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.
Questions about equivalents of audio/video and digital/analog.
Started by ●August 19, 2007
Reply by ●August 19, 20072007-08-19
Reply by ●August 19, 20072007-08-19
Radium wrote:> On Aug 19, 5:55 pm, Jerry Avins <j...@ieee.org> wrote:...>> Ir color differentiation. Or both. > > Huh?Typo: Or color differentiation. Or both.>>> 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?Describe a motion-free process of recording and playing back. Cutting grooves on a disk or magnetizing a moving tape both involve 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. With your idea and my ability to bring it to fruition, we'll both get rich. A motion-free method for printing text would also be a money maker. Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by ●August 19, 20072007-08-19
Radium wrote:> 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.You convinced me: there are stupid questions. Video and movies work by displaying a succession of still pictures close enough together in time and and position to give us the illusion of continuous motion. Think about how slow motion is accomplished with film photography. Speculate about how this might be done with analog video, and extrapolate to digitized video.> 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?> #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.> #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 imageHuh?> 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. Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by ●August 20, 20072007-08-20
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].
Reply by ●August 20, 20072007-08-20
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 withoutAh Radium trolling again i see!!!!
Reply by ●August 20, 20072007-08-20
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.)
Reply by ●August 20, 20072007-08-20
Radium <glucegen1@gmail.com> 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?What you are calling "bit resolution" is more commonly referred to as bits/sample, or in video bits/color or per component. It "enters into the equation" in all digital encoding systems by setting the dynamic range that can be encoded in that system, or, if you prefer, the "accuracy" with which each sample represents the value of the original signal at that point. The number of bits, along with the choice of the maximum value which can be encoded (i.e., what level "all ones" in the sample corresponds to) determines the value represented by the least-significant bit.>> >>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]PCM has nothing to do with it.>>Sample rate in audio = frame rate in videoNo. There is no real analog, in audio, to the frame rate in video, except to the extent that the frame rate IS a sample rate in terms of capturing one complete 2-D image at that point in time - IF that is the way the image capture device works (and not all work this way). More typically, the "sample rate" in audio would be thought of as corresponding to the pixel rate in video.>>Channel in audio = pixel in videoDefinitely not. A "pixel" in imaging is just what the name says - it is a "picture element," meaning one dimensionless point-sample of the original image, at a specific location within the image plane and, in the case of motion video, at a specific time. A pixel is the best analog you will find to a single sample in the case of digital audio.>>Bit-resolution in audio = ? in videoBits per sample is bits per sample, in either case.>>Is it true that unlike the-frequency-of-audio, the-frequency-of-video >>has two components -- temporal and spatial?A better way to say this is that you are concerned with both temporal and spatial frequencies in the case of motion video. (And, in the case of still images - as in digital still photography - spatial frequencies only.)>>II. Digital vs. Analog >> >>Sample-rate is a digital entity.Not really. While today most sampled systems are, in fact, "digital" in nature (meaning that the information is encoded in digital form), there is nothing in sampling theory which restricts its applicability to that realm. 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." Bob M.
Reply by ●August 20, 20072007-08-20
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 >>> 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.It does that digitally. Did you really not know that? Are you trolling after all?> Those Nintendo Entertainment System cartridges were able to playback > without any motion.It does that digitally. Did you really not know that? Are you trolling after all?>>> 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].What would you write into that "RAM"? There are no analog bits. The analog equivalent of a masked ROM is a phonograph record. Think first. Blather afterward, but show some sign of thought or you're not worth bothering with. Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by ●August 20, 20072007-08-20
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.
Reply by ●August 20, 20072007-08-20
Bob Myers wrote:> ... 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."Bob, The degenerate case is just a limit. Signals close to the band edge take a long time to be resolved. The time is of the order if 1/|f-F|, where F is the frequency of the nearer band edge. Just as it takes in the order of 100 seconds to resolve a frequency of .01 Hz, it takes the same time to resolve a frequency of Fs/2 - .01 Hz. When f = Fs/2, it just takes forever. The real works tends to be continuous. Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
