bite rate and size

[maxwell3]

Ive been capturing vhs with iuvcr/huffy at 720x480 .then using tmpgnec to change to mpeg2 720x480 at vbr 6000 .The dvd's look excelent My question is this I can only fit 90 min or so on a dvd . Can I capture or encode at say 352x480 and / or a lower bit rate . All I want to do is have a the dvd look as good as the vhs tape . Any suggestions are welcome

[trevlac]

You should try some samples and see for yourself.

There are quite a few factors that would effect quality; content of source, quality (detail including noise) of source, what resizes to 1/2D1, even how you play it back.

But it is the bitrate that == file size. I'd start here 1st, improve the efficiency of my encoding (like with multipass vbr) with a lower bitrate, maybe try some filters to remove unseen details (if possible) and a lower bitrate.

A smaller framesize can get away with a lower bitrate. But getting to that smaller framesize can lower the quality of your video. For example, a bilinear resize with blur out some details. Another example is a direct cap at 352 on a BT8x8 based card. This will cause a loss of vertical detail due to how the chip works.

So lower the bitrate and see. If you get compression artifacts, tweak the encode, smooth the source, and then maybe drop the framesize. :)

[maxwell3]

I appreciate your response .If I understand correctly I should still capture at 720x480 and play with the frame size and bit rate in tmpg or CCE when I encode to mpeg2 . What If I capture at 352x720 first using iu vcr and huffy 2.2 ? I guess Ill try and play around and do comparisons I was hoping someone had already done some and could save me some time ( in short supply)

[trevlac]

I'm not sure you completely followed me.

1st. Lower the encode bitrate. If this makes it blocky, use 2 pass vbr or other better encode options.

2nd. Smooth your capture before encoding. Encoders might have options for this too.

3rd. Cap at 352x480 and start at #1 again. This may not work depending on the card you have.


You want to lower the bitrate. Personally, I would never cap and then downsize. Although quite a few smart people tell me I'm wrong. :D


To compare to what someone else does would require that you mention what type of source you have, (cartoon, high action, low action) and what card/drivers you are using. And to get an idea of what they/you consider good enough results. Frankly, it would be better for you to test because YMMayVary. :)


PS: You can also ac3 encode the audio to get more space.

[maxwell3]

Thanks again . You mentioned a bilinear resize . What exactly is that

[jggimi]

Click on http://forum.doom9.org/search.php?s=&action=showresults&searchid=440209&sortby=lastpost&sortorder=descending for a short list of threads discussing different resizing algorithms.