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Youtube's Contrast Curve?


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#1 Macks Fiiod

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Posted 25 October 2017 - 02:36 AM

I feel like I'm gonna get "stop using Youtube" replies, but may as well try asking.

 

I'll take hours to grade a short exactly to my liking, and when I put it to Youtube the shadows are crushed to hell. My solution is raising the blacks up to counteract Youtube's odd contrast compression, but I just want to make sure it's perfect.

 

Does anyone have any suggestions or LUTs for achieving a perfect counteraction of this shadow crushing problem?

 

Thanks.


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#2 Phil Rhodes

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Posted 25 October 2017 - 03:05 AM

It's not particularly YouTube, it's a general problem with brightness encoding in digital video. The opposite problem, where blacks appear lifted and everything loses contrast, can also occur.

 

It can be difficult to solve, but generally you're looking for options to control whether brightness encoding is full range (0-255 in 8-bit video) or studio range (16-235.) Various pieces of software include this information in various ways and there are compatibility problems. Try various things.

 

Yes, it's a stupid error that should never have been allowed to become a problem on this scale, but sadly it has.


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#3 Macks Fiiod

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Posted 25 October 2017 - 03:18 AM

It's not particularly YouTube, it's a general problem with brightness encoding in digital video.

 

No but I mean like, Vimeo and watching it off the hard drive it comes out perfect. YT (and other cheap compression uploaders) is the only place where I'm getting this issue.


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#4 Phil Rhodes

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Posted 25 October 2017 - 04:32 AM

That's because it's going through a completely different set of software, or at least with wildly different settings.

 

There's nothing particularly about YouTube that should cause this to happen. They use the same encoder as everyone else. You need to ensure that your uploads are marked full-range in a way that the website understands, or upload them in studio range.


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#5 Tyler Purcell

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Posted 25 October 2017 - 04:59 AM

Youtube's bandwidth is for sure lower than Vimeo, which is evidenced in why you PAY for Vimeo's services and youtube is free. That's not just advertising, that's because you're paying Vimeo to store your files on their servers because they do take up a lot of space since they're such high bandwidth streaming files.

If I upload the same file to Vimeo and Youtube, the quality difference is noticeable right away. From a 10 bit Pro Res file, it's not overly dramatic unless you play the original against the youtube version, then it's pretty noticble.

For me, I don't really shoot stuff with crushed blacks and I have good encoding software, so it's never a problem. The only "issues" I have are blockiness due to the lower bandwidth and of course color bleeding from the 4:2:0 color compression. Vimeo is still 8 bit 4:2:0, but the color bleeding for some reason is a bit better, probably due to the higher bandwidth.

The files you upload need to be perfect first, so 20Mbps .h264 or .h265 at max quality of source, would be a good start. For Vimeo, I always upload Pro Res LT files as my source. They seem to work the best and you can upload via FTP which is a great feature for larger files. For youtube it's always .h264 @ 15 - 20Mbps and I make them using Apple's compressor software which is really good and the latest version has no bugs related to gamma. I then watch it front to back so when I upload I know there aren't going to be any issues.
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#6 Igor Trajkovski

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Posted 08 December 2017 - 06:47 AM

Just bumped on this topic, i rarely go to this subforum...
 

Couple of months ago i was also curious on
what happens on YT with the luma values,
so did a short clip for test.

The description for the video (copy/paste):

10 sec clip from fbelle-nuittes tchart HD.tif
To help see where YT puts the whites and blacks after upload.

Clip was rendered in Sony AVC BluRay 25p preset.
After import again in Sony Vegas, RGB parade showed
all values below 16 and above 235 where there.

After upload on YT, MIN & MAX luma values are 16 & 235.
Everything below and above is clipped.

So, Black on YT is 16, White is 235.



Luma Values after upload to YT (belle nuittes tchart HD, Clip 10sec)


...

You can find the Belle Nuit Testcharts HERE

 

...

I stumbled on Vimeo clip with the same chart - LINK.
It shows it preserves the whole 0-255 range.
However, no info on what codec was used on the upload video.

 


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#7 Martin Facci

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Posted 12 February 2018 - 05:14 AM

Hi!

 

I've struggle with YouTube compression several times... I do recommend if you can, uploading the video ni 1440p instead of 1080p. 

 

If your footage is 4K you have no problem, if it's 1080p, upscale to get to 1440p would get you better results that uploading at 1080p because of the bitrate.

 

With 1080p you get a bitrate from 3.000/kpbs to 6000/kbps. If you upload 1440p you get from 6.000/kbps to 13.000/kbps

 

I've done some test and trust me, there's a really big difference!


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