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what is analog and digital video?

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September 12, 2004 3:02:08 PM

Archived from groups: rec.video.desktop (More info?)

Hi, I would like to know a good explanation about analog and digital
video, is there a web site that explains it well? for dummies?

More about : analog digital video

Anonymous
September 12, 2004 7:26:34 PM

Archived from groups: rec.video.desktop (More info?)

"Andrei" <aberdich@hotmail.com> wrote in message
news:b235a10f.0409121002.527473f7@posting.google.com...
> Hi, I would like to know a good explanation about analog and digital
> video, is there a web site that explains it well? for dummies?

Analog means that values are represented by a signal scaled to the value,
e.g. if a component of a scene is bright, the video signal recorded is
strong. If a component of a scene is dark, the video signal recorded is
weak. When copies are made of an analog signal, degradation is
introduced -- signals aren't recorded at exactly the same strength, and
false signals from the recording process can be introduced which distort the
signal.

Digital means that each component of the scene is represented by a number
representing a discrete quantization, e.g. very bright components may be
represented by the number 255, and very dim components by 0. When digital
video is copied, it is nothing more than copying the set of number from one
medium to another. Since each number is discrete and copied exactly, there
is no degradation of the underlying image, and no noise is introduced that
can cause distortion.

In a nutshell, analog video uses varying signal strength to represent
brightness. Digital video uses discrete numbers to quantize brightness.
Anonymous
September 12, 2004 9:39:40 PM

Archived from groups: rec.video.desktop (More info?)

Andrei wrote:

> Hi, I would like to know a good explanation about analog and digital
> video, is there a web site that explains it well? for dummies?

Analog vs. Digital...

Think cassette tape vs. CD
VHS vs. DVD
Hi8 vs. DV

With the digital formats, you can transfer the bits from one medium to
another without any loss. Transferring an analog format to another
medium is lossy. So when you "capture" DV video from your camcorder,
it's really just doing a digital transfer. With analog video, the data
is sent over the wire in analog form and then digitized by your capture
card.


-WD
Related resources
Anonymous
September 13, 2004 11:26:18 AM

Archived from groups: rec.video.desktop (More info?)

Like somebody said among the other replies here the analog video signal is
sampled and converted into 8bit numbers which gives 255 levels.

Prior to conversion, however, the video signal is split into three signals
which together constitute the necessary information for describing an analog
color video signal. Each of the three signals are then sampled in various
ways depending on the type of digital system you want. In miniDV and DVCAM
(most common in consumer and semipro cameras) the three signals are sampled
with 8 bits(255 levels) for brightness and 4 bits(15 levels) each for the
two color information signals (PAL).

Peter

"Andrei" <aberdich@hotmail.com> skrev i meddelandet
news:b235a10f.0409121002.527473f7@posting.google.com...
> Hi, I would like to know a good explanation about analog and digital
> video, is there a web site that explains it well? for dummies?
Anonymous
September 13, 2004 11:26:19 AM

Archived from groups: rec.video.desktop (More info?)

"Peter O Sjostrand" <po.sjostrand@telia.com> wrote in message
news:uYb1d.103226$dP1.370093@newsc.telia.net...
> Like somebody said among the other replies here the analog video signal is
> sampled and converted into 8bit numbers which gives 255 levels.
>
> Prior to conversion, however, the video signal is split into three signals
> which together constitute the necessary information for describing an
analog
> color video signal. Each of the three signals are then sampled in various
> ways depending on the type of digital system you want. In miniDV and DVCAM
> (most common in consumer and semipro cameras) the three signals are
sampled
> with 8 bits(255 levels) for brightness and 4 bits(15 levels) each for the
> two color information signals (PAL).

I believe all the video components are sampled at 8-bit
resolution, both NTSC and PAL. The difference is how
*often* the samples are taken (thus affecting the overall
bitrate). See "4:1:1" (NTSC) vs. "4:2:0" (PAL), etc.
September 13, 2004 5:41:36 PM

Archived from groups: rec.video.desktop (More info?)

What confuses me is when an analog camcorder records then I connect to
the computer throw a capture card it transforms it into digital
signal?, when I think in a computer I think that every video recording
inside its digital, its right? or an analog video captured in a pc its
still an analog video?

Thanks
Andrei







"Richard Crowley" <rcrowley7@xprt.net> wrote in message news:<10kbabpgp700a04@corp.supernews.com>...
> "Peter O Sjostrand" <po.sjostrand@telia.com> wrote in message
> news:uYb1d.103226$dP1.370093@newsc.telia.net...
> > Like somebody said among the other replies here the analog video signal is
> > sampled and converted into 8bit numbers which gives 255 levels.
> >
> > Prior to conversion, however, the video signal is split into three signals
> > which together constitute the necessary information for describing an
> analog
> > color video signal. Each of the three signals are then sampled in various
> > ways depending on the type of digital system you want. In miniDV and DVCAM
> > (most common in consumer and semipro cameras) the three signals are
> sampled
> > with 8 bits(255 levels) for brightness and 4 bits(15 levels) each for the
> > two color information signals (PAL).
>
> I believe all the video components are sampled at 8-bit
> resolution, both NTSC and PAL. The difference is how
> *often* the samples are taken (thus affecting the overall
> bitrate). See "4:1:1" (NTSC) vs. "4:2:0" (PAL), etc.
Anonymous
September 14, 2004 2:53:27 AM

Archived from groups: rec.video.desktop (More info?)

aberdich@hotmail.com (Andrei) wrote in
news:b235a10f.0409131241.3f7caeea@posting.google.com:

> What confuses me is when an analog camcorder records then I
> connect to the computer throw a capture card it transforms it into
> digital signal?, when I think in a computer I think that every
> video recording inside its digital, its right? or an analog video
> captured in a pc its still an analog video?
>
> Thanks
> Andrei
>
>

Yes, the capture card or external capture device converts the
voltage levels (the analog signals) into numbers (binary values,
digital values, whatever you'd like to call them) and that's what
gets onto your hard drive.

So everything in the computer is digital, just as you surmised.

With digital cameras, the conversion to digital happens in the
camera and the digital values are written to tape (or whatever
storage medium is used in the camera). In this case "capture" is
really "transfer", and the numbers are copied to your hard drive as
numbers.

Part of the secret is how the numbers are organized into files, and
so on, but let's not go there until we've had a chance to rest :-)

HTH,
gino

<SNIP>
--
Gene E. Bloch (Gino) phone 650.966.8481
Call me letters find me at domain blochg whose dot is com
Anonymous
September 14, 2004 5:07:56 PM

Archived from groups: rec.video.desktop (More info?)

aberdich said:

>>an analog video captured in a pc its
still an analog video?>>

Well, at one time there were analog computers, so I guess if you have one of
those you could. :-)


Dave
http://members.tripod.com/~VideoDave
Anonymous
September 14, 2004 5:07:57 PM

Archived from groups: rec.video.desktop (More info?)

> aberdich said:
>>>an analog video captured in a pc its
> still an analog video?>>

"DavesVideo" wrote ...
> Well, at one time there were analog computers, so I guess
> if you have one of those you could. :-)

Even at their prime, analog computers couldn't handle even a tiny
fraction of the bandwidth of ordinary baseband video. I remember
a very sophisticated one that filled two rooms at USC in the early
1960s. It did play a mean game of astro-blaster (or whatever it
was called).

OTOH, my Sony SEG-2000 switcher is a completely analog
video "computer". :-)
Anonymous
September 16, 2004 4:14:52 AM

Archived from groups: rec.video.desktop (More info?)

On 14 Sep 2004 13:07:56 GMT, davesvideo@aol.com (DavesVideo) wrote:

>Well, at one time there were analog computers, so I guess if you have one of
>those you could. :-)

Would you believe me when I tell you they are still used in
state-of-the-art tanks to work out where the target is?
That's something else than video-editing eh? :) 

cheers

-martin-

--
Can the terror of spam be included in the war on terror?
Anonymous
September 16, 2004 4:14:53 AM

Archived from groups: rec.video.desktop (More info?)

Martin Heffels wrote:

>>Would you believe me when I tell you they are still used in
state-of-the-art tanks to work out where the target is?
That's something else than video-editing eh? :) >>

Interesting. I worked in Target recognition and tracking for quite a few years.
10 years ago, it looked like it was heading toward all digital.


Dave
http://members.tripod.com/~VideoDave
Anonymous
September 16, 2004 12:35:42 PM

Archived from groups: rec.video.desktop (More info?)

On 15 Sep 2004 15:02:59 GMT, davesvideo@aol.com (DavesVideo) wrote:

>Interesting. I worked in Target recognition and tracking for quite a few years.
>10 years ago, it looked like it was heading toward all digital.

Maybe the Germans are a bit slow developing new technology ;-) But to
be more accurate, they use a mix of analog and digital computing.
So do we have to call this, hybrid computing?

cheers

-martin-

--
Can the terror of spam be included in the war on terror?
Anonymous
September 17, 2004 1:46:52 AM

Archived from groups: rec.video.desktop (More info?)

Martin Heffels said:

>>Maybe the Germans are a bit slow developing new technology ;-) But to
be more accurate, they use a mix of analog and digital computing.
So do we have to call this, hybrid computing?>>

As a mater of fact, that is what it is called.


Dave
http://members.tripod.com/~VideoDave
!