The road to true digital speakers very long

[Grador]

You can discuss either without discussing the time domain - but I believe that you'd be wrong in both cases.

A 500 Hz sine wave is going to sound (at least to me) "static." It won't be changing as far as I can tell, but as you say, it isn't static. Likewise, a 500 THz signal will also appear to be static to my eyes as orange, but it isn't static.

It's entirely possible, or perhaps likely, that I'm missing the point - but I think that there's some confusion in the light bulb example. The fact that a light bulb can be turned on or off (which you equate to digital) is an artifact that such a device was created to convert electricity to light, and that electricity is applied via a switch. I could use the same thinking to claim that sound is digital because I can turn an electric horn on and off by toggling a switch - it either generates sound or it doesn't.

You are in fact correct, but you are completely missing the point he is making. Video can be produced completely digitally up until the lightbulb happens to introduce a waveform which can be viewed as a separate event from actually producing the image.

If you take your LCD tv and shut off the backlight [the thing creating the waveform] the image is still being created by the panel only at this point there is nothing analog about it at all. Each individual subpixel is trying to block a quantized ammount of light. In an audio system though you must feed it in a pseudo-analog signal that the driver ends up blurring into something analog.



Though i think everyone here is missing the OPs point. There are things called digital speakers and they are useless.
Digital speakers - Wikipedia, the free encyclopedia

 

[Adam]

You are in fact correct, but you are completely missing the point he is making.

I'll have to give it some more thought, but if I am missing the point...I did say that it was likely that I was.

 

[Grador]

You can discuss a picture that way, but not a video. I mean, even if you were to say frame 228234 as opposed to talking about a specific time stamp, it still relates to the time domain given a specific frame rate.

I disagree with this. If you stop a video at an exact point in time it becomes an image. If you stop audio at an exact point in time it is but a single voltage or pressure. The video is still usable the audio is not.

 

[Steve81]

I disagree with this. If you stop a video at an exact point in time it becomes an image.

Exactly, it becomes a still image, ie no longer a video. Of course, this also depends on how you stop the video. If you pull the plug on the BR player, you get a blank screen.

Edit: As a side note, even if it were possible to break down an analog sound wave into a "frame" like a video, would you really want that to keep playing after you paused your video?

 

[Hocky]

I disagree with this. If you stop a video at an exact point in time it becomes an image. If you stop audio at an exact point in time it is but a single voltage or pressure. The video is still usable the audio is not.

It is only visible if there is still something producing the waves. It is the same thing with audio. Just because the movie becomes an image doesn't mean that it stops producing waves.

 

[Grador]

Exactly, it becomes a still image, ie no longer a video. Of course, this also depends on how you stop the video. If you pull the plug on the BR player, you get a blank screen.

Edit: As a side note, even if it were possible to break down an analog sound wave into a "frame" like a video, would you really want that to keep playing after you paused your video?

Well I was more trying to elaborate on the point he was trying to make about timeframe being irreverent. What you just said is correct, but well besides his point.



Really though this could be argued to no end since there really isn't a very good way to say what's analog and what's digital, it just depends upon at what level you're willing to stop looking. Take an old mechanical watch for example, I think everyone would call it analog with slowly sweeping minute and hour hands, but I could rightly say you are wrong. The escapement moves the clockwork along at defined discrete jumps. You could rightly call me insane if I said this though since as a whole people have decided that a 'digital' watch is one that displays discrete digits not one that moves along at discrete jumps internally.

This is the same thing with talking about if an image on a digital tv is truly digital. The physical output has light waves which are technically analog, but it's composed of discrete subpixels allowing discrete quantities of light through. It really just depends upon what level you want to drop down to before you're ready to call it.

Personally to me it depends upon the intended user experience level. On a watch this means "how does the face display time" and on a tv it's...above the subatomic/electromagnetic level. I'm going to call a TV purely digital because every item about it is quantized up down till you get to "light is a wave."

Digital audio is more difficult for me to define. It as well is quantized right up until it hits the air, but something about calling sound digital seems wrong. I think the difference for me hinges upon TVs having multiple levels of quantization while the audio only has one. In it's final result the TV still has pixles which only get blended with distance while the actual output of the audio is analog.

Now if you were to take a bunch of speakers, have each of them play a puretone, and create a hifi signal by summing a huge number of these i would call it "digital" very easily.

 

[Grador]

It is only visible if there is still something producing the waves. It is the same thing with audio. Just because the movie becomes an image doesn't mean that it stops producing waves.

The post i was writing when you posted this touches on it, but I'll express my feelings directly: Correct or not, I fee like the audio wave IS the audio, while light waves are not the 'image'. Obviously that's not physically true, but as a more subjective experiences.

Yes if you go down to an infinitesimally small period of time an image becomes solely some EM potentials, but if you go to a very small period of time a portion of a video is still an image, but a portion of a sound wave is nothing...if that made any sense.

 

[Steve81]

Well I was more trying to elaborate on the point he was trying to make about timeframe being irreverent. What you just said is correct, but well besides his point.

Not to worry; I understand what you guys are saying. As mentioned and consequently implied, I like to be difficult to provoke some interesting conversation.

 

[Hocky]

The post i was writing when you posted this touches on it, but I'll express my feelings directly: Correct or not, I fee like the audio wave IS the audio, while light waves are not the 'image'. Obviously that's not physically true, but as a more subjective experiences.

Yes if you go down to an infinitesimally small period of time an image becomes solely some EM potentials, but if you go to a very small period of time a portion of a video is still an image, but a portion of a sound wave is nothing...if that made any sense.

No, a true snapshot of a video wave is nothing, just like a snapshot of an audio wave is nothing. They both live with respect to time. Just because you perceive them differently and your TV has a pause button doesn't mean that they actually are different. Your pause button isn't pausing anything, it is repeating something. Just like an xx hz freqency tone.

 

[slipperybidness]

Though i think everyone here is missing the OPs point. There are things called digital speakers and they are useless.
Digital speakers - Wikipedia, the free encyclopedia

I skimmed through the article. Using "digital speaker" for this type of configuration is a bit of a mis-nomer (or maybe a buzz-word). Even if the driver is either off or driven to full amplitude, that is still not a digitial speaker, by the textbook definition of digital. Digital is on or off, 2 different and discreet values with no continuous value in between. Pushing a driver to full amplitude, you still hit the continuous values on getting to full amplitude. Thus it is not at discreet values.

 

[Grador]

I skimmed through the article. Using "digital speaker" for this type of configuration is a bit of a mis-nomer (or maybe a buzz-word). Even if the driver is either off or driven to full amplitude, that is still not a digitial speaker, by the textbook definition of digital. Digital is on or off, 2 different and discreet values with no continuous value in between. Pushing a driver to full amplitude, you still hit the continuous values on getting to full amplitude. Thus it is not at discreet values.

See my thoughts on digital/analog above. Technically you could say the same thing about a processor, the voltage changes don't occur instantaneously.

 

[jonnythan]

Define "digital speaker" please.

 

[7beauties]

Definition of digital speaker

I was thinking of everything short of the actual transduction, the compression of air, is digital - just on or off. My engineer friend provided me with the following link. The article may explain more eloquently the definition of a truly digital speaker. The task is daunting, but the article ends by saying that a truly digital speaker will first be available for very small devices, as I recall, cell phones. I'm amazed and delighted by the brilliance of you all.

The Long Road To Digital Loudspeakers

 

[JerryLove]

There seems to be a failing to understand how wavs are actually stored digitally in that article.

And like my conversation above about TV, it seems to fail to understand the effect of such switching in the time domain.

Let's imagine a magical tech which allowed changes in zero time.

TV sits on frame 1, which is supposed to last 1/60-seconds. At the exact moment our clock moves from 1/60 to 2/60, the entire screen is completely changed to frame 2.

This would be awesome. One set of digital information replaced with another.

Now let's imagine we want to make a 20Hz wave where instead of moving from XMin to XMax over 1/20th of a second, it moves instantly at the end of th efirst 1/20th of a second.

Actually: there's a name for this. It's called a "square wave".

Does anyone here think square waves make good music?

And cellphones?!? We are worried about the sound quality from the *DAC* in a cellphone? I think that's near the bottom of the reasons cellphones sound bad.

 

[7beauties]

Square waves

No I don't. I can't imagine sound waves, particularly low frequencies, as "on-off." The only good use I know of for square waves are the ballasts used by HMI light fixtures prominently used in filmmaking. These ballasts square the sine waves of alternating current before igniting ("striking" in film talk) the fixture to prevent flicker; ironically digital lighting. The gas mixture in an HMI (halide-metal-oidide), which becomes excited to a plasma, doesn't have persistence like traditional tungsten filaments.

 

[jonnythan]

Sound and light are both waves.

A green pixel is fundamentally the same as a 1000 Hz sine wave.

 

[JerryLove]

Sound and light are both waves.

A green pixel is fundamentally the same as a 1000 Hz sine wave.

But video isn't light creation.

Video is just color. Full spectrum light is provided by a bulb; or a "white" LCD/LED, or the sun, or not at all.

You are welcome to tell me why I can't have a digital light bulb... but that's not the video portion.

I can describe (which is to say "record") a color in a useful way in zero time.
I'll do so now: FFFFFF.

Can you do that for audio? Is a single "pixel" of a CD of any use at all? No. It's only useful relative to others over the time domain.

Even if I accepted that your premise interacted with my point: the transition from green to black in one frame could be described as "on for 1/60-sec, then off" of a green lightsource.

Of course: we digitize that value in shades: so it's "255 for 1/60-second, then 0"

Add the two other colors "255,0,0 for 1/60-second then 0,0,0"

Repeat for every pixel (I wont do here).

There's digital right there. (at 1 nanosecond I will be 255,0,0)

I'm a loudspeaker. Give me hypothetical digital audio data for exactly 1 unit of time. Tell me where I will want to be for ever Nth value of time into which that 1 unit can be subdivided.

You can't. We don't deal with audio in discrete pieces like we do with video.

 

[Grador]

You managed to describe what I've been attempting to say for a day and a half in a very eloquent way,

 

[Hocky]

But video isn't light creation.

Video is just color. Full spectrum light is provided by a bulb; or a "white" LCD/LED, or the sun, or not at all.

You are welcome to tell me why I can't have a digital light bulb... but that's not the video portion.

I can describe (which is to say "record") a color in a useful way in zero time.
I'll do so now: FFFFFF.

Can you do that for audio? Is a single "pixel" of a CD of any use at all? No. It's only useful relative to others over the time domain.

Even if I accepted that your premise interacted with my point: the transition from green to black in one frame could be described as "on for 1/60-sec, then off" of a green lightsource.

Of course: we digitize that value in shades: so it's "255 for 1/60-second, then 0"

Add the two other colors "255,0,0 for 1/60-second then 0,0,0"

Repeat for every pixel (I wont do here).

There's digital right there. (at 1 nanosecond I will be 255,0,0)

I'm a loudspeaker. Give me hypothetical digital audio data for exactly 1 unit of time. Tell me where I will want to be for ever Nth value of time into which that 1 unit can be subdivided.

You can't. We don't deal with audio in discrete pieces like we do with video.

You might be able to digitally turn a pixel on or off, but the process of getting that color to your eyes is still analog. Just because you can't see the tv move doesn't mean that it doesn't require a cycling wave to produce what you see. It is the same as audio, video just stays digital for a longer period of the process.

 

[Grador]

You might be able to digitally turn a pixel on or off, but the process of getting that color to your eyes is still analog. Just because you can't see the tv move doesn't mean that it doesn't require a cycling wave to produce what you see. It is the same as audio, video just stays digital for a longer period of the process.

Your digital clock is not digital because the light coming off of it is an analog wave.

Under your definition nothing is digital

but really what he was showing was independence of the time domain, which I think he showed successfully