EDAboard.com | EDAboard.eu | EDAboard.de | EDAboard.co.uk | RTV forum PL | NewsGroups PL

Open source VHS: how would you do it?

Ask a question - edaboard.com

elektroda.net NewsGroups Forum Index - Electronics Design - Open source VHS: how would you do it?

Goto page 1, 2, 3, 4  Next

Aleksandar Kuktin
Guest

Sun Aug 14, 2016 1:40 pm   



As a budding member of the Obsolete Interfaces Mafia, I'm always on the
lookout for ways to implement things no-one is using anymore.

Some time ago, I found a video on YouTube of someone driving around
Tokyo. The video has a vague VHS-like feel to it, and since I watched it
many times (I like modern architecture), I got a crazy idea of maybe
implementing a tape storage device. Open source, because if more people
(around me) use it, then my life would be better, since I would be able
to share.

The video in question: https://www.youtube.com/watch?v=5WOqHLZUrbo

I've read a bit about VHS and I'm aware of its basic design, but I'm
short on knowledge about all the various implementation problems you
encounter with it.

How would seasoned veterans attack such a problem? The problem being VHS
in particular and tape storage in general. Where to begin, especially if
you assume you have a blank slate and blue skies (no "retail consumer"
has used tape storage for over 20 years, so there's little prior
expectation or standard - hipster don't count)?

For added points, what about optical tape storage? Can we make a EMP-
resistant (tape-based, because cool) mass storage device that lasts 100
years, at minimum? And that Joe R. Hacker can assemble in his garage/
basement in 2 months and 100-200 dollars?

Ha-ha, only serious.

Aleksandar Kuktin
Guest

Sun Aug 14, 2016 2:32 pm   



On Sun, 14 Aug 2016 12:17:02 +0000, Rob wrote:

Quote:
Aleksandar Kuktin <akuktin_at_gmail.com> wrote:
Some time ago, I found a video on YouTube of someone driving around
Tokyo. The video has a vague VHS-like feel to it, and since I watched
it many times (I like modern architecture), I got a crazy idea of maybe
implementing a tape storage device. Open source, because if more people
(around me) use it, then my life would be better, since I would be able
to share.

The video in question: https://www.youtube.com/watch?v=5WOqHLZUrbo

That video is not at all like VHS! It has none of the characteristic
artifacts of a VHS recording. About the only thing is the 4:3 aspect
ratio which was also used in the VHS days.

Here is a random video that I got when searching for "vhs recording" on
YouTube: https://www.youtube.com/watch?v=5PrAwjl0QY4 You can find many
others.

Look at the horizontal glitches and the overall video resolution. Also
apparent in many VHS-to-digital video transcriptions is an area at the
top or bottom where some lines are permanently pulled sideways or
jittering.


Apologies.

My memory of my youth is short, and full of errors. Sad


Guest

Sun Aug 14, 2016 4:21 pm   



On Sunday, 14 August 2016 12:40:43 UTC+1, Aleksandar Kuktin wrote:
Quote:
As a budding member of the Obsolete Interfaces Mafia, I'm always on the
lookout for ways to implement things no-one is using anymore.

Some time ago, I found a video on YouTube of someone driving around
Tokyo. The video has a vague VHS-like feel to it, and since I watched it
many times (I like modern architecture), I got a crazy idea of maybe
implementing a tape storage device. Open source, because if more people
(around me) use it, then my life would be better, since I would be able
to share.

The video in question: https://www.youtube.com/watch?v=5WOqHLZUrbo

I've read a bit about VHS and I'm aware of its basic design, but I'm
short on knowledge about all the various implementation problems you
encounter with it.

How would seasoned veterans attack such a problem? The problem being VHS
in particular and tape storage in general. Where to begin, especially if
you assume you have a blank slate and blue skies (no "retail consumer"
has used tape storage for over 20 years, so there's little prior
expectation or standard - hipster don't count)?

For added points, what about optical tape storage? Can we make a EMP-
resistant (tape-based, because cool) mass storage device that lasts 100
years, at minimum? And that Joe R. Hacker can assemble in his garage/
basement in 2 months and 100-200 dollars?

Ha-ha, only serious.


I did once briefly look at tape & paper storage to see if it were viable, but the amount of data storable that way is worth more or less nothing, and the input/output bandwidth abysmal. You could calculate it easily enough.

For magnetic tape's multitrack alternative google Tefi cartridges.


NT

Rob
Guest

Sun Aug 14, 2016 6:17 pm   



Aleksandar Kuktin <akuktin_at_gmail.com> wrote:
Quote:
Some time ago, I found a video on YouTube of someone driving around
Tokyo. The video has a vague VHS-like feel to it, and since I watched it
many times (I like modern architecture), I got a crazy idea of maybe
implementing a tape storage device. Open source, because if more people
(around me) use it, then my life would be better, since I would be able
to share.

The video in question: https://www.youtube.com/watch?v=5WOqHLZUrbo


That video is not at all like VHS! It has none of the characteristic
artifacts of a VHS recording. About the only thing is the 4:3 aspect
ratio which was also used in the VHS days.

Here is a random video that I got when searching for "vhs recording"
on YouTube: https://www.youtube.com/watch?v=5PrAwjl0QY4
You can find many others.

Look at the horizontal glitches and the overall video resolution.
Also apparent in many VHS-to-digital video transcriptions is an area
at the top or bottom where some lines are permanently pulled sideways
or jittering.


Guest

Sun Aug 14, 2016 9:22 pm   



>"Ha-ha, only serious"

Well you got the Ha-ha part right. Tape is the worst thing ever. You're better off cutting the data to a vinyl record like an LP.
(33 1/3)

Stamped CDs and DVDs should last forever, but not burned ones. However they have come out with some extremely long life ones though you need a special burner to use them.


Guest

Sun Aug 14, 2016 9:26 pm   



Quote:
"Also apparent in many VHS-to-digital video transcriptions is an area
at the top or bottom where some lines are permanently pulled sideways
or jittering. "


That's time base errors due to differences in the recording and playback machines or tape stretch. It should go through a time base corrector before conversion.

But you'll never get rid of the edges it puts on everything or the effect of the COMB filters which shifts the chroma toward the bottom of the screen.


Guest

Sun Aug 14, 2016 11:07 pm   



Long time ago for Amiga 500 Video Backup System existed.
Recording on VHS was done directly from composite out and reading via RS-232 and small circuit that if I remember rember was just an Op-amp ( or comparator). Took about minute to archive a floppy (800kB).
I used to build "converters" for it; if dig deep enough might find schematics but not any time soon as my boxes with old stuff are 300 miles away.

Marcin

Don Y
Guest

Sun Aug 14, 2016 11:57 pm   



On 8/14/2016 4:40 AM, Aleksandar Kuktin wrote:
Quote:
As a budding member of the Obsolete Interfaces Mafia, I'm always on the
lookout for ways to implement things no-one is using anymore.

Some time ago, I found a video on YouTube of someone driving around
Tokyo. The video has a vague VHS-like feel to it, and since I watched it
many times (I like modern architecture), I got a crazy idea of maybe
implementing a tape storage device. Open source, because if more people
(around me) use it, then my life would be better, since I would be able
to share.

The video in question: https://www.youtube.com/watch?v=5WOqHLZUrbo

I've read a bit about VHS and I'm aware of its basic design, but I'm
short on knowledge about all the various implementation problems you
encounter with it.

How would seasoned veterans attack such a problem? The problem being VHS
in particular and tape storage in general. Where to begin, especially if
you assume you have a blank slate and blue skies (no "retail consumer"
has used tape storage for over 20 years, so there's little prior
expectation or standard - hipster don't count)?


Presumably, you mean "used tape storage for VIDEO"?

Quote:
For added points, what about optical tape storage? Can we make a EMP-
resistant (tape-based, because cool) mass storage device that lasts 100
years, at minimum? And that Joe R. Hacker can assemble in his garage/
basement in 2 months and 100-200 dollars?

Ha-ha, only serious.


The folks interested in (REALLY) long term data storage think in terms
of nickel and tungsten disks (for thousands to billions of years,
respectively).

*Paper* is amazingly durable (thousands of years?) -- but poses
problems with "electronic access".

We could always return to wire recorders...

Don Y
Guest

Mon Aug 15, 2016 1:28 am   



On 8/14/2016 12:22 PM, jurb6006_at_gmail.com wrote:
Quote:
"Ha-ha, only serious"

Well you got the Ha-ha part right. Tape is the worst thing ever. You're
better off cutting the data to a vinyl record like an LP. (33 1/3)


My tape archive has fared better than my DVD archive. But, requires
periodic maintenance.

> Stamped CDs and DVDs should last forever, but not burned ones. However they

<https://en.wikipedia.org/wiki/Disc_rot>

Quote:
have come out with some extremely long life ones though you need a special
burner to use them.



Guest

Mon Aug 15, 2016 1:29 am   



On Sunday, 14 August 2016 15:21:36 UTC+1, tabbypurr wrote:
Quote:
On Sunday, 14 August 2016 12:40:43 UTC+1, Aleksandar Kuktin wrote:

As a budding member of the Obsolete Interfaces Mafia, I'm always on the
lookout for ways to implement things no-one is using anymore.

Some time ago, I found a video on YouTube of someone driving around
Tokyo. The video has a vague VHS-like feel to it, and since I watched it
many times (I like modern architecture), I got a crazy idea of maybe
implementing a tape storage device. Open source, because if more people
(around me) use it, then my life would be better, since I would be able
to share.

The video in question: https://www.youtube.com/watch?v=5WOqHLZUrbo

I've read a bit about VHS and I'm aware of its basic design, but I'm
short on knowledge about all the various implementation problems you
encounter with it.

How would seasoned veterans attack such a problem? The problem being VHS
in particular and tape storage in general. Where to begin, especially if
you assume you have a blank slate and blue skies (no "retail consumer"
has used tape storage for over 20 years, so there's little prior
expectation or standard - hipster don't count)?

For added points, what about optical tape storage? Can we make a EMP-
resistant (tape-based, because cool) mass storage device that lasts 100
years, at minimum? And that Joe R. Hacker can assemble in his garage/
basement in 2 months and 100-200 dollars?

Ha-ha, only serious.

I did once briefly look at tape & paper storage to see if it were viable, but the amount of data storable that way is worth more or less nothing, and the input/output bandwidth abysmal. You could calculate it easily enough.

For magnetic tape's multitrack alternative google Tefi cartridges.


My memory of the figures is hazy... this may be a bit approximate.

IIRC PAL VHS did 240 line resolution with similar horizontal resolution, so one got about 240/625 lines or that squared x 6MHz as a rough data rate = 0.88MHz. Now subtract sync pulses, flyback time & trim the picture edges and you might get say 0.5 - 0.6MHz. Allow for massive redundancy of 10x - you'll need it - gets you about 50kHz data rate in & out.
50kHz x 3hrs = 540megabits or 67Mb. And yes, with a standard transport it'll take 3 hours to record or play that. Not too impressive.

Tape is reliable/durable if splices are avoided, meaning tape ends are clamped without leaders. That drops max rewind speed of course. But they're always a little bit fragile.

Going to grooves as in a 33 or a tefi is a bad move, you then can't get much above audio for your data transfer rate. It also makes writing data difficult, the discs/tapes become WORM.


NT

amdx
Guest

Mon Aug 15, 2016 1:29 am   



On 8/14/2016 12:57 PM, Don Y wrote:
Quote:
On 8/14/2016 4:40 AM, Aleksandar Kuktin wrote:
As a budding member of the Obsolete Interfaces Mafia, I'm always on the
lookout for ways to implement things no-one is using anymore.

https://www.google.com/patents/US4972275

"A tape recording apparatus in the form of a modified VCR is employed to
record broadcast signals received by an antenna while moving through a
radio-broadcast reception area. The recorded signals are maintained in
an undetected, modulated-carrier form so that played-back signals from
the VCR can be coupled to a radio receiver in a fixed location for
testing under mobile conditions. A commercially available VCR is
modified to avoid modulating FM signals by frequency a second time."

They do this now with hard drives, setup their super duper directional
antennas and record the signals. Then the go home and spend leisurely
time listening to what they received.


Quote:
http://www.microtelecom.it/perseus/


The PERSEUS software supports wideband spectrum record/playback up to 2
MSPS with alias images rejection larger than 110 dB in a 1600 kHz bandwidth!

Quote:
http://www.ab4oj.com/sdr/perseus/main.html


Mikek


Guest

Mon Aug 15, 2016 11:59 am   



On Monday, 15 August 2016 10:34:34 UTC+1, Tim Williams wrote:

Quote:
Conventional analog grooves are probably not the way to go. Maybe a
dot-matrix impact tool would be better. It'd be fine for plain digital
(e.g. CD-ROM) encoding.


painfully slow.


NT


Guest

Mon Aug 15, 2016 1:20 pm   



On Monday, 15 August 2016 12:14:08 UTC+1, Tim Williams wrote:
Quote:
tabbypurr> wrote in message
news:4bb7a3b3-10a2-47d5-8a52-c34596826556_at_googlegroups.com...
On Monday, 15 August 2016 10:34:34 UTC+1, Tim Williams wrote:

Conventional analog grooves are probably not the way to go. Maybe a
dot-matrix impact tool would be better. It'd be fine for plain digital
(e.g. CD-ROM) encoding.

painfully slow.


Well, yeah. But you snipped the part about it being archival quality
daydreaming, and the part about wondering how fast something can go.

I would wager that conventional dot-matrix heads are /not/ at the absolute
speed limit for a magnetomechanical component. Your out-of-hand rejection
is neither useful nor justified...


It's several orders of magnitude too slow to be useful.


NT

Tim Williams
Guest

Mon Aug 15, 2016 3:34 pm   



"Don Y" <blockedofcourse_at_foo.invalid> wrote in message
news:noqbd6$l7b$1_at_dont-email.me...
Quote:
The folks interested in (REALLY) long term data storage think in terms
of nickel and tungsten disks (for thousands to billions of years,
respectively).


Hmm, curious...

I wonder if one could make an archival record-RW, with inert atmosphere,
plasma torch and cutting lathe. Torch the track to erase it flat, then cut
a new one. Has to be plasma to be precise enough (or laser or e-beam, but
come on, now..), so as not to obliterate multiple tracks at a pass.

It would be nice to recast the groove rather than cut it, but I don't see an
immediately obvious way for that to be effective. It's not like nickel is
wax that can be smooshed into with a hot needle (and not like that gives
good high frequency response anyway). Cutting of course necessitates
limited erasures, or added material to replace it (which would make erasure
a full-disk flame-spray process, or something like that).

Conventional analog grooves are probably not the way to go. Maybe a
dot-matrix impact tool would be better. It'd be fine for plain digital
(e.g. CD-ROM) encoding. You could make something like a dot-matrix
centerpunch. I wonder how fast the head can actually write, without getting
crazy hot (so basically, if it's magnetic, it'll have to be in the <2T field
range, so steel pole pieces are reasonable and copper wire doesn't
completely melt away).

Interesting unit conversion: a 1T field works out to about 4atm pressure, so
a magnetic solenoid is comparable to a pneumatic one in force-to-size ratio.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com

Sylvia Else
Guest

Mon Aug 15, 2016 4:21 pm   



On 14/08/2016 9:40 PM, Aleksandar Kuktin wrote:
Quote:
As a budding member of the Obsolete Interfaces Mafia, I'm always on the
lookout for ways to implement things no-one is using anymore.

Some time ago, I found a video on YouTube of someone driving around
Tokyo. The video has a vague VHS-like feel to it, and since I watched it
many times (I like modern architecture), I got a crazy idea of maybe
implementing a tape storage device. Open source, because if more people
(around me) use it, then my life would be better, since I would be able
to share.


The recorders used precision machined heads. Few would have the required
skill.

Sylvia.

Goto page 1, 2, 3, 4  Next

elektroda.net NewsGroups Forum Index - Electronics Design - Open source VHS: how would you do it?

Ask a question - edaboard.com

Arabic versionBulgarian versionCatalan versionCzech versionDanish versionGerman versionGreek versionEnglish versionSpanish versionFinnish versionFrench versionHindi versionCroatian versionIndonesian versionItalian versionHebrew versionJapanese versionKorean versionLithuanian versionLatvian versionDutch versionNorwegian versionPolish versionPortuguese versionRomanian versionRussian versionSlovak versionSlovenian versionSerbian versionSwedish versionTagalog versionUkrainian versionVietnamese versionChinese version
RTV map EDAboard.com map News map EDAboard.eu map EDAboard.de map EDAboard.co.uk map