Re: [FFmpeg-devel] [PATCH v1] avfilter/vf_gblur_vulkan: add sizeV option

["Wu, Jianhua" <jianhua.wu-at-intel.com@ffmpeg.org>]

Lynne:
> Sent: Tuesday, February 22, 2022 5:36 PM
> To: FFmpeg development discussions and patches <ffmpeg-
> devel@ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH v1] avfilter/vf_gblur_vulkan: add sizeV
> option
> 
> 22 Feb 2022, 07:27 by jianhua.wu-at-intel.com@ffmpeg.org:
> 
> > Lynne:
> >
> >> Sent: Tuesday, February 22, 2022 1:38 PM
> >> To: FFmpeg development discussions and patches <ffmpeg-
> >> devel@ffmpeg.org>
> >> Subject: Re: [FFmpeg-devel] [PATCH v1] avfilter/vf_gblur_vulkan: add
> >> sizeV option
> >>
> >> 18 Feb 2022, 16:24 by toqsxw@outlook.com:
> >>
> >> >> 29 Jan 2022, 13:34 by toqsxw at outlook.com:
> >> >>
> >> >>> Ping.
> >> >>>
> >> >>>> From: Wu, Jianhua<mailto:jianhua.wu-at-intel.com at ffmpeg.org>
> >> >>>> Sent: 2022年1月21日 19:42
> >> >>>> To: ffmpeg-devel at ffmpeg.org<mailto:ffmpeg-devel at
> >> >>>> ffmpeg.org>
> >> >>>> Cc: Wu, Jianhua<mailto:jianhua.wu at intel.com>
> >> >>>> Subject: [FFmpeg-devel] [PATCH v1] avfilter/vf_gblur_vulkan: add
> >> >>>> sizeV option
> >> >>>>
> >> >>>> [PATCH 1/5] avfilter/vf_gblur_vulkan: add sizeV option [PATCH
> >> >>>> 2/5] avfilter:add shader_vulkan filter [PATCH 3/5]
> >> >>>> avfilter/vf_blend_vulkan: add multiply blend mode [PATCH 4/5]
> >> >>>> avutil/vulkan: don't use strlen as loop >condition [PATCH 5/5]
> >> >>>> avfilter/scale_vulkan: use RET for checking return value
> >> >>>>
> >> >>>> Patches attached.
> >> >>>>
> >> >>>
> >> >>> Hi there,
> >> >>>
> >> >>> Any update?
> >> >>>
> >> >>
> >> >> Sorry, haven't forgotten, but been busy with FFTs lately.
> >> >> Will try to review and test the patches soon.
> >> >>
> >> >
> >> > Hi there,
> >> >
> >> > I'm sorry for bothering you. If there is any update on this thread,
> >> > please do let me know.
> >> >
> >>
> >> Pushed all except the strlen() in a loop condition and the shader filter.
> >> I pushed a different, smaller version for the strlen patch.
> >>
> > Maybe you don't need to use strlen() at all. That patch could be
> > applied separately if you preferred to apply the shader_vulkan filter in the
> future.
> >
> >> As for a shader filter, I'd like something that's a lot less minimal.
> >> You should expose the frame number, framerate (with an avoption to
> >> set it), pixel format to the shader. Keep in mind the API will be
> >> fixed, so we need to get this right the first time hopefully.
> >>
> >
> > Frame number and framerate are okay to set if I can get them from
> > FFmpeg API, but pixel format may not be ideal to expose for there is a
> > lot of pixel formats in FFmpeg. Exposing a pixel format means we need
> > to expose all values related to pixel formats. Instead, we could
> > expose two functions like
> >
> 
> Wrapper functions won't help, shaders would still need to know what
> colorspace to work in.
> I think if you just expose the entire pixdesc flags as-is, so shaders know if it's
> RGB or YUV, and the raw colorspace/transfer/matrix integers, it'll be good
> enough.
> 
> 
> >> You should expose alpha planes as well.
> >>
> > Could you elaborate it further?
> >
> 
> Yes, currently for YUVA images, the alpha channel remains untouched (the
> size of all image arrays is [3]) and unexposed to the shader.
> 
> 
> >> Finally, could you implement N-inputs and M-outputs, configurable via
> >> avoptions? That way, someone could make a custom blend filter without
> >> a separate avfilter which takes multiple inputs. Or a separator filter.
> >> Or a simple source filter that just produces an image pattern.
> >>
> > Sounds great! However, at the present, I've no idea about how this could
> be done.
> > I think the current filter is already useful already for I could make
> > some great video effects just like Shadertoy. More extensions need
> further contributions.
> >
> 
> Just set AVFilter.inputs and AVFilter.outputs to NULL. Then in the init
> function, copy what e.g. af_amix does to set inputs and what e.g.
> af_channelsplit does for outputs. There are probably better examples out
> there if you look.
> I think that this should be up to the shader to initialize, rather than the filter
> user, so perhaps, in the init function, you compile the shader, run an init
> function in the shader which tells you what it requires and does checking,
> then return, and set it up for operation.
> 

I suppose you mean there is a init function in the shader source file and execute
it to read back some configuration data, don't you? If so, looks like a great feature.
And I think, isn't these characteristics should be only added when there is someone
who has the relative requirements?

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