Upgraded, but still dropping frames for some reason...

[Gunnar1979]

Well, since I last posted, I have upgraded my system by dropping in a cubx and a Celeron 433 (oc'd to 488), and I am still dropping frames in VirtualDub. I am capturing off an RRG in YUY2 with HuffYUV in CIF resolution. My capture drive is a UW Seagate on an Adaptec 2940UW, which specs at 7.99 mb/s.

I don't understand. I have the bandwidth on the drive, I have a processor that I don't believe is underpowered for the codec (esp since the processor load never exceeds 40%). What could possible be causing it to drop frames. Per 15 minute clip I drop 30 frames. Why?

Could an upgrade of the VideoTools help? I am running 1.52 with 5.52 video driver. Thanks for any help.

Gunnar

[Dr Mordrid]

Just an observation or two.

The UW SCSI's throughput it marginal. Half frame HuffYUV requires at least 5-6 mb/s and any kind of unusual frame (bright flashs etc.) could very well drive it higher for a frame or so. This is why most of us doing such things believe in throughput overkill: that is having 1.5-3 times the capacity you theoretically need for a given set data rate.

Also I noted you're overclocking your system. 'tis a no-no with Matrox cards in my experience.

Also that CPU is still a bit marginal. You could put a 600mhz CeleronII in there very cheaply and get very close to PIII performance, which would help a lot.

Suggestion: other than the CPU note above I'd bag that SCSI setup for a nice, fast 7,200 rpm Maxtor DiamondMax Plus ATA100 drive. Even on an ATA33/66 controller those things scream and they're quite cheap.

I have used many of the Maxtors and they consistantly post over 20 mb/s sustained sequential writes (the important measure for video) in every benchmark I've tried. As a video drive they're more than fast enough for HuffYUV.

Dr. Mordrid



[This message has been edited by Dr Mordrid (edited 17 January 2001).]

[This_Idiot]

I dunno, am I unusual or something ? I mean, just yesterday it wasn't possible to capture video to a PC. Then all of a sudden it was, and we all got interested.

But it's still pushing the envelope, even now. Dropped frames can be caused by anything from a slow (or fragmented) HD, through incorrect Win swap settings to trying to capture on a Tuesday in Spring with an easterly wind. What's important is how much it is affecting your work. Some folks seem to suffer like hell with a single dropped frame, which can cause the whole of their project to misbehave like an imp on acid. For most of us I think it's a minor annoyance that our kit doesn't perform as well as the guy next door. Well that's OK for me, the guy next door runs some twin-cam hot sports that sneezes every time it gets too hot or too cold. I run a diesel - starts every time, runs 30% better fuel economy even though it won't outrun the guy from the lights.

So you've dropped 30 frames in 15 minutes. At NTSC rates, that's 27,000 frames. Or, if you prefer, a drop rate of one thousandth of one percent (0.00111%). Now go and open a Word document 2700 times and tell me how often you get a failure (that's about 5 years worth for the majority of home PC users).

So all I'm really trying to say is, is this screwing up your work or is it a (very) minor annoyance ?

[Sciascia]

One other thing, I love Virtual Dub. It is a fantastic app that has a ton of features. But one of it's strong suits is not capturing to Huff or any SW compression in my experience. It is not a huge app, but I believe that there is a little more overhead, CPU and other resources, than another apllication, such as the ever popular avi_io. In capturing it is as powerful a tool as V-Dub, but does a much better job at this without dropping frames. Especially for CIF rez, you should be able to pull this off. I can capture full huff (occasionally when the codec doesn't freak out on me) in avi_io, I can't even capture half rez with V-Dub, same compression settings. And I've got some decent toys in their to pull it off, (700M PIII, 256M Ram, IDE RAID...). So in my opinion avi_io is worth a try and it is only a few bucks to register it. Marcus provides fantastic tech support too.

[Gunnar1979]

Thanks for the suggestions. And yeah I guess dropping 30 frames for 15 minutes is not all that bad. I was just wondering if what I was doing was wrong, or if there is a way to get it done right with what I have.

In essence, it isn't going to kill me, but I would like to know if it is my settings or inability to configure everything properly, or is it really my rig that is underpowered.

I'm going ahead with what I have now. But if it is possible to avoid dropped frames, why not?

Thanks