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Digital noise around rendered text

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Curt Schulz
Digital noise around rendered text
on Feb 24, 2011 at 5:38:18 pm

Upon rendering text (pre-rendered text is unaffected) I am getting a halo of digital noise around the text. Please see attached image. I am using FCP 7.0.3. Any advice on how to fix this issue would be greatly appreciated.

Thanks,
Curt

rendered:


unrendered:


Curt Schulz
MBP 2.53 4GB Ram/Mac OS 10.6.4/FCP7.02/Matrox Mini w Max 2.0.0.0150


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Zane Barker
Re: Digital noise around rendered text
on Feb 24, 2011 at 8:14:28 pm

Sorry but unless you provide more info we can only guess.

For starters what are your time line settings?

**Hindsight is always 1080p**


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Curt Schulz
Re: Digital noise around rendered text
on Feb 24, 2011 at 8:27:43 pm

640x480 NTSC
4:3
Pixels: Square
Field Dom: None
Anamorphic: No
QT Settings: Compressor: Pro Res Proxy
29.97

Thanks,
Curt

Curt Schulz
MBP 2.53 4GB Ram/Mac OS 10.6.4/FCP7.02/Matrox Mini w Max 2.0.0.0150


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Bret Williams
Re: Digital noise around rendered text
on Feb 25, 2011 at 5:58:16 am

Isn't pro res proxy just that? A less than full final quality codec? It looks fine before you render because FCP is showing an uncompressed RGB rendition of the frame. Once you render it into a low quality proxy codec it loses quality.

What's up with the 640x480 frame size? What media are you working with? What's the whole intent here?


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Curt Schulz
Re: Digital noise around rendered text
on Feb 25, 2011 at 5:15:34 pm

Brett,
Seems like you have more questions than answers. ProRes Proxy refers to file size and data rate. According to Apple:

"Roughly 30 percent of the data rate of Apple ProRes 422

High-quality offline editing at the original frame size, frame rate, and aspect ratio

High-quality edit proxy for Final Cut Server"

The files are recorded to the the mpeg format at 640x480 from a surgical scope in an OR. Not the highest quality to begin with but I still need to edit it so I run it through ProRes and the quality is the same as the original at a fraction on the other ProRes options.

Curt Schulz
MBP 2.53 4GB Ram/Mac OS 10.6.4/FCP7.02/Matrox Mini w Max 2.0.0.0150


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Tony Silanskas
Re: Digital noise around rendered text
on Feb 25, 2011 at 5:26:53 pm

[Curt Schulz] "I run it through ProRes and the quality is the same as the original at a fraction on the other ProRes options."

Are you saying you convert it to ProRes Proxy? If so, Brett is correct as the quality is not the same as the original. It is a "proxy" quality clip. ProRes LT will get you close to the original quality with the file size you have.

tony


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Curt Schulz
Re: Digital noise around rendered text
on Feb 25, 2011 at 8:39:30 pm

I've run tests and there is no difference in the quality of the original mpeg and the ProRes Proxy, what I see on the screen and what my final output looks like compared with the original. If you could offer a more detailed explanation of what you mean by quality maybe I could better understand this, I just use my eye. Maybe I'm reading the white paper on ProRes wrong, but the bit rate for Proxy is half of the LT. I store over 200 hours of surgical footage and have started using ProRes Proxy to cut down on space.

Back to my original question, I have since use the "send to compressor" function and exported a h.264 .mov version and it does not have the digital noise. If I export a fully rendered ProRes Proxy from FCP, I get the noise in the export. Weird.

Thanks for feedback BTW,
Curt

Curt Schulz
MBP 2.53 4GB Ram/Mac OS 10.6.4/FCP7.02/Matrox Mini w Max 2.0.0.0150


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Tony Silanskas
Re: Digital noise around rendered text
on Feb 25, 2011 at 9:34:03 pm

What I meant by quality was that ProRes Proxy is roughly 12Mb/s for the SD, ProRes LT is 29 Mb/s and ProRes 422 is 42Mb/s. So you are gaining a lot more information in the file when going from Proxy to LT and LT to standard ProRes. This becomes a big issue when you start to color correct or add effects to a shot since you want as much information from the original file as possible when doing these things. And with any type of compression, the less the bitrate, the more the artifacting as it has less information to display. And this true when you render out graphics in a Proxy timeline as it's rendering to the low bit-rate Proxy codec. But I've used Proxy and agree it looks way better than it should sometimes, given it's small footprint.

Now, I say if you think it looks good and the client's happy then go for it, as it saves a bunch of space and renders faster. One thing you could check is to see if you are rendering in High-Quality and Best Motion settings in your sequence settings. It seems weird though that "Sending to Compressor" makes it look better. And I'm happy to see "Sending to Compressor" work for you as I gave up on it years ago.

tony


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Bret Williams
Re: Digital noise around rendered text
on Feb 26, 2011 at 6:20:42 am

The easiest thing to compress is soft fuzzy video. Which, is sorta what you have with your mpeg source video. The ProRes Proxy is probably enough data rate to look exactly the same. UNTIL you add nice sharp uncompressed text. It doesn't have enough data rate to look as it does before it's rendered. When you render it, it goes from uncompressed, to a very small pro res proxy data rate.

My guess on the send to compressor? If you haven't rendered it, then it's actually sending the unrendered caches to compressor for compression to h.264 and skipping the render step in fcp. If this is true, it goes against nearly everyone here's understanding of how this function works, and is certainly a fantastic argument for using it. Most here do not use the send to compressor function because it's slower and in the past, tied up your edit system. Perhaps some changes were made in FCP 7 that I was unaware of. I may test it myself.


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Bret Williams
Re: Digital noise around rendered text
on Feb 26, 2011 at 6:47:04 am

And I'll be damned, maybe I was the last to know it, but what I said is exactly what you were seeing. Sending directly to compressor ignores all rendered files (your artifactly prores proxy ones) and uses the original source media and compresses directly to whatever you've chosen in the send to compressor dialogue. The h.264 you're encoding to is infinitely of better quality than pro res proxy. And from the manual I never read anymore...

"When Should You Export Directly to Compressor?
The advantage of exporting a sequence to Compressor directly from Final Cut Pro is that rendering happens as part of the transcoding process, potentially saving you time and eliminating unwanted artifacts."

And so I did some tests. I even made a seq with sorensen as the rendering codec. Rendered a bit and it of course now looks horrible. Looked fine before rendering. Send that rendered section to compressor and the resulting h.264 looks beautiful. It completely ignored my intermediate sorensen render, and rerendered it all from scratch to h.264. Wow cool.


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Bret Williams
Re: Digital noise around rendered text
on Feb 26, 2011 at 7:35:36 am

I was surprised too Tony. And made a new thread about it. Seems everyone has missed out on quite an interesting feature that was probably added with v.7 nearly 2 years ago. Send to compressor actually ignores all the render files, AND the seqeunce codec and sends the RAW original file data to be transcoded/compressed from scratch to whatever compressor codec you've chosen. What he saw wasn't a fluke and that's why I went and tested it. I too had discarded send to compressor because even for a rendered sequence is was an insanely long export. Now I know why. Because it WAS making things better.


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