Time base correction

[Lenny]

I use a Videonics MX1 digital video mixer's composite video output
ahead of my VCR so that I can watch and distribute my DVD player's
output throughout my house. Without the MX1 the picture is of course
unwatchable. I am told that it is the TBC function of the MX1 that is
actually eliminating the Macrovision signals. Is this true, and if so
is the original sync first stripped off the incoming signal and then
regenerated by the TBC? I saw a circuit in a past issue of Electronic
Design for a sync stripper. It was relatvely simple to build. I'm
assuming that this would strip both the sync as well as the
macrovision. Then I guess I would have to come up with a method of
recreating the sync signals? I have tried some black box "Copyguard
eliminators" off the Net and they are all junk and don't work. I do
want to strees that I am not interested in making bootleg video
copies. I only want to be able to run the DVD output through my VCR
because it is a HI FI stereo machine and is connected to my music
system. The VCR's RF output also functions as a channel 3 modulator
which is then amplified and injected into my MATV distribution system.
How difficult would it be to build whatever portion it is of the MX1
that appears to be solving my problem, or does someone have another
solution?
Thanks very much, Lenny Stein, Barlen Electronics.

 

[Paweber02]

I use a Videonics MX1 digital video mixer's composite video output
ahead of my VCR so that I can watch and distribute my DVD player's
output throughout my house. Without the MX1 the picture is of course
unwatchable. I am told that it is the TBC function of the MX1 that is
actually eliminating the Macrovision signals. Is this true, and if so
is the original sync first stripped off the incoming signal and then
regenerated by the TBC? I saw a circuit in a past issue of Electronic
Design for a sync stripper. It was relatvely simple to build. I'm
assuming that this would strip both the sync as well as the
macrovision. Then I guess I would have to come up with a method of
recreating the sync signals? I have tried some black box "Copyguard
eliminators" off the Net and they are all junk and don't work. I do
want to strees that I am not interested in making bootleg video
copies. I only want to be able to run the DVD output through my VCR
because it is a HI FI stereo machine and is connected to my music
system. The VCR's RF output also functions as a channel 3 modulator
which is then amplified and injected into my MATV distribution system.
How difficult would it be to build whatever portion it is of the MX1
that appears to be solving my problem, or does someone have another
solution?
Thanks very much, Lenny Stein, Barlen Electronics.

The problem with the "simple" stabilizer boxes is that they predate the version
of macrovision used in DVD players. The DVD player actually generates the
macrovision interference in response to a flag in the disk content; the
macrovision is not on the disk. There are evidently at least 3 levels of
macrovision interference available in DVD players: The first is identical to
that used on videocassettes (which is embeded in the signal); the second adds
something to the sound; the third adds chroma distortion (vari-colored lines)
possibly by screwing with the burst.

There are late-model boxes less elaborate than a MX1 that will handle all 3.
The Sima SCC color-corrector box, for example. About US$100 when I bought
mine. But it will free up the MX1 for other things.

 

[Chris]

paweber02@aol.com5z378 (Paweber02) wrote in
news:20040510155810.19729.00001245@mb-m10.aol.com:

I use a Videonics MX1 digital video mixer's composite video output
ahead of my VCR so that I can watch and distribute my DVD player's
output throughout my house. Without the MX1 the picture is of course
unwatchable. I am told that it is the TBC function of the MX1 that is
actually eliminating the Macrovision signals. Is this true, and if so
is the original sync first stripped off the incoming signal and then
regenerated by the TBC? I saw a circuit in a past issue of Electronic
Design for a sync stripper. It was relatvely simple to build. I'm
assuming that this would strip both the sync as well as the
macrovision. Then I guess I would have to come up with a method of
recreating the sync signals? I have tried some black box "Copyguard
eliminators" off the Net and they are all junk and don't work. I do
want to strees that I am not interested in making bootleg video
copies. I only want to be able to run the DVD output through my VCR
because it is a HI FI stereo machine and is connected to my music
system. The VCR's RF output also functions as a channel 3 modulator
which is then amplified and injected into my MATV distribution system.
How difficult would it be to build whatever portion it is of the MX1
that appears to be solving my problem, or does someone have another
solution?
Thanks very much, Lenny Stein, Barlen Electronics.


The problem with the "simple" stabilizer boxes is that they predate
the version of macrovision used in DVD players. The DVD player
actually generates the macrovision interference in response to a flag
in the disk content; the macrovision is not on the disk. There are
evidently at least 3 levels of macrovision interference available in
DVD players: The first is identical to that used on videocassettes
(which is embeded in the signal); the second adds something to the
sound; the third adds chroma distortion (vari-colored lines) possibly
by screwing with the burst.

There are late-model boxes less elaborate than a MX1 that will handle
all 3. The Sima SCC color-corrector box, for example. About US$100
when I bought mine. But it will free up the MX1 for other things.

TBC is a Time Base Corrector and is used to regenerate the entire sync
interval including black levels, serration pulses, etc. The macrovision
I'm familiar with plays games with the black level and the vertical
sync. They say it is NTSC compatible so why do so many people, including
myself, have so many problems with it? Stripping away everything but the
raw video and then regenerating these stripped intervals usually
corrects it. My Video CopyMaster does this and delivers a great picture.
However I have noticed a new type of macrovision that works around this.
I think it embeds digital info in one of the unused video lines to
disable digital video equipment and plays the level games with the sync
and stuff. What happens is that if I try to record a DVD on DV tape, I
get a great picture right before the machine goes into record lockout.
Does anyone have info on this?
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[the terminator]

In article <Xns94E5BE588623chrismNSitproductsco@207.69.154.202>,
Chris <chrism@NSitproducts.com> wrote

TBC is a Time Base Corrector and is used to regenerate the entire sync
interval including black levels, serration pulses, etc. The macrovision
I'm familiar with plays games with the black level and the vertical
sync. They say it is NTSC compatible so why do so many people, including
myself, have so many problems with it? Stripping away everything but the
raw video and then regenerating these stripped intervals usually
corrects it. My Video CopyMaster does this and delivers a great picture.
However I have noticed a new type of macrovision that works around this.
I think it embeds digital info in one of the unused video lines to
disable digital video equipment and plays the level games with the sync
and stuff. What happens is that if I try to record a DVD on DV tape, I
get a great picture right before the machine goes into record lockout.
Does anyone have info on this?

MACROVISION is hidden in the vertical retrace. It confuses the AGC
circuits on a VCR, but a Television is tolerant enough to deal with it.

A time base corrector strips off the H and V sync, and replaces it with
it's own, rock steady version. Since Macrovision isn't part of the
television standard, it will be stripped off too. Not sure about the
closed captions or VITS, never really bothered to see if the captions
survived the process. It also replaces the chroma burst with a new one,
and it tries to correct any devations in the process.

As to recording on DV from a DVD, there is a gentlemen's agreement
between macrovision and the vcr makers not to make machines that can
defeat macrovision's system. I would guess that DV machines look for
the macro pulses in the vertical retrace, and promptly react to them.

Macrovision also patented many of the techniques used to defeat their
copy protection system, so there are a limited number of ways to beat
them without running into patent infringement problems.

But some DVD titles out there don't have the macrovision enabled. One
of my Terminator discs is like that.

Adult titles don't have macrovision either. The reason is simple: Cost.
These guys don't spend money if they don't have to. Since Macrovision
charges a fee to use their system, plus a per copy levy, for the limited
run of an adult (or "multi-angle disc") title it wouldn't be cost
effective.

 

[Chris]

the terminator <none-at-@valleynet.on.ca> wrote in
news:none-at--738264.16500111052004@nntp.bloor.is.net.cable.rogers.com:

In article <Xns94E5BE588623chrismNSitproductsco@207.69.154.202>,
Chris <chrism@NSitproducts.com> wrote


TBC is a Time Base Corrector and is used to regenerate the entire
sync interval including black levels, serration pulses, etc. The
macrovision I'm familiar with plays games with the black level and
the vertical sync. They say it is NTSC compatible so why do so many
people, including myself, have so many problems with it? Stripping
away everything but the raw video and then regenerating these
stripped intervals usually corrects it. My Video CopyMaster does this
and delivers a great picture. However I have noticed a new type of
macrovision that works around this. I think it embeds digital info in
one of the unused video lines to disable digital video equipment and
plays the level games with the sync and stuff. What happens is that
if I try to record a DVD on DV tape, I get a great picture right
before the machine goes into record lockout. Does anyone have info on
this?

MACROVISION is hidden in the vertical retrace. It confuses the AGC
circuits on a VCR, but a Television is tolerant enough to deal with
it.

A time base corrector strips off the H and V sync, and replaces it
with it's own, rock steady version. Since Macrovision isn't part of
the television standard, it will be stripped off too. Not sure about
the closed captions or VITS, never really bothered to see if the
captions survived the process. It also replaces the chroma burst with
a new one, and it tries to correct any devations in the process.

As to recording on DV from a DVD, there is a gentlemen's agreement
between macrovision and the vcr makers not to make machines that can
defeat macrovision's system. I would guess that DV machines look for
the macro pulses in the vertical retrace, and promptly react to them.

Macrovision also patented many of the techniques used to defeat their
copy protection system, so there are a limited number of ways to beat
them without running into patent infringement problems.

But some DVD titles out there don't have the macrovision enabled. One
of my Terminator discs is like that.

Adult titles don't have macrovision either. The reason is simple:
Cost. These guys don't spend money if they don't have to. Since
Macrovision charges a fee to use their system, plus a per copy levy,
for the limited run of an adult (or "multi-angle disc") title it
wouldn't be cost effective.

A TBC regenerates the H and V sync. I understand that. But what I'm
saying is that if the H and V are regenerated, and I believe that
includes VITS, the only other logical place to hide macrovision would be
in the unused video lines. I thought that closed caption was in these
video lines, too, but I never needed to research it so I can't say for
sure. I know that if you shrink the vertical hieght a little, you can
see the closed caption digital info. Therefore it must be part of the
video, probably within the first few lines. The stabilizer I have is a
Sima CopyMaster and it works great. Most of the time when I have a copy
guarded DVD, the CopyMaster cleans it up. However there are a few where
the picture would be stable but the deck goes into record lockout. Where
ever these pulses are, they seem to occur randomly within a minute or 2
of restarting record.
Gentlemans agreement between japanese manufacturers? On something like
this? These greedy cut-throats gladly sell each other out to get the
upper hand. I don't see that happening without very large sums of money
being exchanged. Something else I don't see happening.


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