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Weird, horrible image pixelation on output video

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Xavier Bonet
Weird, horrible image pixelation on output video
on Aug 4, 2017 at 1:15:29 pm
Last Edited By Xavier Bonet on Aug 4, 2017 at 1:16:03 pm

Sometimes, my exported videos have, at some point, a very noticeable drop in quality; that is, the image becomes very pixelated, as you can see below.

What you're seeing is two immediately consecutive frames. One (and all the previous ones) are OK; the other (and all the next ones) are completely and horribly pixelated, as you can see.

Now, in this case it happens in a very busy frame, due to the leafs on the trees, and it does tend to happen when the scene is busy or when there's a lot of movement, but I have seen it happen from time to time in scenes that don't seem to justify it. So I'm wondering if it's my video output settings, a bug in the software, or an issue that's happening with the hardware while rendering (i.e. an external drive skip or crash, or something similar in my computer).

The videos I'm talking about are mainly destined to be up on YouTube, so I believe the output settings I've been using thus far are adequate (some may even say a little overkill, taking into account that YouTube will process and compress the video, lowering the bitrate). But you be the judge of that.

Hardware-wise, I'm rendering this on a MacBook Pro (Retina, 15-inch, Mid 2015) with a 2,5 GHz Intel Core i7 Processor, 16 GB 1600 MHz DDR3 RAM Memory, AMD Radeon R9 M370X 2048 MB Graphics, and a 500 GB Internal SSD. I mainly work from and to (source/output) a LaCie Rugged RAID (4 TB) external HDD, setup in RAID 0 mode, that is, with a real read/write speed of roughly 220-230 MB/s; and have a second external HDD — My Passport Ultra, 2 TB, around 100 MB/s read/write — for some common source materials such as music, sounds, images, etc.

As you'll see below, I'm keeping the source/output values the same. Most of my footage is

My PPro export settings are as follow:

Format: H.264
Source: 1920x1080 (1,0), 29,97 fps, Progressive
Output: 1920x1080 (1,0) 29,97 fps, Progressive, VBR, 2 pass, Target 25.00 Mbps, Max 25.00 Mbps

Basic video settings:
Profile: High
Level: 4.2

[√]Render at Maximum Depth
[√] Use Maximum Render Quality

And the end result is (for example) 2705 MB for a 14:55 video.

So I'm leaning toward thinking that it's an software error rather than the result of my export settings. I think my settings are placed rather high for a YouTube video. Plus, the fact that the frame immediately before the issue starts (and the frames that came before), which is of the same scene, same complexity, perhaps even more movement, has nothing. So the pixelation just begins out of nowhere and stays there, in this case, for over 4 seconds, until there's a cut edit to another shot.

Finally, I'll add that, no, the source material doesn't have that pixelation, and that I've been seeing this happening on and off both in CC 2015 and CC 2017.

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Jeff Pulera
Re: Weird, horrible image pixelation on output video
on Aug 4, 2017 at 1:44:30 pm

Uncheck the Max Quality option - that only benefits scaling of video, which you are not doing.

I would also uncheck MAX DEPTH as that is more for 10-bit sources and such. You are going to H.264 which is definitely 8-bit. Most likely doing nothing more than increasing render times with both boxes checked, with no benefit.

I don't follow the logic of having the same value for TARGET and MAX - the idea is to have the AVERAGE (Target) bitrate, and then lower and higher values. Maybe having Target and Max the same is messing with the encoder on complex scenes?

Have you simply tried using the YouTube 1080p export preset? More is not always better.


Jeff Pulera
Safe Harbor Computers

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Xavier Bonet
Re: Weird, horrible image pixelation on output video
on Aug 4, 2017 at 2:30:03 pm

Hi, Jeff, thanks a million for your response! It's really been useful. Not in the way of fixing the issue, as I'm now convinced it was a software/hardware error, but in the way of fixing my workflow and probably giving back to my life many, many hours I would no doubt continue losing in the future.

I had read from a pretty reputable source that the values I had were a bit overkill for YouTube but, overall, probably the best for keeping a master copy of videos that are not meant to be professional videos (i.e., in my case, best-possible-quality for the video originals I upload to YouTube). In fact, there I had read that the built-in YouTube export presets were not good and not to be trusted. Thanks to you, I've just proved that wrong.

I exported the trouble-segment 4 times after your answer: 1) Using the built-in "more-is-not-always-better" 😉 YouTube 1080 preset; 2) Using my previous values but un-checking both Max options; 3) Using my previous values (Max options checked) and upping the Max bitrate to 35; 4) A control using my previous values as-is.

So, first of, none had the horrible pixelation issue. Which lead me to believe that it wasn't really and issue of the scene or its complexity, at least per se, but rather an error of the software/hardware that occurred when it was rendering that part or that part's complexity when it had already been rendering 70% of the video (i.e., the tired-computer syndrome, I guess one could call it...)

Next, to my surprise and chagrin (for all that time I had wasted waiting for my 2GB+ videos to export) the best output was... the "more-is-not-always-better" YouTube 1080 preset... 😒 Yes, I inspected the details and it had more definition, especially in the borders of things. Which is really surprising, as it has a little over half the bitrate, no Max options checked, only one pass, etc., etc. To my mind, there's no reason why it should be better, when every value chosen for output is worst than every value I had preset. But that's where your phrase comes in: "More is not always better;" in fact, in this instance, it's worse. Not only were the other three exports worse than the YouTube 1080 one, but the one with a higher Max bitrate was in fact the worst of all. Between the ones with the Max options checked/unchecked there was really no distinguishable difference, which corroborates your assertion that in my case, at least, it makes no difference, except stretching out rendering time.

So although I have yet to understand why and then fix the pixelation issue, I can tell you it's the last time I'll use anything higher than the YouTube 1080 option for my videos destined for YouTube.

So thanks again for your invaluable help!

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