Help... Why is virtual dub capturing at a 4.5:3 aspect ratio?

[Jamestq]

Hi everyone,

Just finished my windows xp capture build with an ATI all in wonder 9000.

I have previously captured Hi8 footage using a digital 8 camera via FIREWIRE.

Now i have captured uncompressed YUY2 via S-video on my capture machine to compare it, while i am loving the quality improvements one thing is making me confused and sad. The video captured on the XP machine via virtual dub is doing it in a a 4.5:3 aspect ratio and the footage looks horizontally stretched. While firewire captured footage looks much more true to life and is a 4:3 ratio.

I cant see any settings in virtual dub that allow me to change the aspect ratio can someone please enlighten me as to what i am doing wrong.

Both captured footage are at a resolution of 720x480

Thanks

[latreche34]

Lossless or losslessly compressed AVI don't have an aspet ratio, It just captures the raw footage pixel by pixel or sample by sample, The original specification of analog to digital conversion mandates that the pixels are not square, they have to have their defined shape or pixel aspect ratio (PAR) within a video format and resolution, a.k.a SAR short for sample aspect ratio, their defined shape will lead to an overall frame aspect ratio of 4:3, Note that the active video resolution of a scan line is 704 not 720. So you have to set your player to display the frame as 4:3, If encoding set the SAR accordingly, I don't have the exact numbers on top of my head but we discussed it numerous times here.

[Jamestq]

Quote:

Originally Posted by latreche34

Lossless or losslessly compressed AVI don't have an aspet ratio, It just captures the raw footage pixel by pixel or sample by sample, The original specification of analog to digital conversion mandates that the pixels are not square, they have to have their defined shape or pixel aspect ratio (PAR) within a video format and resolution, a.k.a SAR short for sample aspect ratio, their defined shape will lead to an overall frame aspect ratio of 4:3, Note that the active video resolution of a scan line is 704 not 720. So you have to set your player to display the frame as 4:3, If encoding set the SAR accordingly, I don't have the exact numbers on top of my head but we discussed it numerous times here.

Thank you so much for this detailed information i have learnt so much today I thought i was doing something wrong but its nice to find out its normal. I fixed the aspect ratio in virtual dub 2 on my editing PC now the captures now look amazing especially QTGMC deinterlaced in Hybrid (an amazing program btw). Way worth building a XP capture computer the difference in quality between DV capture and using a All in wonder is amazing especially the color saturation and depth.