[FFmpeg-devel] [PATCH v2 1/2] avfilter: add a hflip_vulkan filter

Wu, Jianhua jianhua.wu at intel.com
Thu Nov 18 07:59:43 EET 2021


> Andreas Rheinhardt: 
> Wu, Jianhua:
> > Andreas Rheinhardt wrote:
> >> Wu Jianhua:
> >>> The following command is on how to apply hflip_vulkan filter:
> >>>
> >>> ffmpeg -init_hw_device vulkan -i input.264 -vf
> >>>
> >>
> hwupload=extra_hw_frames=16,hflip_vulkan,hwdownload,format=yuv420p
> >>> output.264
> >>>
> >>> Signed-off-by: Wu Jianhua <jianhua.wu at intel.com>
> >>> ---
> >>>  configure                     |   1 +
> >>>  libavfilter/Makefile          |   1 +
> >>>  libavfilter/allfilters.c      |   1 +
> >>>  libavfilter/vf_hflip_vulkan.c | 276
> >>> ++++++++++++++++++++++++++++++++++
> >>>  4 files changed, 279 insertions(+)
> >>>  create mode 100644 libavfilter/vf_hflip_vulkan.c
> >>>
> >>
> >>> +
> >>> +static const AVOption hflip_vulkan_options[] = {
> >>> +    { NULL },
> >>> +};
> >>> +
> >>> +AVFILTER_DEFINE_CLASS(hflip_vulkan);
> >>> +
> >>
> >> What is the point of this class with its empty options?
> >
> > The AVFILTER_DEFINE_CLASS needs the hflip_vulkan_options and the
> > reason why it's NULL is that the most other filters do it like that.
> >
> 
> And why do you add an AVClass at all?
> (The reason that there are some filters with AVClass and empty options is a
> bug in avfilter_init_str() which errors out when given options for a filter
> without AVClass, although it is perfectly fine to set options on a filter without
> AVClass, namely generic AVFilter options (this is important for e.g. framesync
> filters, but not for this filter here).)
> 

Simply I think it is a convention. Yeah. It's not needed at all. I'll remove it and update later.


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