I've got 1080/30p video, AVCHD format, captured with a maximum bit rate of 24mb/sec. Edits fine in Premiere CS4, looks crisp and vibrant on screen.

I need to export some of the smaller edits to YouTube. I've tried the included YouTube presets in CS4. That is, I go to Export...Media, and in the Export Settings pop-up, I choose a format of "H.264", and a preset of "YouTube Widescreen HD". When I take the defaults for all the other settings I get a pretty washed out (low saturation), low res (limits to 720/24p) and somewhat choppy video stream with more noise in the audio than I hear when editing in Premiere.

Clearly, I need to change some of the other settings to improve the look of the video and the sound. But what needs to change, and how much?

It looks as if I need to have a level of "4.2" or higher to get 1080p. But what level is optimal? Then it looks as if I should increase the really small target and max bit rates to better reflect the way the video was captured. But should I set the max bit rate all the way up to the capture bit rate of 24mb/sec? One would think that something smaller might be more appropriate for YouTube, but what?

I've spend hours and hours searching for this information, and have tried a number of variations. It's clear to me that I'm just groping in the dark. And light greatly appreciated!

Did you set it to Maximum Render Quality? Its in that little dropdown menu on the right.
Or choose the HDTV 1080p preset.
Or have a look at wmvHD 720p, gives excellent quality.

Ann can I ask what is the Maximum Render Quality and how does it differ from not clicking it?

Did you set it to Maximum Render Quality? Its in that little dropdown menu on the right.
Or choose the HDTV 1080p preset.
Or have a look at wmvHD 720p, gives excellent quality.

I don't see a maximum render quality dropdown -- at least not on the Export Settings pop-up. Or is it on some other page?

The HDTV 1080p presets all seem to be for TV frame rates (29.97 as opposed to 30, which is what the camera actually used and what computers seem to want to see -- when I try this quicktime chokes on it, stutters up a storm, while it runs actual 30p just fine, but there's no preset for HDTV 1080/30p).

EDIT: Mea culpa. The camera documentation says it's recording at 30p. Premiere's metadata for the clip says it's at 29.97p. I've gotta go with Premiere on this one. Weirdly, when I've re-encoded this at 29.97, it plays just fine now.

What I'm currently trying is a custom preset based on the YouTube Widescreen HD preset:

format: H.264
Preset: YouTube Widescreen HD 1080 30p (<- my custom preset)

On the video tab:
tv standard: ntsc
framerate: 30
profile: high
level: 5.0
bit rate encoding: vbr 1 pass
target bit rate: 18
max bit rate: 24

What I get for this trouble is a fairly short rendering time (since the render isn't changing resolution or frame rate), a file that looks fine on my local computer using quicktime (well, there is some motion artifacting [woman talking with her hands, waving about], but the camera was running flat out at its maximum 24Mb/sec bit rate), and a file that YouTube uploads and processes like normal. But... YouTube makes available for viewing just an extremely compressed very low res version -- no 1080, or 720, or 480 version at all.

So... I'm now officially lost. Please help me overcome my cluelessness.

You need to be on version 4.2.1

Holy cats! I thought I'd looked everywhere. Didn't see that particular, um, button? Got it now, I'll give that a try. Thanks!

EDIT: Don't see any visual difference with this button checked. It did increase rendering time about 50% however.

But... YouTube makes available for viewing just an extremely compressed very low res version -- no 1080, or 720, or 480 version at all.

So... I'm now officially lost. Please help me overcome my cluelessness.

The answer is... patience. Turns out that it takes YouTube several hours to render the higher resolutions. I couldn't find anything that said that, but that's what happens. When I use the settings I listed, and leave the uploaded vid. overnight, the next morning it's available in resolutions up to and including the 1080/30p that I uploaded.

Silly newbies and their learning curves, eh?