Humbly requested: Filter SDK / Easy filter sample

[Leuf]

SimpleSample::SimpleSample(PClip _child, int _SquareSize, IScriptEnvironment* env) :
GenericVideoFilter(_child), SquareSize(_SquareSize) {

Could someone explain this to a poor C programmer who hasn't learned inheritance? I know enough to know it's inheritance, but the SquareSize(_SquareSize) has me stumped. I just need to understand well enough to add some more arguments, one of which is a string, the rest are all ints.

[Si]

class SimpleSample : public GenericVideoFilter {   
int SquareSize;
string parameter2;

public:
 
SimpleSample(PClip _child,	int _SquareSize,  string _parameter2, IScriptEnvironment* env);
 
SimpleSample::SimpleSample(PClip _child, int _SquareSize, IScriptEnvironment* env) :
	GenericVideoFilter(_child), SquareSize(_SquareSize), parameter2(_parameter2) {
...

AVSValue __cdecl Create_SimpleSample(AVSValue args, void* user_data, IScriptEnvironment* env) {
    return new SimpleSample(args[0].AsClip(),
		 args[1].AsInt(0),
		 args[2].AsString(""),
		 env);  
}


extern "C" __declspec(dllexport) const char* __stdcall AvisynthPluginInit2(IScriptEnvironment* env) {
    env->AddFunction("SimpleSample", "c[SIZE]i[PARAM2]s", Create_SimpleSample, 0);

    return "`SimpleSample' SimpleSample plugin";

Should show how to introduce a 2nd parameter.

AFAIK the SquareSize(_SquareSize) is just one of the ways to intialise variables and isn't anything clever or complicated (or how else would I be able to use it )

regards
Simon

[Leuf]

Yep, I figured it out. I just moved the initializing into the constructor, since I have about 15 arguments the line was pretty ungodly.

I think the next logical step for the sample filter would be to modify the existing pixels rather than just overwrite them with a color. Something simple like add 10 to green, iirc the vdub sdk does something like that.

[Si]

I think the next logical step for the sample filter would be to modify the existing pixels rather than just overwrite them with a color. Something simple like add 10 to green, iirc the vdub sdk does something like that.

...

if (vi.IsRGB24()) {		

   ...

   //Now enhance the greeness of a square in the middle of the frame

   dstp = dst->GetWritePtr();
   dstp = dstp + (dst_height/2 - SquareSize/2)*dst_pitch;

   for (h=0; h < SquareSize;h++) { 
      for (w = dst_width/2 - SquareSize*3/2; w < dst_width/2 + SquareSize*3/2; w+=3) { 

         *(dstp + w + 1) = max(255,*(dstp + w + 1) + 10); // Increase Green value by 10 limiting it to 255 (assumes src already copied to dst)
     }								
      dstp = dstp + dst_pitch; 
      srcp = srcp+ src_pitch; 
   }
}

(untested)

regards
Simon

[Bidoche]

@Leuf

In the initialiser list (ie the list between : and { ) you must initialise superclasses (if there are any) and you can initialise members too.
If you don't initialise members there, they are default initialised.
For int and other primitives types, the default init is a no op so it's cost nothing more, but with classes it's generally better to use initialisers.
And sometimes, you have to use them : when the variable is not assignable (ie cannot use = ) like const objects and some objects where copy has no meaning.

is there a way to add text (debug information) on a PVideoFrame ?

[sh0dan]

The easiest way is to invoke the Subtitle filter.

IIRC the syntax is something like:

PClip result = env->Invoke(child, "Subtitle", AVSValue(text));
return result.GetFrame(n,env);

For more advanced output, have a look at Donalds fast and nice algorithm in Dup and Decomb.

oki thx ^^ i'll try this.

another (stupid) question:
if i need some operation on 2D-matrix (FFT/iFFT,DCT/iDCT,sum,product)
is there in avisynth some functions for this or do i need to include library (do you know a good one ?)

[Bidoche]

There are no such things in avisynth.

You can use boost/uBlas to provide matrix. Only sum and product I fear, you would have to make FFT and DCT yourself.
I don't know of any library who provide those as well.

[trbarry]

if i need some operation on 2D-matrix (FFT/iFFT,DCT/iDCT,sum,product)
is there in avisynth some functions for this or do i need to include library (do you know a good one ?)

My DctFilter() works by doing an 8x8 DCT, modding the values, and then using iDCT, using functions pilfered from Xvid. So you might use the source as a basis for a new filter. See:

www.trbarry.com/DctFilter.zip (src & dll)

- Tom

@Bidoche
I wrote the FFT function. it works fine but too sloooowwwww !! (so i didn't start to code the iFFT).
i heard that fftw is a higly optimized FFT library, but i don't undestand how to use it (i started c++ 2days ago... noob inside ^^)

@trbarry
thanks a million ^^

edit1: oops an error:
identifier "_aligned_malloc" is undefined
pWorkArea = (short * const) _aligned_malloc(8*8*2, 128);
edit1b: _aligned_malloc isn't defined in my malloc.h (VCPP6.0 SP5)

edit1c: replaced by malloc(8*8*2) and everythingrules ^^

edit2: oohhh your code is clean, nice to read ^^
edit3: i suppose sse2 optimization is disabled for the same reason than xvid.

@siwalters
your simplescript is a great educationnal tool ^^. Very easy to learn every colorspaces and spatial filtering.
What about a TemporalSimpleScript ? ^^ (i started to read sansgrip code)

[trbarry]

edit1: oops an error:
identifier "_aligned_malloc" is undefined
pWorkArea = (short * const) _aligned_malloc(8*8*2, 128);
edit1b: _aligned_malloc isn't defined in my malloc.h (VCPP6.0 SP5)

I just had that same error when installing VS6 sp5 under on a new XP system. I think it was fixed by also installing the asm processor pack, PP5. It got fixed somehow. ?? Aligned malloc is needed if you do SSE2 specific code which gives errors when things are not 16 byte aligned.

- Tom

[sh0dan]

Have a look at audio.cpp instead.

To make an audio filter, remove the GetFrame part and put in a
void __stdcall YourClass::GetAudio(void* buf, __int64 start, __int64 count, IScriptEnvironment* env) function.

[Guest]

_aligned_malloc() is part of the platform SDK.

[snowmoon]

Geocities appears to be hating me... I can't download the sample .zip file. * GOT IT - You might want to link it off your site since geocities won't allow direct inking from this site *


Thanks

[Si]

@Sigmatador (Sorry didn't realise thread had changed )
I was hoping someone else would do this

@wer
All the main source code is also available via Avisynth.org


regards
Simon

[cudmore]

All the sample code is very helpful but I would like to write a filter that operates on more than one clip. Something like:

Dissolve(clip clip1, clip clip2 [,...], int overlap)

Does anyone have a pointer to sample code for writing a filter to operate on multiple clips?

I can't seem to be able to figure out how to access more than one clip in the GetFrame() method. All I can find are examples that operate on:

PVideoFrame src = child->GetFrame(n, env);

Where are the other clips when the filter takes multiple clips?

Thanks

Bob Cudmore

[Si]

@cudmore
I've given it a go and it seems I can get it to work.

So SimpleSample1.7 is available here (need to right-click and download as usual)

I've only modded the YUY2 code (cause 1 - I'm too lazy to do the YV12 and Avisynth doesn't work anymore in RGB on my computer )

regards
Simon

[bkam]

I have been looking at this thread, and I am also interested in writing filters. I have very little coding knowledge, however, so little that I don't know how one would even go about compiling / what program to use etc. From what I gather this is C (that's right, I don't even know C, but I am determined). So if someone could tell the tools needed to get started with this (since this is a beginners sticky), it would be really cool, like what programs you are using to compile etc. I hope it doesn't seem pointless to explain if I have never coded anything really, but everyone starts somewhere right? And I have coded assembly language for TI calculators for fun a few years ago, this code looks much nicer than that . But still I am a coding n00b, so any help is appreciated! Thanks!