Avisynth Exception Error on national television

[sharper]

Yes, Avisynth made it big today by displaying a flickering red text roughly saying "Avisynth Exception Error 00x04398F78GE" on the swedish tv channel TV4 MediTV. I work at MediTV as technical operational manager and I was puzzled. How did this happen?

I used Avisynth in a conversion process where 2100 music videos were converted from an obscure Matrox AVI file format to MPEG2 broadcast streams for serving on a large Omneon media server. A C# program browsed the old music archive and created long batch files that TMPGenc could read, plus 2100 .avs files to serve the video into TMPGenc since it didn't read the Matrox i-frame codec. The conversion process took 1,5 weeks on 5 desktop computers.

Naturally, there was no way to look through 2100 music videos, hence I made some random tests and it all looked fine. Apparently, someway into a few of the files, Avisynth crashed. Since Avisynth displays its error messages through the output video window, TMPGenc encoded the message throughout the rest of the video. The audio passed through AVIsynth without corruption.

And today we finally added one of the corrupted videos to the playlist. After a few seconds, the screen went black and we all fixed our eyes on the screen for a moment as red flickering text begun to appear. Finally, the broadcast controller asked: "What's Avisynth?"

If anyone has a method for optically scanning 2100 videos to look for red text, please tell me...

/axel

[Schlumpf]

Wouldn't know how to find red text within a video, but there were some discussions that dealt with automatically reckognizing the difference between two or more frames and outputting them to a textfile. And an errormessage should stay exactly the same now matter how long you display it. Search for it on the forums.

[mf]

Wow!

I wouldn't know what the exact specifications are of an AVISynth error message (cause VDub traps the C++ errormessage and displays it in a dialog box instead, and it's been ages since I worked with AVS and anything else than VDub), but it should be pretty simple to do. Lemme wake up (I've just gotten out of bed), think a little, and I'll come up with something. Hang on :).

[Arachnotron]

why not scan 1 frame from all files -say frame 1000 or some other frame number that is present in even the shortest clip- and count the number of colors? for an synthetic error message, I assume there would only be two, background and foreground color. No part of a videoclip, even a purely black shot, should contain that few colors.

Even better would be to also take the last frame, to catch crashes halfway into the clip. Using only one or two frame per clip should speed things up a bit.

As to how to script that in AVS, I'm a newbe, so I don't know :)

[scharfis_brain]

or: just write a batch-processor, that cuts out a still frame from the middle of every video.
those images are saved with the corresponding title & interpret filename.

now just look thru all 2100 images manually using irfanview.
looking at approx. 2100 images shouldn't need more than one hour.

[Leak]

Originally posted by scharfis_brain
or: just write a batch-processor, that cuts out a still frame from the middle of every video.
those images are saved with the corresponding title & interpret filename.

now just look thru all 2100 images manually using irfanview.
looking at approx. 2100 images shouldn't need more than one hour.

Ummm... it'd go even faster with something like ACDSee's browser - looking at 16 or so thumbnails at a time should be even quicker; AVISynth's error messages will still stand out if the images are downsized... :)

np: Fluxion - Enhancement (Vibrant Forms II)

[scharfis_brain]

hehe, IrfanView provides a thumbnail browser, too!

[Soulhunter]

Or save them as PNG and sort them by filesize then !!!

Plain black with some red text should need much less filesize as a usually movie frame... ;)


Bye

[sharper]

Originally posted by scharfis_brain
or: just write a batch-processor, that cuts out a still frame from the middle of every video.
those images are saved with the corresponding title & interpret filename.

now just look thru all 2100 images manually using irfanview.
looking at approx. 2100 images shouldn't need more than one hour.

Quite an idea, I'll pitch it during the next coordination meeting.

Originally posted by Soulhunter
Or save them as PNG and sort them by filesize then !!!

Plain black with some red text should need much less filesize as a usually movie frame... ;)

Bye

Even better, this method would also sort out entirely black frames - I've spotted videos where parts were entirely black. This may well be due to the source material and not the conversion process but still vital to eliminate.

Thanks for some great creativity guys!

/axel

[Tuesday]

I know it might sound dumb, but surly if u just organize the files by total file size the ones with the error in will have the smallest size by far as the MPEG2 encoder will have been encoding a still frame which surly cant take up as much space as a broadcast stream - or am i being obtuse?

[torok]

Originally posted by Tuesday
I know it might sound dumb, but surly if u just organize the files by total file size the ones with the error in will have the smallest size by far as the MPEG2 encoder will have been encoding a still frame which surly cant take up as much space as a broadcast stream - or am i being obtuse?

So long as you are not using multiple-pass VBR to assure a consistant bitrate and every clip is the same length.