[This article was first published in the September, 2010, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe.]
I’ve had an extensive email correspondence with Patrick Nugent about some video artifacting he was seeing in materials compressed for DVD.
I want to share with you what Patrick found that solved the problem:
I may have found a solution to my problem. I showed the video to somebody who immediately indicated that artifacting was occurring though he couldn’t offer a solution to the problem.
Subsequently, after Googling “artifacting”, “compression” and perhaps “compressor”, I found a thread where somebody recommended NOT compressing the video using the 2 Pass VBR in Compressor. Rather, one should use the 1 Pass CBR.
So, I used the 1 Pass CBR, raised the average bit rate to 6.8 and, lo and behold, no obvious artifacting going on. I realize that you recommend using the 2 Pass VBR in your videos (which I have been doing), but the 1 pass seemed to have solved my problem. The file size jumped from 3.9GB to 4.3GB (this disc will be replicated); there doesn’t seem to be any difference in quality.
Larry replies: Thanks, Patrick, for sharing this with me.
7 Responses to Eliminating Compression Artifacts
hm… I had the same situation, but I took other approach.
I have changed the software (from compressor to telestream) I had no problems with compressed material (from HD to SD).
IHMO apple compressor was a little bit “confused” where to put higher bit rate and where to put lower bit rate, so obviously Constant Bit rate solved the artifact…
But this is my observation, I didn’t read the whole mail… I would stick to 2 VBR
Hi, I have some FLV; MP4; AVI and MPEG2 videos suffering from picture block artifacts – those annoying black shadows that plague dark images only found on online videos.
Do you know of a software that will remove these negative effects from moving videos, not still photos ??
Ideally I would like an all in one stand-alone software for Windows 7
Please send me a link from where I could download such a software safely and any links to how to use tutorials.
Thank you.
Greetings Larry and community..
We have shot a ton with the GH4… and have not seen this issue before….
We have a subject who is wearing a striped shirt, and it is flickering/flashing a ton.
In the past we would have avoided these types of clothes/textures on actors, but the GH4 has been so solid for us and we have not paid close attention to what on camera people wear as much recently.
GH4; V-LOG; 100mbps; FCP X; The shirt’s texture is quite bad– very tight horizontal stripes.
We’ve tried all the output and timeline options, all seem to render the same.
We always sharpen our footage slightly in post. Sharpening obviously makes it worse.
Any pointers on how to best salvage the footage would be great!
Maybe there’s a plugin or encoding solution?
Steven:
This flickering is most often caused by moiré – the low resolution of video causes thin lines that are close together to vibrate. There’s no easy fix, however you are correct, sharpening will make it worse.
Try blurring the image a bit, or, better, mask the shirt and blur that. The softer the edges, the less the moiré.
Also, be sure you are not shooting interlaced video. (1080i) Interlacing makes moiré worse.
Larry
Thanks Larry.
I double checked and these file were shot in the typical UHD 24fps 100mbps (GH4) setting which I’m fairly confident is progressive.
I don’t see a particular designation that they are progressive frames vs interlaced… but I’m not even sure the GH4 has an interlaced option.
Is moire a direct result of compression?
We shoot using GH4 and other small cameras not because of budget, but because of ease of use (entire workflow is streamlined) We do own a RED camera, but it is larger process to use.
I suppose my question is… The newer slate of mirrorless cameras (the new Olympus and GH5 for example) will shoot at a higher bitrate rate — over 300mbps I believe. Will that decreased compression solve or mostly solve the moiré issue or are there other factors at play?
Steven:
There are other factors at play. Thin lines cause problems – the lower the resolution, the more the problems. If everything you shot was viewed at 4K, you’d probably – but not guaranteed – be OK.
As resolution decreases and the lines get closer together moiré develops. While HD handles this MUCH better than SD, it doesn’t go away. Moiré is caused by insufficient pixels to accurately describe the edges in an image – especially when these edges are close together; as in stripes.
The basic rules of costuming still apply: Avoid thin lines, avoid fine patterns, use blockier patterns and colors.
Larry
You have quite the knack for explaining things… not sure if you’ve ever been told that;)
Thanks much Larry.
I watched the video on a 4K TV and also watched it on quicklime using the “actual size function” and all the moire disappeared.
Vimeo does their own downscaling. It’s decent, but not great.
I uploaded the 4K file and it looks better downscaled on vimeo than it does on QT (in real time)
Thanks again.