Re: [FFmpeg-devel] [PATCH 1/2] ffplay: add -scaling_quality option for SDL

[Ramiro Polla <ramiro.polla@gmail.com>]

Hi,

On Mon, Jun 10, 2024 at 9:04 PM Marton Balint <cus@passwd.hu> wrote:
> On Tue, 4 Jun 2024, Ramiro Polla wrote:
> > On Thu, May 30, 2024 at 11:36 PM Ramiro Polla <ramiro.polla@gmail.com> wrote:
> >>
> >> ---
> >>  doc/ffplay.texi  | 2 ++
> >>  fftools/ffplay.c | 6 +++++-
> >>  2 files changed, 7 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/doc/ffplay.texi b/doc/ffplay.texi
> >> index 93f77eeece..60f883e159 100644
> >> --- a/doc/ffplay.texi
> >> +++ b/doc/ffplay.texi
> >> @@ -72,6 +72,8 @@ as 100.
> >>  Force format.
> >>  @item -window_title @var{title}
> >>  Set window title (default is the input filename).
> >> +@item -scaling_quality @var{value}
> >> +Set SDL_HINT_RENDER_SCALE_QUALITY value (default is "linear").
> >>  @item -left @var{title}
> >>  Set the x position for the left of the window (default is a centered window).
> >>  @item -top @var{title}
> >> diff --git a/fftools/ffplay.c b/fftools/ffplay.c
> >> index b9d11eecee..75d2bec777 100644
> >> --- a/fftools/ffplay.c
> >> +++ b/fftools/ffplay.c
> >> @@ -351,6 +351,7 @@ static int filter_nbthreads = 0;
> >>  static int enable_vulkan = 0;
> >>  static char *vulkan_params = NULL;
> >>  static const char *hwaccel = NULL;
> >> +static const char *scaling_quality = NULL;
> >>
> >>  /* current context */
> >>  static int is_full_screen;
> >> @@ -3683,6 +3684,7 @@ static const OptionDef options[] = {
> >>      { "framedrop",          OPT_TYPE_BOOL,   OPT_EXPERT, { &framedrop }, "drop frames when cpu is too slow", "" },
> >>      { "infbuf",             OPT_TYPE_BOOL,   OPT_EXPERT, { &infinite_buffer }, "don't limit the input buffer size (useful with realtime streams)", "" },
> >>      { "window_title",       OPT_TYPE_STRING,          0, { &window_title }, "set window title", "window title" },
> >> +    { "scaling_quality",    OPT_TYPE_STRING, OPT_EXPERT, { &scaling_quality }, "set SDL_HINT_RENDER_SCALE_QUALITY value (default=linear)", "value" },
> >>      { "left",               OPT_TYPE_INT,    OPT_EXPERT, { &screen_left }, "set the x position for the left of the window", "x pos" },
> >>      { "top",                OPT_TYPE_INT,    OPT_EXPERT, { &screen_top }, "set the y position for the top of the window", "y pos" },
> >>      { "vf",                 OPT_TYPE_FUNC, OPT_FUNC_ARG | OPT_EXPERT, { .func_arg = opt_add_vfilter }, "set video filters", "filter_graph" },
> >> @@ -3831,7 +3833,9 @@ int main(int argc, char **argv)
> >>              }
> >>          }
> >>          window = SDL_CreateWindow(program_name, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, default_width, default_height, flags);
> >> -        SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "linear");
> >> +        if (!scaling_quality)
> >> +            scaling_quality = "linear";
> >> +        SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, scaling_quality);
> >>          if (!window) {
> >>              av_log(NULL, AV_LOG_FATAL, "Failed to create window: %s", SDL_GetError());
> >>              do_exit(NULL);
> >> --
> >> 2.39.2
> >>
> >
> > Can anyone comment on this? I had a few doubts on this patch:
> > - does the option name properly convey its functionality?
> > - is the documentation too terse?
> > - should we include the accepted values in the documentation, even
> > though they are sdl-specific?
>
> What is the benefit of having such option? I don't really see a strong use
> case for it. Also you want to propagate the scaling quality to placebo
> backend as well? Does it acutally make sense to do that?

I use this option to set scaling quality to "nearest" when I want the
display to be pixelated in fullscreen.

I haven't thought about the placebo backend. I'll have a look when I
get the time.
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