GF4 Video Capture

[Marro]

I tried capturing video from a DSS receiver with my GF4. Using the s-video input.

It works alright but there's some not so pretty scanlines or something like that in the video.

test 01 (http://members.rogers.com/amarro0535/test 01.avi)

test 02 (http://members.rogers.com/amarro0535/test 02.avi)

You'll need divx 5.02 :scared:

Any ideas? Is this normal?

[DrAsperigus]

T0MB0 is the best person to answer this question.

No audio?

[Marro]

No audio. Didn't want to make the file any bigger than it needed to be, plus my main concern right now is those scan lines.

[Marro]

Captured using 320x240 and can't see the lines now.

Could be the smaller size that makes them blurry, but I’m guessing that that capture size is more natural for the capture chip. :crap:

Edit:

The video encoder is used to encode PC graphics data at maximum 800 x 600 resolution to PAL (50 Hz) or NTSC (60 Hz) video signals.

Nah, it cannot be the resolution then.

[X-Todd]

is that the interlace shit coming out?

[Marro]

On the clips? I guess. It shows more on fire or white stuff. No likey.

[Ker]

Originally posted by Marro
I tried capturing video from a DSS receiver with my GF4. Using the s-video input.

It works alright but there's some not so pretty scanlines or something like that in the video.

test 01 (http://members.rogers.com/amarro0535/test 01.avi)

test 02 (http://members.rogers.com/amarro0535/test 02.avi)

You'll need divx 5.02 :scared:

Any ideas? Is this normal?


Yes, NTSC tv is interlaced, and the scanlines are the interlacing. You can run a deinterlacing filter on it (video editing program), or see if your Capture card has the hardware to remove it. Hauppauge cards do that I know of, some other as well..

[Ker]

also..


gamma correct your monitor, the brightness/contrast of the .avi is just about awful ;)

[Marro]

Too bright? :cheese:

I was dicking around with the driver settings when I found the interlacing stuff, didn't set it back to default.

I'll check and see if any the capture programs I have do that interlace removal thing you mention.

Thank You.

Edit:

NTSC and PAL video both use a system called interlacing to increase visible resolution. A whole frame – 525 horizontal lines in NTSC, 625 in PAL – is split into two fields, which are sent back-to-back. Scanlines from the two fields interleave with each other to form a complete picture with twice the vertical resolution, as shown on the left. NTSC sends alternating fields of 262 and 263 scanlines at 60 fields per second; PAL sends alternating fields of 312 and 313 lines at 50 fields per second.

Frame sizes with 240 lines or less of vertical resolution usually cause non-interlaced captures, as shown on the right. This is the same way your computer usually paints its screen: right-to-left, and top-to-bottom, just like how you read a book. Your capture card continually grabs single frames and saves them to disk. Non-interlaced captures off of video are limited to 60fps for NTSC, 50fps for PAL. However, most capture cards in this mode stick to a single kind of field for the operation – either even or odd -- and so the limit is usually either 30fps or 25fps.

If your vertical resolution is higher, such as 480, you are probably capturing in interlaced mode, shown on the left. Your capture card grabs two consecutive fields and combines them to form a single frame, which is saved to disk. The main problem with interlaced capture is that the two fields don’t have to correspond to the same frame. Instead of capturing 30 (25) frames per second and encoding them into pairs of fields, video cameras actually send alternating fields of 60 (50) different pictures.

I think I understand better now. I think :ninja:

Edit #2: The DivX codec has a parameter called "Source Interlace". Guess I'll have to toy with it and see if it helps. :)