Premiere / Media Encoder CS5 and deinterlacing

Question

Maybe it's just me, but I'm not at all happy with the deinterlacing results from Premiere CS5 and Media Encoder. I've been using Premiere since CS3 and hoped for improvement in CS4, but no. And now with CS5, it's still just not good...
This is what I do in an nutshell: I edit 1080i HDV video in Premiere (using 1080i timelines) and export it to several formats, including 720p for Youtube. Now, whatever I do, I alway get some staircasing / aliasing on deinterlaced output. Not really bad and hardly noticable on video, but very noticable on logo's (which - ironically - are progressive to start with). Preview in Premiere looks fine, but as soon as I put the content through media encoder: staircasing. Even with the new "Use maximum render quality" option enabled.
When I output my 1080i timeline as 1080i MPEG2 video everything looks pristine (motion adaptive deinterlacing is then done upon playback by my nVidia graphics card). When I leave all rendering options the same and export 1080p or 720p - leaving deinterlacing to media encoder - staircasting is easily visible on logo's and detail is lost in the video compared to real-time deinterlaced output by my graphics card.
I guess my main question is: Why can't Adobe get this right? nVidia and ATI can do it very well and in realtime on their graphics cards (and have been able to do so for several years now) and freeware filters such as the ones used by ffdshow do a far better job too.
Why can't a high-end and expensive video editing solution like CS5 get this right? Hugely disappointing

Answer 1

Hi Todd, Steve,
I'm running CS5 a Cuda enabled system  (Intel Core i7 965, 12 GB DDR3, MSI GeForce GTX 285 with 2GB memory and a secondary GeForce 9400GT 1GB, running Windows 7 Ultimate 64 bit).
Cuda support is enabled in premiere CS5, as my timelines are yellow even when I enable cuda accelerated effects such as color correction. So no problems there.
I work with 1080i50 HDV and AVCHD files, which I normally use in a HDCAM EX 50i timeline (I use HDCAM EX because that enables me to render all effects and graphics in 1920x1080, instead of a HDV timeline which renders everyting in 1440x1080). I have tried using native HDV timelines too, but that reduces horizontal sharpness on our logo and on sceen graphics, while the deinterlacing problems I encounter are exactly the same.
The problem is that when I export an HDCAM EX timeline to 720p, I get noticable degradation in image sharpness and visible jaggies on our on-screen logo. The same applies when I export to 1080p. When I export to 1080i (so no deinterlacing is done by Premiere or Media Encoder), the file looks great on playback (deinterlacing done in real time by my nVidia card).
For the last few weeks I've been working a round the problem in a way which is not ideal for me, but which does seem to provide better results:
I now work with HDCAM EX 25p timelines instead of 50i, and I set the 'field options' flag for all my clips to 'always deinterlace'. This results in a loss of temporal resolution on my timelines (which I don't really want, since I also export to PAL 50i) but it results in noticably better sharpness and less aliasing on 720p output.
I'd love to share my on-screen logo title if you wish to have a look at it. Our logo contains a circle which shows easily visible jaggies when deinterlaced incorrectly. Please let me know how to get the files to you.
Thanks,
Eric