1080i to NTSC Mpeg-2 Looks Horrible - Solution

[Greg Penetrante]

Hello,

For those of us who edit 1080i60 jobs and then have to produce SD DVDs with said assets, did you ever notice how HORRIBLE the downconverts look when using Compressor or FCP?

For example, horizontal lines become 'fuzzy' and pixels look blocky and aliased when looking at a 100% zoom of the downconverted frame. Strange interlacing artifacts become apparent when observing motion.

Logic would dictate that downscaling an HD image would make great SD. NOT SO. It seems Compressor's downsizer has issues with interlaced material. Downrezzing with FCP into a anamorphic DV50 timeline looks a little bit better, but not as pristine as if the job was shot in SD to begin with. Perhaps After Effects may do a better job -- I don't know.

My client needed SD and HD versions of his project. And he complained loudly of the quality difference between an SD-originated project and an SD Downconverted project. I tend to agree: Apple/FCP/whatever does a lousy job of downsizing HD 1080i to NTSC.

The ONLY Software solution that did a decent job of downrezzing was Sorenson Squeeze 4.3. Its downreszzed mpeg-2 streams look much better than Compressor's. And Squeeze took half the time that Compressor did on the same HD asset (4hrs vs. 8hrs) when using single-pass VBR.

After more research and experimentation, I came across the best looking solution to downconverting. It was sitting right in front me: AJA Kona LHe Hardware Downconvert straight into Pioneer DVR-320 DVD Recorder via s-video. Duh!

The Pioneer's mpeg-2 encoder looks pretty close to Apple's when doing interlaced material. All I do is take the resulting DVDR, rip the mpeg/ac3 streams into DVD Studio Pro and finish the authoring. The cool thing about the Pioneer 320 is that I can customize the bitrate to fit the exact TRT of my program.

The nice benefit of hardware downconvert/encoding is that it happens in real time. Minimal fussing or waiting. The only downfall is the D/A->A/D conversion stage when going to the Pioneer.

If anybody else has solutions please feel free to post 'em ;-) Merry Christmas...


-Greg

[Dave Stern]

great idea! new life for the SD DVD recorders to boot! nice one..

[Nate Weaver]

I get great downconverts using Compressor.

Is it possible something's not right?

[Dave Perry]

I've had problems downconverting HDV or AIC projects from FCP but now that we are shooting 10 bit uncompressed HD we are getting wonderful results.

I had real problems with HDV material and field reversal issues. We just finished up some work shot in uncompressed HD this week and I told my boss how relieved I was to be able to just drag my masters into Compressor, choose my settings and let'er rip.

One thing you could try with HDV is when you finish the project, print it back to tape then capture out of the camera downconverted to SD. I don't know what camera you are shooting with but the stuff we shoot to tape with our XL H1 downconverts to DV out of the camera beautifully.

All you would need to do is capture the one clip then just drag it out of your finder window into Compressor. No need to mess with FCP after the capture.

[Greg Penetrante]

Hello,

I'd realized that I forgot to post some particulars. I use the Sony F350. The particular project in question was recorded with SP mode (1080i60 25mbit CBR). I edit with FCP 5.1.2 / Sony XDcam HD 25mbit CBR sequence presets.

I think it's a field reversal issue. The mpegs are blocky and aliased, especially with horizontal lines. I lose half the vertical resolution with Compressor. I've checked all settings. When I encode the same clip with Squeeze I get improvement. When I use Kona/Pioneer I get the same quality as if the show was originated on SD but sharper. I'll post some sample clips in a bit...

Keep in mind that Compressor does work splendidly with progressive material. Interlaced HD stuff has the problems (in my experience).

best regards.
-Greg

[Nate Weaver]

Originally Posted by Greg Penetrante

Keep in mind that Compressor does work splendidly with progressive material. Interlaced HD stuff has the problems (in my experience).

Aha. Let me do some playing and I'll see what I can find. All my stuff is prog.

[edit]
I slapped the default Apple 8-bit uncompressed Compressor setting, and you're right, there's a field order problem. I think I found the issue (what's causing the field order mistake in the preset). Will post back in a couple.

[Greg Penetrante]

Here is a linked file to show you the problem I am having with Compressor... the source file is 1080i60 XDcam HD 25mbit CBR.

Notice the line-doubling (not the interlacing... look closer) ;-)

http://www.pacsdc.org/gp-test1.m2v


best regards,
-Greg

[Nate Weaver]

Okay, I got it. Strange problem with how the Apple presets work.

I experimented with taking a 25mbit 60i XDCAM mov, and dropping into Compressor. I then applied the Apple 8-bit Uncompressed preset.

Looking at the source clip properties before you set a compression preset lists the source clip as having upper field first, which is correct.

If you look at the Frame Controls tab of the preset BEFORE you put it on a clip, all of the controls are greyed out, and the top drop-down on that tab says "Automatic". The Frame Control tab is of course where field order is set.

After you assign a clip this preset, the Frame Controls set themselves to "Off". What's weird is that you can correct this to "Automatic", then go change something on another tab, and then come back to it and it will say "Off" again! Apparently auto just don't work in some situations.

So anyway, I changed the Frame Control tab to "Custom", and then specified "Bottom first". I also turn off Adaptive Details, as it slows down rendering for me.

Anyway, after all this, I got a perfect downconvert.

p.s., I add a Sharpen Filter at 1.5 also, takes the dullness out but still leaves a nice un-edge-enhanced feel.

[Nate Weaver]

I just burned your clip in DVDSP and watched on NTSC, it's just a straight up field-order goof. It was a little difficult to confirm on the computer.

Do my trick above. If going from timeline to MPEG2 directly, make sure you specify bottom field first on the first tab of the MPEG2 preset.

[Nate Weaver]

Here's a link to an m2v I made. You'll have to burn it to a DVD to see it correctly, of course.

http://homepage.mac.com/nweaver/.Mov...ownconvert.m2v

[Greg Penetrante]

Nate,

Many thanks for your valuable insights! ;-) I'll try your suggestions.

Your clip does look much better; however, I burned your clip to a DVD. Watched it on Sony PVM1354Q monitor. The clip still appears to suffer field order problems. Hmm... When the camera pans right notice the strong flickering of the window arches. Also, the horizontal lines appear to be pixel-doubled, albeit not to the same degree as my footage. If you closely watch the picture frame borders and the crown moulding, you will see aliasing along the h/v edges. [is it just me?? ;-) or does anyone else notice??]

Can you try doing a downconvert from your blackmagic and watch that? See if it may look better than Compressor. ..?

best regards,
-Greg

[Nate Weaver]

Originally Posted by Greg Penetrante

Your clip does look much better; however, I burned your clip to a DVD. Watched it on Sony PVM1354Q monitor. The clip still appears to suffer field order problems. Hmm... When the camera pans right notice the strong flickering of the window arches. Also, the horizontal lines appear to be pixel-doubled, albeit not to the same degree as my footage. If you closely watch the picture frame borders and the crown moulding, you will see aliasing along the h/v edges. [is it just me?? ;-) or does anyone else notice??]

Can you try doing a downconvert from your blackmagic and watch that? See if it may look better than Compressor. ..?

[edit]

You're right, my m2v is messed up. But my first attempt at XDCAM to 8bit Unc was broken using the Apple template, then I found out the problem, and applied my fix to the Apple M2V template.

I didn't burn my own m2v. See how overconfident I am? Oops.

I'll have time to monkey with it tonight. But I DID fix the problem when going from timeline or file to 8-bit Uncompressed.