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#16 |
Regular Crew
Join Date: Dec 2005
Location: Miami, Florida USA
Posts: 114
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Re: Major Aliasing Problem
<shaking my head> Don't understand the angst some are displaying about learning the ins and outs of 30P from someone who really knows what he's talking about.
I am by no means at the freelance level of Doug Jensen but, like him, I rarely shoot anything that isn't 30P anymore. Have yet another 30P shoot this Friday where they specifically asked for it. Many of the network news magazine shows want 30P. Have you folks watched PBS, 60 Minutes or the CBS Sunday Morning News lately? That's pretty much all they want. At least that's what they asked for from me. Granted, there's 60i video mixed in but for the elements I've been involved with shooting them, it's been 30P I saw the link from the company labeling a format 1080I 30...seems strange but I'm no engineer, just a guy who gives the client what they ask for so they give me a check in return. There's a lot of misinformation in this thread and it's NOT coming from Doug Jensen. I'm not trying to begin a flame war of who is and isn't professional. Just pointing out I'm yet another freelancer with real world clients who want 30P more and more. We're not talking about taking a raw feed out of the camera directly to whatever monitor or tv set you happen to own. We're talking about an image which is edited, then broadcast to achieve the look they want. If it was a problem, they wouldn't be coming back again and again for more. edit: I want to be very clear that I am not trying to insult or demean anyone with my above comments. Just trying to share some information. ;)
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John DuMontelle - Freelance / Miami, Florida - USA http://www.latincamproductions.com/ |
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#17 | |
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Join Date: Oct 2009
Location: Reno, NV
Posts: 553
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Re: Major Aliasing Problem
Quote:
Are the files recorded by the nanoflash tagged as interlaced or progressive? Last edited by Eric Olson; March 21st, 2012 at 04:47 PM. |
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#18 |
Regular Crew
Join Date: Dec 2005
Location: Miami, Florida USA
Posts: 114
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Re: Major Aliasing Problem
Hi Eric,
Looking at video information and....not sure where to find an answer to your question. Here's the info I have for my latest 30P shoot I did for PBS network of the raw BPAV files. Video Format Port: DIRECT Codec: MPEG2 HDLong 35bps FPS - Capture: 29.97P Format: 29.97P Layout: 1920 X 1080 16:9 Pull-Down - Type: 1-1 Frame Phase: 00 That's the video information I get seeing the files in my XDCAM Browser. So...would the double "0" for Frame Phase provide the answer? I'm not sure...just asking.
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John DuMontelle - Freelance / Miami, Florida - USA http://www.latincamproductions.com/ |
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#19 |
Major Player
Join Date: Oct 2009
Location: Reno, NV
Posts: 553
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Re: Major Aliasing Problem
This appears to be a correctly tagged 1080p progressive 35mbps file. Is there aliasing with this one too? I thought the aliasing was only a problem with the 50mbps file recorded by the nanoflash.
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#20 |
Regular Crew
Join Date: Dec 2005
Location: Miami, Florida USA
Posts: 114
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Re: Major Aliasing Problem
No, I've never had aliasing problems...we just got caught up in a discussion about the positives and negatives of 30P and that took everything off track.
My video is perfect! Of course! LOL ;)
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John DuMontelle - Freelance / Miami, Florida - USA http://www.latincamproductions.com/ |
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#21 | |
Regular Crew
Join Date: Jan 2009
Location: Chicago, IL
Posts: 36
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Re: Major Aliasing Problem
Quote:
My question was how can it be both 1080i and 30p? I believe the difference is in how the image is captured and then recorded. The picture is captured as progressive, in other words, all pixels at once. It is recorded as interlace, the picture is spilt AFTER capture, and therefore there are no 'interlace artifacts' as we think of them. I like to think of it as two different 'flavors' of interlace, ha ha! Can anyone confirm/debunk this explanation? |
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#22 |
Major Player
Join Date: Oct 2009
Location: Reno, NV
Posts: 553
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Re: Major Aliasing Problem
A video can't be 30p and 1080i at the same time.
Processing a progressive frame as two interlaced fields is the probable cause of the aliasing observed in the first post. Luckily the nanoflash records with 4:2:2 chroma subsampling, otherwise there would be additional chroma artifacts from using the interlaced 4:2:0 algorithm on a progressive 4:2:0 frame. |
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#23 | |
Inner Circle
Join Date: Jan 2006
Posts: 2,699
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Re: Major Aliasing Problem
Quote:
Up until a few years ago, the correct nomenclature for what you are both referring to would have been "1080/60i" (30 frames, 60 fields), and for the comparable progressive system it would have been "1080/30p". The relevant standard setting bodeis then decided it would be better (and don't shoot me, I'm just the messenger only.... :-) ) to ALWAYS refer to framerates, and NOT framerate when progressive, fieldrate when interlaced. To avoid confusion (!!!!!!!!) it was further defined to change the way it was written, such that i or p before the hyphen indicated new (and official) nomenclature. Consequently 1080/60i should now be referred to as 1080i/30. Both mean the same thing - but the former is strictly "old" terminology. Earlier Steve Kalle said "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". And the point is that 1080/30i and 1080i/30 DO NOT mean the same thing. The former means an interlaced system of 15fps framerate, using old terminology! The latter is the correct way of referring to one of the main current broadcast standards. At least according to the bodies responsible for standard setting. GRADUALLY the new terminology is replacing the old, and arguably is more logical. Given the confusion it has caused (and still is causing) it could be argued forever whether the change was worth it. I'm not going to get hung up on that, but officially 1080i/30 is the correct terminology. |
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#24 | |
Inner Circle
Join Date: Jan 2006
Posts: 2,699
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Re: Major Aliasing Problem
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#25 | |
Trustee
Join Date: Aug 2009
Location: Chicago, IL
Posts: 1,554
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Re: Major Aliasing Problem
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#26 |
Inner Circle
Join Date: Jan 2006
Posts: 2,699
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Re: Major Aliasing Problem
What I understood to be the reasons were more academic - that sometimes referring to framerate (progressive and psf) and sometimes fieldrate (interlace) was illogical. If framerate is ALWAYS specified it becomes more consistent and it's possible to tell at a glance the raw data rate from the two figures, (So 1080i/30, 1080p/30 and 1080psf/30 will all have the same aount of uncompressed data - 1080p/60 will be double.)
I agree with the logic - but the question of whether the confusion the change has caused was worth it (witness this thread) is another one. I'm not going to go into that, the main point is that, officially, 1080i/30 is now the correct terminology. |
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#27 |
New Boot
Join Date: Mar 2012
Location: Moss, Norway
Posts: 16
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Re: Major Aliasing Problem
[QUOTE=Steve Kalle;1721934]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.....
If I have the same problem or not, I'm not sure, but here's my situation: I'm shooting with EX1 at 1080p/25 (PAL region). In Vegas, the project setting is 25fps and progressive. However, in the preview windows, it says 50i. Why? When I render to an m2ts file plus ac3 audio file, and pack them together to an iso file in DVD architect and play it on an LCD HDTV, severe aliasing appears: A black wire against a grey sky background appears with white lines on both sides of the black wire; all crispy dark details have white glare around them; contrast seems exaggerated, TV set says "1080i" is playing (from media player, not blu-ray player). What happens? When in the workflow did it all shift from progressive to interlaced? When I play back the same m2ts file on my computer, everything is normal (!!)... PLEASE help... ;) |
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#28 |
Trustee
Join Date: Aug 2009
Location: Chicago, IL
Posts: 1,554
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Re: Major Aliasing Problem
Hi Dag,
Your aliasing problem is most likely due to the scaling algorithm being applied by the DVD player to scale the resolution up to your HDTV. This aliasing issue varies between every DVD player because they all use various scaling algorithms with some being worse than others. The best way to combat this issue is to apply anti-aliasing effects in your NLE (if it has them - Premiere Pro has an anit-flicker setting and an anti-alias effect which essentially applies a slight blur but I think it focuses more on high frequency). From my experience, very slight aliasing in the source footage can show up as ugly aliasing in a DVD on an HDTV due to the DVD player's up-scaling. |
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#29 |
Major Player
Join Date: Oct 2009
Location: Reno, NV
Posts: 553
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Re: Major Aliasing Problem
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#30 | |
New Boot
Join Date: Mar 2012
Location: Moss, Norway
Posts: 16
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Re: Major Aliasing Problem
Quote:
I'm using the QNAP NMP1000 media player. QNAP Systems, Inc. ( NMP-1000 ) - Quality Network Appliance Provider It's not fast enough to play iso-files, so I put the iso file on a virtual drive, and copy the BDROM catalog onto the QNAP, which plays it well. Actually, I experience the same aliasing problems playing the m2ts file in windows media player, output via HDMI to a HDTV set. On the PC monitor however, it looks good. Weird... The footage is native 1080p/25 from the XDCAM EX1, so why it appears as 50i in Vegas when playing it from the timeline, is also a mystery. Also, when the rendered file is opened in DVD architect, the file appears as 25i, even though I've selected "Maintain source file format"... Even more weird... |
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