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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » CP750 remote control (Page 1)

 
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Author Topic: CP750 remote control
Wim Nagtegaal
Film Handler

Posts: 7
From: Alphen aan den Rijn
Registered: Sep 2019


 - posted 10-02-2019 09:40 AM      Profile for Wim Nagtegaal   Email Wim Nagtegaal   Send New Private Message       Edit/Delete Post 
We would like to control the volume from the theater to make fine adjustments to the trailer volume. After searching on the internet there has been an Android app to do that from Roman Braun. The app seems to have disappeared from the Playstore and the apk download sites. Already tried a message to Mr. Braun but no answer. Does anybody know more about this or does he have the apk available? We would like to use an old Android phone so the software being 'aged' should not be a problem. I've done some testing with a Windows PC and that seems to work with the described commands, but we would like to use a smartphone which is more compact than a laptop.

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Marcel Birgelen
Film God

Posts: 3171
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 10-02-2019 10:40 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
Download a copy of Android Studio and do-it-yourself? [Smile]

As long as it only needs to work within the same network and doesn't need to traverse NAT, etc. it's still a pretty trivial thing to build, as long as the only thing you want to control is the fader setting.

Keep in mind that opening up your CP750 from any odd network will involve some security risks.

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Wim Nagtegaal
Film Handler

Posts: 7
From: Alphen aan den Rijn
Registered: Sep 2019


 - posted 10-02-2019 10:46 AM      Profile for Wim Nagtegaal   Email Wim Nagtegaal   Send New Private Message       Edit/Delete Post 
Already thought of that, but if somebody else has done it, why reinvent the wheel [Wink] .
Also thought about security, the idea is to connect an AP to the cinema network and not show the network name (SSID). Then connect only an old Android phone to the WiFi network which can only be used as remote control. Switch off the AP when the equipment is not in use.

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Scott Norwood
Film God

Posts: 8115
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99


 - posted 10-02-2019 02:53 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
Hiding your SSID doesn't really do much for security.

Why not just get the CP750 remote fader box (cat. 868)?

If your cinema has automation equipment, there might be a way to use a remote interface to the automation system to control the CP750.

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Marcel Birgelen
Film God

Posts: 3171
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 10-02-2019 04:47 PM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
Hiding your SSID is indeed not a real security measure. Applying a WPA2 key with sufficient strength and something like a MAC filter will probably shield most of it though. Still, I don't really like to expose a control network directly via wireless, it's usually a firewall with VPN I want to put in front of it.

I guess the APK was pulled, because it was targeted at a rather old Android API level. Maybe some archive still has it, but you need to watch out for those bad archives that push crapware down your throat.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12679
From: Annapolis, MD
Registered: Dec 1999


 - posted 10-02-2019 11:26 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
There needs to be a bit of a reality check here. Hiding the SSID will stop 99% of the lookie-loos that are merely sniffing for an available WiFi network. Putting a suitable password on it will knock out most of that last 1% to the point of just what are you worried about on the projection network.

I'll admit, I take it a step further, the Wifi network isn't even on the same subnet as the projection network and you have to pass through my firewall and know the specific IP addresses (again, not even on the same subnet as Wifi) and even then only specific ports needed for the manger to get to the devices they want to control. So you'd need to know where the CP750s are on a different range before connecting up to the Wifi that doesn't call attention to itself and is password protected and, if need be, also MAC filtered.

I would say it also depends where you are in the world as to how heavy you need to protect yourself.

As more stuff gets web-ui based however, the desire for a WiFi connection has been increasing dramatically.

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Marcel Birgelen
Film God

Posts: 3171
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 10-03-2019 12:46 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
The problem with putting your "control network" in the same subnet as where you put the access point is that it will carry all the broadcast traffic on that network to the outside, so there will always be plenty traffic to snoop. Combine this with not-so-strong WPA2 keys and other vulnerabilities and your network may be more open than you think.

A cinema may not be such a juicy target, but still no excuse for sloppy security. Cyber-attacks in many forms are a fact of life now, whether it's just a bunch of script kiddies poking some "fun" with their latest set of toys or something more sophisticated.

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Wim Nagtegaal
Film Handler

Posts: 7
From: Alphen aan den Rijn
Registered: Sep 2019


 - posted 10-03-2019 03:30 AM      Profile for Wim Nagtegaal   Email Wim Nagtegaal   Send New Private Message       Edit/Delete Post 
Ok, I understand the security implications for the WiFi, but no SSID, MAC filter and switch the AP off when the theater is not in use should do, we think. Long passwords are already in place and maybe we can add a firewall.

But the main question: does anybody has the apk for that old app??

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12679
From: Annapolis, MD
Registered: Dec 1999


 - posted 10-03-2019 05:32 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
I know there are sites that claim to still have it. I downloaded it a LONG time ago when it was still available from the play store and it still works on my S8.

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Wim Nagtegaal
Film Handler

Posts: 7
From: Alphen aan den Rijn
Registered: Sep 2019


 - posted 10-03-2019 06:46 AM      Profile for Wim Nagtegaal   Email Wim Nagtegaal   Send New Private Message       Edit/Delete Post 
Tried a lot of them but they all hang or redirect to the Playstore.

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Steve Moore
Expert Film Handler

Posts: 211
From: Leeds, West Yorks, UK
Registered: Apr 2008


 - posted 10-03-2019 07:47 AM      Profile for Steve Moore   Email Steve Moore   Send New Private Message       Edit/Delete Post 
I still have a working version of the APK myself, from when I recently upgraded my phone and could no longer find it and managed to extract it from my old phone. If interested I could try upload it to somewhere like a google drive and send a link perhaps?

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Wim Nagtegaal
Film Handler

Posts: 7
From: Alphen aan den Rijn
Registered: Sep 2019


 - posted 10-03-2019 08:04 AM      Profile for Wim Nagtegaal   Email Wim Nagtegaal   Send New Private Message       Edit/Delete Post 
That would be great!! Please send me a DM (if possible) then I can send you my email address and mail it to me in a zip file (should not be that large).

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Scott Norwood
Film God

Posts: 8115
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99


 - posted 10-03-2019 12:24 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
If I read Steve's post correctly, he has the cinema network on the opposite side of a firewall on the wireless network. That would separate the broadcast traffic.

If a theatre uses the standard Dolby-style IP numbering convention, it wouldn't be too hard to guess the IP addresses of the projector, processor, automation, etc.

That said, I agree that Steve's approach is probably good enough for most, since it's just designed to keep people from wrecking havoc with screenings, which does not exactly require military-grade security.

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Marcel Birgelen
Film God

Posts: 3171
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 10-03-2019 06:08 PM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
quote: Scott Norwood
If I read Steve's post correctly, he has the cinema network on the opposite side of a firewall on the wireless network. That would separate the broadcast traffic.
That's correct. Also, the firewall should avoid you being able to scan for any equipment on that network.

Some cinema stuff is surprisingly fragile, like the CP650's network interface. It's pretty easy to wreak havoc on such a device by just sending arbitrary traffic to its control TCP port for example. At the very least, it's easy to block legitimate macro calls from getting thru.

quote: Scott Norwood
If a theatre uses the standard Dolby-style IP numbering convention, it wouldn't be too hard to guess the IP addresses of the projector, processor, automation, etc.
Just listening to broadcast traffic is sufficient to see eventually practically all active speakers on an Ethernet network. You don't even need to actively scan it. That's why it's actually a good idea to use a separate subnet for mobile networks in many cases.

quote: Wim Nagtegaal
That would be great!! Please send me a DM (if possible) then I can send you my email address and mail it to me in a zip file (should not be that large).
If the original author responds, maybe ask him if he would be willing to share the APK with the rest of the world?

Maybe we can motivate Brad to put it up in the warehouse section of this site, that way, the tool, which is still useful, can live on, even if he doesn't officially support it anymore.

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Wim Nagtegaal
Film Handler

Posts: 7
From: Alphen aan den Rijn
Registered: Sep 2019


 - posted 10-04-2019 03:08 AM      Profile for Wim Nagtegaal   Email Wim Nagtegaal   Send New Private Message       Edit/Delete Post 
quote: Marcel Birgelen
If the original author responds, maybe ask him if he would be willing to share the APK with the rest of the world?
When he responds, I'll ask him.

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