Two issues with Vegas and Sony Ax100 4K at DVinfo.net

Andy Smith · August 2nd, 2015, 03:12 PM

I have two issues which I would like to see if anyone else has experienced.

1). When rendering down from 4K to 2K using the Sony AVC (or Mainconcept MPEG2) to Blu-ray 24p I get pumping/flashing of light areas during movement of the image. For example in a shot of a house with white drain pipe the drain pipe flashes in intensity as you slowly pan across. Also happens with window frames etc.

2). Rendering down to SD DVD produces a poor quality image with shimmering on any movement even when setting to two pass MPEG2. I have to use Video to Video converter which uses ffmpeg as a compressor which gives a MUCH better image quality.

Andy

Juris Lielpeteris · August 2nd, 2015, 10:57 PM

Hi, Andy
This phenomenon is called Aliassing and is not specific for the AX-100
https://en.wikipedia.org/wiki/Aliasing
https://en.wikipedia.org/wiki/Anti-aliasing_filter

Andy Smith · August 3rd, 2015, 05:18 AM

Juris, many thanks for the links about the issue, very interesting. Luckily the effect is not such that it spoils the video, it is just noticeable as an element not visible in the original clips.

Dave Blackhurst · August 9th, 2015, 03:01 PM

You may want to play with frame rates - this came up in the never ending thread when the AX100 came out - I myself saw it as a "flashing" (could also call it "shimmer" or "pulsing") sort of effect on high contrast edges. Some criticized the camera as being somehow defective, when it's really just a by product of the super sharp image quality!

I believe it is at least in part the result of high shutter speeds creating what in effect a series of 30 "stills" per second, which then creates a jerky feel to moving images. This "effect" can then make it look like high contrast elements are flashing or pulsing as they move...

Once I started to run in manual and keep shutter speeds down (auto can bump them WAY up, I've had best luck under 125, 60 or 90 seem to be workable with ND's even in bright sunlight), it introduced a slight natural motion blur that for the most part eliminated the "pulsing".

In turn, you may want to try to fiddle with settings while exporting? I found the "fix it while shooting" effective, never been a "fix it in the mix" kind o' guy!

Hopefully you'll find this useful, not sure how one would fix existing footage if the shutter was too fast, maybe a "blur" filter of some sort? Of course we want the super sharp 4K image, seems a shame to add "blur" to it!

August 2nd, 2015, 03:12 PM	#1
Andy Smith Regular Crew Join Date: Feb 2015 Location: Newbury UK Posts: 46	Two issues with Vegas and Sony Ax100 4K I have two issues which I would like to see if anyone else has experienced. 1). When rendering down from 4K to 2K using the Sony AVC (or Mainconcept MPEG2) to Blu-ray 24p I get pumping/flashing of light areas during movement of the image. For example in a shot of a house with white drain pipe the drain pipe flashes in intensity as you slowly pan across. Also happens with window frames etc. 2). Rendering down to SD DVD produces a poor quality image with shimmering on any movement even when setting to two pass MPEG2. I have to use Video to Video converter which uses ffmpeg as a compressor which gives a MUCH better image quality. Andy

August 2nd, 2015, 10:57 PM	#2
Juris Lielpeteris Major Player Join Date: Oct 2012 Location: Riga, Latvija, EU Posts: 292	Re: Two issues with Vegas and Sony Ax100 4K Hi, Andy This phenomenon is called Aliassing and is not specific for the AX-100 https://en.wikipedia.org/wiki/Aliasing https://en.wikipedia.org/wiki/Anti-aliasing_filter

August 3rd, 2015, 05:18 AM	#3
Andy Smith Regular Crew Join Date: Feb 2015 Location: Newbury UK Posts: 46	Re: Two issues with Vegas and Sony Ax100 4K Juris, many thanks for the links about the issue, very interesting. Luckily the effect is not such that it spoils the video, it is just noticeable as an element not visible in the original clips.

August 9th, 2015, 03:01 PM	#4
Dave Blackhurst Inner Circle Join Date: Feb 2007 Location: Apple Valley CA Posts: 4,874	Re: Two issues with Vegas and Sony Ax100 4K You may want to play with frame rates - this came up in the never ending thread when the AX100 came out - I myself saw it as a "flashing" (could also call it "shimmer" or "pulsing") sort of effect on high contrast edges. Some criticized the camera as being somehow defective, when it's really just a by product of the super sharp image quality! I believe it is at least in part the result of high shutter speeds creating what in effect a series of 30 "stills" per second, which then creates a jerky feel to moving images. This "effect" can then make it look like high contrast elements are flashing or pulsing as they move... Once I started to run in manual and keep shutter speeds down (auto can bump them WAY up, I've had best luck under 125, 60 or 90 seem to be workable with ND's even in bright sunlight), it introduced a slight natural motion blur that for the most part eliminated the "pulsing". In turn, you may want to try to fiddle with settings while exporting? I found the "fix it while shooting" effective, never been a "fix it in the mix" kind o' guy! Hopefully you'll find this useful, not sure how one would fix existing footage if the shutter was too fast, maybe a "blur" filter of some sort? Of course we want the super sharp 4K image, seems a shame to add "blur" to it!