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#1 |
Trustee
Join Date: Aug 2009
Location: Chicago, IL
Posts: 1,554
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Major Aliasing Problem
Has anyone seen this level of aliasing from their EX1/3/1r? I have never seen aliasing this bad with either my EX3 or EX1. However, I was recording to my nanoFlash at 50Mb/s L-GOP; so, I don't know if the encoding algorithm used in the nano combined with the higher bitrate can cause this aliasing issue. After seeing what the nanoFlash does when recording a camera with a lot of noise using the 100+Mb/s L-GOP codec, I am curious as to whether the Sony codec can increase aliasing.
Hmmm. Something odd is happening. When I exported a frame from Premiere Pro CS5, the jpeg did not have any aliasing. But, when I rendered within the timeline, there was considerable aliasing when viewed at 100%. |
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#2 |
Inner Circle
Join Date: Jan 2004
Location: Boca Raton, FL
Posts: 3,014
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Re: Major Aliasing Problem
Did you mean to attach a screen shot or something?
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#3 |
Inner Circle
Join Date: Jun 2003
Location: San Jose, CA
Posts: 2,222
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Re: Major Aliasing Problem
Steve, are you able to host some clips on a Web server? If you did a parallel SxS and Nanoflash, recording, it would be good to see.
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#4 | |
Trustee
Join Date: Aug 2009
Location: Chicago, IL
Posts: 1,554
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Re: Major Aliasing Problem
Quote:
One jpeg was exported from PPro's Program Window using its export button, but it does not show any aliasing which is very surprising. The other image is from the Print Screen function and then cropped in Photoshop which shows the aliasing. When I play the video either thru PPro or from a rendered file, I can see the aliasing as well. I will upload a video to vimeo shortly, but I must leave right now to go vote. |
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#5 |
Inner Circle
Join Date: May 2005
Location: Burnaby, BC, Canada
Posts: 3,053
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Re: Major Aliasing Problem
Check your playback and paused resolutions. Are they at Full? If they are, and the problem presists, try turning off GPU acceleration as your next step.
To truly double check, playback your nanoFlash files in VLC to see if you see the same problem in the originals. This is not aliasing, this is scaling a half-resolution image to double it's size. This is most likely a Premiere issue. |
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#6 | |
Trustee
Join Date: Aug 2009
Location: Chicago, IL
Posts: 1,554
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Re: Major Aliasing Problem
Quote:
PS - His suit was actually a greyish black, but my EX3's beautiful IR issue rears its ugly head here. However, I was able to fix it and get it to look very close to its original color by using a couple effects in PPro where I targeted the shadows and midtones. This clip was rendered before I CC'd. Thanks for the comments so far :) |
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#7 | |
Major Player
Join Date: Oct 2009
Location: Reno, NV
Posts: 553
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Re: Major Aliasing Problem
Quote:
My guess is the 30p source from the nanoflash is being misinterpreted as 60i. As a result the scaling and display algorithms are working with 540 line fields that are consequently aliased. Try checking your source files with mediainfo to see if they are tagged as progressive or interlaced. http://mediainfo.sourceforge.net/en |
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#8 |
Regular Crew
Join Date: Apr 2011
Location: Rochester NY
Posts: 104
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Re: Major Aliasing Problem
Yeah, there's no standard for showing 30 fps progressive on a consumer television so you are
guaranteed to get problems from TV's that expect 60i getting 30p and trying to deinterlace the result. If you final product is TV, consider shooting one of the formats that TV's understand like 1080 30i or 720 60p. The 1080 30p is really a web only thing or a special effect. Also, I don't think the effect you are seeing is what most people would call aliasing. You have caused a temporal problem with the fields/frames by trying to pack a novel video standard into a pipeline designed for an existing video standard. You can get "temporal" aliasing in a situation like this but it would be because you were shooting interlaced footage that had so much vertical detail that the deinterlacer in the TV couldn't properly figure out what was detail and what was motion. The "spatial" type of aliasing is virtually impossible with the EX1/EX3 unless you use bad resampling in Premiere which has already been discussed. |
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#9 | |
Vortex Media
Join Date: Jan 2009
Location: Florida
Posts: 3,438
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Re: Major Aliasing Problem
Quote:
Second, you are NOT "guaranteed to get problems with 30P". 30P is now the defacto standard for most high-end broadcast television production in the USA. If you are doing things correctly, 1080/30P that is displayed or broadcast as 1080/60i should look flawless and identical to the original 30P. You're just taking each frame and dividing it into two identical fields. The result looks exactly the same as 30P. So, the reason that Blu-ray and broadcast television don't need a 30P mode is because 30P material shown as 60i is the same thing. Believe me, 30P is NOT a "web only thing". And finally, shooting 720 is short sighted, It's not even HD. It's medium definition and soon won't even be around anymore. I don't even know if you can buy a 720P television anymore unless it has very small screen. 1080/30P -- that is today's standard.
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Vortex Media http://www.vortexmedia.com/ Sony FS7, F55, and XDCAM training videos, field guides, and other production tools |
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#10 |
Major Player
Join Date: Jul 2009
Location: Hampshire, UK
Posts: 693
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Re: Major Aliasing Problem
720p is very much a standard supported by modern televisions, so there is no need to worry. Unless you are talking about 720p native panels which frankly you don't need to display 720p.
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Marcus Durham Media2u, Corporate Video Production For Your Business - http://www.media2u.co.uk |
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#11 |
Vortex Media
Join Date: Jan 2009
Location: Florida
Posts: 3,438
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Re: Major Aliasing Problem
I guess I didn't make myself clear. Obviously 720P can be displayed on a 1080 TV. Do you seriously think I don't know that? Guess what, I also know that SD can also be viewed on modern televisions. But that doesn't mean that 720P or SD look good.
My point is that most TVs being sold today are full 1920x1080 and 720P is clearly on the way out. A new large screen TV with native 720P resolution would be rare if not non-existent, and that was not the case a couple of years ago. 720P was just a stop-gap resolution who's time is quickly fading away. In my opinion, it is short sighted to shoot in 720P today unless you are 100% sure you'll never want to use it in a 1080P production someday down the road. I prefer to future-proof my footage because you never know what you might need. Take my word for it, 720P will soon (if not already) have the same stigma that SD footage does today. I hope that clears it up.
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#12 | |
Major Player
Join Date: Oct 2009
Location: Reno, NV
Posts: 553
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Re: Major Aliasing Problem
Quote:
1080 30i makes sense because the 1080 is the size of the frame and 30i is the rate of the frames. If you want the rate of the fields, than it should logically be 540 60i which specifies the size of the fields and rate of the fields. However, in the quest for larger numbers, camera manufacturers often write 1080 60i which mixes the size of the frame with the rate of the fields. Now back to the aliasing. If you extract every other line from a interlaced frame you get a field, however, if you extract every other line from a progressive frame all you get is a downsampled image that was obtained using a very alias prone downsampling method. Therefore, it is important that 30p be distinguished from 30i during playback and editing. Last edited by Eric Olson; March 21st, 2012 at 02:04 PM. |
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#13 |
Vortex Media
Join Date: Jan 2009
Location: Florida
Posts: 3,438
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Re: Major Aliasing Problem
This is really getting ridiculous. 30i is not a real frame rate and does not exist. Please show me one legitimate industry source that recognizes 30i as a real frame rate. If it was a real frame rate, 30i would only be 15 fps. Just as 60i is only 30 fps. It takes TWO interlaced fields to create one frame.
Fields and Frames = two different things. Frame rate - Wikipedia, the free encyclopedia I know this thread has drifted off track form the original subject, so I won't post again on this topic no matter how much misinformation is being thrown around in the next post.
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#14 | |
Trustee
Join Date: Aug 2009
Location: Chicago, IL
Posts: 1,554
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Re: Major Aliasing Problem
Quote:
I appreciate the comments so far, but I know of one reputable company who refers to 1080 30i instead of 1080 60i - Aja. Actually, they list it as "1080i 30". KONA LHi - AJA Video Systems I do believe the 1080i 30 is correct because the '30' refers to the number of frames per second. 1080 60i is incorrect because it is not 60 frames per second, but 30 fps. All of the 'Video Formats' include the frame size and frame rate, not fields per second; thus, 1080i 30 is correct, and so is 1080i 25. |
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#15 | |
Regular Crew
Join Date: Apr 2011
Location: Rochester NY
Posts: 104
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Re: Major Aliasing Problem
Quote:
is going to go into a deinterlacer which may or may not do what you claim. Some hardware deinterlacers that I have seen (some of the Bravia ~2006 era at least) definitely do not interprete 30P in 60i and make a nice 30p screen. Do you have any references to back this up? If you are shooting un-controlled live action there is a good bit of judder/loss of temporal resolution with 30p. Not quite 24p but it's not smooth. |
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