Dropping frames

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I shouldn't but I am dropping frames. My hardware: Pentium III, 450Mz, 64MB, Dynalink MagicTView tv card, IBM 45GB 7200rpm ATA-100 HD installed as secondary slave to a CD-ROM (which is never in use when capturing). Set-Up: Win98 SE, Desktop Computer no power management, read-ahead optimisation NONE, disabled write behind caching for all drives, windows managed virtual memory, defragmented all disks, DMA on. Capturing with VirtualDub: 352x288 (PAL), 24bit RGB, 25fps, uncompressed. Results: Data rate 7350 k/s, CPU usage 10%-30%, irregular dropping of frames from 5 to 150 out of 13500. The funny thing is everyone keeps talking about the magic 2GB file size limit while system seems to work fine untill about 4GB. Can anyone figure this one out. I have been trying to get it right for months and no luck. Please help and thanks in advance.

-- Mike (no.one@xtra.co.nz), February 19, 2001


My questions is, why would you want to install your IBM ATA-100 as a slave to a CD-ROM other than convience. My guess is that you put it there as an add on. Am I right? My recommendation is to reconfigure your system to having your fastest HD as primary. ATA-100 needs THE special cable for optimum operation. I'm not sure that it is recommended that you hang any non-ATA hardware off of it or not. A friend got one of those HD's as his primary and the system performance is phenominal. Does your mother board support ATA-100 or did you have to configure your HD as as non-ATA?

Windows disk caches off of the C: drive, so overall system performance is pretty much dependent on the speed of that drive.

I find that it is not that unusual to drop some frames when a capture begins which could be due to HD spin up. If the frame droppage is sporadic, well that's anybody's guess.

Memory is really dirt cheep right now. PC133 256Meg for less than $60. You really should beef that up.

The 2GB/4GB/etc. limit depends on your operating system version.

-- me (snake_mountain@hotmail.com), February 19, 2001.

Aside from what me above has said (all true), what codec are you using for capture? Is it h/w or s/w? I'm asking because for the framerate and resolution you have specified your datarate seems too high. I use a G200 Marvel and at those specs, using the in-built Matrox h/w codec at 4:1 compression and full uncompressed audio 44K/16/stereo the data rate is around 1200k/s. You have to likewise know, for comparison, that type 1 DV AVI (720x576, 48k/16/stereo), the data rate is about have of what you have specified, ~3500k/s.

-- Mehmet Tekdemir (turk690@yahoo.com), February 19, 2001.

me, you are right. It is an add on. Sole purpose space and speed for capturing from videos. Win98 has an anoying habit of interupting HD read-writes for its own purposes. Consequence dropping frames. That is why the HD is on a secondary controller. The tech questions/statements are somewhat beyond my understanding. A shop stuch th HD in for me.

Not only is droppage sporadic but somtimes doesn't start until about a min. of capture. Realy vierd!!!

Mehmet, I don't use any codec. Capturing full frames uncompressed. That is why the high data rate. Hoping to get better quality VCDs. My videos are bad enough as it is.

Thans guys for giving it a go. I am not giving up. If you got any ideas please let me know.

-- Mike (no.one@xtra.co.nz), February 20, 2001.


I have been able to capture "uncompress RGB" using a Celeron 266 (soon to be a P3 850E), ATI Wonder, WD 20G ATA/33 HD, VirtualDub from VCR (RCA jack connection)without droping any frames at 70% CPU utilization. I've even been able to capture MPG1!

As Mehmet ask, even though you say you capture full frame, which codec did you use? Even some of the so-called RAW codec's use a 4:1 compression. Is it "uncompress RGB" or MPG1?

If you really want to optimise your system for Video, I would suggest that you do a complete rebuild. Move your ATA-100 HD to IDE1 using the special ATA cable and not hang a slave off of it at all. Put your remaining old/slow HD as master on IDE2 and your CD as slave on IDE2. Fdisk, format, and install your operating system. You'll have a brand new PC in an afternoon. I would assume that your CD is of the rw flavor so just remember to copy all of your still compressed application install programs on a CDrw, such as Virtual Dub, etc. If you've never done this before find someone local that will do if for you for the cost of the few beers that it takes. (I've averaged two rebuilds a week).

-- me (snake_mountain@hotmail.com), February 20, 2001.


I'm having problems with capturing AVI & converting it to MPEG1 or MPEG2.

PROBLEM 1: Frame-Dropping I have tried BOTH Virtualdub & WINTV video capture software but I seem to have problem of FRAME DROPPING.

I'm in the UK so my WINTV is set ot PAL format. I try to capture at 25fps but it usually results in lots of frame dropping so I do 20fps instead. I also get the same problem if I try to capture AVI at LARGER THAN 320x240.

-MY current IMAGE FORMAT is 24bit RGB. -I use MS MPEG4 codec but even at 25fps I get frame dropping.

Are there any way around this, i.e. to eliminate frame-dropping if I increase the video dimension and increase fps?

PROBLEM 2: AVI2MEG2 & Synchronisation I currently convert AVI to MPEG with AVI2MEG2 v1.24 beta 12.

When I convert AVI (produced by WINTV capture) to MPEG, the video is NOT in-sync with the audio though the audio is OK, i.e. ONLY the video skips a bit. The original AVI however, is perfectly in-sync.

What adjustments to the settings of AVI2MPEG2 do need to make, if any?

Also, what's the difference between AVI2MPEG2 & AVI2MPEG2vfw ? I have a HAUPAUGE WINTV card so which of these 2 is MORE suitable for me?

-- Mike (mikester_the_mp3_man@yahoo.co.uk), March 12, 2001.

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