Compressor: DVDs Less Than Satisfactory at DVinfo.net

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Old June 1st, 2006, 09:52 PM   #1
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Compressor: DVDs Less Than Satisfactory

I have 1080i HDV footage that looks fantastic (quality-wise) during editing. But when I put it on a SD DVD, resampling/compressing the footage with Apple's Compressor, the result looks less than desirable.

It's only about nine minutes long (it's a short) so I used the 16:9 90 Minute DVD Best Quality preset. Even at this "best quality," when played back on a set-top DVD player, I notice a lot of compression artifacts, especially during movement, and the overall video doesn't look as sharp as I would have expected, even for SD. It definitely looks "home made" and that's embarrassing.

Is there a way to get Compressor to output better MPEG 2? Turning up the bitrate doesn't really do much.
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Old June 2nd, 2006, 07:32 PM   #2
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you need to know what bitrates you are encoding at, if it's two-pass or single pass encoding, vbr or cbr, etc.
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Old June 2nd, 2006, 08:02 PM   #3
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I do know, it's VBR (so two-pass) 6.2 Mbps average with a max of 7.7.

I'm using a closed IBBP GOP structure with a max of 15 frames per group.

I haven't experimented much with GOP structure, perhaps this is the trick I should learn? Although IBBPBBPBBPBBPBP sounds rather efficient to me. Maybe I could try not using B frames, so, one I and 14 Ps or something. *shrug*
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Old June 2nd, 2006, 10:10 PM   #4
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Since your video is under an hour you could use a CBR bit rate of 8-8.5 Mbps. You should certainly be able to get decent quality at that bit rate.
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Old June 3rd, 2006, 11:02 AM   #5
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some encoders will do vbr with single pass encoding... does the compressor software specifically state that two-pass encoding is being used with vbr? i'm harping on it because that is usually one of the most important things that you can do to improve the picture quality.

i would not mess around with the frame structure, if you get it too far out of whack, it won't be dvd-legal.

are you using an intermediate codec to edit the footage with?
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Old June 3rd, 2006, 01:50 PM   #6
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Quote:
Originally Posted by Dan Euritt
some encoders will do vbr with single pass encoding... does the compressor software specifically state that two-pass encoding is being used with vbr? i'm harping on it because that is usually one of the most important things that you can do to improve the picture quality.
While it may improve the quality, it shouldn't make a huge difference at higher bit rates.

Whatever he does, his DVD is not going to look as good as his original HD footage.

Quote:
Originally Posted by Dan Euritt
i would not mess around with the frame structure, if you get it too far out of whack, it won't be dvd-legal.
Definitely agree with you there. I never touch the frame structure.
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Old June 4th, 2006, 11:34 PM   #7
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vbr will not improve the picture quality at the same cbr bitrate, but two-pass encoding should make a difference at all bitrates.

how much of a difference would depend on several things, including the quality of the source file being used, and how sophisticated the encoder is... in the case of this apple compressor, you could be right :-/
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Old June 5th, 2006, 12:24 AM   #8
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Well okay, I recompressed the footage using 8.5 Mbps CBR with an IPPPPPPPPPPPPPP GOP since I read up on GOP and they said to avoid B frames (the motion-based one) if you can spare the disc space. So that looked slightly better, but "normal" people probably wouldn't notice a difference.

Still, it doesn't compare to professional DVDs like feature films, which is what I want. So yes, I'm thinking maybe Compressor isn't all it's cracked up to be. :/

So then! Are there any good compressor recommendations for Mac OS X?

Last edited by Michael Jordan; June 5th, 2006 at 01:23 AM.
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Old October 25th, 2006, 10:58 PM   #9
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Did you end up finding a solution Michael?
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Old October 26th, 2006, 12:31 AM   #10
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Michael, also add a sharpening filter at about 4.0 or 5.0 in the preset inspector.

HD needs a little sharpening when downconverted usually.
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Old November 7th, 2006, 10:31 AM   #11
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Michael,

I'm by no means an expert on dvd authoring, but I've been going thru the same trouble, and sought out your thread, hoping to find a good answer. Since there wasn't one, I tried a few things, which have been very expensive (time-wise) as my project is 2 hours and the render times have been -let's say- surprising.

The artifacts that I have been seeing in my workflow are of two types...standard mpeg color space compression macroblocking, and what I would describe as a chunky looking interlacing--I think this second type is what you are seeing when you describe motion artifacts. The first set of artifacts can be dealt with by the quality settings previously discussed. (which in my case increased the render time from 12 to 26 hours). Seeing as your project is only 10 minutes or so, you should be able to get the best quality in this regard (because of its length, my project can only benefit a little from this).

The second group of artifacts are the most problematic for me...although I'm not sure if it would be noticed by the customer. I'm playing back on an HD set, and the "chunky interlace" lines are quite apparent, I've meant to try it on an SD set, but I decided to get it right for myself and experimented with a couple of things.

The simplest approach is this....(and I hope you are using FCP): copy the clips in your 1080i sequence and then paste them into a new 720p30 sequence (easy setup in fcp). Render out this sequence (in my case, another 18 hours), and then using the best setting for your project length (vbr 2 pass, field dominance progressive). This will give you a smooth, interlace-artifact free render that perhaps is a little soft. I haven't tried the sharpening suggestion ( as it will double my render time in compressor...) but It makes sense as you typically want to sharpen higher resolution sources when downconverting.

I also tried using the nattress plugin and a 720p60 timeline. They both doubled the render time, but didn't create a better final project.

In hindsight, I shot my project knowing I would be going to dvd, but I chose 1080i as my workflow, because I wanted to pull a few slomo's. In reality though, if I had shot 30f in the first place, I'd have saved a lot of time (of course I wouldn't have learned as much)....

Hope this helps.

Barry
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