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25th November 2013, 12:59 | #162 | Link |
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Keyakusha,
What i simply meant is, i thought those tapes, or rather what was in the content of the tape was 10bit. For example, letīs say Lord of the Rings, it was recorded in 10bit and thatīs itīs original source (an example here). Then they are going to broadcast it on TV etc. And they get a copy of that source, meaning they put it on the broacast tape, so it isnīt upsampled, it stays the same. Same goes for everything else, but of course if there is 8bit stuff it getīs upsampled. But if Nothing is 10bit which seems to be the case, than thatīs my disappointment. But of course i know that 10bit itself helps a lot if post-processing has been done at something above 8bit, as less information will be removed, the leap between 8bit to 10bit is quite high, though 10bit to 16bit is enormous, but luckily the improvement in actual quality is much less from my understanding, which makes it "a waste". |
1st December 2013, 08:34 | #163 | Link | |
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Consumers can generate 10bit video with prosumer cameras, like Canon XL H1 or Sony HVR-V1U, but it might be better to ask on a videographer enthusiast forum than here. |
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1st December 2013, 08:52 | #164 | Link |
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Well, I tried to explain what I mean but it seems i failed at it so I've withdraw from this discussion. But let's try once more ^^
For some reason you got an impression that I'm saying that there are no >8bit material or something... this is not it. Of course there are >8bit things produced by some hardware and not generated on PC. For the movies like LotR it is of course more likely that they could be >8bit starting from the camera shooting stage. But if we are talking about global scale, which includes TV shows and various other material, then most of the content was never 10bit to begin with. It is whatever simply upsampled because standard requires it/someone requested it this way or it was modified/edited at some point. That said, I believe the codec should be optimized for more common usage scenarios. Especially that for big studios who have things in >8 bit from the beginning there are 0 reason to use lagarith. I bet many of them never even heard of it and there is no reason for them to do such a research, they already have all the tools they need. Not to mention that many of them simply refuse to work with anything free/opensource. So why optimize codec for them and not for the world of "mere mortals"? (rhetorical question. I don't need an answer) Edit: anyway, sorry for going offropic. Personally I'm not even interested in lagarith, it is too slow, so feel free to optimize for whatever you want. Last edited by Keiyakusha; 1st December 2013 at 09:25. |
1st December 2013, 14:04 | #165 | Link |
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Ah well than i had understood it correctly, at least half way.
That Tapes (Though not Broadcast tapes) can be done in higher bit depth. But as you say, itīs impossible to obtain them, the only way to get such a "master tape" would be to either have the resources and contacts for it. Or that it the company owning it has gone bankruptcy and itīs sold or something. Keyakusha, I fully understand what you mean, and as you say, the reason to even have 10bit as lossless currently, doesnīt even exist, the only reason for it i can think of with is for experimentations and certain individuals. But i however donīt by any means want it NOT to be there, support and optimization in any case is always good, it doesnīt matter if the thing is useless now or not, If it can be added and someone wants to, then by all means do so! And can also agree with it being slow. But for 2D (Pixel and simple stuff) itīs totally unbeatable, you canīt even compare it with UT Video Codec which is the rival i think. On "Normal" videos however, Lagarith isnīt that great in terms of speed, but i think it can be optimized as it has been laying around for quite some time compared to UT which has been updated all the time. But anyway, if i can help with anything for updating Lagarith i am on. Sadly Programming wise i am at a total newbie level, but making tests samples or something is something i should be able to do. |
1st December 2013, 14:54 | #168 | Link |
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He's referring to the "random" glitches (artifacts) that some people seem to be getting with Lagarith.
AFAIK, Lagarith uses arithmetic coding, which - in its most simple form - uses infinite-precision real numbers. Computers don't have that. So, in practice, we usually use a "range coder" instead of a plain arithmetic coder. It is essentially one and the same thing, yes. But the "range coder" works entirely on integer math (rather than using real numbers). This makes it more suitable for implementation on a real-world computer. Also ensure that the results are always deterministic. Lagarith, on the other hand, seems to implement arithmetic coding based on limited-precision floating point math. This is kind of "delicate" with respect to rounding errors and stuff. And this is what may cause nondeterministic behavior
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1st December 2013, 15:15 | #169 | Link |
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But it does not effect Encoding does it?
Meaning all encodes movies will always be 100% alright. But decoding them CAN fail, but redoing it CAN succeed, meaning itīs not a permanent error? Weird that it uses such system if it isnīt perfect as these stuff are supposed to Always work in All scenarios. |
1st December 2013, 15:41 | #170 | Link | ||
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(Or in other words: Regardless of weather the video already was encoded "wrongly", or whether it was encoded "correct" but now can't be decoded "correctly", the end result is always the same. You can't get the correct output now!) Quote:
Also keep in mind that the "perfect" (error free) software doesn't exist in reality. We usually accept that a "high quality" software has about one bug per 1000 lines of code
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1st December 2013, 15:45 | #171 | Link |
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But if the error occurs (Artifact) is it always there, or does it appear from time to time depending if the decoder fails to reach the correct number?
And well yeah "error free" is more of a term what should be striven for. But something thatīs fundamentally wrong like this, isnīt what i would expect from a Codec. |
1st December 2013, 15:51 | #172 | Link |
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That's the "nice" thing about undefined behavior: Everything is possible. You just don't know what is going to happen. And the result can (but doesn't have to) be different each time
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1st December 2013, 15:52 | #173 | Link |
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Well if the Possibility exist, then you can at least Save the content by converting it. If the error Always occurs thatīs impossible.
But i find it weird that i myself have never been inflected by this, i tend to use Lagarith quite a lot. |
1st December 2013, 16:17 | #174 | Link | |
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FFV1, for the record, also uses arithmetic coding (it's integer-based, though, not floating point). It loses to Lagarith in a couple of areas though - mainly solid color frames* and things like line drawings (and speed; Lagarith is faster than FFV1). FFV1 also supports all those high bit depth pixel formats. *unless you use the lower efficiency VLC coder for FFV1 - then it actually gets close to Lagarith for solid color frames (because it switches to inter-frame? that's...unexpected, and feels wrong - it's what VirtualDub seems to report, though). Lagarith stores solid color frames as flags and presents them to the decoder as real intra frames. Case in point, a simple BlankClip script (RGBA, 10 seconds, 640x480 @ 24 fps): Lagarith: 15 KB FFV1 (-coder 1 -context 1): 1.85 MB FFV1 (-coder 1 -context 0): 1.85 MB FFV1 (-coder 0 -context 1): 70.1 KB FFV1 (-coder 0 -context 0): 70.1 KB -coder 0 = VLC -coder 1 = AC |
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1st December 2013, 16:26 | #175 | Link |
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It's more that floating point isn't entirely perfect, so things might be +1 or -1 from where they should be when decoded; those errors can add up, but they're pretty rare and hard to notice usually. It has C, MMX, SSE, and SSE2 versions of a lot of functions, all of which may have different rounding characteristics; it's impossible to tell since there's no testbed. Then again, there might just plain plain old bugs, too.
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1st December 2013, 16:49 | #176 | Link | |
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And because the probability model is usually updated after each symbol, one wrong symbol can cause all future symbols to be wrong too BTW: This is also the reason why, when dealing with floating point numbers, we never check for equality directly, but instead assume the numbers are "equal" if the absolute difference is below a certain threshold.
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1st December 2013, 18:48 | #177 | Link | |
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1st December 2013, 18:58 | #178 | Link | |
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1st December 2013, 21:31 | #179 | Link | ||
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2nd December 2013, 01:59 | #180 | Link | ||
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