just when I thought I had it all working...

[unstuck2]

I've been capturing off of 8mm tapes to an avi file and encoding with TMPGenc plus (using default settings) followed by TMPGenc dvd author.

the first 5 dvds came out great. All files were convereted using Tmpgenc "defaults" (whatever the wizard came up with):
most files were converted at 720X480, one at 352X480, all at 29.97 fps. And the maximum bitrates varied for every file from the 3000s range to 8000! All looked great once put on dvd.

The last 5 hours of video I captured have poor quality with a lot of pixlation especially where there is a lot of movement. Here's what I did differently:
1 I overrode the resolution from 352X 480 to 720X480, thinking this would give me better clarity. (Would changing this resolution setting not help the quality?)
2 I performed a batch encoding of two avi's.

Could the batch encoding have caused a problem, or should I not fool around with the resolution setting the "wizard" comes up with?

The avis for these files have since been deleted. Do I need to recapture the 5 hours of vieo or can I do something with the m2v files I've still kept to improve the final DVD output?
Thanks for your comments.

[Tommyknocker]

Since we do not know what TMPGEnc is using for settings now, you may want to try to set your own settings with a DVD-RW. Anyway, when you open the wizard, select the appropiate DVD template (NTSC/PAL), the continue with the way you ran your wizard normally. You do not have to encode the entire video again, just a sample, about one minute or so, and about the encoding. The sample will be in the file you named. Burn this file to a DVD and see what happens.

[poopyhead]

I overrode the resolution from 352X 480 to 720X480, thinking this would give me better clarity. (Would changing this resolution setting not help the quality?)
2 I performed a batch encoding of two avi's.

1) no..changing resolution will NOT give better quality....in fact, if you keep the same bitrate (or avg. bitrate w/ VBR)...increasing the resolution will NOT increase the filesize.

when you increase the resolution, technically...you're video will look sharper...BUT that is if you increase the bitrate.....otherwise, if you use the same amount of bitrate for both 352x480 and 720x480, each pixel in the latter will have less bitrate allocated to it, despite having more pixels overall.

so...if you don't change the bitrate, but do change the resolution..here's what's gonna happen...

higher resolution->sharper, but more macroblocks (just plain blockiness)
lower resolution->less sharp, but also less blockiness

it's a tradeoff

2) batch encoding shouldn't affect the quality...

[txpharoah]

higher resolution->sharper, but more macroblocks (just plain blockiness)
lower resolution->less sharp, but also less blockiness

No. Macroblocks are determind by the bitrate. In fact, low bitrates on lower resolutions will result in LESS macroblocks.

Example:
720x480 at 3.0 MB/s will be crap quality (takes 8.0 to be perfect).
352x480 at 3.0 MB/s will be pretty decent quality (take 4.0 to be perfect).

Upping the res won't accomplish anything if the source if not 720x480. Your 8mm tapes are about 325x220 (digital approximate of your analog source). The 352x480 is already better than your source (keep it here).

[poopyhead]

higher resolution->sharper, but more macroblocks (just plain blockiness)
lower resolution->less sharp, but also less blockiness

No. Macroblocks are determind by the bitrate. In fact, low bitrates on lower resolutions will result in LESS macroblocks.

errr....2 sides of the same coin....

however, macroblocks is not completely dependent on bitrate...it's a combination of bitrate and resolution..for the purpose of clarity in my example, i kept the bitrate constant to illustrate the effect of different resolutions on macroblocks.

it could also be seen by keeping the resolution constant, but changing the bitrate...with more bitrate resulting in less macroblocks

Example:
720x480 at 3.0 MB/s will be crap quality (takes 8.0 to be perfect).
352x480 at 3.0 MB/s will be pretty decent quality (take 4.0 to be perfect).

i was speaking in general.....yes...lowering resolution will have less macroblocks...but will not be as sharp. of course, you pointed out the source resolution of the 8mm tapes doesn't warrant the 720x480 resolution, but if we were encoding from DVD (which seems to be more common), then the source is 720x480....so the sharpness vs. blockiness tradeoff does occur

[txpharoah]

2 sides of the same coin....

Agreed.

A 720x480 8.0 MB/s will be sharpest.
A 352x480 8.0 MB/s will be sharp, though less than 720.

However, those are not typical uses of bitrate/res. But fine for an example to illustrate your point.

but if we were encoding from DVD (which seems to be more common)

I actually doubt this. I've never used DVD as the source. It was already DVD. Why bother?

Maybe you meant DV? In that case, go for 720x480 at 4.9+ MB/s. Stick to 8.0 to avoid any possibility of macroblocks.

[unstuck2]

thanks guys for all the replies. This is very helpful.

Unfortunately last night before bed, I started another encoding project that is burning right now. I made some guesses as to the settings: 720X480 @ 3.638MB/sec. I also changed the motion search to Normal from the default estimate search. This made for a 4 hour encoding of a 2 hour video! After reading your responses, I am not too hopeful about the quality I am going to get. (BTW I do the full video instead of a snipette because to see it on my DVD player I have to burn a DVDR anyway)

For 8mm tape projects from now on I'll stick to 352X480 and keep the bitrate as high as possible. do you use "constant quality" in the TMPGenc settings and punch in the bitrate setting you want? There has to be a guide on this here somewhere (I'll look).
I think the confusion with the resolution came from the first project I did which was off of a DV, and TMPGenc DVD author does not let you mix two different resolution videos on the same track, so I decided to do everything in 720X480.
Thanks again. I'll let you know how the one I'm burning now comes out. Good to figure it out though, I have ~15 more hours of 8mm tape to go through!