Best SVCD Capture Resolution...

[SHaque]

I am able to capture from my NTSC DSS dish at 720x480 without dropping frames (Huffy codec), and can later resize this to 480x480 in order to convert to SVCD. But is this the best way to do it? Would I actually get better quality by capturing directly to 480x480 or perhaps 640x480?

I'd appreciate any help you can offer!

-Shahid

[Vejita-sama]

You want to capture at the HIGHEST possible quaility possible, then resize/reduce as necessary. 640x480 is a PC resolution w/ a DAR of 1:1. Since you plan to make SVCDs I would stick to resolutions that produce direct TV DAR of 4:3.

[SHaque]

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On 2001-10-20 20:15:23, Vejita-sama wrote:
You want to capture at the HIGHEST possible quaility possible, then resize/reduce as necessary. 640x480 is a PC resolution w/ a DAR of 1:1. Since you plan to make SVCDs I would stick to resolutions that produce direct TV DAR of 4:3.
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I'm not very familiar with how to determine DAR. Would 720x480 have the correct DAR? When I resize from 720x480 to 480x480 I definitly do not notice any aspect ratio problems...

-Shahid

[Anonymous65]

The aspect ratio doesn't really matter when capturing. The vertical resolution is 480, and is fixed. The horizontal resolution is best in multiples of 2, so the best capture resolution for SVCD would be 960x480. Obviously capture at this resolution is a problem, so go the highest you can, like 720. When capturing for VCD, capture at 704x240 for best video quality (352x2=704).

[stanwebber]

save yourself some time and capture 480x480(or target resolution x 480). the resizing algorithm in use by even the most basic tv tuner chipset is more than up to the task

[Anonymous65]

The problem is that the "Tuner" does not capture at 640x480 and then resize to your wanted size. If that was the case, 352x240 captures would look very nice. The analog to digital conversion done by the BT8xx chip is actually sampling the video at the rate you specify. So, by oversampling, and then reducing it later, you get better quality. However, the conversion to mpeg does take longer when it has to do the reduction. But, you get two advantages, better sharpness and less edge noise in the mpeg encoded stream. You get the biggest gain oversampling making VCD's, and less gain making SVCD's. When capturing VCD you normally loose a whole field of video.

[Anonymous65]

Also, Vdub can do the 480 to 240 reduction when capturing, but it cannot do the horizontal reduction WHILE capturing. I would like to see a filter for Vdub that would do a 2:1 cubic reduction for both horizontal and vertical resolutions. Then, the capture card could be set for 704x480, but save only the scaled 352x240 on the hard drive. This would make the ultimate VCD source file.

[stanwebber]

sorry, my information is the bt8x8 chip samples the video at full-frame rates before resizing to the capture resolution you specify; however, all bets are off if you capture below x480 as one of the fields is completely discarded before resizing