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View Poll Results: What deblockıng ?
aa.mp4 is loooking more optimal 7 31.82%
bb.mp4 is looking more optimal 2 9.09%
I can't say 13 59.09%
Voters: 22. You may not vote on this poll

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Old 30th November 2006, 05:35   #1  |  Link
IgorC
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How strong deblocking filter do you prefer?

It might be usefull to know what deblocking is more or less preferible for people.

Mostly metrics as SSIM like high deblock as -1 or 0 for tipical case as dvd source and bitrtaes 600-1500 kbit/s
But most of people say that they prefer less deblocking like -2

I uploaded 2 samples http://www.mytempdir.com/1090663

One has higher deblocking and it has higher metric. Another has one step weaker deblocking and for me it's more pleasant.

It will be also helpfull if someone will describe conditions of watching like distance, envoirment, CRT/LCD etc.

It's not a thread like 'what is the better'. Each one just say what prefer and it permits to recolect some statistic information.

Last edited by IgorC; 30th November 2006 at 05:45.
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Old 30th November 2006, 05:59   #2  |  Link
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For anime, I tend to use a deblock of 0,0. Generally I play with reducing threshold more than strength (so 0,-2 more than -2,0), but I tend to run a gamut of tests to compare for every major encode I do. For me, I tend to prefer the appearance of 'nominal' deblocking to mosquito noise and related stuff. I watch with a CRT usually around a meter away.
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Old 30th November 2006, 10:12   #3  |  Link
DarkZell666
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I personally didn't find the need to use anything else than 0,0.

It probably depends on what folks do with their material. For near-transparent (read: high-bitrate) encodes, it'll be better to use a negative deblocking, and for very low bitrate encodes it'll be better to use a positive deblocking (high quality/bitrate distortion).

*Edit: I like how you describe -1 or 0 has "high deblock" xD. Sorry for being a little sarcastic but ... can't you count up to 6 ?
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Last edited by DarkZell666; 30th November 2006 at 11:25.
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Old 30th November 2006, 11:21   #4  |  Link
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0 is a strong deblock, because x264 is weighted that way. The commonly useful range is about -3 to 1; I've never needed to use anything outside that except for testing, and I use a very wide range of bitrates (or crfs or however you want to describe it). If it was centered for sharper high quality instead of low, the current -1 or -2 would be 0. 0 now is perfect for around the "one-cd" quality range though.
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Old 30th November 2006, 11:37   #5  |  Link
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If you're right, and if other AVC implementations are tuned differently, does this mean the deblocking values are written to the bitstream as something different from the -6 to +6 integer values ? How do the decoders treat the deblocking scale ?

Imagine x264 encodes a file at 0,0 and that Nero (supposing it's tuned differently) encodes the same file with 0,0. If the (0,0) value couple is stored in the bitstream "as-is", the decoder will obviously be wrong for one (or both) of the encodes, and one of them will look a bit more blurred. There must be a common deblocking scale defined somewhere ... unless different values are computed by the encoder for the decoder to "know" how the encoder deblocked. This leaves me wondering quite a bit
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Old 30th November 2006, 12:01   #6  |  Link
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Quote:
Originally Posted by DarkZell666 View Post
If you're right, and if other AVC implementations are tuned differently, does this mean the deblocking values are written to the bitstream as something different from the -6 to +6 integer values ? How do the decoders treat the deblocking scale ?
IMO:
I don't think the deblocking setup is stored like that ( a level in result file ) ... but your value will setup the amount of deblocking in the result data ...

Else, where is the interrest ?! ... FFDShow can do the same by post processing ...

( maybe this is unreadable ... sorry for that ... )

[Edit]
IMO :
If the deblocking is a deblock setup value stored in video file ( -1 for exemple )
-> in this case, some decoder may apply different deblocking power due to their interpretation of this value.
-> in this case, FFDShow can do (about) the same by post processing, so why add that ?!

but IMO the value in x264 is used to compute how much "block" will "request" for deblock in the result video stream ...

Last edited by Seb.26; 30th November 2006 at 12:39.
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Old 30th November 2006, 12:29   #7  |  Link
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Deblocking in AVC isn't as simple as in ASP, there's a decoding part to it

As you (didn't ) see in CoreAVC, there's an option to disable deblocking. It's natively part of the AVC standard
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Old 30th November 2006, 12:32   #8  |  Link
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Quote:
Originally Posted by DarkZell666 View Post
Deblocking in AVC isn't as simple as in ASP, there's a decoding part to it
As you (didn't ) see in CoreAVC, there's an option to disable deblocking. It's natively part of the AVC standard
... Sorry, I haven't understand what you want to say ...
( Or you don't understand what I want to say ... lol ... I will edit my previous post )

NB: I haven't seen the deblocking setup in CoreAvc 1.2 cause I can't use it ... ... but I saw it in 1.1 ...

Last edited by Seb.26; 30th November 2006 at 12:43.
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Old 30th November 2006, 12:46   #9  |  Link
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Quote:
Originally Posted by DarkZell666 View Post
If you're right, and if other AVC implementations are tuned differently, does this mean the deblocking values are written to the bitstream as something different from the -6 to +6 integer values ? How do the decoders treat the deblocking scale ?

Imagine x264 encodes a file at 0,0 and that Nero (supposing it's tuned differently) encodes the same file with 0,0. If the (0,0) value couple is stored in the bitstream "as-is", the decoder will obviously be wrong for one (or both) of the encodes, and one of them will look a bit more blurred. There must be a common deblocking scale defined somewhere ... unless different values are computed by the encoder for the decoder to "know" how the encoder deblocked. This leaves me wondering quite a bit
In the bitstream, Alpha deblock ranges from 0-255, Beta deblock ranges from 0-18. (Or maybe they both have a range of 156 possible values, I'm not exactly sure how to read this code.) I have no idea exactly what those numbers mean or how they translate to actual deblocking strength, although I do know Nero and x264 scale their deblock settings differently.

Seb26, deblocking is done by the decoder in AVC because motion compensation works better, the encoded stream doesn't get out of sync with what the encoder sees. However, if AVC deblock is disabled, then extra post-processing can pick up some of the slack.
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Last edited by foxyshadis; 30th November 2006 at 12:49.
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Old 30th November 2006, 12:52   #10  |  Link
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Quote:
Originally Posted by foxyshadis View Post
In the bitstream, Alpha deblock ranges from 0-255, Beta deblock ranges from 0-18. (Or maybe they both have a range of 156 possible values, I'm not exactly sure how to read this code.) I have no idea exactly what those numbers mean or how they translate to actual deblocking strength, although I do know Nero and x264 scale their deblock settings differently.
So if the a_Deblock and b_Deblock values produced by both encoder are the same ( obtain this can need differents deblock setup in the encoder ), them the deblocking will the same ... of course ...

[Edit] Yes, it's logic ... FFDShow doesn't have the motion vectors ( and a lot of other usefull data ) so it can only work with the frame as a bitmap ... CoreAvc can use the frame as a bitmap but with all data from the encoder ...

Quote:
Seb26, deblocking is done by the decoder in AVC because motion compensation works better, the encoded stream doesn't get out of sync with what the encoder sees. However, if AVC deblock is disabled, then extra post-processing can pick up some of the slack.
( hum ... how to write what I think ... ?! )
The deblocking is done by the decoder, ok, but does it "only" use the frame with associated data ( motion data & Co ) like a simple posts processing filter but with access to more data, or does the encoder pre-define "where and how" the deblocking will occur ?!

Thanks

Last edited by Seb.26; 30th November 2006 at 13:10.
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Old 30th November 2006, 13:08   #11  |  Link
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Just as I thought then ^^

So x264's [0;0] deblock could in fact be [160;6] and nero's [0;0] could be [128;5].

Thx for clarifying foxyshadis
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Old 30th November 2006, 13:49   #12  |  Link
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Actually, both Nero & x264 defines deblocking strength 0 in the same way ( i.e, the value in the bitstream will be the same ). However, the two encoders have a different decision, which leads to x264 having a different size/psnr than nero at the same quantizer. That can be translated as nero Q 24 ~ x264 Q 25.5 ( or the reverse, I don't remember ). But since the deblocking strength is function of the quantizer, it means that, at the same size/psnr, x264 will deblock more ( in my example ) than nero, since Q25.5 is more deblocked than Q24.
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Old 10th December 2006, 23:51   #13  |  Link
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@IgorC, what encoder you used in examples, and what deblocking settings you use.

I found that x264 0,0 sometimes have sharper picture than elecard -1,-1
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Old 11th December 2006, 15:17   #14  |  Link
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Quote:
Originally Posted by shon3i View Post
@IgorC, what encoder you used in examples, and what deblocking settings you use.
last Elecard with light settings. aa.mp4 deblock -2 , bb.mp4 deblock -1
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Old 11th December 2006, 15:58   #15  |  Link
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From the poll results, I believe I'm the only one to prefer smooth-looking pictures ...

How come so many didn't spot a difference though ? There definitely was *something* different ... =)
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Old 11th December 2006, 16:23   #16  |  Link
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Third option is not for "I don't see difference", it's for "I don't know which one looks better", I think.

I picked 3rd option, test was with FFDShow and LCD monitor.
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Old 12th December 2006, 01:10   #17  |  Link
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The last 2 movies I ripped with x264 were very high quality (and sensitive) for the resolution, and I used -4,-4 for both.
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Old 12th December 2006, 10:30   #18  |  Link
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I see almost no difference(ffdshow no PP, CRT monitor)

0:0 looks fine to me(I hate blocking). I Have tested -2:0 -2:-2 -4:-4 and some other combinations a lot of people seem to apply on each film.. But I must be blind( :P ) as it looked not so much different... there was only a little more smeging blocking and ringing.
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Last edited by xyloy; 12th December 2006 at 10:31. Reason: ffdshow not "ffddow" :D
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Old 12th December 2006, 12:11   #19  |  Link
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Quote:
I see almost no difference(ffdshow no PP, CRT monitor)

0:0 looks fine to me(I hate blocking).
Me too, aslo in x264, 0,0 to me looks nice, but i have dilema with elecard, because his -1,-1 looks smoother than x264 0,0
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Old 13th December 2006, 00:53   #20  |  Link
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I prefer the sharper one, despite it having less deblocking. But ideally I like a sharp deblocking setting (I start at -2-2 for x264) with mp4guy's anti-blocking custom quantization matrix. That gives the best of both, i.e. sharp and block-free on a suitable source, at the cost of maybe 30% increased bitrate (still beats Xvid).
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