What is needed to achieve a video capture rate of 30 f p s?

[jayant]

I am assuming that the quality of videos as I see them after making a VCD 2.0 would be superior with a video capture rate of 30 frames per second.

I have the AIW-128 Rage card and Pentium III (700 MHZ) processor on my system but if I try to capture at 30 fps with VirtualDub, I get error messages indicating dropped frame rate going to 5 to 10% or even higher, asking me to try and capture at a lower frame rate. Are the AGP-1 cards by the very nature of technology used, limited to a capture rate of 15 frames per second?

Will the problem be automatically solved, if and when I can procure the 2G/4G AIW Radeon 8500 card which I am unable to get for the PAL system?

Or is there any fine tuning possible even with the Rage card to achieve a capture rate of 30 frames per second?

P. Jayant

[WildStyle]

You wrote,

"I am assuming that the quality of videos as I see them after making a VCD 2.0 would be superior with a video capture rate of 30 frames per second."

Wrong assumption. If your target is an NTSC tv, then you should capture to 23.97 frames per sec. If the target is Pal, 25 fps.

Check if you have DMA transfers enabled on your OS.

Try capping at a lower resolution.


WS

[jayant]

The fps I actually tried was 25. I think VideoDub automatically adjusts it downward to the exact value necessary. It is in fact at that rate that I got the error message.

I have checked in the Control Panel Device Resorces and the DMA Channel is enabled.

From your reply, do I conjecture that 25 fps is feasible even with AGP-1 cards, if all the settings like "enabling the DMA" are strictly implemented?

Is Pentium III speed adequate? Is the Hard Disk Speed relevant? Is there a minimum for that? Does a SCSI improve the performance? What other parameters should I check up?

P. Jayant

[kinneera]

I can capture 29.97 fps with the PCI version of this card, so your bus isn't the problem. You're capturing in regular mode (F6) and not internal mode (F5), right? The weak link might actually be your sound card...what is it?

[jayant]

I am capturing with Internal Mode in VirtualDub. PAL system. Frame rate 25 fps. Frame size 320 x 240.

I am intrigued by your reference to the Sound card as the "weak link". How does the Sound Card hamper reaching higher capture rate? I have a SoundBlaster Live Value card which does not cause any problems as far as the audio is concerned in Windows ME. In the XP partition, it gives stuttering and cyclic heavy breathing sound in the background, only while listening to a live TV broadcast with ATI TV. The audio is fine even in XP while playing mpg files with Windows Media Player or a VCD with the ATI VCD Player.

P. Jayant

[kinneera]

Well, to answer your question first, ATI cards (and most other low end average consumer level cards) route the audio through your sound card for synthesis into PCM WAV...so if your sound card can't perform this task fast enough to keep up with the audio packets its receiving from the capture card it will either (a) cause desync or (b) the capture card/software will automatically drop frames to prevent (a).

However, you are using the same soundcard as me, and it hasn't caused me any problems. So to me, the most obvious problem is that you are capture in internal mode. Don't do that, it isn't supposed to be VirtualDub's general capture mode - in addition to dropping frames like mad even on fairly good systems (I have a PIII 800, and I get 15-25% frame drops if I capture that way), it doesn't appear to support segmented captures in that mode.

Use regular capture mode (F6), and you shouldn't have any problems.

[rocraz]

Hi there,

I guess I can help you with the doubt about new ATI AIW RADEON 8500DV. I own this card and it is installed on an Athlon XP 1800 computer, 512Mbytes and 40Giga HD (7200rpm ATA100).
Using this hardware and Ulead VS 6 or VirtualDub I am able to capture from my VCR at 30 FPS without problems (using those softwares there is 0 frames dropped, but using Adobe Premiere trial version I get some frames dropped).
By the way, I live in Brazil and am able to capture PAL-M or NTSC with AIW 8500DV.
Cheers and HTH,
Rodolfo Vaz