vo_gpu, options: don't return NaN through API

Internally, vo_gpu uses NaN for some options to indicate a default value
that is different depending on the context (e.g. different scalers).
There are 2 problems with this:

1. you couldn't reset the options to their defaults
2. NaN is a damn mess and shouldn't be part of the API

The option parser already rejected NaN explicitly, which is why 1.
didn't work. Regarding 2., JSON might be a good example, and actually
caused a bug report.

Fix this by mapping NaN to the special value "default". I think I'd
prefer other mechanisms (maybe just having every scaler expose separate
options?), but for now this will do. See you in a future commit, which
painfully deprecates this and replaces it with something else.

I refrained from using "no" (my favorite magic value for "unset" etc.)
because then I'd have e.g. make --no-scale-param1 work, which in
addition to a lot of effort looks dumb and nobody will use it.

Here's also an apology for the shitty added test script.

Fixes: #6691

1 files changed, 37 insertions, 0 deletions

diff --git a/TOOLS/lua/nan-test.lua b/TOOLS/lua/nan-test.lua
new file mode 100644
index 0000000000..d3f1c8cc8f
--- /dev/null
+++ b/TOOLS/lua/nan-test.lua
@@ -0,0 +1,37 @@
+-- Test a float property which internally uses NaN.
+-- Run with --no-config (or just scale-param1 not set).
+
+local utils = require 'mp.utils'
+
+prop_name = "scale-param1"
+
+-- internal NaN, return string "default" instead of NaN
+v = mp.get_property_native(prop_name, "fail")
+print("Exp:", "string", "\"default\"")
+print("Got:", type(v), utils.to_string(v))
+
+v = mp.get_property(prop_name)
+print("Exp:", "default")
+print("Got:", v)
+
+-- not representable -> return provided fallback value
+v = mp.get_property_number(prop_name, -100)
+print("Exp:", -100)
+print("Got:", v)
+
+mp.set_property_native(prop_name, 123)
+v = mp.get_property_number(prop_name, -100)
+print("Exp:", "number", 123)
+print("Got:", type(v), utils.to_string(v))
+
+-- try to set an actual NaN
+st, msg = mp.set_property_number(prop_name, 0.0/0)
+print("Exp:", nil, "<message>")
+print("Got:", st, msg)
+
+-- set default
+mp.set_property(prop_name, "default")
+
+v = mp.get_property(prop_name)
+print("Exp:", "default")
+print("Got:", v)