Capturing res problem and video card question

[solipsismx]

okay I have two major problems. This should be easy for you veterans...

I'm editing a skate video for my friends. The source is just a VHS-C camcorder. We captured everything at 320-240 and at 15 frames per second (accidentally) with an avert 98 tv card. It looked great on the screen. We edited everything with adobe and converted it to mpeg with some cheap program that came with my cd burner. After it was converted to mpeg, it still looked good. Well when we burned it to VCD, and watched it on tv (ntsc) it looked VERY pixelated and terrible.
I know I should've captured everything at 30fps so I can fix that, but what resolution should I have captured it in? Some people say 352x480 is good while others say you should capture it as high as you can. I just want it to look as good or close to as good as a vhs-c tape which isn't great. And I don't understand the 4:3 and 1:1 ratio thing. Isn't the ratio determined by the resolution?
My last question has to do with video cards.. My avert98 tv card only captures at 320x240 and 640x480. But the 640x800 only captures at 13 fps (I have a 1ghz comp with 320 mgs of ram so I'm sure my comp isn't the problem). Can anybody recommend an affordable (i.e. around $150) card that can capture at a high resolution at 30 fps?

[deadpac]

If you can get your Avert 98 TV card to work with Virtual Dub, then you don't need to waste another $150 on another capture card. Virtual Dub allows you to set your own resolution.

Capturing at anything higher than 352x240 NTSC or 352x288 PAL is usually not worth it, if you are going to end up only encoding to standard VCD MPEG-1 specs. Besides increasing the resolution will put more strain on your computer when capturing. Unless you want to creat XVCDs then increasing the bitrate is cool too and a slight increase on the resolution should do it, but if you go this route, then you will lose the amount of time you can place on a single CD-R disc.

VCD MPEG-1 352x240 NTSC or 352x288 PAL at 1150kb/s
or

XVCD MPEG-1 yourXresolution at your_bitrate_kb/s

In my opinion if you want to come close to recreating the quality of your source then I would recommend encoding your video to XVCD 2pass VBR with a max bitrate of 2000kb/s; average bitrate of 1750kb/s and miniumum bitrate of 1150kb/s. IMHO

[TheInformer]

Capturing at 352x240 throws away half the fields.
Capture at 352x480 instead and then resize to 352x240.

Just my two cents...

[loudanddeep]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2002-01-15 16:31:23, TheInformer wrote:
Capturing at 352x240 throws away half the fields.
Capture at 352x480 instead and then resize to 352x240.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

Does this process yield a better result than capturing at 352x240 in the first place?

If so, please explain why?

dp

[sommersby]

I have gotten the best results from tape by capturing at 640x480, there is a good reason that this resolution works so well that has been explained here a number of times. I use either huffyuv or picvideo with about equal results.

[Dave B]

Capturing resolution is always a hot topic on these formus.

Many people argue that you should capture at your desired end resolution as any excess data will be lost in the resize. In some instances, this can be true. However the majority of people on these forums encode to VCD and SVCD which requires the source material to be encoded using the MPEG codecs.

The MPEG codecs always produce a better output when a cleaner, more detailed input is provided. Hence a 352X288 resolution will only provide half the detail that a 352x576 input source will provide.

Calculating the optimum capture resolution however, is more complex than just saying more resolution, more detail. To fully understand capturing you must first understand how a television picture is constructed. In its simplest form, think of a TV picture (PAL in this example) of 576 lines of information running horizontally across the screen. TV pictures do not understand resolutions such as 640x480 and would render such information as 480 lines of TV picture and the 640 vertical resolution would be converted to a single line of data which would be fired onto the TV screen.

As a rule of thumb, always try to capture at the maximum horizontal resolution that the source provides (i.e. 576 PAL or 480 NTSC) Horizontal resolution should really make little difference but as horizontal resizing can produce artifacts, many people capture at a similar horizontal resolution to that of their destination format.

So for PAL VCD you might capture at 352x576 (and then resize to 352x28 and PAL SVCD might be 480x576.

Capturing all 576 lines will however require de-interlacing when producing a VCD but this is a separate issue which has been covered many times in the forum.

[Bstansbury]

"Rule of Thumb"

Your post says 'Always try to capture at the source resolution',... but if you input is Video 8mm from a camcorder,... the input res (for NTSC) is 320x240.

It seems from you note that you have "Lots of experience" in capture and video, TV,,.etc. Can you simplify this for us beginners by just filling in some blanks,..i.e.

1. I capture 8 mm camcorder data in AVI at xxxxxx YUY2?
2. I capture TV broadcast signals in AVI at xxxxx ??
3. If I want to capture data that is going to a VCD I set the capture for xxxxx, yyyy, zzzz.

I know that this minimal answer will not help us understand fully why we are doing it this way,... but at least it will get us started and onto the next page,..where we can take the time to get educated.

Thanks in advance.

[dphirschler]

Education is always a good idea. For instance, I was not able to make intelligent decisions about my capturing and encoding before I understood several key concepts:

Interlacing
3:2 Pulldown or Telecining
video framerate vs. film framerate
the nature of MPEG compression

What I learned researching these topics led me to my decision to:

1. capture at 480x480 (or at least 352x480)
2. apply the 'Telecide' filter in Virtual Dub
3. remove duplicate frames by applying the 'Inverse Telecine' filter in TMPGenc.
4. encode as an NTSC film VCD (or SVCD)

Also, before encoding apply temporal cleaner filters to further clean the video so that it will compress/encode better.


Darryl

[solipsismx]

thanks for the advice guys (although I'm still pretty confused). Anyway, I tried capturing at 640x480 (for ntsc) and it looked great. But when I encoded it to mpeg, it had more artifacts than any of my other captures (at lower resolutions). I think it might be because I'm using some cheap program that came with my cd burner to encode them. Can virtual dub encode avis? I remember it saying you could just save it as an mpeg but this doesn't seem to be true. Do you think the problem is my encoder or the options or lack of filters I used?

After experimenting with VHS tapes off the TV (not commercial) here is the best settings I found for VHS capture with Vdub:
1. Use 352*480 or 576 for PAL.
2. Resize while capturing to 352*240 / 288. There is an option in Vdub's menu "Vertical reduction". this will deinterlace the video and produce the correct res at the same time. It also helps lower the file size and clean up the video.
3. Now comes the hard part. Yoy might need a lot of space for the captured avi if you choose to compress video to MJPEG or Huff. I do this to provide the best possible image to the mpeg encoder.
4. Feed the avi to TMPGENC (free mpeg1 encoder) with VCD template options. Burn with NEro or other VCD compat software. TMPGENC is great for VCDs.

You could choose to capture straight to an avi only codec like divx if your friends can watch it on their PCs only.
Or you could try to use some vdubs filters to clean up the avi a little.

[Bstansbury]

Darryl,

Thanks for the answers. Sounds like very good info. I have some education about Video, and MPEG and was very deep into it for awhile before I retired. Now I find that I no more about my pitching wedge than MPEG. Funny how things like that just drift away. Now that I'm getting interested in Video CD's, I find it very necessary to re-educate myself.

Right now I'm having all kinds of problem with Vdub,...
is strange because I had it working fine for a good period of time,..then all of a sudden it has lost all audio input?

Thanks again.