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 ) 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!!

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);
}