Dropped frames.....what's usually the cause?

[Emanef]

I'm experimenting with the settings on my AIW7500Radeon card, and nearly always seem to get <1% dropped frames (twice has it shown nothing, presumably when it didn't drop). Is this usually linked to the hard disk transfer speed?

[Mirror_Image]

What codec/resolution/bitrate are you using when the frame drops happen? If it's just occurring briefly when you start to capture, I wouldn't worry too much (unless you need those start frames). If you right-click on the % dropped during capture and change the display to frames rather than time, you can see the exact quantity dropped, not just a percentage.

[vitualis]

A common source of tiny degrees of dropped frames (when your CPU is not taxed) is if there is a slight timing difference between your capture card and sound card (frames are dropped to keep sync -- a good thing).

There is probably little you can do about this.

Regards.

[Sulik]

Also, if you drop one single frame at the beginning, and then never drop a frame anymore for hours, MMC will still show <1% since it's not exactly 0%.
It's better to use the exact frame count to get an idea of how many frames you're dropping.

[Emanef]

Yes, thanks, I've changed it to shows actual frames dropped.

Had it capturing for an hour last night at 480x428 and 8 were dropped in total, and I think most of them were at the start.

[Emanef]

Just tried capturing at 720x576 with 6kbps, 90% motion detection (still not sure what this does - should it be higher or lower?!), standard frames types (I, 3P, 2B). A five minute capture dropped 24 frames, half of which were in the first five seconds.

That's pretty decent isn't it?

[HillJack]

Another cause is that your hard drive just can't keep up with the data being streamed to it.

I can't capture at 720x480 without compression - I end up with a 40% frame drop. Thats with a mere 11% CPU usage and dma enabled. It just can't keep up.

If there's too much data for your hard drive to handle, it will drop frames.

[Emanef]

That makes sense.....it also explains why I get much better quality capturing at 720x576 with high settings (which plays back really clear)than AVI (which plays back shite......fuzzy and dropped frames.....!)

I think with my system and intentions, I probably best just capturing straight to mpeg at the setting I need....

Thanks.