troubleshooting and diagnosing

[nbi]

I'm having a lot of trouble with Avisynth output. I've sifted through all the documentation I can find and also the forums, but can't find anything helpful. It seems all the "Troubleshooting" links in these forums are invalid. Before I ask for in-depth help I want to make sure I've done everything I can. Can someone point me to a detailed and comprehensive troubleshooting guide with content like "symptom x means you should check y", etc. ?

My avs scripts are being parsed ok, but the output is complete garbage, flashing parts of the original, artifacts from prior frames, periods of blackness. I've tried both 2.5.8 and 2.5.7 without success. Other apps (ffmpeg, mencoder, virtualdub) don't have any problems with the source video, but maybe it has some attribute that's causing problems for Avisynth. Without a good reference on troubleshooting and limitations I'm at a loss on how to proceed.

[Guest]

Pete! My buddy. I want everyone to know that Pete is a FIDE Chess Master. He's a smart guy.

The best way to get help is to get specific. So post a link to an *unprocessed* sample of your source material (50MBytes is no problem for most people here). You can use any upload site, such as megaupload.com. Post the link and tell us what your goal for it is, e.g., are you trying to make an Xvid for playing on a PC, trying to make something to put on a DVD, etc.? The more you tell us, the better advice you will get.

There is no general troubleshooting guide like you ask for. But by learning to correctly process various examples, your knowledge base and tool chest will grow and soon you'll be telling the noob's how to do things.

Oh, and one more thing...e4. Your resignation will be gracefully accepted, as computers have shown that e4 is winning.

Welcome to the forum!

[Adub]

Well, any friend of neuron2 is a friend of the Doom9 community.

I echo neuron2 in welcoming you to the forum! Also, if uploading a unprocessed sample is difficult or can't be done for certain reasons, screenshots and posting your script works wonders as well.

Welcome, again!

[nbi]

Thanks for the welcome.

What I'm trying to do is generate NTSC DVD compliant video clips which I can then feed to dvdauthor (via QDVDauthor). The source clips need to be cropped and padded. Unfortunately doing this via ffmpeg seems to degrade video quality too much (discussion thread at: http://forum.videohelp.com/topic339130.html). Then someone pointed out Avisynth which looks very promising.

I think I made a significant breakthrough. Through experimentation I discovered that AviSource doesn't load my TechSmith codec generated AVIs properly, but to my pleasant surprise DirectShowSource does. The only problem is that the audio is not recognized so I eventually need to recombine video and audio streams via AudioDub. I'm very wary of AV sync problems so I'm reluctant to split and recombine streams, but it wasn't a problem on the first successful test so maybe it isn't a problem at all. I would prefer not to do any unnecessary splitting/combining though.

[Guest]

I thought TechSmith was used for screen capture. How would audio sync arise in that scenario?

Anyway, keeping audio sync is not usually a problem when demuxing/remuxing AVIs.

DirectShowSource() can be problematic, so it would be worth trying to sort out your issues with AviSource(). A small sample would be useful for us.

[nbi]

I thought TechSmith was used for screen capture. How would audio sync arise in that scenario?

It wouldn't. But as I said I need to crop and pad the clips. Avisource produces garbage. DirectShowSource properly handles the video, but I need to mux the audio back in because it doesn't find the audio in the source clip. Neither is perfect, but at least I have a workaround for the DirectShowSource audio problem. Just to be clear, the internal filters are not the problem with Avisource, I get garbage just from opening with Avisource().

Anyway, keeping audio sync is not usually a problem when demuxing/remuxing AVIs.

DirectShowSource() can be problematic, so it would be worth trying to sort out your issues with AviSource(). A small sample would be useful for us.

VirtualDub 1.7 has no problems with the original (i.e. no Avisynth) clip. Here's the file info (I left the audio out):
length: 410 frames (1:22.00)
decompressor: TSCC (TechSmith Screen Capture Codec)
key frames: 6
min/avg/max/total key frame size: 8876/23103/92785 (136k)
min/avg/max/total delta frame size: 2/94/3152 (38k)

Now if I open the .avs (which only contains AviFileSource) I get:
length: 410 frames (1:22.00)
decompressor: Uncompressed RGB24
key frames: 410
min/avg/max/total key frame size: 1379040/1379040/1379040 (552155k)
min/avg/max/total delta frame size: no delta frames
rate: 55162 kbps

Hmmm. This doesn't look good. Avisynth seems to be getting confused.

Here's the corresponding Avisynth Info():
color: rgb24
fps: 5
fieldbased: no
parity: bottom field first
video pitch: 2032 bytes
has audio: yes
channels: 1
sample type: int 16 bit
sample per sec: 44100
cpu: X87 MMX ISSE SSE SSE2

If someone could send me a list of their working configuration I might be able to see what's amiss with mine.

[foxyshadis]

You can try avisource("...",fourcc="TSCC"), perhaps try the pixel_type parameter with RGB32 in case the codec's conversion is screwy. (vdub always requests RGB.)

[nbi]

Originally Posted by foxyshadis

You can try avisource("...",fourcc="TSCC"), perhaps try the pixel_type parameter with RGB32 in case the codec's conversion is screwy. (vdub always requests RGB.)

Thanks.

fourcc="TSCC" results in an exception:

Avisynth open failure:
Evaluate: System exception - Access Violation

What is this even telling me? That it can't access the techsmith dll ? That would make no sense since other apps can. Argh, I hate frickin Windows. Why can't 3.0 be done already?

I'll give other pixel_type parameters a try.
Thanks for the suggestions.

Ok, RGB24 is the only pixel_type parameter value that doesn't cause an exception. But when I preview the input it's garbage like I reported previously.

[Guest]

Are you going to give us a sample? There's not much we can do without it.