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HD to SD DVD aliasing issues
Slightly OT, but maybe not…
I’m getting some aliasing issues on my DVD made from HD timelines. I usually make SD 8-Bit DVD’s all the time and they look great. But, when I’m sourcing from HD, it looks terrible. Here’s my work flow, maybe you guys can figure out the issue.
OSX (10.4.11) FCP (6.0.2) DVCProHD720p60 timeline (Everything shot at 30fps and all looks great) I export as a QT (7.4.1) reference movie. Then, take that into Compressor (3.0.2) Use the Compressor DVD: Best Quality 90 Min Preset (Pgm is only 10 min) Change only the following settings:
-16:9
-Quality: 6.6/7.8Take that file into DVDSP (4.2.1) The final DVD has terrible aliasing. I’ve tried changing the Compressor presets for different Frame controls, but to no luck. Can you guys give me any advice to where I’m getting the aliasing problem?
Why I think it might not be OT is, should I drop the HD timeline into a SD timeline first, then continue like I usually do with SD programs? I shouldn’t have to waste time doing that.
Thanks in Advance.
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37 Replies
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[Ernie Santella] “I shouldn’t have to waste time doing that. “
No you shouldn’t.
Make sure in the frame controls tab that your have your output fields set to ‘same as source’ (which will yield progressive).
See if that woks for you.
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Just tried a test that setting and it still has some aliasing. The best looking DVD’s still come from dropping my HD timeline into an SD timeline.
Any other ideas or different work flows you guys are using?
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First of all, for a 10 minute program, there is no reason to use Best Quality or VBR encoding. Set your bit rate for CBR 1-pass encoding at around 7-7.5. However, I don’t think this is your problem. It might have something to do with your monitor. I tried 3 different tests (you can see my post in the Sony CineAlta XDCAM forum). I exported directly to Compressor from the HD timeline, then I tried editing in HD & pasting that into an SD timeline before exporting, and lastly, I did the full edit in an SD timeline before exporting. All three yielded identical results. The DVD looked great on my big HD TV, but on my SD CRT TV, I got mild aliasing, most notably on slow pans. I’m thinking this may be because my SD monitor does not support Progressive video.
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Thanks for your post. I am judging the results as my client will see them, off a DVD in a standalone DVD player. By your test, they should all same on the same monitor/player. But, they don’t. The HD-Compressor-DVDSP looks bad, the HD-to-SD-Compressor-DVDSP looks fine. There’s something going on in the HD-to-Compressor version.
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One more thing worth trying. Export directly to Compressor from your HD timeline and don’t render first. That’s what I did.
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Can you please post a screen grab?
Jeremy
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maker sure your frame size controls in compressor are set to Best. That helps a lot. In my experience you cannot entirely eliminate aliasing, it may go away but rear itself on a tough scene with hard angle edges. But you can minimize its effect.
You will have a lot more aliasing going on if you HD to SD within fcp. It has a lousy resizing engine.
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Chris, I’m getting the exact opposite. When I drag my HD timeline into an SD timeline, then export, it looks much better that exporting directly to Compressor.
I’m trying to save the HD-to SD timeline time factor.
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[Ernie Santella] “When I drag my HD timeline into an SD timeline, then export, it looks much better that exporting directly to Compressor.”
I have noticed of late that the connection between fcp and compressor has problems. if you export from fcp to compressor directly. Odd artifacts and jitter issues (not field order)
so I export the timeline as is by itself, THEN compress.
I just did a 90 minute feature that was 720P and it turned out to be perfect quality using this method. -
I don’t have problems with it either.
Try to create your own DVD preset instead of using Apple’s Perhaps it’s doing something you don’t want it to.
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