USB capture quality issues

[mijalis]

Hi all,
I have a Sony MiniDV TRV12E (PAL) with USB (v1) and DV outputs.
Since, I haven't got a firewire card, I started capturing home video using the USB out.
The problem is that, compared to playing video from camcorder directly to the TV, the USB captured video is jerky (something like lost frames).
For capturing I used 3 different programs: VirtualDub, Ulead VS 7 and the included software ImageMixer (Pixela Corp.)
I captured in uncompressed RGB-24 (AVI) at 25fps @ 320X240 (PAL) which, usually, shouldn't be more than 6MB/sec.

I guess that USB (max 12Mbits/sec = 1.5MBytes/sec) just can't cope with the data stream...but I am not sure..
Will getting a firewire card fix this problem and make my homevideos smoothier, or there is something I'm doing wrong?
Has anybody else experienced the same behaviour using USB capture?

PC configuration: intel 2.4, 256 MB ram, HD: WD 40GB-8mb cache, nvidia mx440.

Thanks in advance.

[scharfis_brain]

your homevideos are 7**x576 @ 25 fps interlaced, while your capture is only 320x240.

interlaced means, that you'll have the smoothness of 50fps on TV. this is achieved through first transferring the odd and later the even lines of the picture...

but when you capture 320x240 (384x288 wopuld be better in this case) you'll only get the even OR odd lines of the video, which makes it look a little bit jerky (maybe film-like-jerky).
to get the full smoothness, you have to capture with 576 lines... But I doubt that this would be possible with USE, exept, your BOX is able to make MPEG-2 on the fly..

[bb]

USB is good for downloading photos from your camcorder to the PC. For video you should use firewire.

bb

[OvERaCiD23]

A FireWire card can be had for about $30 (US). That shouldn't stretch anyone's budget too far, and is well worth it if you want to have HQ video. If you search in this forum, I believe there was a discussion on FireWire cards a month or so ago.

[mijalis]

Originally posted by OvERaCiD23
A FireWire card can be had for about $30 (US). That shouldn't stretch anyone's budget too far, and is well worth it if you want to have HQ video. If you search in this forum, I believe there was a discussion on FireWire cards a month or so ago.
Ok, i found a Sunix pci card (in Greece) for just €15
(http://www.sunix.com.tw/en/Promotion-1.php?sid=123#top)
I am going to buy it and i will post the results here..
Thanks..

[mijalis]

I just installed the firewire card, the quality is much better now with full 720x576 resolution compared to the poor 320x200 quality of USB capture..
Colours are perfect, motion is smooth, so everything is OK now :)

The bottom line is:
Do not ever use USB for DV capturing. It is probably good only for use as a web camera.

[FredThompson]

USB 1.1, you mean, USB 2.0 can actually run faster than firewire...

[bb]

FireWire 800 is even faster :p

bb

[mijalis]

Originally posted by FredThompson
USB 1.1, you mean, USB 2.0 can actually run faster than firewire...
You are right, but the point is that all camcorders use USB 1.1, probably with 1-2 exceptions...
At least up to last month I remember I found only one camcorder (I think it was a Hitachi with DVD writer) that supported USB 2.0.