How to eliminate lost frames?

[Bartab]

My system: 800mhz (was 550, read below) Celeron, 248meg ram. IBM Deskstar on Ultra DMA 66 IDE chain (ABIT BE6-II motherboard) with an ATI All In Wonder Radeon capturing with VirtualDub. Huffyvu codec.

Originally on the 550mhz I was capturing with about 10 frames lost out of 100,000 at 640x480. Not bad really, but I wanted to get it to zero so since CPU's are cheap (< $100) I upgraded to a 800mhz. The problem is I'm getting the exact same frame dropping

So how do I eliminate all lost frames without reducing capture size? . MJPEG drops a ton of frames, which really suprised me. Any gotchas in the setup?

Also, all captures we're over line-in. Captures using cable as a source drop about 10% frames total. Why is that?

[Freddie100]

I upgraded from an AMD 1.4G with frame drops to a P4 with no frame drops.

[patrickm]

lost frames can also be caused by the source (such as a VCR), some are inserted or skipped to preserve sync and aren't really 'dropped frames' but rather sync corrections. we had a pretty detailed thread about this a while back, search for "vcr jitter" and my name and i think you'll find it.

sound cards can also be responsible for 'makeup frames' because of bad clock integrity. as you capture, watch the jitter numbers on the lower left and the rate #s on the right. the audio should be very stable around 44100 Hz (stable is more important than EXACTLY this value, which is hardly ever perfectly attained), and the video should be as close to 29.970 (or 25.00 for PAL, etc) as possible. this usually bounces around some in the 3rd and later decimal places, and not too much to worry about there.

since you're on a radeon, you're using the WDM-VFW wrapper, which is a lower performance interface than real VFW that virtualdub would like to use. however, there are no VFW drivers for radeon, so you're out of luck.

cable tv is usually a pretty crappy signal to capture from just because you not only have to decode the channel, but there's noise on the line that can occasionally be interpreted as false sync pulses and result in looking for frames that aren't there or dropping a real one halfway through. in this case, it might help to run the cable to the vcr or tv tuner, and use the composite output to capture from. then you have less to deal with at the video card level, since the vcr is separating things for you. this problem is worse if you use a crappy cable company like adelphia or cox that habitually overdrive their networks.

don't put your windows swap file on your capture drive, capture to a different partition or drive.

as for MJPEG, what color format are you compressing FROM? i think yuv2 is native to the ATI cards, but RGB is resampled from software, so that wastes cycles. i have an AiW 128 Pro, so it's the same Rage Theater capture stuff, just that i get real vfw drivers. i do MJPEG all the time with almost no real drops (just the resync every 5-8 minutes like you're getting) but i'm not overly thrilled with some of the artifacts i get. but the ATI cards' quality is pretty good, it's noticeably better than the BT878 card i also have, and there's much less jitter than the bt878.

[mgargett]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-07-20 21:37:25, Freddie100 wrote:
I upgraded from an AMD 1.4G with frame drops to a P4 with no frame drops.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

Do you happen to work for Intel? The Athlon 1.4 is faster than P4's.. it's basically been proven.

[im new]

Sometimes, depending on your capturing software, empty frames are added to keep the audio in sync. These will show up as dropped frames.

V-Dub, AV_IO, and Studio software from Pinnacle do this. But I'm sure others do.

Play back your file, and if you can detect that you dropped 10 frames out of 100,000, damn your good

[Freddie100]

AMD is faster than P4 on everything but multimedia. I have two AMD's 1.4g computers and a p4 1.4g computer. The p4 outperforms the AMD's on video capturing. I like the AMD's for everything but that.

<font size=-1>[ This Message was edited by: Freddie100 on 2001-07-22 17:50:46 ]</font>

[patrickm]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
AMD is faster than P4 on everything but multimedia. I have two AMD's 1.4g computers and a p4 1.4g computer. The p4 outperforms the AMD's on video capturing. I like the AMD's for everything but that.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

speed isn't the issue, it's hardware and software design. some cards and drivers are specifically optimized for intel. if you have those items, intel will perform better. if your stuff favors AMD, AMD will win out.

[RWC]

Hi

AMD is still best overall incuding multimedia. Depend on hardware and vdieo card match right driver.

[RWC]

Hi again!

Also I add that get 1394 card will not drop frame.