I'm using Adobe Encore CS3 to author and burn real Blu-Ray discs. Encore will accept MPEG2, AC3 and MP4 as separate files from Vegas.

Will Encore accept an mp4 elementary video stream and an AC3 audio one?

I'm using MPEG2 and .AC3 almost exclusively but, yes, I believe that I have been able to load an .MP4 (actually h.264) elementary stream. I'll make sure and post back to this thread.

My source is 1920 x 1080i video, I edit in Vegas and save as an MPEG 1920 x 1080i file (I think 24 Mbits) and then burn to disk using ULead DVD MovieFactory 6, onto Sony BD-R and BD-RE, creating a BDMV disk. I save as a combined video and audio file

John,
I am glad to hear it works for you. I am trying the same trick, and burning $19 coasters; I almost have a complete set for my family of four.
To mutilate the old song, I am "Enraged, Bothered and Bewildered."

I am using Encore, with its recent update for h.264 files...the new Sony Blu-ray burning, the BWU-200S...and I am getting nowhere.

Can you cite briefly, what you prepare in Vegas, how you prep it in Encore, and what burner and player you are using?

Every time I burn a disc, not even the burner will read it!

If your using windows XP you can't read them.
They are burnt in the UDF 2.6 format.
Vista can read them without any problems.

If your using XP then Nero 8 Ultra with the Blu-Ray add-on pack can read and play them under XP.
So can PowerDvd7 Ultra. I think both programs though require you to have a machine that's fast enough, if PowerDvd7 Ultra sees your machine as not meeting the spec's it will not play the disk.
But XP cannot read these disks in the UDF 2.6 format, even when I load UDF reader software so I use Vista to read them from explorer.
Maybe those coasters are good.

Well, I cannot play them on my Blu-ray player, either. Just got the Sharp BD-HP20U player, and it has played none of them.

I tried the simplest possible project in Adobe Encore, which was to take a 2 minute AVI and create a new timeline. I had Encore "build" the project straight to Blu-ray disc, no menus or anything, in H.264 encoding.
My error message was somewhat encouraging, which was "Cannot play this disc." Somehow that sounds better to me than "Incompatible disc."
So I tried again with a MPEG-2 project.
Same error message.
Which leads me to my plea to John, who I hope fervently checks this forum on the weekends, to give me his recipe for using Encore to make playable discs.
And, 4eyes, even though I was sorely tempted to stomp on the coasters, or at least throw them against the wall, I have continued to treat them with some reverence. Maybe something will rescue them...