Radium wrote:
> On Aug 19, 4:39 pm, Jerry Avins
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.
Various compression schemes do that with varying degrees of resulting
quality.
> 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.
No it's like compressing the bit rate; MP3, for example.
> 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.
Both
>>> 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"?
There is none.
> The analog-equivalent of bit-resolution = dynamic range
>
> The analog-equivalent of sample rate = ?
Bandwidth.
>
> Thanks for the link
Use it. Get facts and stop reasoning from false analogies. If you want
to know how many angels can dance on the head of a pin, build a better
microscope. Aquinas can't tell you, and you can't deduce the answer.
Jerry
--
Engineering is the art of making what you want from things you can get.
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