
>  >
> > [...]
> > > +    av_reduce(&out->outpic->pixel_aspect.num, &out->outpic->pixel_aspect.den,
> > > +               out->outpic->pixel_aspect.num,  out->outpic->pixel_aspect.den,
> > > +         FFMAX(out->outpic->pixel_aspect.num,  out->outpic->pixel_aspect.den));
> > 
> > you want to use av_gcd() here i think
>  
> Check the attached patches (I'll apply them to soc if are OK).
> 
> > > +
> > > +    avfilter_start_frame(out, avfilter_ref_pic(out->outpic, ~0));
> > > +
> > > +    scale->sliceY = 0;
> > > +}
> > > +
> > > +static void draw_slice(AVFilterLink *link, int y, int h)
> > > +{
> > > +    ScaleContext *scale = link->dst->priv;
> > > +    int outH;
> > > +    int vsub, hsub;
> > > +    uint8_t *data[4];
> > > +
> > > +    avcodec_get_chroma_sub_sample(link->format, &hsub, &vsub);
> > > +
> > > +    data[0] = link->cur_pic->data[0] + y * link->cur_pic->linesize[0];
> > > +    data[3] = link->cur_pic->data[3] + y * link->cur_pic->linesize[3];
> > > +
> > > +    if (link->cur_pic->data[2]) {
> > > +        data[1] = link->cur_pic->data[1] + (y>>vsub)*link->cur_pic->linesize[1];
> > > +        data[2] = link->cur_pic->data[2] + (y>>vsub)*link->cur_pic->linesize[2];
> > > +    } else {
> > > +        // Probably a paletted format
> > > +        data[1] = link->cur_pic->data[1];
> > > +        data[2] = link->cur_pic->data[2];
> > > +    }
> > 
> > looks like its missing some special case for a palette
> 
> I need to know more about paletted formats...

usePal() formats (see the marco in swscale which that are)
have data[1] set to a 256 entry 4 byte per entry table 
above slice code should not play with that but just pass it through

and patches for soc look IMHO

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

If you really think that XML is the answer, then you definitly missunderstood
the question -- Attila Kinali
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