Capture resolution question?

[videopete]

I am a bit confused as to which capture resolution to use for my Hi8mm home video captures. The guide suggests 352x480 mpeg2 capture but the main resolution suggestion page suggests 720x480 for Hi8 ?? My camcorder is actually a Sony Hi8 XR (extended resolution) - can record up to 440 lines of resolution. Can anyone suggest the minimum capture resolution using the ATI AIW9600Pro card and MMC 9.0.2 software ??

(2) Also, what's the main difference between a 1-4-2 mpeg2 capture and a 1-2-2 mpeg2 capture?? 1-2-2 suggests LESS compression during the capture which should yield higher quality ? Is this true?

Thanks!

[davideck]

352x480 is inadequate for resolutions above 240 lines.
https://forum.videohelp.com/viewtopic.php?t=306900

1-4-2 / 1-2-2 mpeg2 is unusual terminology. Where does it come from?

[videopete]

With 1-4-2 and 1-2-2, I am referring to the mpeg2 video sequence (p frames, b frames) - mpeg2 compression. Since I am capturing direct to mpeg2 format - I assumed that less compression might yield a higher quality result...

[pijetro]

As far as capturing is concerned, i've always had great success, and even better speeds (.AVI to MPEG conversion) with Half D1 captures.
Especially if it's going to be watched on my 31" tube TV..
As far as the MPEG compression is concerned, use more p and b frames for footage that's still and has little motion.

I assumed that less compression might yield a higher quality result...

It's not quite black and white..
As far as you're concerned, higher quality comes from every element of your capturing process..
VCR's, cables, tapes, TBC (time base corrector), etc....
I would read up on the stickies at the Restoration forums to get a better grasp of what it takes to get good quality capture, rather than worry about the nuances of IPB frames of MPEGs at this point..

Good luck!!!

[edDV]

For Hi8 I capture 720x480 at least 7200 Kb/s. I wouldn't go any lower if the material is hand held. If these tapes were shot professionally from a tripod with controlled exposure, then you might get a bit more compression if that is important. I wouldn't go below 6000 Kb/s VBR.

352x480 would severely degrade a Hi8 source unless your camera quality is unusually poor. It could be argued that 640x480 is adequate for Hi8 but that isn't a choice offered by the DVD standard.

[edDV]

As far as capturing is concerned, i've always had great success, and even better speeds (.AVI to MPEG conversion) with Half D1 captures.
Especially if it's going to be watched on my 31" tube TV..

If the goal is only display, not preservation, then you can lower the resolution to match your current TV but be aware that you are loosing nearly half of the resolution potential of the format. Low end Hi8 camcorders may not record the higher frequency luminance (detail) but try to make that judgement from a high quality TV with a S-Video connection.

[videopete]

Interesting...

I thought that Hi8 yields approx. 400lines of resolution. Hi8 XR can achieve UP TO 440 lines under best conditions. Wouldn't 352x480 suffice? My concern is that if I go up to 720x480 captures/encodes, then the bit rate would need to increase which results in bigger filesizes on the final DVD which may or may not give me better results. I want the minimal capture resolution to achieve near perfect, if not perfect, results without going overboard. Some people indicate 352 is sufficient, while others argue for 720x480 captures - it's not clear. There should be some mathematical formula to easily convert from lines of resolution to pixels required to capture - and be done with it......

[davideck]

There should be some mathematical formula to easily convert from lines of resolution to pixels required to capture

There is.
For a 4:3 aspect ratio, the theoretical minimum number of pixels per line required = 4/3 times the "horizontal lines of resolution".

440 * 1.33 = 586 pixels

The thread that I referenced above provides more info.
https://forum.videohelp.com/viewtopic.php?t=306900

Here is a general reference about resolution;
http://www.hometheaterhifi.com/volume_6_3/essay-video-resolution-july-99.html

Perhaps you are confusing "horizontal lines of resolution" with the number of horizontal lines in the raster.

[edDV]

There is vertical resolution limited by the number of scan lines with perceived resolution limited further by the Kell factor (see ref above). 480i vertical resolution is locked in to around 330 unless you do something silly like tossing every other field. But you need 480 scanned lines to achieve 330 "lines of perceived resolution" as read from a chart.

4:3 and 16:9 aspect ratios demand more raw resolution in the horizontal direction. "Lines of resolution" is read from a test chart that references a central circle where horizontal and vertical resolution are measured by the eyeball the same way regardless of aspect ratio.

Horizontal resolution is where the action is. It is limited first by recording format and next by the capture camera lens, CCD sensor and video processing performance. If you buy a cheap Hi8 camcorder the camera may only deliver 200 lines of horizontal resolution even though the recording format can handle 400-440 lines. You need to determine how good or crappy your camcorder performs but purchase price and year bought are good indicators. Everything gets better and cheaper over time.

A good consumer Hi8 camcorder like my 1990 Sony CCD-V5000 ($3000 at the time) will get close to those 440 lines limited mostly by inherent noise in the Hi8 recording format. The same camcorder performs much better when recorded to DV format over S-Video. At that level of performance, there is no benefit of 720x480 over 640x480 but DVD doesn't give you the choice. The choice is 352x480 (too low) or 704x480 or 720x480.

440 lines of horizontal resolution does not mean 440 pixels. The chart is measuring distinction of alternate black and white lines. You need more pixels (~1.4x or more) to resolve alternate lines. The wider the aspect ratio, the more horizontal pixels you need for the same performance. 4:3 Hi8 maxes around 640x480. DV and DVD use 720x480 for either 4:3 or 16:9. At 4:3 aspect ratio, 720x480 is good for about 500-550 "horizontal lines of resolution".

If you want the optimal Hi8 tape transfer, you bite the bitrate bullet and archive at 704 or 720x480 @ 7000 Kb/s or more average bitrate. The more shakey the camerawork, the less interframe compression you will get so dial in more bitrate.


EIA resolution test chart. This is put in front of the camera lens and read off a good monitor.

[videopete]

Thanks for all your input. This is great advice.