[FFmpeg-user] Strange results with delogo filter, maybe a bug

[sxe]

Hi Moitz,
any tips how to procede with this issue if i get no feedback soon?
Should i report this as a bug somewhere? Or is the user mailing list
the right place for a developer to pick it up?

Thanks,
Andy

On Tue, Aug 26, 2014 at 2:11 PM, Moritz Barsnick <barsnick at gmx.net> wrote:
> Hi James,
>
> On Tue, Aug 26, 2014 at 12:43:53 +0200, James Darnley wrote:
>> Did you try adding yuvj420p?  What about the other yuvj* "colourspaces"?
>
> I didn't try, but I reckoned that if the target format PNG implies
> non-YUV colorspaces (does it?) and RGB24 is quite common (is it?),
> there would be a conversion from yuvj420p -> rbg24 somewhere along the
> way in the chain anyway.
>
> But indeed there's no obvious reason for me to omit those.
>
>> I'm not familiar the filter at all but using interleaved RGB data could
>> be very wrong if it treats neighbouring samples as separate pixels.
>
> That's why I noted that I have no idea what I am doing. ;-)
>
> Indeed, now I tried adding those AV_PIX_FMTs to the delogo source as
> well. The "scaler" is now auto-inserted behind delogo with this log:
>
> [auto-inserted scaler 0 @ 0xb3db7e0] w:854 h:480 fmt:yuvj420p sar:1/1 -> w:854 h:480 fmt:rgb24 sar:1/1 flags:0x4
>
> Using the delogo filter (with w=0:h=0), the result of these conversions
> is still identical whether the filter uses yuvj420p or rgb24.
>
> By the way, trying this hint with the original unhacked filter:
>
> https://trac.ffmpeg.org/ticket/225#comment:9
>
>> A way to skirt this "problem", which I don't know if it is one
>> actually, is to use the option
>>
>>   -vf mp=eq=0:0
>>
>> It's an equaliser filter used to adjust brightness and contrast
>> ported from mplayer.
>> As you can see it does no modification to the values of contrast and
>> brightness but helps leaving untouched the pixel values range.
>
> did not help with the result. (This was an attempt to find a way to
> preserve the contrast despite the colorspace conversion, regardless of
> the delogo filter "hack".)
>
> Moritz
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