How can i detect an error from avisynth script with vfw?

[jonny]

When an error occour in an avisynth script, avisynth return a valid clip with the message, how can i detect this?

Thanks
jonny

[Belgabor]

Have a look at the VirtualDub sources, its shown there. (iirc basically you have to get a special interface for the AVIFile object)

[jonny]

I'll do, thank you very much!

[UGAthecat]

if you haven't found it already...iirc, you can use AVIFILEINFO or AVISTREAMINFO on a video stream and the error will be returned in one of the values. I know i've seen the errors generated by AVISynth using these before in VB. Also, if anyone wants info on using AVIFile stuff in VB, check out http://www.shrinkwrapvb.com
To get info on using avifileinfo and avistreaminfo, go to this page in the tutorials on shrinkwrapvb: http://www.shrinkwrapvb.com/avihelp/avihlp_2.htm

[jonny]

Finally found the solutions in VDub source code... this may help others:



#include<windows.h>
#include<vfw.h>
#include<stdio.h>


const GUID AvisynthGUID = {0xe6d6b708, 0x124d, 0x11d4, {0x86, 0xf3, 0xdb, 0x80, 0xaf, 0xd9, 0x87, 0x78}};


struct IAvisynth : IUnknown
{
virtual int __stdcall GetError(const char **) = 0;
};


void main()
{
PAVIFILE PAviFile;
IAvisynth *PAvisynth;
const char *AvisynthE;


AVIFileInit();
if (AVIFileOpen(&PAviFile, "test.avs", OF_READ, 0) == 0)
{
if (PAviFile->QueryInterface(AvisynthGUID, (void **)&PAvisynth) == S_OK)
{
if (PAvisynth->GetError(&AvisynthE))
printf("%s\n", AvisynthE);
else
printf("Ok!\n");
PAvisynth->Release();
}
AVIFileRelease(PAviFile);
}
AVIFileExit();
}




@UGAthecat:
AVIFILEINFO or AVISTREAMINFO seems to does not return this info, i'm missing something?




EDIT: at the start i was searching for "iirc" :D, before learning that means "if i remember correctly"

[jonny]

Is someone able to give me some tips about translating this from cpp to plain c?


const GUID AvisynthGUID = {0xe6d6b708, 0x124d, 0x11d4, {0x86, 0xf3, 0xdb, 0x80, 0xaf, 0xd9, 0x87, 0x78}};

struct IAvisynth : IUnknown
{
virtual int __stdcall GetError(const char **) = 0;
};

PAVIFILE f;
IAvisynth *PAvisynth;
const char *AvisynthE;

AVIFileInit();
AVIFileOpen(&f, "test.avs", OF_READ, NULL);
f->QueryInterface(AvisynthGUID, (void **)&PAvisynth);
if (PAvisynth->GetError(&AvisynthE))
{
...
}
...


Many thanks
jonny

[jonny]

I have found a solution some days ago... dunno if this could be useful for others... anyway it's here:

const GUID AviSynthGUID = {0xe6d6b708, 0x124d, 0x11d4, {0x86, 0xf3, 0xdb, 0x80, 0xaf, 0xd9, 0x87, 0x78}};

DECLARE_INTERFACE_(IAviSynth, IUnknown)
{
STDMETHOD(QueryInterface) (THIS_ REFIID, LPVOID FAR *) PURE;
STDMETHOD_(ULONG,AddRef) (THIS) PURE;
STDMETHOD_(ULONG,Release) (THIS) PURE;
STDMETHOD_(int,GetError) (THIS_ const char **) PURE;
};

...

PAVIFILE f;
IAviSynth *iavs;
const char *error;

AVIFileOpen(&f, "test.avs", OF_READ, 0);
f->lpVtbl->QueryInterface(f, &AviSynthGUID, (void **) &iavs);
if (iavs->lpVtbl->GetError(iavs, &error))
{
// error here!
}

(there is no full error checking to simplify the code reading)

[Amnon82]

Is there a way to use this in delphi?

[jonny]

you could make an external dll with this code.
i have no idea about doing this in pure delphi

[Amnon82]

Can you compile the dll? I'll try it, but it will be the first time for me, creating dlls. I must search the net how to do it ...

[jonny]

no experience with dlls

some time (years!) ago, i was using this external app:

http://jonny.leffe.dnsalias.com/doom9/avsinfo.rar

you have to write a file called "avsinfo.in", containing the .avs filename, call "avsinfo.exe" and read back "avsinfo.out"

avsinfo.out:

the first 2 chars of this file indicate success ("ok") or an error (" " - 2 spaces)
the rest of the file contain the error message in case of errors, video infos in case of success:

dwWidth, dwHeight, dwScale, dwRate, dwLength, separated by "#"

(if "avsinfo.in" does not exists, "avsinfo.out" is not written)


PS: if you need to modify it, you can compile it with "cl avsinfo.cpp /link vfw32.lib"


dirty but easy :)

[Amnon82]

I'll take a look. thx ...