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Addressing Compression Artifacts in Dark Colors

beezo

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I was wondering if anybody has any insights into how to minimize compression artifacts in dark colors.

I can't help but think that there must be some way of telling software, "Hey, I want to compress this video image from 25 gigs to 5, but I want most of those 5 gigs to be spent on gradients in the dark color spectrum."

Does anybody know of anything that works like this?
 

ThrowgnCpr

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Please be more specific about your workflow. There are a lot of factors to consider, not just the final file size.
 

Captain Khajiit

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^^ Blocking artifacts in dark areas are a result of insufficient bitrate (in other words, compressing your source too heavily).  There are ways to do what you are asking, but the real solution is to re-evaluate what you have set out to achieve.  What's so special about 5GB?  If you want a file that doesn't need to be burnt to disc (and I guess that you do), use CRF encoding and forget about hitting a particular file-size  For x264, encode a sample with a CRF of 23.  If you don't like the result, reduce the value by 1 until you do; then use that value for all your encodings.
 

beezo

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Captain Khajiit said:
^^ Blocking artifacts in dark areas are a result of insufficient bitrate (in other words, compressing your source too heavily).  There are ways to do what you are asking, but the real solution is to re-evaluate what you have set out to achieve.  What's so special about 5GB?  If you want a file that doesn't need to be burnt to disc (and I guess that you do), use CRF encoding and forget about hitting a particular file-size  For x264, encode a sample with a CRF of 23.  If you don't like the result, reduce the value by 1 until you do; then use that value for all your encodings.

To be clear, what you're describing is simply adjusting the bit rate, correct?  I understand that a higher bit rate would decrease compression artifacts in the blacks.  What I'm trying to see is if anybody knew of way to compress a file, from a 25 - 30Mbs rate down to something like 5-8Mbs while still minimizing the blacks from getting the obvious compression artifacts.  I understand that this may not be possible, but I just wanted to ask a stupid question, just in case.

I'm not working on anything in particular at the moment that concerns this.  I just had the realization the other day that I cannot watch anything streaming that is heavy in the darker palette because it looks awful, despite my high speed internet connection.  It just got me thinking about those damn compression artifacts to see if anybody had a workaround of which I was unaware.
 

Captain Khajiit

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beezo said:
I can't help but think that there must be some way of telling software, "Hey, I want to compress this video image from 25 gigs to 5, but I want most of those 5 gigs to be spent on gradients in the dark color spectrum."

beezo said:
To be clear, what you're describing is simply adjusting the bit rate, correct?  I understand that a higher bit rate would decrease compression artifacts in the blacks.  What I'm trying to see is if anybody knew of way to compress a file, from a 25 - 30Mbs rate down to something like 5-8Mbs while still minimizing the blacks from getting the obvious compression artifacts.

You've switched from describing a file-size to describing a bitrate.  The bitrate required to achieve a given quality is source dependent – some sources compress better than others.  You can trade off blocking for a softer image, but I don't imagine you'd be keen on that.  If for some reason the bitrate has to be within a certain range, you'd be better off reducing resolution, e.g. 1080p→720p.
 
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