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Old 28th December 2017, 08:38   #1  |  Link
Neillithan
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x265 - Always choose 10bit?

A month ago, I was told to enable 10bit mode, without being asked if my input footage was 8bit.

Is there a reason to encode in 10bit even if the input footage is 8bit?
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Old 28th December 2017, 09:54   #2  |  Link
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you'd get much less banding in your encode in 10 bit. x265 still suffers too much from that when using 8 bit. Your input doesn't matter much what bit depth it has (8 or 10)

do note that a lot of gear still doesn't support 10 bit yet, computers excluded. If you have a HW decoder that can deal with 10 bit, displaying it on an 8 bit display (like a TV) is not an issue. If your TV is 10 bit, even better
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Old 29th December 2017, 18:17   #3  |  Link
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Is there a reason to encode in 10bit even if the input footage is 8bit?
Pro:
1. better compression
2. no banding through compression precision
Con:
1. higher compression complexity -> potentially more cpu usage
2. higher decoding complexity -> potentially more cpu usage
3. not all decoders support it

Personally I only encode in 10bit,..

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Old 30th December 2017, 21:59   #4  |  Link
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I did a test on a 8 bit TV-episode encoded with x265 10 bit (Preset Medium) CRF 19 and compared it to a 8 bit encoding (same preset and crf) and I couldnt see any difference, but the file size came out 200 mb bigger for the 10 bit encode. Is there a video (Youtube ?) that will show the difference of 10 bit encoding on a 8 bit source compared to a 8 bit encoding of the same source ?
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Old 31st December 2017, 02:04   #5  |  Link
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There are actually some video blogs that will point you in the direction you are looking. You can quickly google something like benefits of 10 bit x265 encoding. What you will be looking for is things that you can see only in frame by frame comparisons really, and in areas where there would normally be lots of dithering, like clouds and leaves and backgrounds. Information that would easily be lost. The 10bit profile makes it less objectionable when dealing with gradients.
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Old 31st December 2017, 09:03   #6  |  Link
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Quote:
Originally Posted by GZZ View Post
I did a test on a 8 bit TV-episode encoded with x265 10 bit (Preset Medium) CRF 19 and compared it to a 8 bit encoding (same preset and crf) and I couldnt see any difference, but the file size came out 200 mb bigger for the 10 bit encode. Is there a video (Youtube ?) that will show the difference of 10 bit encoding on a 8 bit source compared to a 8 bit encoding of the same source ?
You're better using 2-pass with equal bitrate/settings for comparing.

CRF in 10bit can be lower(quality) compared to 8bit.
CRF19 in 8bit, you can go CRF 21-23 in 10bit.
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Old 31st December 2017, 15:12   #7  |  Link
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You're better using 2-pass with equal bitrate/settings for comparing.

CRF in 10bit can be lower(quality) compared to 8bit.
CRF19 in 8bit, you can go CRF 21-23 in 10bit.
That is what I cant get into my head. So if I encode a 8bit movie as 10 bit I can use higher CRF and still keep the same quality as if I encoded the movie in 8 bit with CRF 19.

How can that be ?
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Old 31st December 2017, 19:06   #8  |  Link
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Why does 10-bit save bandwidth (even when content is 8-bit)?
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Old 31st December 2017, 21:33   #9  |  Link
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That is what I cant get into my head. So if I encode a 8bit movie as 10 bit I can use higher CRF and still keep the same quality as if I encoded the movie in 8 bit with CRF 19.

How can that be ?
10bit improve about 5-7% of compression quality
usually in x264 10bit can avoid banding, on x265 it's a bit different, better quality but isn't banding-free.
always compare 2 pass vs 2 pass at the same bitrate
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Old 1st January 2018, 00:13   #10  |  Link
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Originally Posted by Neillithan View Post
Is there a reason to encode in 10bit even if the input footage is 8bit?
Ultimately, your choice of encode methodology depends entirely on how you intend to display those encodes. If you're stuck supporting 8-bit only hardware, then you're stuck with 8-bit encoding. Can't avoid it.

However, if you only ever intend to have your encodes played on new 10-bit capable hardware, then you should unequivocally encode in 10-bits at all times, for all of the reasons that everyone has mentioned.

The tangible benefits of 10-bit encoding will exist forever, but the ephemeral problems of compatibility will vanish once hardware that supports 10-bit formats becomes commonplace. Just look at the spec sheets for existing 2017 models, and upcoming 2018 models.

So, simple choice: are you held hostage by ageing hardware, or are you free to explore the best possible options?
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Old 1st January 2018, 06:44   #11  |  Link
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Sadly 10-bit H.264 will probably never be supported by decoding hardware.

Happily most mobile devices will probably be able to do software decoding of 10-bit H.264, albeit while using a lot more power.
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Old 1st January 2018, 16:43   #12  |  Link
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Sadly 10-bit H.264 will probably never be supported by decoding hardware.

Happily most mobile devices will probably be able to do software decoding of 10-bit H.264, albeit while using a lot more power.
Why use H.264 when H.265 is out ? H.265 10 bit is supported by many devices.
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Old 1st January 2018, 17:05   #13  |  Link
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Why use H.264 when H.265 is out ? H.265 10 bit is supported by many devices.
It does, but still needs more work.

x264 is still getting updates, but you can still just use a few builds older than the latest version and not look back for archival purposes.

Dollars to donuts, if it's not going to have HDR in the end result, I'd rather go with x264.

It'll be some time before I upgrade any piece of hardware to natively decode HEVC without framedrops.

I'm not much for standalone hardware or media players, so I use my PC more often.
And I have yet to upgrade my graphics card to support the 4K HDR movies and then I still have to upgrade my CPU to handle all that far better, but I think if I want to upgrade my CPU to one of the newest generations out there, I'd have to upgrade my mother board, and if I'm going to upgrade my motherboard, I might as well get one that supports better RAM and get a new case for it as well. And maybe look into water cooling.

For my personal case? No HDR? Then go x264 hi10p.
Blurays to hi10p is sufficient enough until I up my game to start working on the 4K BD's, by which time, hopefully x265 will be on par.

And, true, it's far more improved since a few years ago.
But, alas, I have miles and miles to go before I sleep.
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Old 2nd January 2018, 19:14   #14  |  Link
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I had quite a bad experience with re-encoding H.264 sources to HEVC while enabling 10bit encoding: zero quality improvement while file sizes become significantly larger (at least 5%).
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Old 2nd January 2018, 21:33   #15  |  Link
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Sounds like unrealistic expectations to me...

An encode cannot be better than it's source.
It might look more pleasing in some regard (e.g. smoothed gradations by means of dithering) - but it will never be better.

If you are getting large filesizes, you are...
a) encoding a source that is already (highly) compressed or
b) using the wrong settings / targets or
c) expecting too much.
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Old 2nd January 2018, 21:40   #16  |  Link
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I had quite a bad experience with re-encoding H.264 sources to HEVC while enabling 10bit encoding: zero quality improvement while file sizes become significantly larger (at least 5%).
you're doing something wrong. I get almost half size reduction when using x265 10 bit @ CRF 21 compared to 8 bit x264 @ CRF 18. Am hard pressed to notice difference in quality between the two

post your settings, if you will
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Old 2nd January 2018, 22:29   #17  |  Link
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you're doing something wrong. I get almost half size reduction when using x265 10 bit @ CRF 21 compared to 8 bit x264 @ CRF 18. Am hard pressed to notice difference in quality between the two

post your settings, if you will
Do you compare "x264 8bit @ CRF 18 encoded to x265 10bit @ CRF 21" or "H264 source encoded to x264 8bit @ CRF 18 vs H264 source encoded to x265 10bit @ CRF 21" ?
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Old 2nd January 2018, 22:34   #18  |  Link
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Originally Posted by Nico8583 View Post
Do you compare "x264 8bit @ CRF 18 encoded to x265 10bit @ CRF 21" or "H264 source encoded to x264 8bit @ CRF 18 vs H264 source encoded to x265 10bit @ CRF 21" ?
the latter
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Old 3rd January 2018, 01:57   #19  |  Link
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It'll be some time before I upgrade any piece of hardware to natively decode HEVC without framedrops.
Your cpu should be enough to sw decode hevc without framedrops
moreover h264 10bit hw support doesn't exist and luckily will not.
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Old 3rd January 2018, 02:16   #20  |  Link
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Originally Posted by Motenai Yoda View Post
Your cpu should be enough to sw decode hevc without framedrops
moreover h264 10bit hw support doesn't exist and luckily will not.
Worth checking out before diving into the rabbit hole.

I should start with the UHD drive first.
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