Solved

VISCA protocol from SONY

Posted on 1998-02-12
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Last Modified: 2013-11-21
VISCA is an acrynom of Video System Control Architecture.
(I think it's a SONY standard or something like that)

I try to develop a remote control for a videoconference camera (SONY EVI-D31) via a PC's COM-Port.
The communication protocol is VISCA, as mentioned above.

I run into trouble for 6 months now, because I don't know exactly how to handle the incoming HEX-Strings from the camera.
I have all the commands for controlling the cam, even the expected answers on these commands.
But I have no idea how to manage the acknowledges for the commands and the inquiries. (The timing they are coming is absolutely strange to me...).
Does anybody has a ready solution regarding the communication with the VISCA protocol ?
Perhaps written in VC++ ? (pleassse)

Any idea where I could get further informations ?
Don't send me info on VISCA...I need solutions on communication with visca.
(SONY told me to buy their selfmade application...very helpful...)

I'll start with 150 pts. but be sure, that you'll get ALL the rest of my points when you can help me out of here !


Best regards from germany

-Stavi-
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Question by:mitrakis
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by:jrhelgeson
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Are you trying to program the interface to communicate with a PC, or Mac?

VISCA device control is not compatible with the System Update file included with Mac OS 7.5.1, 7.1, and 7.1.1, and the Mac OS 7.5.x System Enabler required by the Power Macintosh 8100/100 and later.

Could you be using the Sony Control-L and Control-C interface? They are similar to VISCA, and can be used with Sony's V-Box to make a consumer-grade VCR capable of device control.

Sounds like you might be running into problems reading & understanding the timecoding that is being fed from the camera.

The standards that may be being used are: Society of Motion Picture and Television Engineers(SMPTE), the European Broadcasting Union (EBU), or Sony's RC timecode.  Most likely you are running into one of the 2 latter standards.

Timecode identifies the duration of a video clip, or its starting and ending points. Timecode enables video editors to locate frames accurately, and to synchronize picture and audio elements, or frame-accurate synchronization. SMPTE timecode identifies each frame with a unique address in the "hours:minutes:seconds:frames" form. SMPTE timecode can be Longitudinal Timecode (LTC), which is recorded in the second audio track of a video tape, or can be  Vertical Interval Timecode (VITC), which is recorded in the vertical space between frames.

There are several SMPTE timecode standards that are used with different frame rates. Since the SMPTE timecode for National Television Standards Committee (NTSC) video assumes a frame
rate of 30 frames per second (fps), even though the actual NTSC standard is 29.97 fps, there is a 0.1 percent discrepancy between real playing time and the timecode's duration measurement. The
drop-frame format, developed to address this discrepancy, drops two frame counts (i.e., actual frames are not dropped) from the count every minute, for 9 out of 10 minutes. The nondrop-frame
timecode ignores this discrepancy and is not duration accurate.

While SMPTE is the standard timecode used in North America, EBU is the standard timecode used in Europe. EBU is based on PAL or SECAM video signals which have a playback rate of 25 fps, and is a nondrop-frame standard only.

I will post this as a comment to encourage more input from other experts, but if this serves to answer your question I will post it as such.

Hope this helps!

Joel R. Helgeson

*I have worked for several years as the MIS of a Multimedia Production Studio.
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by:jrhelgeson
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Check out the TAO Editizer, I just remembered it.
I think it sounds like you are trying to do the same thing this does.  Check it out.

Just perform a search for "TAO Editizer" on infoseek, you'll find plenty of information.

jr
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by:jrhelgeson
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Just kidding!
The address for TAO systems is:

http://www.taosys.com

jr
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by:jrhelgeson
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mitrakis,
Have I helped any?  Let me know.
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by:mitrakis
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Thanks for your efforts.

Yep. All camera functions are available in my app.
You can use it local, in networks and soon the cam will be controllable via internet.

Anyway, this isn't the answer I expected =;-)

I've had problems to distinguish the answers sent from the camera on certain commands.
It is regrettable that this is due to the numerous mistakes in SONYs service manual concerning the communication protocol.

E.G.:
The complete command isn't sent, when the microcontroller STARTS to execute the command.

Inquiring the pan/tilt status after "power on", it doesn't return "normal function". (status is "moving failed" !)

These, and many other mistakes have made a successful work nearly impossible.
SONY wasn't able to help me out.

So I decided to connect a protocol analyzer from Hewlett Packard to.

Aha...
Everything was clear now !
And what have we learned ?

Never trust service manuals from SONY.


Oops...very long story...

Please let me grade your answer jrhelgeson.

-Stavi-

P.S.:
Every answer in experts exchange is worth a good grade.
Believe me =:-)
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jrhelgeson earned 150 total points
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Thank you very much!
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