Hi:

I=2E Audio vs. Video

Digitized (mono) audio has a single sample per each sampling
interval.

In the case of digital video, we could treat each individual sample
point location in the sampling grid (each pixel position in a frame)
the same way as if it was a sample from an individual (mono) audio
signal that continues on the same position in the next frame. For
example, a 640=D7480 pixel video stream shot at 30 fps would be treated
mathematically as if it consisted of 307200 parallel, individual mono
audio streams [channels] at a 30 Hz sample rate. Where does bit-
resolution enter the equation?

Digital linear PCM audio has the following components:

1=2E Sample rate [44.1 KHz for CD audio]
2=2E Channels [2 in stereo, 1 in monaural]
3=2E Bit-resolution [16-bit for CD audio]

Sample rate in audio =3D frame rate in video
Channel in audio =3D pixel in video
Bit-resolution in audio =3D ? in video

Is it true that unlike the-frequency-of-audio, the-frequency-of-video
has two components -- temporal and spatial?

AFAIK, the-frequency-of-audio only has a temporal component. Do I
guess right?

II. Digital vs. Analog

Sample-rate is a digital entity. In a digital audio device, the sample-
rate must be at least 2x the highest intended frequency of the digital
audio signal. What is the analog-equivalent of sample-rate? In an
analog audio device, does this equivalent need to be at least 2x the
highest intended frequency of the analog audio signal? If not, then
what is the minimum frequency that the analog-equivalent-of-sample-
rate must be in relation to the analog audio signal?

III. My Requests:

No offense but please respond with reasonable answers & keep out the
jokes, off-topic nonsense, taunts, insults, and trivializations. I am
really interested in this.


Thanks for your assistance, cooperation, and understanding,

Radium

On Aug 19, 2:50 pm, rfisc...@sonic.net (Ray Fischer) wrote:

> Radium <gluceg...@gmail.com> wrote:

> >Hi:

> >I. Audio vs. Video

> >Digitized (mono) audio has a single sample per each sampling
> >interval.

> >In the case of digital video, we could treat each individual sample
> >point location in the sampling grid (each pixel position in a frame)
> >the same way as if it was a sample from an individual (mono) audio
> >signal that continues on the same position in the next frame. For
> >example, a 640=D7480 pixel video stream shot at 30 fps would be treated
> >mathematically as if it consisted of 307200 parallel, individual mono
> >audio streams [channels] at a 30 Hz sample rate. Where does bit-
> >resolution enter the equation?

> >Digital linear PCM audio has the following components:

> >1. Sample rate [44.1 KHz for CD audio]
> >2. Channels [2 in stereo, 1 in monaural]
> >3. Bit-resolution [16-bit for CD audio]

> >Sample rate in audio =3D frame rate in video
> >Channel in audio =3D pixel in video
> >Bit-resolution in audio =3D ? in video

> >Is it true that unlike the-frequency-of-audio, the-frequency-of-video
> >has two components -- temporal and spatial?

> No. Video is converted to a linear data stream corresponding
> (roughly) to scan lines. The color and brightness information
> is split apart and converted into parallel data streams.

Okay. So a digital video device with greater bit-resolution can allow
for more levels of luminance?

What is the video-equivalent of bit-resolution?

> Compression for digital video may group areas of the image
> and/or eliminate some of the color components.

Does compression also eliminate some of the brightness components?

> >II. Digital vs. Analog

> >Sample-rate is a digital entity. In a digital audio device, the sample-
> >rate must be at least 2x the highest intended frequency of the digital
> >audio signal. What is the analog-equivalent of sample-rate?

> There is no sampling in analog so there is no sampling rate.

There is no analog-equivalent of sample-rate? Then what the limits the
highest frequency an analog audio device can encode?

What determines the highest frequency signal an analog solid-state
audio device can input without distortion?

Analog solid-state audio device =3D a purely analog electronic device
that can record, store, playback, and process audio signals without
needing any moving parts.

The above device inputs the electrical signals generated by an
attached microphone. These electric signals are AC and represent the
sound in "electronic" form. Sound with a higher-frequency will
generate a faster-alternating current than sound with a lower-
frequency. A louder sound will generate an alternating-current with a
bigger peak-to-peak wattage than a softer soft.

What mathematically determines the highest-frequency electric signal
such a device can intake without distortion?

rfischer@sonic.net (Ray Fischer) wrote:
>Radium <glucegen1@gmail.com> wrote:
>>II. Digital vs. Analog
>>
>>Sample-rate is a digital entity. In a digital audio device, the sample-
>>rate must be at least 2x the highest intended frequency of the digital
>>audio signal. What is the analog-equivalent of sample-rate?
>
>There is no sampling in analog so there is no sampling rate.

But that was not the question. The analog-equivalent is
bandwidth.

In a purely analog channel frequencies higher than the
upper limit of the channel's bandwidth will not be
passed. When using a digital channel no analog signal
frequencies higher than 1/2 the Nyquist rate (i.e., the
sampling rate) will be passed.

Granted, that with an analog channel the limit is never
a sharply defined frequency; hence in practice there is
not a instant cutoff, but rather a number of negative
effects that become more significant as the signal
frequency approaches and goes beyond the arbitrarily set
"upper limit". Generally phase distortion increases and
signal level decreases, for example. The upper limit is
a function of how much distortion is acceptable for the
application.

In a digital channel you cannot pass frequencies higher
1/2 the Nyquist rate, which in theory is a very sharp
cutoff but in practice it becomes very similar to the
gradual analog cutoff. The reason for that the extreme
negative effects associated with distortion of inputs
that are above that frequency virtually always require
analog filters at the input to absolutely avoid any
frequencies above 1/2 the Nyquist rate. (Alias
frequencies are generated at the output rather than a
signal which is the same as the input, and the
distortion is 100%. ) Hence analog filters that have the
exact same effects as would be seen with an analog
channel are used at the input of an analog to digital
conversion.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com

On Aug 19, 4:39 pm, Jerry Avins <j...@ieee.org> wrote:

> Radium wrote:

> > In the case of digital video, we could treat each individual sample
> > point location in the sampling grid (each pixel position in a frame)
> > the same way as if it was a sample from an individual (mono) audio
> > signal that continues on the same position in the next frame. For
> > example, a 640?480 pixel video stream shot at 30 fps would be treated
> > mathematically as if it consisted of 307200 parallel, individual mono
> > audio streams [channels] at a 30 Hz sample rate. Where does bit-
> > resolution enter the equation?

> It might actually make sense to look at it that way in some situations,
> but I'll bet you can't think of one.

This would be a start if I want to decrease the frequency of a video
signal without decreasing the playback speed.

The application here is to change the frequency of the video signal
without altering the frame-rate, sample-rate, or tempo of the video
signal.

This is like changing the pitch of audio on playback without modifying
the sample-rate or playback speed.

Adobe Audition provides this affect.

Using this software, you can also change the tempo of a song without
affecting the pitch.

> As for bit resolution, what does
> that term mean to you? I think it means the number of bits used to
> represent each sample, whatever the situation.

Same here. In audio, a greater bit-resolution provides more levels of
loudness that a smaller bit-resolution. In video, what does a greater
bit-resolution provide that a smaller bit-resolution doesn't? More
levels of light intensity? More colors? I am just guessing.

> > Digital linear PCM audio has the following components:

> > 3. Bit-resolution [16-bit for CD audio]

> So you do know what the term means.

Yes. I know what it means. However, I don't know what its video-
equivalent is?

> > II. Digital vs. Analog
>
> > Sample-rate is a digital entity. In a digital audio device, the sample-
> > rate must be at least 2x the highest intended frequency of the digital
> > audio signal. What is the analog-equivalent of sample-rate? In an
> > analog audio device, does this equivalent need to be at least 2x the
> > highest intended frequency of the analog audio signal? If not, then
> > what is the minimum frequency that the analog-equivalent-of-sample-
> > rate must be in relation to the analog audio signal?

> There are no samples in an analog system, so there is no sample rate.

Okay. Then what is the analog-equivalent of a "sample"?

The analog-equivalent of bit-resolution = dynamic range

The analog-equivalent of sample rate = ?

> http://www.dspguru.com/

Thanks for the link

On Aug 19, 5:55 pm, Jerry Avins <j...@ieee.org> wrote:

> Radium wrote:

> > Okay. So a digital video device with greater bit-resolution can allow
> > for more levels of luminance?

> Ir color differentiation. Or both.

Huh?

> > The above device inputs the electrical signals generated by an
> > attached microphone. These electric signals are AC and represent the
> > sound in "electronic" form. Sound with a higher-frequency will
> > generate a faster-alternating current than sound with a lower-
> > frequency. A louder sound will generate an alternating-current with a
> > bigger peak-to-peak wattage than a softer soft.

> All true. How to you record it with no moving parts?

Other than the microphone [obviously], why does there need to be any
moving parts? If a digital audio device can play audio back without
any moving parts, why can't an analog audio device be designed to do
the same?

The device below is *not* analog. It uses sampling so its digital:

http://www.winbond-usa.com/mambo/content/view/36/140/

I'm curious to why there are no purely-analog devices which can
record, store, and playback electric audio signals [AC currents at
least 20 Hz but no more than 20,000 Hz] without having moving parts.
Most of those voice recorders that use chips [i.e. solid-state] are
digital. Analog voice recorders, OTOH, use cassettes [an example of
"moving parts"].

On Aug 19, 6:08 pm, Jerry Avins <j...@ieee.org> wrote:

> Radium wrote:

> > This would be a start if I want to decrease the frequency of a video
> > signal without decreasing the playback speed.

> Various compression schemes do that with varying degrees of resulting
> quality.

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.

2. Decreasing the spatial frequency of the images in the video-signal
without low-pass filtering the images or increasing their sizes. An
example of this would be making the sharp areas of an image look
duller without decreasing the "sharpness" setting [an example of low-
pass filtering] on the monitor or increasing the size of the image.
Normally, when the size of an image is decreased, its sharpness
increases [it's like compressing a lower-frequency sound wave into a
higher-frequency one]. Likewise, when the size of an image is
increased, it looks duller [like stretching a higher-frequency sound
wave into a lower-frequency one]. Low-pass filtering simply decreasing
the sharpness of an image while increasing its dull characteristics --
which is what I don't want.

#1 Decreases the rate at which objects in the video move without
decreasing the video's playback speed or eliminating originally-
rapidly-moving objects [such as the rapidly flapping wings]

#2 Decreases makes a still image less sharp by stretching everything
within the image without increasing the size of the image or
eliminating sharp portions of the original image

Both #1 and #2 are visual-equivalents of decreasing the pitch of a
recorded audio signal without decreasing the audio's playback speed.

Radium wrote:
> On Aug 19, 7:47 pm, Jerry Avins <j...@ieee.org> wrote:
>
>> Radium wrote:
>
>>> Other than the microphone [obviously], why does there need to be any
>>> moving parts? If a digital audio device can play audio back without

Ah Radium trolling again i see!!!!

Radium wrote:
> On Aug 19, 5:55 pm, Jerry Avins <j...@ieee.org> wrote:
>
>> Radium wrote:
>
>>> Okay. So a digital video device with greater bit-resolution can allow
>>> for more levels of luminance?
>
>> Ir color differentiation. Or both.
>
> Huh?
>
>>> The above device inputs the electrical signals generated by an
>>> attached microphone. These electric signals are AC and represent the
>>> sound in "electronic" form. Sound with a higher-frequency will
>>> generate a faster-alternating current than sound with a lower-
>>> frequency. A louder sound will generate an alternating-current with a
>>> bigger peak-to-peak wattage than a softer soft.
>
>> All true. How to you record it with no moving parts?
>
> Other than the microphone [obviously], why does there need to be any
> moving parts? If a digital audio device can play audio back without
> any moving parts, why can't an analog audio device be designed to do
> the same?
>
> The device below is *not* analog. It uses sampling so its digital:
A good whack on head with heavy stick is in this category too!
>
> http://www.winbond-usa.com/mambo/content/view/36/140/
>
> I'm curious to why there are no purely-analog devices which can
> record, store, and playback electric audio signals [AC currents at
> least 20 Hz but no more than 20,000 Hz] without having moving parts.
> Most of those voice recorders that use chips [i.e. solid-state] are
> digital. Analog voice recorders, OTOH, use cassettes [an example of
> "moving parts"].
>
Audio IS mechanical so something has to move.

Stanislaw

On Aug 19, 7:48 pm, Stanislaw Flatto <comp...@brownbear.com.au> wrote:

> Audio IS mechanical so something has to move.

Then how is it possible for a digital audio device [like an iPod] to
play audio back w/out moving a disc or tape? There is a digital chip
storing info and playback does not require moving anything. Just how
is this possible? If it works in digital, why can't it work in analog?

On Aug 19, 7:47 pm, Jerry Avins <j...@ieee.org> wrote:

> Radium wrote:

> > Other than the microphone [obviously], why does there need to be any
> > moving parts? If a digital audio device can play audio back without
> > any moving parts, why can't an analog audio device be designed to do
> > the same?

> Describe a motion-free process of recording and playing back. Cutting
> grooves on a disk or magnetizing a moving tape both involve motion.

The iPod is motion-free yet it's still able to record and playback.

Those Nintendo Entertainment System cartridges were able to playback
without any motion.

> > The device below is *not* analog. It uses sampling so its digital:

> >http://www.winbond-usa.com/mambo/content/view/36/140/

> > I'm curious to why there are no purely-analog devices which can
> > record, store, and playback electric audio signals [AC currents at
> > least 20 Hz but no more than 20,000 Hz] without having moving parts.
> > Most of those voice recorders that use chips [i.e. solid-state] are
> > digital. Analog voice recorders, OTOH, use cassettes [an example of
> > "moving parts"].

> It's this simple: nobody has invented a way. I doubt than anyone ever
> will. If you know how, communicate with me privately.

I don't know how but I guessing that it involves the analog equivalent
of Flash RAM [if re-writing is desired] or the analog equivalent of
Masked-ROM [if permanent storage is desired].

someone wrote:
> There is no analog-equivalent of sample-rate? Then what the limits the
> highest frequency an analog audio device can encode?
>
> What determines the highest frequency signal an analog solid-state
> audio device can input without distortion?

The basic physics of material objects leads to some
limitations. At some frequency, a given force can
no longer accelerate the mass of a given physical
transducer or recording substance by an amount
greater than does thermal noise (and other sources
of noise, such as friction, wear, dust, magnetic
particle size, film grain size, etc.)

On Aug 19, 8:37 pm, Jerry Avins <j...@ieee.org> wrote:
> What would you write into that "RAM"? There are no analog bits.

Well, some types of RAM bits are stored as analog voltages
on a MOS gate capacitor. I think old CCD devices could
output some measure of the voltage per bit cell. Or you
could consider the charge digital if you could count the
number of electrons in each well.

Radium wrote:
> On Aug 19, 7:48 pm, Stanislaw Flatto <comp...@brownbear.com.au> wrote:
>
>> Audio IS mechanical so something has to move.
>
> Then how is it possible for a digital audio device [like an iPod] to
> play audio back w/out moving a disc or tape? There is a digital chip
> storing info and playback does not require moving anything. Just how
> is this possible? If it works in digital, why can't it work in analog?
>
And exactly what DO you hear when those signals run their "magic"?

I have analog audio tapes yet from the night the King passed away and
they are respectfully silent till somehow directed toward 'moving' membrane.
So what does this prove?

Stanislaw

In article <1187572498.074750.50210@i38g2000prf.googlegroups.com>,
Radium <glucegen1@gmail.com> wrote:

>I'm curious to why there are no purely-analog devices which can
>record, store, and playback electric audio signals [AC currents at
>least 20 Hz but no more than 20,000 Hz] without having moving parts.
>Most of those voice recorders that use chips [i.e. solid-state] are
>digital. Analog voice recorders, OTOH, use cassettes [an example of
>"moving parts"].

The fact that it's an AC (inherently-varying) signal being recorded,
means that *something* has to move... if only some amount of
electrical charge. If the electrons don't move, the output can't vary
and all you have is a DC voltage.

And, in fact, this concept of moving electrical charges is the basis
for one type of analog signal storage and playback device which has no
moving (mechanical) parts... the CCD, or Charge Coupled Device. It
consists of a large number of charge storage devices (typically MOSFET
transistors with dielectrically-isolated gates) hooked up as a sort of
shift register or "bucket brigade". Each gate stores a charge which
is proportional to the input signal present at a given moment in time.
Several thousand times per second, a clock pulse causes each storage
cell to generate an output voltage proportional to the charge in its
storage gate, and then to "capture" onto its gate the signal being
presented by the previous gate in the chain.

In effect, the signal is propagated down the chain at a rate
proportional to the clock rate.

Why aren't these devices used more than they are? They're not very
efficient, and they're noisy. Every time the charge is copied from
one cell to the next, a bit of imprecision (noise) creeps in... so the
fidelity isn't great. And, because the device has to be able to hold
a very wide range of charges (since the charge is directly
proportional to the signal level) the storage gates have to be fairly
large.

The net result is that an audio CCD is capable of storing a
decent-quality signal for only a few tens or hundreds of milliseconds,
from input to output.

Another sort of a purely analog signal-storage device, with no moving
parts other than the electrons which convey the signal, is a simple
length of transmission line (with perhaps some amplifiers mid-way).
Put a signal in at one end, get the same signal back out the other end
some number of microseconds or milliseconds later.

Once again, they're not terribly efficient and are prone to be noisy.

For storage of large amounts of information, in a small space, with
high fidelity, using digital storage techniques is much more
efficient - largely because each storage cell must only store 2
different information states (0 and 1) rather than a large number of
possible levels.

--
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!

On Aug 19, 7:59 pm, Jerry Avins <j...@ieee.org> wrote:

> Radium wrote:

> > 2. Decreasing the spatial frequency of the images in the video-signal
> > without low-pass filtering the images or increasing their sizes. An
> > example of this would be making the sharp areas of an image look
> > duller without decreasing the "sharpness" setting [an example of low-
> > pass filtering] on the monitor or increasing the size of the image.
> > Normally, when the size of an image is decreased, its sharpness
> > increases [it's like compressing a lower-frequency sound wave into a
> > higher-frequency one]. Likewise, when the size of an image is
> > increased, it looks duller [like stretching a higher-frequency sound
> > wave into a lower-frequency one]. Low-pass filtering simply decreasing
> > the sharpness of an image while increasing its dull characteristics --
> > which is what I don't want.

> That's a reasonable summary of what you don't want to do. What do you
> think you might do instead?

The video-equivalent of changing the 'pitch' of audio recording
without changing the playback speed.

> > #1 Decreases the rate at which objects in the video move without
> > decreasing the video's playback speed or eliminating originally-
> > rapidly-moving objects [such as the rapidly flapping wings]

> Something has to give. If the flapping of the wings is slowed, so is the
> motion of everything else.

The motion of 'everything else' *is* slowed. However, the playback
speed remains constant.

Repetitive or cyclical motion (such as a ball bouncing, or a wagon
wheel rotating, or a bird-flapping its wings, or an exposed model of a
piston engine operating, or a flag waving in the wind) in the movie
are slowed without lengthening the clip.

> > #2 Decreases makes a still image less sharp by stretching everything
> > within the image without increasing the size of the image or
> > eliminating sharp portions of the original image

> Huh?

Sorry that should read "makes a still image less sharp by stretching
everything within the image without increasing the size of the image
or eliminating sharp portions of the original image"

My bad.

Anyways, this is an original picture:
http://www-dse.doc.ic.ac.uk/~nd/surpris ... limage.jpg

This is how the picture looks after low-pass filtering -- YUK!:

http://www-dse.doc.ic.ac.uk/~nd/surpris ... lopass.jpg

I don't want low-pass filtering. I simply want all frequencies to be
downshifted similar to decreasing the pitch of audio without slowing
the playback speed. The analogy is lower the frequencies of all
components in the image w/out increasing the size of the image or
doing any low-pass filtering.

http://www-dse.doc.ic.ac.uk/~nd/surpris ... eport.html

> > Both #1 and #2 are visual-equivalents of decreasing the pitch of a
> > recorded audio signal without decreasing the audio's playback speed.

> Says who? You're reasoning from false analogy again.

How is it false?

On Aug 19, 8:34 pm, "Bob Myers" <nospample...@address.invalid> wrote:

> Sampled analog systems are certainly
> not very common today (unless you count certain forms of
> modulation as "sampling," and in fact there are some very close
> parallels there), but the theory remains the same no matter which
> form of encoding is used. In any event, you must sample the
> original signal at a rate equal to at least twice its bandwidth (actually,
> very slightly higher, to avoid a particular degenerate case which
> could occur at EXACTLY 2X the bandwidth) in order to preserve
> the information in the original and avoid "aliasing."

Is the CCD [Charge Coupled Device] a "sampled analog system"?

On Aug 19, 8:54 pm, dpl...@radagast.org (Dave Platt) wrote:

> The fact that it's an AC (inherently-varying) signal being recorded,
> means that *something* has to move... if only some amount of
> electrical charge. If the electrons don't move, the output can't vary
> and all you have is a DC voltage.

By "moving parts" I mean mechanical parts. Not electrons.

> And, in fact, this concept of moving electrical charges is the basis
> for one type of analog signal storage and playback device which has no
> moving (mechanical) parts... the CCD, or Charge Coupled Device. It
> consists of a large number of charge storage devices (typically MOSFET
> transistors with dielectrically-isolated gates) hooked up as a sort of
> shift register or "bucket brigade". Each gate stores a charge which
> is proportional to the input signal present at a given moment in time.
> Several thousand times per second, a clock pulse causes each storage
> cell to generate an output voltage proportional to the charge in its
> storage gate, and then to "capture" onto its gate the signal being
> presented by the previous gate in the chain.
>
> In effect, the signal is propagated down the chain at a rate
> proportional to the clock rate.

Is CCD a form of analog non-volatile RAM?

> Why aren't these devices used more than they are? They're not very
> efficient, and they're noisy. Every time the charge is copied from
> one cell to the next, a bit of imprecision (noise) creeps in... so the
> fidelity isn't great. And, because the device has to be able to hold
> a very wide range of charges (since the charge is directly
> proportional to the signal level) the storage gates have to be fairly
> large.

I wonder how a PC would perform if it used CCDs in place of digital
storage devices. Lots of errors.

> The net result is that an audio CCD is capable of storing a
> decent-quality signal for only a few tens or hundreds of milliseconds,
> from input to output.

What is the highest frequency an audio CCD can input and output? My
guess is 0.5x the clock rate.

> Another sort of a purely analog signal-storage device, with no moving
> parts other than the electrons which convey the signal, is a simple
> length of transmission line (with perhaps some amplifiers mid-way).

Where is the "storage" in this device?

> Put a signal in at one end, get the same signal back out the other end
> some number of microseconds or milliseconds later.

Where is the signal being stored?

>Come on, Dave, a CCD is a digital device, subject to aliasing. The
>charges represent the signal at a particular instant of its average over
>a particular interval. (My CCD digital camera can take time exposures.)
>A CCD's content may not be quantized in amount, but it is quantized in
>time. In a camera, where the charges pertain to individual pixels, the
>result is also quantized in space.

"Digital" and "subject to aliasing" are two different things.

As I believe the term "digital" is usually meant, it implies a
two-state (on/off) storage representation. It's not just that the
signal amplitude is quantized, but that the quantization uses a
power-of-two representation and storage system of some sort.

In that sense, an audio CCD uses a digital clocking structure to move
the charge along, but uses a non-digital system for representing the
signal level (a linear number of electrons). Yes, it's quantized in
time, and the electron charges themselves are quantized... but I don't
think that either of these qualifies it as "digital".

"Analog" is a very fuzzy and imprecise term, and I think that a CCD
can reasonably be called an analog system.

Even audio cassette tape is quantized in both time and amplitude, at
the level of the individual magnetic domains in the oxide or metal
particles.

--
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!

On Aug 19, 10:08 pm, Jerry Avins <j...@ieee.org> wrote:

> Radium wrote:

> > The video-equivalent of changing the 'pitch' of audio recording
> > without changing the playback speed.

> That's just arm-waving words. Describe the result, not as an analogy,
> but as a specification. If it turns out that you can't think critically
> after all, I have no time for you.

The purpose of this visual "pitch-shifting" is like a way to record/
playback/transmit/receive/store supreme-quality video while using the
least bandwidth and storage space necessary when low-pass filtering is
not an option.

Using this video frequency-shifting, a high-quality video can be
stored in an extremely slow moving video-cassette with limited amount
of tape. Due to the video-tape's extremely slow speed the temporal and
spatial frequencies of the incoming video signals must be downshifted
in order to be encoded at such slow speeds. Due to the limited length
of film in the cassette, the movie must not be made longer than what
it originally is. Due to other inadequacies in the film, the spatial-
frequency must also be decreased, but the image size must not
increase.

> > The motion of 'everything else' *is* slowed. However, the playback
> > speed remains constant.

> Explain how everything can slow town without increasing the time to
> complete a motion. Sounds have duration and pitch. motion has no analog
> of pitch in that sense. Describe the result you want, not "something
> like" the result.

A 2 hour high-quality movie should be able to be stored in device with
limited high-frequency response and limited amount of storage space.
There should be absolutely no aliasing -- temporal or spatial - but at
the same time, the length of the movie should not be increased, sizes
of objects in images should not increase, image size should not
increase and no low-pass filtering should be used.

> > Repetitive or cyclical motion (such as a ball bouncing, or a wagon
> > wheel rotating, or a bird-flapping its wings, or an exposed model of a
> > piston engine operating, or a flag waving in the wind) in the movie
> > are slowed without lengthening the clip.

> Tell me again how the crankshaft can take run one fifth speed without
> using more time to make a turn.

I wish I knew. This 'pitch-shifting' is a lot more confusing than I
thought. Yet I still find it so interesting. Sorry.

> > Sorry that should read "makes a still image less sharp by stretching
> > everything within the image without increasing the size of the image
> > or eliminating sharp portions of the original image"

> Tell me again how everything in an image can be stretched to double size
> without making the image twice as big.

Nothing in the image has its size increased. They are simply smoothed
out.

This is similar to a graph of digital audio in Adobe Audition. You
decrease the pitch of the audio in the file by half [without changing
the tempo] and the waves in the graph will appear twice as long but
without increasing the horizontal length of the graph.

> > I don't want low-pass filtering. I simply want all frequencies to be
> > downshifted similar to decreasing the pitch of audio without slowing
> > the playback speed. The analogy is lower the frequencies of all
> > components in the image w/out increasing the size of the image or
> > doing any low-pass filtering.

> >http://www-dse.doc.ic.ac.uk/~nd/surprise_96/journal/vol4/sab/report.html

> Justify why you think that images and sounds are subject to the same
> transformations.

The less sample rate you have in digital audio, the lower the
frequency of the audio must be in order to prevent aliasing. There
isn't enough bandwidth to include the higher-pitches.

Similarly an imaging device with insufficient spatial bandwidth will
result in image distortion if excessively fine detail is put into the
camera.

Hence, if you want to get decent imagery in a low-bandwidth imaging
device, your best bet is to decrease the spatial frequency because
transferring it into the imaging device.

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 is it false?

> Images have no visual equivalent of pitch. Pitch is temporal. Images are
> spatial.

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.

[Followup-to: set]

On Sun, 19 Aug 2007 22:11:11 -0700, Radium wrote:

>> And, in fact, this concept of moving electrical charges is the basis
>> for one type of analog signal storage and playback device which has no
>> moving (mechanical) parts... the CCD, or Charge Coupled Device. It
>> consists of a large number of charge storage devices (typically MOSFET
>> transistors with dielectrically-isolated gates) hooked up as a sort of
>> shift register or "bucket brigade". Each gate stores a charge which
>> is proportional to the input signal present at a given moment in time.
>> Several thousand times per second, a clock pulse causes each storage
>> cell to generate an output voltage proportional to the charge in its
>> storage gate, and then to "capture" onto its gate the signal being
>> presented by the previous gate in the chain.
>>
>> In effect, the signal is propagated down the chain at a rate
>> proportional to the clock rate.
>
> Is CCD a form of analog non-volatile RAM?

No, it's quite volatile; more like dynamic RAM.

A major problem with any form of analogue "RAM" is that the stored "value"
will degenerate over time. A digital circuit can regenerate its contents,
either continuously (like static RAM) or periodically (like dynamic RAM),
but you can't do that for an analogue value.

>> Why aren't these devices used more than they are? They're not very
>> efficient, and they're noisy. Every time the charge is copied from
>> one cell to the next, a bit of imprecision (noise) creeps in... so the
>> fidelity isn't great. And, because the device has to be able to hold
>> a very wide range of charges (since the charge is directly
>> proportional to the signal level) the storage gates have to be fairly
>> large.
>
> I wonder how a PC would perform if it used CCDs in place of digital
> storage devices. Lots of errors.

With an analogue quantity, it isn't a case of error or no error; it's a
case of how much error. There's always *some* error.

>> Another sort of a purely analog signal-storage device, with no moving
>> parts other than the electrons which convey the signal, is a simple
>> length of transmission line (with perhaps some amplifiers mid-way).
>
> Where is the "storage" in this device?

The capacitance and inductance of the transmission line.

>> Put a signal in at one end, get the same signal back out the other end
>> some number of microseconds or milliseconds later.
>
> Where is the signal being stored?

See above.

On Sun, 19 Aug 2007 23:26:16 -0700, dplatt@radagast.org (Dave Platt)
wrote:

>"Digital" and "subject to aliasing" are two different things.
>
>As I believe the term "digital" is usually meant, it implies a
>two-state (on/off) storage representation. It's not just that the
>signal amplitude is quantized, but that the quantization uses a
>power-of-two representation and storage system of some sort.

My reading of the possible systems goes like this.

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

Aliasing is going to happen as soon as you move beyond the first line
of that list.

d

--
Pearce Consulting
http://www.pearce.uk.com

On Sun, 19 Aug 2007 18:14:58 -0700, Radium <glucegen1@gmail.com> wrote:

>If a digital audio device can play audio back without
>any moving parts, why can't an analog audio device be designed to do
>the same?

Because if it could, there would be no need to invent digital which has the
advantage of non-moving parts....................

-m-
--
Official website "Jonah's Quid" http://www.jonahsquids.co.uk

On Sun, 19 Aug 2007 20:54:06 -0700, dplatt@radagast.org (Dave Platt) wrote:

>Another sort of a purely analog signal-storage device, with no moving
>parts other than the electrons which convey the signal, is a simple
>length of transmission line

Here is a better one: transmit the analogue system to the sun, and you have
16 minute, once-of storage. If you want to save your recording for a longer
time, you can pick more planets and stars, further away, and bounce your
radiosignal off them. It is obviously not random-access, but it is very
analogue.

-m-
--
Official website "Jonah's Quid" http://www.jonahsquids.co.uk

On Mon, 20 Aug 2007 03:51:54 -0400, Jerry Avins <jya@ieee.org> wrote:

>Don Pearce wrote:
>> On Sun, 19 Aug 2007 23:26:16 -0700, dplatt@radagast.org (Dave Platt)
>> wrote:
>>
>>> "Digital" and "subject to aliasing" are two different things.
>>>
>>> As I believe the term "digital" is usually meant, it implies a
>>> two-state (on/off) storage representation. It's not just that the
>>> signal amplitude is quantized, but that the quantization uses a
>>> power-of-two representation and storage system of some sort.
>>
>> My reading of the possible systems goes like this.
>>
>> 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
>>
>> Aliasing is going to happen as soon as you move beyond the first line
>> of that list.
>
>I like your categories. It is possible in concept to have a signal that
>is quantized in magnitude and continuous in time, but (unless we resort
>to counting electrons) I don't think it's possible in practice.
>
Yes, I was thinking about that possibility while I was typing, but
since I've never come across such a system I decided it would
complicate things unnecessarily to include it.

d

--
Pearce Consulting
http://www.pearce.uk.com

On Mon, 20 Aug 2007 04:16:44 -0400, Jerry Avins <jya@ieee.org> wrote:

>Actually, I did invent something along those lines, but I was foolish
>enough yo leave the plans in my (not yet perfected) time machine, and
>they disappeared.

Shame on you! Radium will be very disappointed now.

-m-
--
Official website "Jonah's Quid" http://www.jonahsquids.co.uk