Author: NobodyDate: 20:33 20-08-07
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On Mon, 20 Aug 2007 11:54:07 -0600, Bob Myers wrote:
>> It's the quantisation which makes something "digital".
>>
>
> So is the output of an ideal D/A converter "digital,"
> then?
Maybe. If you intend to feed it to an ADC such that the ADC will output
the original bits, then it is (i.e. multi-level encoding). If you intend
to feed it to a low-pass filter to remove the quantisation noise, it isn't.
> It is most certainly quantized; it cannot take
> on any values between adjacent output levels,
> which are themselves separated by one "LSB" step
> size.
That doesn't make it quantised.
> What makes something "digital" is the representation
> of information by numeric values ("digits"), or their equivalent,
> as opposed to its representation by analogous variations
> in some other quantity (which is "analog"). This is the
> only definition which consistently makes sense.
Whether or not a signal is "digital" depends upon what you intend to do
with it. A PCM signal conveying the digits 01010101... is digital; a
square wave generated within an audio synthesiser isn't, even if the
signals are identical.
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Author: Floyd L. DavidsonDate: 20:35 20-08-07
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nospam@nospam.com (Don Pearce) wrote:
>On Mon, 20 Aug 2007 13:33:34 -0800, floyd@apaflo.com (Floyd L.
>Davidson) wrote:
>>>>
>>>>A "quantized analogue signal" is digital by definition.
>>>>
>>>
>>>No, you haven't. You merely have a signal at a set of discrete levels.
>>
>>Sheesh! That *is*, by definition a digital signal.
>>
>If you put that signal through an analogue amplifier, it will be
>amplified. That makes it an analogue signal.
It wasn't analog until you ran it through an analog amplifier.
>If you want to amplify a
>signal in the digital domain, you must perform maths on the numbers.
>Can you really not see the difference?
Non-sequitur. When you quantize an analog signal you
have a digital signal. Just as it is possible to
convert an analog signal to a digital signal, it is
possible to convert a digital signal to analog.
One way to do it is to generate a digital PAM signal and
pass it through an analog channel.
>>>You need an analogue to digital converter to take each of those
>>>quantized levels and convert it into a digital word (of 1s and 0s).
>>>
>>>Digital means "represented by digits", not "in discrete
voltage
>>>steps".
>>
>>Bullshit son. Look it up. I've provided you with
>>quotes from an authoritative reference, twice now. You
>>don't have to take my word for it, that *is* the agreed
>>technical definition of the term.
>
>Sorry, but you are wrong. And any reference you have found that makes
>such a claim is not authoritative; it is also wrong.
As if *you* are an authority! Bullshit son.
The NTIA is an authority, and MilStd specifications are
also authoritative. That is the reason I cited them.
And the *fact* is that you have not and cannot cite any
authoritative standards body that does not agree with
them.
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>;
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
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Author: RadiumDate: 20:37 20-08-07
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On Aug 20, 8:47 am, "Bob Myers" <nospample...@address.invalid> wrote:
> You can also
> reduce the temporal frequency in the case of motion video.
That's what I was talking about. Reducing the temporal frequency of
the video w/out low-pass filtering or increasing the length of the
movie.
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Author: Don BoweyDate: 20:38 20-08-07
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On 8/20/07 5:17 PM, in article
1187655470.606369.55890@j4g2000prf.googlegroups.com, "Radium"
<glucegen1@gmail.com> wrote:
> On Aug 20, 12:11 am, nos...@nospam.com (Don Pearce) wrote:
>
>> analogue - a continuous representation of the original signal
>> sampled - a representation of the signal at discrete time points
>> quantized - a sampled signal, but with the possible levels constrained
>> to a limited set of values
>> digital - a quantized signal, with the individual levels represented
>> by numbers
>
> I agree with your list.
>
> That means the device in the link below is neither analog nor
> digital.
>
> http://www.winbond-usa.com/mambo/content/view/36/140/
>
> I'd like to see a purely-analog device which can record, store, and
> playback electric audio signals [AC currents at least 20 Hz but no
> more than 20,000 Hz] without having any moving parts [except of course
> for the diaphragms present in the microphone and speaker and the
> electrons that make up the electric signal] and without any amount of
> sampling.
>
> The CCD is out of the question as it uses sampling.
>
Which means you still do not understand basics.
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Author: Floyd L. DavidsonDate: 20:41 20-08-07
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Scott Seidman <namdiesttocs@mindspring.com> wrote:
>floyd@apaflo.com (Floyd L. Davidson) wrote in
>news:87zm0mjrfy.fld@apaflo.com:
>
>>>quantized - a sampled signal, but with the possible levels constrained
>>>to a limited set of values
>>
>> That is by definition a digital siganl. As soon as the possible values
>> are "constrained to a limited set", it is by definition digital data.
>>
>>
>
>Wouldn't this make the output of a D/A converter digital by definition?
It is in fact! It's a digital PAM signal. Indeed, v.90 modems
make use of it.
However, just as you can convert an analog signal to digital, you
can indeed convert digital to analog. One method is to produce a
digital PAM signal and run it through an analog channel. What
you get directly from the D/A is technically called "quasi-analog"
because of that.
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>;
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
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Author: Floyd L. DavidsonDate: 20:43 20-08-07
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nospam@nospam.com (Don Pearce) wrote:
>On 20 Aug 2007 21:42:18 GMT, Scott Seidman
><namdiesttocs@mindspring.com> wrote:
>
>>floyd@apaflo.com (Floyd L. Davidson) wrote in
>>news:87zm0mjrfy.fld@apaflo.com:
>>
>>>>quantized - a sampled signal, but with the possible levels constrained
>>>>to a limited set of values
>>>
>>> That is by definition a digital siganl. As soon as the possible values
>>> are "constrained to a limited set", it is by definition digital
data.
>>>
>>>
>>
>>Wouldn't this make the output of a D/A converter digital by definition?
>
>It certainly would. But apparently there are those that can't see the
>difference between a limited set of values, and a set of numbers
>describing those values.
You don't appear to understand that the limited set of values makes
it digital, by definition. PERIOD.
Of course if you then run that digital PAM signal through virtually
any analog channel, it no longer has a limited set of values...
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>;
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
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Author: RadiumDate: 20:58 20-08-07
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On Aug 20, 3:15 am, Richard Dobson <richarddob...@blueyonder.co.uk>
wrote:
> Radium wrote:
> > I am talking about:
> > 1. Decreasing the temporal frequency of the video signal without low-
> > pass filtering or decreasing the playback speed - an example of which
> > would be decreasing the rate at which a bird [in the movie] flaps its
> > wings. Hummingbirds flap their wings too fast for the human eye to
> > see. So the flap-rate of the wings could be decreased until the
> > flapping is visible to the human eye - without decreasing the playback
> > speed of the video. This decrease in flap-rate without slowing
> > playback is visually-analogous to decreasing the pitch of a recorded
> > sound without decreasing the playback speed. In this case, low-pass
> > filter would involve attenuating rapidly-changing images while
> > amplifying slowly-changing images -- I don't want this.
> There are some mixed metaphors here. There is a video equivalent to
> audio pitch shifting. think of the latter represetned in the frequency
> domain (spectrum) - the peak correspindsing to the source partial moves
> down (or up). the video equivalent is colour cycling or shifting. But
> most simply, reds would be shifted to orange, green shifted to blue,
> violet to ultra-violet (and hence llost to view). An alternatyive
> stratgy is colour rotation using the artists colour wheel, where,
> ideally, diametrically opposite colours are complementary. There is no
> equivalent that I know of to colour complemenariness in audio.
Never thought of it this way. My description of visual "pitch-
shifting" is to alter the temporal and spatial frequencies of a video
signal without using low/high-pass-filtering, changing the speed of
the video or changing the size of the images that make up the movie.
Real-time pitch-shifting is done for audio on the phone. Certain voice-
changing devices allow women to sound like men on the phone, without
decreasing the speed at which they talk. The pitch of the audio is
decreased but the speed remains the same.
I would like something similar to be done with the spatial and
temporal of a video signal in real-time. I would like to be able to
work not only for recorded video but also for video signals that are
being transmitted/received in real-time -- such as a live TV show.
> I ~think~ I get what Radium wants - he wants to be able to modify a
> recorded scene the way one can modify a CGI virtual scene, e.g. by
> setting a slower wing flapping rate while leaving other parts of the
> scene unchanged.
Actually I don't want other parts to be unchanged. What I would like
is the temporal frequencies [of all parts of the video] to be
decreased but without decreasing the speed of the video signal.
> The only audio parallel I can think
> of is wanting to pitch shift just one instrument in a polyphonic
> texture, leaving other voices unchanged.
The audio parallel is the following:
http://www.adobe.com/products/audition/overview2.html#kmhead3
"Time and pitch processing: shift pitch without changing tempo - and
never introduce audio artifacts."
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Author: Dave PlattDate: 21:24 20-08-07
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In article <6M2dner4stOKoVfbnZ2dnUVZ_qelnZ2d@comcast.com>,
glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:
>> Actually I don't want other parts to be unchanged. What I would like
>> is the temporal frequencies [of all parts of the video] to be
>> decreased but without decreasing the speed of the video signal.
>
>That might be harder. For audio, it can be chopped, such as
>removing 1/60th of a second every 1/20th to speed it up by 1.5.
>If that is done faster than the modulation (vocalization),
>and slower than the frequencies of interest (maybe 400Hz-3.5kHz
>for voice) it works pretty well. Probably less well for music.
>
>As far as I know, that is usually done asynchronously to the
>source signal. One could imagine removing cycles of a 1.23kHz
>voice, for example.
>
>For video the modulation (wing flapping) is not separate from
>the source frequency. If you know you are trying to separate
>wing flapping, it could be done by cutting out whole flap
>cycles, assuming only one bird is in the scene, and is doing
>most of the motion. Otherwise, I don't think there is anything
>you could do.
Some of the TV networks are speeding up syndicated reruns by using
this sort of technique. They appear to be using the "chop out audio
samples" method to speed up the dialog (without pitch-shifting it) and
dropping out complete frames of the video. This works fairly well
when watching scenes with little action, but causes an odd
stuttering-jerk effect when the camera pans or somebody walks across
the screen.
I think I prefer it to the old technique of cutting out whole scenes
or sub-scenes, though.
--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
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Author: Jerry AvinsDate: 21:26 20-08-07
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Floyd L. Davidson wrote:
> Jerry Avins <jya@ieee.org> wrote:
...
>> I can
>> demonstrate a circuit using analog components that
>> transforms a continuous ramp input into a staircase
>> output. Moreover, the output levels can be individually
>> adjusted. Is the output digital? (We're discussing an
>> arbitrary definition here. There is no wrong answer.)
>
> The output is apparenlty analog. At least you have said
> *nothing* that indicates otherwise.
Apparently analog but actually digital? That would be in keeping with
your assertion that quantizing an otherwise analog signal digitizes it.
> Do you think all digital signals are square waves and
> anything that has square waves is digital? Your example
> above suggests that you might, but it simply isn't true.
By old vacuum-tube signal generator was certainly analog. It produced
square waves among other wave shapes.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Author: Jerry AvinsDate: 21:30 20-08-07
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Floyd L. Davidson wrote:
> Jerry Avins <jya@ieee.org> wrote:
>> ... A signal can be
>> quantized without any need to measure it or describe it
>> with a number.
>
> That isn't true. In order to quantize it you *must*
> decide on non-overlapping ranges of *values*, and a
> specific quantity value that equates to those values.
>
>> An example is the signal being measured
>> in a quantum Hall-effect experiment.
>
> Explain.
http://www.warwick.ac.uk/~phsbm/qhe.htm
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Author: Jerry AvinsDate: 21:32 20-08-07
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Floyd L. Davidson wrote:
...
> Anything that is quantized is digitized.
A signal can be quantized without having been measured. How doe that fit
your scheme?
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Author: RadiumDate: 21:40 20-08-07
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On Aug 20, 7:15 pm, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:
> For video the modulation (wing flapping) is not separate from
> the source frequency. If you know you are trying to separate
> wing flapping, it could be done by cutting out whole flap
> cycles, assuming only one bird is in the scene, and is doing
> most of the motion. Otherwise, I don't think there is anything
> you could do.
I don't want to separate the wing-flapping or anything from the video.
I want all temporal components of the video signal to be slowed
without changing the length or speed of the video. Just like Adobe
Audition and certain voice-changers allow the pitch of the audio
signal to be decreased without changing the length or speed of the
audio.
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Author: Jerry AvinsDate: 21:42 20-08-07
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Radium wrote:
...
> Actually I don't want other parts to be unchanged. What I would like
> is the temporal frequencies [of all parts of the video] to be
> decreased but without decreasing the speed of the video signal.
...
> The audio parallel is the following:
>
> http://www.adobe.com/products/audition/overview2.html#kmhead3
>
> "Time and pitch processing: shift pitch without changing tempo - and
> never introduce audio artifacts."
The video analog of acoustic pitch is color. Both are our biological
response to frequency.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Author: RadiumDate: 21:54 20-08-07
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On Aug 20, 12:37 am, Jerry Avins <j...@ieee.org> wrote:
> Radium wrote:
> > I wish I knew. This 'pitch-shifting' is a lot more confusing than I
> > thought. Yet I still find it so interesting. Sorry.
> Don't be sorry. If you work out the details, I'll help you to see the
> inherent contradictions they impose, but I won't argue with you about it.
The problem is, I have a hard time accepting when I'm told that there
is no video-equivalent to pitch-shifting-without-changing-tempo.
> > Similarly an imaging device with insufficient spatial bandwidth will
> > result in image distortion if excessively fine detail is put into the
> > camera.
> That's true only if you mean spatial aliasing. Otherwise, you're using
> "distortion" in a non-standard way.
Okay.
> > Just like if you have an 11.025-KHz-sample-rate digital audio device,
> > you need to make sure the pitch of the audio you are inputting into
> > the device does not exceed 5.5125 KHz.
> How does that make for "decent imagery? It amounts to a low-pass filter,
> about which you remarked, "ugh".
Well, the image looked bad. It's similar to what happens when you set
the "sharpness" setting on a PC-monitor or TV-screen too low.
> > Spatial frequency is how fine or dull an image is. Pitch is determined
> > by audio frequency. I am using the spatial frequency as an analogy.
> Stop with analogies. Say what you mean.
I am saying what I mean -- or at least what I think I mean.
> Here's the picture of you that I have in my head: You were a precocious
> kid, and impressed those around by asking questions that were further
> out than what most kids asked. (Reading a lot leads one to do that.) The
> adults around you patted you on the head and praised you for digging
> into subjects they knew little or nothing about.* They knew so little
> about it that they didn't understand much of what you talked about, and
> so couldn't set you back on the rails when you wandered away from
> reality. No matter, the praise kept coming anyway, and you learned that
> if you imagined something, it was golden. It wasn't really, but those
> around you taught you to believe that it was. Now you find yourself
> going on about your imaginings with people who _do_ understand the
> subject you fantasize about and their reaction hurts, but you're finding
> it very hard to get out of bullshit mode and ask basic questions. It
> hasn't sunk in yet that you don't even have basic answers because you
> still believe that the fantasies you construct are real. I hope you get
> over that. In the meanwhile, I feel sorry for you.
Well, I've always had a special interest in things that I find
difficult to answer or make sense of. Video-equivalents-of-audio-
entities are certainly one of them.
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Author: RadiumDate: 21:56 20-08-07
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On Aug 20, 6:42 pm, Jerry Avins <j...@ieee.org> wrote:
> The video analog of acoustic pitch is color. Both are our biological
> response to frequency.
True. Maybe I am just using the wrong words.
Instead of "pitch-shift", I should say "frequency-shift" because
that
is what I really mean.
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Author: Jerry AvinsDate: 21:59 20-08-07
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Radium wrote:
> On Aug 20, 7:15 pm, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:
>
>> For video the modulation (wing flapping) is not separate from
>> the source frequency. If you know you are trying to separate
>> wing flapping, it could be done by cutting out whole flap
>> cycles, assuming only one bird is in the scene, and is doing
>> most of the motion. Otherwise, I don't think there is anything
>> you could do.
>
> I don't want to separate the wing-flapping or anything from the video.
> I want all temporal components of the video signal to be slowed
> without changing the length or speed of the video. Just like Adobe
> Audition and certain voice-changers allow the pitch of the audio
> signal to be decreased without changing the length or speed of the
> audio.
He wants to walk the same distance at half speed and complete the trip
in the same time as before. I give up!
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Author: Floyd L. DavidsonDate: 22:00 20-08-07
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Jerry Avins <jya@ieee.org> wrote:
>Floyd L. Davidson wrote:
>> Jerry Avins <jya@ieee.org> wrote:
>
> ...
>
>>> I can
>>> demonstrate a circuit using analog components that
>>> transforms a continuous ramp input into a staircase
>>> output. Moreover, the output levels can be individually
>>> adjusted. Is the output digital? (We're discussing an
>>> arbitrary definition here. There is no wrong answer.)
>> The output is apparenlty analog. At least you have
>> said
>> *nothing* that indicates otherwise.
>
>Apparently analog but actually digital? That would be in
>keeping with your assertion that quantizing an otherwise
>analog signal digitizes it.
You *didn't* quantize it. Or at least nothing you said
assures that it has been quantized, and given "levels can
be individually adjusted" is high suggests that it is not
quantized.
>> Do you think all digital signals are square waves and
>> anything that has square waves is digital? Your example
>> above suggests that you might, but it simply isn't true.
>
>By old vacuum-tube signal generator was certainly
>analog. It produced square waves among other wave shapes.
Hot damned, you *are* aware of that. Amazing...
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>;
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
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Author: Floyd L. DavidsonDate: 22:01 20-08-07
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Jerry Avins <jya@ieee.org> wrote:
>Floyd L. Davidson wrote:
>> Jerry Avins <jya@ieee.org> wrote:
>
>>> ... A signal can be
>>> quantized without any need to measure it or describe it
>>> with a number.
>> That isn't true. In order to quantize it you *must*
>> decide on non-overlapping ranges of *values*, and a
>> specific quantity value that equates to those values.
>>
>>> An example is the signal being measured
>>> in a quantum Hall-effect experiment.
>> Explain.
>
>http://www.warwick.ac.uk/~phsbm/qhe.htm
Why don't you tell us what you think this means. I
have no need to spend my time tracking down your
comments.
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>;
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
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Author: Ron N.Date: 22:05 20-08-07
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On Aug 20, 6:40 pm, Radium <gluceg...@gmail.com> wrote:
> I want all temporal components of the video signal to be slowed
> without changing the length or speed of the video. Just like Adobe
> Audition and certain voice-changers allow the pitch of the audio
> signal to be decreased without changing the length or speed of the
> audio.
But pitch changing software does change the speed of
all the details in the audio. Instead of 200 vibrations
per phoneme, you might get only 100 after the pitch
changer does its distortion. The onset of the phoneme
will be 5 mS less accurate. I suppose the equivalent
in the temporal component of a video scan line would
be taking a picture of a house with 6 or 8 windows and
changing the house to be about the same width but only
having 3 or 4 windows across, and maybe moving the house
so that it is an even number of window widths from the
house next door. An artist could probably do this kind
kind of caricature for you before storing a lower
data rate description of the resulting picture.
You could also shift the all colors down into infrared,
but couldn't see the result anymore, although you
might be able to use it as a hand warmer on a cold day.
And just how do you that this reply was not generated
somehow involving an escaped AI experiment?
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Author: Don BoweyDate: 22:14 20-08-07
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On 8/20/07 5:43 PM, in article 876439hg3o.fld@apaflo.com, "Floyd L.
Davidson" <floyd@apaflo.com> wrote:
> nospam@nospam.com (Don Pearce) wrote:
>> On 20 Aug 2007 21:42:18 GMT, Scott Seidman
>> <namdiesttocs@mindspring.com> wrote:
>>
>>> floyd@apaflo.com (Floyd L. Davidson) wrote in
>>> news:87zm0mjrfy.fld@apaflo.com:
>>>
>>>>> quantized - a sampled signal, but with the possible levels
constrained
>>>>> to a limited set of values
>>>>
>>>> That is by definition a digital siganl. As soon as the possible values
>>>> are "constrained to a limited set", it is by definition
digital data.
>>>>
>>>>
>>>
>>> Wouldn't this make the output of a D/A converter digital by definition?
>>
>> It certainly would. But apparently there are those that can't see the
>> difference between a limited set of values, and a set of numbers
>> describing those values.
>
> You don't appear to understand that the limited set of values makes
> it digital, by definition. PERIOD.
>
> Of course if you then run that digital PAM signal through virtually
> any analog channel, it no longer has a limited set of values...
Including a two foot piece of cable, or two inches with a small cap.
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