Quantcast Capturing MPEG2 to KVCD MPEG1 - digitalFAQ.com Forums [Archives]
  #1  
07-10-2003, 09:21 AM
dredj dredj is offline
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Hello, I have an ATI AIW 8500DV, and would like to backup my vhs tapes to kvcdx3. Since I will not be doing any editing on the captured video, will it be a good idea to just capture mpeg2 at higher bitrate say 8MB/s and resolution 352x480 and then use that source to encode to mpeg1 kvcdx3 ?

thanks,
dredj
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  #2  
07-10-2003, 11:38 AM
kwag kwag is offline
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Hi dredj,

Yes you can. Just capture at the highest bitrate you can

-kwag
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  #3  
07-10-2003, 12:28 PM
dazedconfused dazedconfused is offline
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@ Kwag,

Please correct me if I'm wrong (which may very well be the case! ), but if dredj is capturing at 352x480, then shouldn't he probably only encode that material to a resolution that is equal to or lower than 352x480? Otherwise, wouldn't he just be "blowing up" a lower resolution picture into a higher one? (and isn't it generally recommended to avoid doing this because it increases filesize while giving you no visual benefits?). I always thought that downsizing from a higher resolution (i.e. 720x480 to 528x480) was okay because then the pixel information was already there for you, whereas this isn't the case when upsizing from a lower resolution to a higher one

So shouldn't dredj probably either just encode at 352x480, or else capture his material at a higher-than-kvcdx3 resolution if possible?

Also, now that I think of it...since he's capturing from VHS, isn't there a certain resolution that VHS uses (it escapes me at the moment, but I think it's in the vicinity of vcd or cvd rez), thus making it counter-productive to encode any higher than the resolution used by his original VHS tapes?

Or am I just living up to my trusty nickname here Thanks for the insight...and good luck dredj!

-d&c
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07-10-2003, 12:54 PM
kwag kwag is offline
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Quote:
Originally Posted by dazed&confused
@ Kwag,

Please correct me if I'm wrong (which may very well be the case! ), but if dredj is capturing at 352x480, then shouldn't he probably only encode that material to a resolution that is equal to or lower than 352x480?
Yes, I missed the KVCDx3 target

@dredj,

If your source is VHS, there's no sense encoding higher that 352x480(576)

-kwag
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  #5  
07-10-2003, 01:16 PM
dazedconfused dazedconfused is offline
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Thanks for clarifying Kwag! (it's always nice to know I'm not just going crazy...well, not too crazy anyway! ). It's been quite awhile since I've done any vhs conversions, so this thread came in handy for me too. Thanks dredj.

-d&c
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  #6  
07-10-2003, 09:00 PM
dredj dredj is offline
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Thanks for the info guys, my follow up question is, will there be any big difference between captuirng avi to kvcd mpeg1 and capturing mpeg2 to kvcd mpeg1? Also what's the highest bitrate you recommend...10MB/s or too high? Also, since it's VHS and mpeg1, should I use 352x240 during encode or stick to same as the capture resolution which is 352x480?

Btw the reason I want to try this is to eliminate the convertToYV12() line on my avs script (v252), as it makes the final product less detailed...basically seems like smoky picture. So maybe by going to this route it will eliminate it.




Thanks,
Dredj
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  #7  
07-11-2003, 12:07 AM
dazedconfused dazedconfused is offline
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Hi dredj,

I've only ever captured to mpeg1/mpeg2 myself, so I can't really comment firsthand on quality differences between capturing to avi versus mpeg2 before converting to kvcd. However, I've often read that the best method, if/when possible (if you've got a big fast hard-drive and cpu) , is to capture using a "lossless" codec like huffyuv or mjpeg. This takes up a lot of space though.

For people without excess drive space, I've often seen the recommendation that capturing to mpeg2 at a high bitrate will suffice (don't recall how high right off hand...I'd venture ~5Mb/s to 8Mb/s would probably be good enough...but surely you can always go higher if your PC can handle it). You should be safe as long as you capture at just a low enough bitrate (for your chosen resolution) so that it doesn't cause your PC to drop too many frames (you might wanna defrag 1st too) .

I'm affraid I can't answer any of your other questions definitively (or even very non-definitively for that matter! ), so hopefully Kwag or someone else more experienced can offer some advice. As for the encoding afterwards, I'd probably keep it at 352x480, but the best thing to do is probably to rely on your own eyes by doing 2 small sample encodes @ 352x240 & 352x480 and comparing them on your tv. Good luck...let us know how you make out. This thread's getting me interested in the ol' vhs collection again...might hafta dust it off one of these days.

-d&c
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  #8  
07-11-2003, 12:33 AM
dredj dredj is offline
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HI D&C,

Thanks for the input, actually right now what I am doing is capture my VHS through DV Cam passthrough using DVIO. I have plenty of disk space for avi capture and each movie is just about 50min length (Barney's, Blues Clues...all my Son's Tapes ).

Anyway some of the reason why I would like to experiment this option were:

1. Eliminate colorspace conversion (my avi capture through DV is RGB, and some of the filters on the optimal script requires YV12 which produces smoky picture. I can't use YUY2 as it gives me one half of the screen in color pink and the other half is just the normal color).

2. Try to see if I can capture the close caption when capturing to mpeg2 as suggested by Kwag.

3. Try to minimize encoding time, reduce filesize and increase CQ.


I've been doing a lot of testing already for almost 2 months, tried 352x240 and the result is smooth but too blurry. Tried 528x480, well it looks nice but when I try 352x480 my eyes said that's much better, so I'm sticking to 352x480 resolution. ...sorry Kwag I tried to use your recommendation kvcd3 but I think my capture is not cooperating well with me.

Anyway, I just finish encoding a sample clip using optimal script and 352x480 and colorspace YV12....I have to inlcude TMPGenc simple color correction to remove the smoky picture and make the output much clearer and sharper.. (I use bright=20, contrast=90, Gamma=60 and I can't seem to find the correct values when using avisynth's tweak filter, hence I just use TMPGenc). I'm currently burning it now and will let you know what's the result.

And one more test I am currently doing, I found some few suggestions on the forum while i'm doing the encode, such as use MAX GOP 24 instead of 30, use temporalcleaner instead of temporalsoften....and I'll do that right after I finish burning my first testcase....

Thanks,
Dredj
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  #9  
07-11-2003, 07:42 AM
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Hi dredj

I had that same problem (one half of the screen in color pink and the other half is just the normal color) capturing using YUY2 colorspace and would also convert to YV12. However, I found that the Asharp(2,4) filter was apparently the culprit in the optimal script (does anyone know why?) - don't know why maybe you can replace it with Unfilter.

I haven't had much luck so far using the optimal script with my analog Camcorder captures - getting very low CQ values. Might be due to the fact I get large values for 'nf' in the optimal script. Maybe someone else has another explanation (anyone?) Right now I am getting better results using the 2.0x script

Post your results if and when you find those 'optimal' conditions, I'm sure it would help me
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  #10  
07-11-2003, 02:11 PM
dredj dredj is offline
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Hi ChuckM,

Did u use the VHS optimize script ?

Thanks,
dredj
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  #11  
07-11-2003, 02:42 PM
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Yes, though was using with AviSynth 2.5 with TomsMoComp as the deinterlacer.
Also was using a Dust filter (using the LoadPluginEx) and Convolution3d
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