Luma discussions

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Luma discussions

boelle


2017-02-20 13:32 GMT+01:00 smf <[hidden email]>:
On 20/02/2017 10:41, [hidden email] wrote:
The "dust" he writes about applies to my understanding only to the "modern plasma TV" he used and which I expect does bad job handling off specs signals.

Old tv's are blurry and uses anlogue processing. Plasma TV's have crisper pixels & depending on the TV and how it's setup could have less than 8 bits of colour resolution per channel. This makes irregularities in the video signal more visible, which is especially worse if the plasma TV has a much larger screen size.

VCD and DVB suffer from the same problem as they were developed to be satisfactory with old tv's.


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Re: Luma discussions

silverdr-2
While you certainly added noise, I believe you forgot to add any signal to those reposted messages, didn't you?

> On 2017-02-20, at 13:34, Bo Herrmannsen <[hidden email]> wrote:
>
>
>
> 2017-02-20 13:32 GMT+01:00 smf <[hidden email]>:
> On 20/02/2017 10:41, [hidden email] wrote:
> The "dust" he writes about applies to my understanding only to the "modern plasma TV" he used and which I expect does bad job handling off specs signals.
>
> Old tv's are blurry and uses anlogue processing. Plasma TV's have crisper pixels & depending on the TV and how it's setup could have less than 8 bits of colour resolution per channel. This makes irregularities in the video signal more visible, which is especially worse if the plasma TV has a much larger screen size.
>
> VCD and DVB suffer from the same problem as they were developed to be satisfactory with old tv's.
>
>
>       Message was sent through the cbm-hackers mailing list
>

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Re: Luma discussions

boelle
Well i tried to reduce noise in another thread :-D

Sadly i'm not good at magic so the noise just turned up somewhere else :-/

2017-02-20 15:09 GMT+01:00 <[hidden email]>:
While you certainly added noise, I believe you forgot to add any signal to those reposted messages, didn't you?

> On 2017-02-20, at 13:34, Bo Herrmannsen <[hidden email]> wrote:
>
>
>
> 2017-02-20 13:32 GMT+01:00 smf <[hidden email]>:
> On 20/02/2017 10:41, [hidden email] wrote:
> The "dust" he writes about applies to my understanding only to the "modern plasma TV" he used and which I expect does bad job handling off specs signals.
>
> Old tv's are blurry and uses anlogue processing. Plasma TV's have crisper pixels & depending on the TV and how it's setup could have less than 8 bits of colour resolution per channel. This makes irregularities in the video signal more visible, which is especially worse if the plasma TV has a much larger screen size.
>
> VCD and DVB suffer from the same problem as they were developed to be satisfactory with old tv's.
>
>
>       Message was sent through the cbm-hackers mailing list
>

--
SD!


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Re: Luma discussions

André Fachat

Twitterizing a mailing list doesn't help with signal to noise ratio either IMHO

André

Am 20. Februar 2017 3:11:18 PM schrieb Bo Herrmannsen <[hidden email]>:

Well i tried to reduce noise in another thread :-D

Sadly i'm not good at magic so the noise just turned up somewhere else :-/

2017-02-20 15:09 GMT+01:00 <[hidden email]>:
While you certainly added noise, I believe you forgot to add any signal to those reposted messages, didn't you?

> On 2017-02-20, at 13:34, Bo Herrmannsen <[hidden email]> wrote:
>
>
>
> 2017-02-20 13:32 GMT+01:00 smf <[hidden email]>:
> On 20/02/2017 10:41, [hidden email] wrote:
> The "dust" he writes about applies to my understanding only to the "modern plasma TV" he used and which I expect does bad job handling off specs signals.
>
> Old tv's are blurry and uses anlogue processing. Plasma TV's have crisper pixels & depending on the TV and how it's setup could have less than 8 bits of colour resolution per channel. This makes irregularities in the video signal more visible, which is especially worse if the plasma TV has a much larger screen size.
>
> VCD and DVB suffer from the same problem as they were developed to be satisfactory with old tv's.
>
>
>       Message was sent through the cbm-hackers mailing list
>

--
SD!


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Re: Luma discussions

Justin-2
I don't agree.  The is this possible thread has over e hundred emails in it about several different subjects. It is useless to search on in the future. Breaking it apart into coherent conversations makes sense.

And on topic, I agree that the issue with that old article is clearly that it is describing behavior of the scaler and quantization of the signals coming out of the 64 and cannot be relied on to describe the behavior of different revisions.

Justin

On Feb 20, 2017, at 16:28, André Fachat <[hidden email]> wrote:

Twitterizing a mailing list doesn't help with signal to noise ratio either IMHO

André

Am 20. Februar 2017 3:11:18 PM schrieb Bo Herrmannsen <[hidden email]>:

Well i tried to reduce noise in another thread :-D

Sadly i'm not good at magic so the noise just turned up somewhere else :-/

2017-02-20 15:09 GMT+01:00 <[hidden email]>:
While you certainly added noise, I believe you forgot to add any signal to those reposted messages, didn't you?

> On 2017-02-20, at 13:34, Bo Herrmannsen <[hidden email]> wrote:
>
>
>
> 2017-02-20 13:32 GMT+01:00 smf <[hidden email]>:
> On 20/02/2017 10:41, [hidden email] wrote:
> The "dust" he writes about applies to my understanding only to the "modern plasma TV" he used and which I expect does bad job handling off specs signals.
>
> Old tv's are blurry and uses anlogue processing. Plasma TV's have crisper pixels & depending on the TV and how it's setup could have less than 8 bits of colour resolution per channel. This makes irregularities in the video signal more visible, which is especially worse if the plasma TV has a much larger screen size.
>
> VCD and DVB suffer from the same problem as they were developed to be satisfactory with old tv's.
>
>
>       Message was sent through the cbm-hackers mailing list
>

--
SD!


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smf
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Re: Luma discussions

smf
On 20/02/2017 14:33, Justin Cordesman wrote:
> I agree that the issue with that old article is clearly that it is describing behavior of the scaler and quantization of the signals coming out of the 64 and cannot be relied on to describe the behavior of different revisions.

If putting it through a scaler makes display noise more visible that is
usually hidden with a combination of your crt, your eyes and your brain
then it is perfectly valid to use that to determine which revision is
better than any other.



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Re: Luma discussions

Justin-2
Only if it is repeatable, which I'd suspect it is not.  Things like color gamut being reduced on an old plasma, and quantization errors from the scaler are not indicative of actual performance by the C64.  It is also entirely possible for features in the scaler that are intended to do things like reduce compression artifacts or normalize analog noise will misbehave and generate new artifacts from legitimate signal or in attempts to reduce artifacts present in the original signal. Early ones are simple edge detection algorithms that do smoothing.

Also, artifacts that are invisible under normal use are irrelevant, and not all signal defects are subjectively a problem.  For example, adding a small amount of analog noise to a noiseless video stream makes people score it as more detailed than the noiseless version when they are untrained viewers.

Justin

On Feb 20, 2017, at 17:34, smf <[hidden email]> wrote:

On 20/02/2017 14:33, Justin Cordesman wrote:
> I agree that the issue with that old article is clearly that it is describing behavior of the scaler and quantization of the signals coming out of the 64 and cannot be relied on to describe the behavior of different revisions.

If putting it through a scaler makes display noise more visible that is
usually hidden with a combination of your crt, your eyes and your brain
then it is perfectly valid to use that to determine which revision is
better than any other.



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Re: Luma discussions

boelle
i can throw in my 0.02 DKK here

while the 2 same rev chips can differ slightly as back in the day quality control was a unmarked village in siberia.. also remember that all the components arround it has tolerance too.

only sure way is to adjust each individual unit with a scope and freq. counter (same scope used on all of course).

2017-02-20 16:49 GMT+01:00 Justin Cordesman <[hidden email]>:
Only if it is repeatable, which I'd suspect it is not.  Things like color gamut being reduced on an old plasma, and quantization errors from the scaler are not indicative of actual performance by the C64.  It is also entirely possible for features in the scaler that are intended to do things like reduce compression artifacts or normalize analog noise will misbehave and generate new artifacts from legitimate signal or in attempts to reduce artifacts present in the original signal. Early ones are simple edge detection algorithms that do smoothing.

Also, artifacts that are invisible under normal use are irrelevant, and not all signal defects are subjectively a problem.  For example, adding a small amount of analog noise to a noiseless video stream makes people score it as more detailed than the noiseless version when they are untrained viewers.

Justin

On Feb 20, 2017, at 17:34, smf <[hidden email]> wrote:

On 20/02/2017 14:33, Justin Cordesman wrote:
> I agree that the issue with that old article is clearly that it is describing behavior of the scaler and quantization of the signals coming out of the 64 and cannot be relied on to describe the behavior of different revisions.

If putting it through a scaler makes display noise more visible that is
usually hidden with a combination of your crt, your eyes and your brain
then it is perfectly valid to use that to determine which revision is
better than any other.



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Re: Luma discussions

André Fachat
In reply to this post by Justin-2

With "Twitterizing" I wasn't referring to multiple topics, I totally agree with you there. It is just numbers of mails with very little content each.

Regards
André

Am 20. Februar 2017 15:43:03 schrieb Justin Cordesman <[hidden email]>:

I don't agree.  The is this possible thread has over e hundred emails in it about several different subjects. It is useless to search on in the future. Breaking it apart into coherent conversations makes sense.

And on topic, I agree that the issue with that old article is clearly that it is describing behavior of the scaler and quantization of the signals coming out of the 64 and cannot be relied on to describe the behavior of different revisions.

Justin

On Feb 20, 2017, at 16:28, André Fachat <[hidden email]> wrote:

Twitterizing a mailing list doesn't help with signal to noise ratio either IMHO

André

Am 20. Februar 2017 3:11:18 PM schrieb Bo Herrmannsen <[hidden email]>:

Well i tried to reduce noise in another thread :-D

Sadly i'm not good at magic so the noise just turned up somewhere else :-/

2017-02-20 15:09 GMT+01:00 <[hidden email]>:
While you certainly added noise, I believe you forgot to add any signal to those reposted messages, didn't you?

> On 2017-02-20, at 13:34, Bo Herrmannsen <[hidden email]> wrote:
>
>
>
> 2017-02-20 13:32 GMT+01:00 smf <[hidden email]>:
> On 20/02/2017 10:41, [hidden email] wrote:
> The "dust" he writes about applies to my understanding only to the "modern plasma TV" he used and which I expect does bad job handling off specs signals.
>
> Old tv's are blurry and uses anlogue processing. Plasma TV's have crisper pixels & depending on the TV and how it's setup could have less than 8 bits of colour resolution per channel. This makes irregularities in the video signal more visible, which is especially worse if the plasma TV has a much larger screen size.
>
> VCD and DVB suffer from the same problem as they were developed to be satisfactory with old tv's.
>
>
>       Message was sent through the cbm-hackers mailing list
>

--
SD!


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Re: Luma discussions

Gerrit Heitsch
On 02/20/2017 04:56 PM, André Fachat wrote:
> With "Twitterizing" I wasn't referring to multiple topics, I totally
> agree with you there. It is just numbers of mails with very little
> content each.
>
> Regards
> André

One can also just delete what's no longer important in a reply. Like I
did in this one. I really hate the 'always include a fullquote in a
reply', it makes emails way too large.

  Gerrit



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Re: VIC revisions (was: Is it at all possible?)

silverdr-2
In reply to this post by smf

> On 2017-02-20, at 16:33, smf <[hidden email]> wrote:
>
> On 20/02/2017 14:33, Justin Cordesman wrote:
>> I agree that the issue with that old article is clearly that it is describing behavior of the scaler and quantization of the signals coming out of the 64 and cannot be relied on to describe the behavior of different revisions.
>
> If putting it through a scaler makes display noise more visible that is usually hidden with a combination of your crt, your eyes and your brain then it is perfectly valid to use that to determine which revision is better than any other.

I wrote this a few times already now: If you pass the signal through an upscaler that handles such non-compliant signals gracefully, the differences don't show up that much if at all.

When you pass it through one that doesn't, then you only determine, which chip revision/batch/wafer-position/... is "better" for the particular ADC/upscaler in use. I believe it to be very much possible that when using another upscaler, another chip/batch/wafer-position may come out as better. I haven't specifically tested various chips looking for subtle differences when using "good" upscalers but I used various VIC revisions with one and nothing was more striking than the difference between R1 and all the newer ones. Yet I agree that this is far from being "scientific". I shall find some time to do some more objective tests. Not only about luma levels ;-)

--
SD!


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Re: Netiquette (was: Is it at all possible?)

silverdr-2
In reply to this post by boelle
> 2017-02-20 15:09 GMT+01:00 <[hidden email]>:
> While you certainly added noise, I believe you forgot to add any signal to those reposted messages, didn't you?

> On 2017-02-20, at 15:11, Bo Herrmannsen <[hidden email]> wrote:
>
> Well i tried to reduce noise in another thread :-D

The last time I checked adding noise was hardly reducing it, unless you add the very same but shift its phase 180 deg. I think Bose, Plantronics and a few others do it already better than anyone of us can :-P

> Sadly i'm not good at magic so the noise just turned up somewhere else :-/

Of course you may elect not to follow those simple points but - as you were already suggested - it is worth to consider differences between what other people expect when using web forums or twitter or dozens of "chat" applications and a closed mailing list. The audience of the latter is usually more conservative and appreciates observing at least:

- bottom-posting. At least as long as it is feasible (and with desktop clients it always is)

- cutting the quotes to what remains important

- condensing your thoughts and posting one slightly longer post with articulated points/observations/questions instead of multiple ones, whenever only a new thought pops up, which doesn't really add much if anything.

There is also an old way of changing the subject of the thread, which doesn't violate the above. You may notice it above ;-) Use it when you can add something to the discussion yet feel that the discussion drifted too far from the original subject.

P. S. Obviously nobody's perfect (with one exception, and no - I am not religious person ;-) and e. g. /me may be guilty of violating some of those occasionally too.

--
SD!


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