Uncompressed Digital Video vs. Uncompressed Digital Audio

[Don Pearce]

It's the old "do the math" game.

30 images a second, with say 720x480 DVD video, 24 bit data words.

345,600 pixels

1,036,800 bytes

31,104,000 bytes per second.

This is a data rate that is almost thinkable for a single PC hard drive.

30 images a second, with say 1920x1080 HD video, 24 bit data words.

2,073,600 pixels

6,220,800 bytes

186,624,000 bytes per second.

RAID array, for sure!

Back in the real world, the most uncompressed video seen outside of a camera
is usually more like M-JPEG w/o i-frames.

No problem - just buy one of these.

http://www.codexdigital.com/

d

 

[Gene]

Interesting little box, bet there are some really mean
little DSP(s) inside... probably not 386 code...

************* cut-n-paste**************
Can the DiskPacks simply be connected to another computer to access the
data?
The Codex DiskPacks feature proprietary hardware connectors designed for
thousands of connect/disconnect cycles and this precludes them from simply
being connected to any other computer to access this original data.
Moreover, the material on the DiskPacks is not stored in an
industry-standard format (such as DPX frames) but in the camera source's
native output - conversions to DPX, QuickTime, HD video, AVI etc. are done
only when the material is accessed in a Codex system.

Gene

 

[Arny Krueger]

No problem - just buy one of these.

http://www.codexdigital.com/

I think I saw something about 20,000 Pounds. I think that was currency, not
weight - right? ;-)

 

[Norbert Hahn]

Um, MPEG is compressed. I was looking for uncompressed digital video.

Have a look at http://en.wikipedia.org/wiki/CCIR_601

This is closest to raw digital video.

Norbert

 

[Richard Crowley]

Have a look at http://en.wikipedia.org/wiki/CCIR_601

This is closest to raw digital video.

CCIR 601 appears to be 4:2:2 That means that the
chrominance data is compressed 2:1 (Like analog NTSC
is).

Of course DV is compressed 4:1:1 (NTSC) or 4:2:0 (PAL)

 

[Ron N.]

...




CCIR 601 appears to be 4:2:2 That means that the
chrominance data is compressed 2:1

Only if you regard reducing the sample rate as a
form of compression. But then your typical 44.1kHz
audio CD has also likely been reduced in sample rate
from 48 or 96 kHz as recorded in the studio. Is
that compression? Or just an appropriate choice
of filtering and data format?

The chrominance in 601 is reduced to a bandwidth
that better matches the typical human perceptual
bandwidth of the luminance channel.


IMHO. YMMV.

 

[Richard Crowley]

Only if you regard reducing the sample rate as a
form of compression.

If it weren't compression, they wouldn't bother doing it.

But then your typical 44.1kHz audio CD has also likely
been reduced in sample rate from 48 or 96 kHz as
recorded in the studio. Is that compression?

Many would say "yes".

Or just an appropriate choice of filtering and data format?

Selecting a sample rate always performs some sort of
"compression". One could argue that setting the sample
rate of audio merely selects what you want your HF
cutoff to be.

OTOH, purposely digitally sub-sampling (or analog band-
width-limiting) the color part of the image is a data-saving
perceptual shell game similar to the lossy compression
done by MP3, AAC, Ogg, et.al.

The chrominance in 601 is reduced to a bandwidth
that better matches the typical human perceptual
bandwidth of the luminance channel.

And yet the casual observer can tell the difference
between full-bandwidth RGB and reduced-color rez
video transmission schemes when viewed side-by-
side.

 

[glen herrmannsfeldt]

Ron N. wrote:

(snip)

As for storing uncompressed formats, didn't amateur radio
types try storing monochrome (very) slow scan video on
audio tape?

There was a story in Popular Science many years ago that I
still remember about storing fast scan (normal TV) video
on 0.25 inch audio tape. It ran the tape at 120in/s,
with the cover page of the story showing the results after
the tape breaks. They heat the record/play head to reduce
friction. 10 inch tape reels were normally used to get a
reasonable time. I don't believe it ever got popular.

-- glen

 

[Vladimir Vassilevsky]

There was a story in Popular Science many years ago that I
still remember about storing fast scan (normal TV) video
on 0.25 inch audio tape. It ran the tape at 120in/s,
with the cover page of the story showing the results after
the tape breaks. They heat the record/play head to reduce
friction. 10 inch tape reels were normally used to get a
reasonable time. I don't believe it ever got popular.

When I was a kid, I was trying to record the video signal from TV to a
modified conventional cassette tape recorder. For that purpose, the
recorder was operating in the fast forward mode, so the tape speed was
about 2m/s. I was able to establish the horizontal and vertical sync,and
even to see something, however I woudn't call this a picture.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com

 

[Steve Underwood]

Ron N. wrote:

(snip)


There was a story in Popular Science many years ago that I
still remember about storing fast scan (normal TV) video
on 0.25 inch audio tape. It ran the tape at 120in/s,
with the cover page of the story showing the results after
the tape breaks. They heat the record/play head to reduce
friction. 10 inch tape reels were normally used to get a
reasonable time. I don't believe it ever got popular.

-- glen

I used to use 2" wide (so far more robust) instrumentation tape at 120
inches/second. The drives used air bearing guides, to reduce friction,
but dragged the tape across ordinary heads with no special method of
dealing with heat or friction. They did have elaborate arrangements to
stabilise the tape as it passed over the heads, though. A 15" reel of
tape ran for about 16 minutes, and had 24 or 28 tracks. Those drives
used to be the mainstay of instrumentation in a number of fields (mostly
military). They could put a fair quality TV picture onto each of their
24 tracks. Several people made drives of that kind - Ampex, Honeywell,
Enertec, and others. We used to fly compact versions, while large floor
standing ones were used in the lab.

So, the popular science article was not describing anything crazy. I
just wonder about handling 0.25" tape at that speed.

Regards,
Steve

 

[Mr.T]

Selecting a sample rate always performs some sort of
"compression".

Not at all. Compression involves a manipulation of data *within* the range
under consideration. (either lossy compression or lossless)
If extraneous data falls completely outside the required range, then no
compression is necessary within that range.

One could argue that setting the sample
rate of audio merely selects what you want your HF
cutoff to be.

No, there would be no *real* argument at all, since that *is* what it does.

MrT.

 

[Richard Crowley]

"Richard Crowley" wrote ...

Not at all. Compression involves a manipulation of data *within* the range
under consideration. (either lossy compression or lossless)
If extraneous data falls completely outside the required range, then no
compression is necessary within that range.


No, there would be no *real* argument at all, since that *is* what it
does.

And limiting the bandwidth is a form of "data compression".
It was invented before our grandparents were born in
the days of early telephony.

 

[Jerry Avins]

Richard Crowley wrote:

...

And limiting the bandwidth is a form of "data compression".
It was invented before our grandparents were born in
the days of early telephony.

Call it data reduction if you wish. "Compression" is generally given a
more restricted meaning.

Jerry

 

[Michael A. Terrell]

Engineering is the art of making what you want from things you can get.

That is also the definition of "Creative recycling".


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Mr.T]

And limiting the bandwidth is a form of "data compression".
It was invented before our grandparents were born in
the days of early telephony.

No, you are simply misusing the term "compression".
By your definition *everything* that does not include DC-infinity (ie.
everything full stop) is therefore "compressed".
Good luck with getting that generally accepted as a new definition.

MrT.