Newbie filter development question : invoking other filters

[Bob Wya]

Hi

After weeks of battling with a problem I have finally given up and come on the forums!! I am developing an avisynth filter against 2.58 using MS Visual 2008. I should say that although I have done a Comp Sci degree (years ago :o) I am a bit clueless about programming in C++ (object scope, etc. boogles my brain)!! Also I cannot figure out how I would hook up VS 2008 to debug my filter (since I am simply calling it by running a .avs test script).

Basically my filter class constructor does the following:
(1) SampleClip: parse every frame detecting border sizes
(2) UpdateClip: invoke a chain of internal Avisynth filters (trim, subtitle, resize, addborders, etc.) to (optionally) preview the filter "in action"
(3) avsfile_write: writes an avisynth script with the appropriate trim(), resize(), addborder() commands. This file is outputed to the current working directory.

The GetFrame(): function simply accesses frame in a new clip created in step (2).

I have a couple of problems:
(1) I can't find a way to access the name of current .avs file that is being framecoded from.
(2) My code crashes when I try and change the original frame size (using envoked resizing filters). Frame-served output is fine when I retain equal frame sizes between the source and desination clips.
The actual crash occurs in the GetFrame() function (with the first frame being served). I presume the destination clip I create (at the end of UpdateClip()) is somehow not updating the clip properties of the 'env' class or something??!!

Heres some snippets of my (rather bloated) source code!! Please ask if I have not explained myself clearly enough!! :thanks:

Bob



class autocentre : public GenericVideoFilter
{
...
PClip source_clip, trimed_subclip, text_overlayed_subclip, resized_subclip, subclip_with_borders, destination_clip;
...
public:
autocentre(PClip _child, int _mode, const char *_matrix, const char *_ResizeCommand, int _targetWidth, int _targetHeight,
int _leftCrop, int _topCrop, int _rightCrop, int _bottomCrop,
int _widthMultipleOf, int _heightMultipleOf, double _hardThreshold, double _softThresholdLimit, double _medianDeviationLimit,
int _horizontalBlocksThreshold, int _verticalBlocksThreshold, IScriptEnvironment *env) : GenericVideoFilter(_child) {
...
}
...
}

...

int __stdcall autocentre::UpdateClip(IScriptEnvironment* env)
{
...
for (unsigned int i_frame_range=0; i_frame_range<v_clip_regions.size() ; ++i_frame_range) {
...
start_frame = v_clip_regions[i_frame_range].start;
end_frame = v_clip_regions[i_frame_range].end;
...
AVSValue trimargs[3] = { source_clip, start_frame, start_frame-end_frame-1};
trimed_subclip = env->Invoke("Trim",AVSValue(trimargs,3)).AsClip();
...
AVSValue arguments[13] = { text_overlayed_subclip, overlay_text_p, frame_crop_borders[en_left]+(target_clip_width>>5), -1,
frame_number, frame_number, "Arial", font_size, 0x00aaaa00, 0x00000011, 4, -2, 10};
text_overlayed_subclip = env->Invoke("Subtitle", AVSValue(arguments, 13)).AsClip();
...
AVSValue arguments[7] = { text_overlayed_subclip, target_clip_width, target_clip_height, float(frame_crop_borders[en_left]), float(frame_crop_borders[en_top]),
float(frame_crop_borders[en_right]), float(frame_crop_borders[en_bottom]) };
resized_subclip = env->Invoke(command_string.c_str(), AVSValue(arguments, 7)).AsClip();
...
AVSValue arguments[6] = { resized_subclip, v_new_black_borders[en_left], v_new_black_borders[en_top], v_new_black_borders[en_right], v_new_black_borders[en_bottom], 0x000000 };

v_clip_regions[i_frame_range].destination_subclip = env->Invoke("AddBorders", AVSValue(arguments, 6)).AsClip();
...
}
AVSValue *p_arguments;
p_arguments = new AVSValue[v_clip_regions.size()];
for (unsigned int i_frame_range=0; i_frame_range<v_clip_regions.size() ; ++i_frame_range) {
p_arguments[i_frame_range] = v_clip_regions[i_frame_range].destination_subclip;
}
if (v_clip_regions.size() == 1)
destination_clip = v_clip_regions[0].destination_subclip;
else
destination_clip = env->Invoke("UnAlignedSplice", AVSValue(p_arguments, v_clip_regions.size())).AsClip();
}

PVideoFrame __stdcall autocentre::GetFrame(int frame_number, IScriptEnvironment* env)
{
return destination_clip->GetFrame(frame_number, env);
}

[Gavino]

AVSValue arguments[13] = { text_overlayed_subclip, overlay_text_p, frame_crop_borders[en_left]+(target_clip_width>>5), -1,
frame_number, frame_number, "Arial", font_size, 0x00aaaa00, 0x00000011, 4, -2, 10};
text_overlayed_subclip = env->Invoke("Subtitle", AVSValue(arguments, 13)).AsClip();
That doesn't look right - you are applying Subtitle to a clip that has not yet been defined. Should this not be trimed_subclip?

You should enclose the Invoke calls in try/catch blocks to catch any errors that might arise.

[Bob Wya]

That doesn't look right - you are applying Subtitle to a clip that has not yet been defined. Should this not be trimed_subclip?

You should enclose the Invoke calls in try/catch blocks to catch any errors that might arise.

Uhhhm yeh sorry that was a cut and paste error (I had been trying something different earlier in my code - to see if it made any difference!!)

I am writing to a log file. Like I say the code completes fine when I don't alter the clip resolution (I see the frame-served video). When I change the resolution I see this at the end of my log file:

...
target clip width=1280
target clip height=1016
left crop=0.0
top crop=2.0
right crop=0.0
bottom crop=-2.0
invoked resize command: Lanczos4Resize
completed subclip processing!!
UpdateClip() exit
filter complete
GetFrame(0)

and the Media Player Classic window either disappears or shows something about a stream error (??)

Are you saying that the invoked filters may have created the error? Despite the code actually appearing to get successfully through the constructor completely and crapping out in the standard GetFrame() function for my filter?
:confused: :confused: :confused:

Can I log any environment/ clip parameters in my GetFrame() function - before it returns the first frame - that might clarify why it is not working/ causing Avisynth to crash?

Thanks
Bob

[Gavino]

Are you saying that the invoked filters may have created the error? Despite the code actually appearing to get successfully through the constructor completely and crapping out in the standard GetFrame() function for my filter?
:confused: :confused: :confused:
If it gets that far, then I suppose the Invokes must have completed without raising an exception. Nevertheless, it is good practice to use a try/catch to trap any errors which might occur.
Can I log any environment/ clip parameters in my GetFrame() function - before it returns the first frame - that might clarify why it is not working/ causing Avisynth to crash?
You could log various clip properties (width, height, etc) of both this (from the vi variable) and destination_clip (from GetVideoInfo()).

Thinking about it, the problem probably is that these do have different sizes. If your final clip has different dimensions to the child (source) clip, then you need to change vi.width and height in your constructor.

[Bob Wya]

Sweet!!

I just added:

vi=destination_clip->GetVideoInfo();

to the end of my constructor (UpdateClip() function).

Did a bit of hacking around to get my invoking filter functions tidied up a bit. Now loh and behold I get a fully working and resized output video stream!

I don't suppose you know the answer to my other question?
(1) I can't find a way to access the name of current .avs file that is being framecoded from.

Basically I am trying to take the input .avs script and spit out an altered copy (with a name something like '...-new.avs'). This is so that I can easily automate the processing of a folder of DVD-Rebuilder .avs scripts.

:thanks:
Bob

[Gavino]

I don't suppose you know the answer to my other question?
"I can't find a way to access the name of current .avs file that is being framecoded from. "
See stickboy's solution at post #7 in this thread. It's a script function which you can 'Invoke' from your code (put it in a .avsi file in your plugins folder and it will always be available).

[Bob Wya]

See stickboy's solution at post #7 in this thread. It's a script function which you can 'Invoke' from your code (put it in a .avsi file in your plugins folder and it will always be available).

Thanks, like hundreds of other people no doubt, I've found or been directed to that thread... Hmmm I'll just wait till it's in the Avisynth API (where it should have been put months ago) rather than use some 'gross hack'... :eek:

:thanks:
Bob

[jmartinr]

You might consider using the trick and use the filename you get as an inputparameter for your filter.