AviSynth+ thread Vol.2

[wonkey_monkey]

Ah, then probably Average just doesn't handle arrays as input. It's getting only one parameter, the array, which is not the right number as far as it is concerned. You need to separate out the elements and send them as individual parameters (if you can do such a thing).

[real.finder]

yes, that why I said "way to convert array to arguments"

[cretindesalpes]

Another thing: is the Avisynth+ ABI still restricted to MSVC? Or could Clang/MSYS2 or GCC compile plug-ins now?

[FranceBB]

Originally Posted by cretindesalpes

Another thing: is the Avisynth+ ABI still restricted to MSVC? Or could Clang/MSYS2 or GCC compile plug-ins now?

If I remember correctly MSVC yes, Clang yes, GCC no, in the sense that if you compile a plugin with GCC, then you need an Avisynth build compiled with GCC as well, otherwise you're not gonna be able to run such plugin, so you can't mix GCC builds of plugins with MSVC builds of Avisynth and since almost every build of everything is done with MSVC, then no one compiles with GCC.
Stephen (also called "qyot" for the Doom9 friends) did some successful experiments a while ago in which he compiled Avisynth with GCC and tried to use GCC Compiled plugins with it and it worked, however no one uses it for obvious reasons...
At least this is true on Windows, but it's different for Linux and Mac OSX (yep, as hard to believe as it is, Avisynth is cross platform now eheheheh)

[qyot27]

Originally Posted by cretindesalpes

Another thing: is the Avisynth+ ABI still restricted to MSVC? Or could Clang/MSYS2 or GCC compile plug-ins now?

Clang is probably okay if you're using clang-cl. Other than that, there be dragons. The only way that's guaranteed would be as a C plugin (in which case the GCC-centric symbol logic is the assumed default), not a C++ plugin.

And currently something has broken the ability for FFmpeg to use GCC builds, although the GCC builds actually compile. It definitely is something on our side, since archived builds (r2831, from 2019) work with the same newer (May 2021) FFmpeg binary.

[Myrsloik]

Originally Posted by cretindesalpes

Another thing: is the Avisynth+ ABI still restricted to MSVC? Or could Clang/MSYS2 or GCC compile plug-ins now?

It's still the MS C++ ABI only. The only two compilers that support it are MSVC and clang-cl (not other variants of clang, they use the GCC ABI). It's trivial to try out clang-cl, simply select clang in the visual studio installer and then you can choose it as the platform toolset. Binaries are usually noticeable faster.

Do however note that clang-cl doesn't understand the instruction set selection (as done through property pages) very well which can cause problems with intrinsics being rejected.

[cretindesalpes]

I see. So I’ll stick with MSVC for the Avisynth+ version of fmtconv for the moment.

[real.finder]

Originally Posted by cretindesalpes

I see. So I’ll stick with MSVC for the Avisynth+ version of fmtconv for the moment.

if MSVC is not good for you, you can always use C API of avs/avs+ https://github.com/Asd-g/AviSynth-VM...c9cac81f082269

AviSynth+ can even autoload C plugins unlike the old AviSynth, also you don't need to use loadCplugin in avs+, loadplugin work with it too

[vcmohan]

Sorry for asking a simple question. How does one read a double value for an input parameter by the plugin? args[n].AsFloat() I vaguely remembered actually outputs a double but when I tried args[n].AsFloat(0.001) I got a warning of truncating double to float. The input string has f for the value.

[cretindesalpes]

You can use AsDblDef(), but anyway the stored type within the AVSValue is always a float.

[StainlessS]

You can append default value with trailing 'f', args[n].AsFloat(0.001f)
[not sure if Avs+/visual studio, gives warning now for default value as double without trailing f]
EDIT: AsDblDef() probably better way, never used it.
With VS2008 and earlier, I sometimes had to use something like eg

d = (double)args[n].AsFloat(0.001f)
f = (float)args[n].AsFloat(0.001f)

[StvG]

Originally Posted by vcmohan

Sorry for asking a simple question. How does one read a double value for an input parameter by the plugin? args[n].AsFloat() I vaguely remembered actually outputs a double but when I tried args[n].AsFloat(0.001) I got a warning of truncating double to float. The input string has f for the value.

The original post.

Originally Posted by pinterf

There is an AsFloatf version of AsFloat that should be used to avoid warnings. This function exists for this very reason.
EDIT: maybe I explained the opposite: to avoid return value warning. You can use AsDblDef, but since there is no double in AVSValue there is no point of doing that.

Side note: internally there is no double type in Avisynth. Double and 64 bit integer types are impossible to implement. Reason: AVSValue defined in avisynth.h has its maximum value size dependent of the size of pointer - pointer type is 4 bytes on a 32 bit system - so only a 32 bit float can be held there, no 64 bit double. 64 bit systems would easily support them - of course this needs an interface update - I had plans for that but there are always more important stuffs in the development queue. With the extinction of 32 bit Avisynth versions nobody will care if interface would change.

[DTL]

Some idea to Avisynth core clip properties:

Add property to indicate full-band color 4:4:4 clip and half-color band (half vertical, half-horizontal or half-both, may be bitmask ?).

For example fresh non-distorted in spectrum 4:4:4 clip upconverted from 4:2:0 source is half-banded in color in both vertical and horizontal directions. But the next in chain filters can not get this information currently. Also this property need to be user-controllable so if user damage half-banding it may set property to full-band.

It may be useful hint for processing like color subsampling processing and other.

Also use it automatically in Convert4:4:4To4:2:0 and from 4:4:4To4:2:2 operations with defaulting chromaresample to sinc for half-band marked clips and may be current default bicubic (gauss prefferable with fixed p-param adjusted after tuning) for full-band marked 4:4:4 sources.
Also it is very great to add to Contert() the abiliti to pass kernel chromaresampler params (for example p for gauss) because currently used defaults (?) may be far from good for chromaresample.

[FranceBB]

Originally Posted by DTL

Also it is very great to add to Contert() the ability to pass kernel chromaresampler params (for example p for gauss) because currently used defaults (?) may be far from good for chromaresample.

^This^
As result of this discussion: Link

In Converttoyv12, YUY2, yv16, yv24, YUV420, YUV422, YUV444 etc only the built in resizing kernels are supported and with no additional parameters, so that is actually limiting.
I know that just only around 5% of the Doom9 population is actually even bothering to specify the resizing kernel when changing chroma, but anyway I'm in favor of a full args support in the default built-in conversion, to be fair.

[vcmohan]

Originally Posted by StainlessS

You can append default value with trailing 'f', args[n].AsFloat(0.001f)
[not sure if Avs+/visual studio, gives warning now for default value as double without trailing f]

On MS VC 2019 community version tried:-
float d = args[].AsFloat(0.5f)
warning conversion double to float
float d = args[].AsFloat(0.5)
argument truncation from double to float
initializing from double to float.
So it always expects a trailing f in default value, but outputs a double. A bit confusing and is not right.
double d = args[].AsDblDef(0.5) works ok

[cretindesalpes]

You also can use AsFloatf() which takes a float and returns a float.

[StainlessS]

Dont think AsDblDef() or AsFloatf() work in avs 2.58, so I dont use either.

[DTL]

An idea - it looks avisynth support dropping out only error messages. But it may be good for hinting and warning of user to have some method to output warning messages too. In complex processing it may be method to put info about not very best current processing path or where developer not sure and/or ask to pay special attention (where quality may be degraded or where parameter in most cases need adjustment etc).

[Dogway]

Is there a way to know how string floats get converted to single floats in Expr? I was reading IEEE 754 but nothing on it hinted the following findings:

Merge(a,b,0.25)

equals

Expr(a,b,"x 0.749999 * y 0.249999 * + ")

or

Merge(a,b,0.5)

equals

Expr(a,b,"x y + 0.500001 * ")

For example I tested in this online converter, and 0.25 turns out as 0.25 and 0.5 as 0.5.

[cretindesalpes]

Expr only works with float (no double). Integer multiples of powers of 2 can be represented exactly (like 0.75 = 3 * 2^-2). Other values are rounded, and the exact rounding process depends on the implementation of the standard library used to compile the program. Generally you can expect about 6 digits of precision.