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Video Installation and Troubleshooting for SGI Visual Workstation 320/540
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1. Software Prerequisites

Following software versions are required to succesfully use video output on 
the SGI Visual Workstations 320 and 540:

1.1  viz Version 2.0 Patchlevel 8 and above

    Support for video output is not included in viz version 
    below patchlevel 8.


1.2  SGI Digital Media Software 4.1.1

    This software is available from several locations:

    - from the viz installation CD 
            file: sgi/SGIDMediaSW4_1_1/SGIDMediaSW4_1_1.exe
    - from the SGI Support web site 
            http://support.sgi.com
    - from the peak ftp server 
            ftp@ftp.peak.co.at:/PATCHES/SGI_320_540_NT/VIDEO/SGIDMediaSW4_1_1.exe

    Please read the release notes for installations instructions.


1.3  SGI Digital Media Overlay Patch 4.1.2

    WARNING: DIGITAL MEDIA PATCH 4.1.1 MUST BE INSTALLED BEFORE THE 4.1.2 
             OVERLAY IS APPLIED. APPLYING THIS OVERLAY TO ANY OTHER DIGITAL 
             MEDIA SOFTWARE VERSION MAY RESULT IN UNSTABLE, NONFUNCTIONAL, 
             OR AN OTHERWISE UNUSABLE DIGITAL MEDIA ENVIRONMENT.

    Installation Instructions

    A. Uncompress the archive file

    B. Close all your applications.

    C. From an NT command line shell (cmd.exe), stop the SGI digital
       media services. Issue the following commands:

       C> net stop sgidmsvc
       C> net stop sgijack
       C> net stop sgilivid

       If you are unable to stop any of these services, check to see
       that there are no applications using the software.

    D. Execute the ovinstall.cmd script which will copy files to the
       appropriate destinations.

    E. Doublecheck that all files were copied during the ovinstall
       process. In case of any errors, please make sure that the
       corresponding file has write permission and repeat step D.
       
    F. Reboot the system.

This overlay patch is available from several locations:

    - from the viz installation CD 
            file: sgi/SGIDMediaSW4_1_1/SGIDMediaSW4_1_2.zip
    - from the peak ftp server 
            ftp@ftp.peak.co.at:/PATCHES/SGI_320_540_NT/VIDEO/SGIDMediaSW4_1_2.zip


2. Supported Video Modes

viz supports two different video modes:

2.1. Standard Mode (viz 2.0 Patchlevel 8 and above)
    
    The video output behaviour is similar to the video output on the ONYX.
    Everything seen on the computer monitor is directly going to video.        
    It requires the graphics to be genlocked to the same source as the 
    video output jacks and running on the same frequency (50/60 Hz)

    Advantage: This mode provides the smallest possible video delay. 

    Disadvantage: If an animation is loosing frames by any reason
            (graphics overload, machine busy on other processes),
            also the video output will stutter.  
    
    
2.2. Video Synchronous Mode (viz 2.0 Patchlevel 10 and above)
    
    Here we introduce a buffering scheme running in sync with
    the video output signal, i.e. the rendering is synchronized
    to the video output.

    Advantage: depending on the size of the buffer, viz will
            be much more tolerant towards rendering interruptions 
            by external commands or other processes running on the
            machine. As certain frames are still available for
            output during such circumstances, the video will 
            continue to run smoothly.

    Disadvantage: depending on the size of the buffer, we are
            introducing a much higher delay between the start
            of an animation and the result being visible on the video.
                


3. Configuration

Following configuration steps are necessary in order to output video
depending on the desired mode:

3.1  Standard Mode

    - The computer monitor must be set to 50Hz (PAL) or 60Hz (NTSC) using
      the standard display control panel.
      
    - In the viz configuration, go to the section 'Output Screen Layouts'
      and select the desired video format (PAL/NTSC Analog for SGI VW 320,
      PAL/NTSC Digital for SGI VW 540 with Digital Video Option) and the 
      required output format (RGBA on SGI VW 540 only)
      
    - Using the video control panel, select the required genlock source
      for the video output jacks (in the Timing tab). If you use an SGI
      VW 540 with digital video option, please make sure that both
      digital output jacks are set to the same genlock source and that
      the 'Serial Digital 1 Out' jack is set to 'Jack carries Program' 
      and the 'Serial Digital 2 Out' jack is set to 'Jack carries Alpha'
      (in the corresponding Misc tabs).
      
    - If you want to use a video input jack as the genlock reference,
      please use the 'Graphics Display Framelock ...' entry in the 
      file menu of the video control panel to select the appropriate
      input jack. Note: there is no entry for Reference-In; if you need
      to genlock the graphics to the Reference-In jack, you need to
      specify this as a startup option during viz startup (see later).
      Note also that you should never use a video output jack as a graphics 
      framelock source because this will result in undefined system behaviour
      if there is not signal output to the appropriate jack, e.g. if viz
      is not running.
      
3.2. Video Synchronous Mode

    - The computer monitor may run at any refresh rate, but anyway
      it is recommended to set it to 50Hz (PAL) or 60Hz (NTSC)
      in order to see animations smoothly also on the computer screen.
      
    - In the viz configuration, go to the section 'Output Screen Layouts'
      and select the desired video format (PAL/NTSC Analog for SGI VW 320,
      PAL/NTSC Digital for SGI VW 540 with Digital Video Option) and the 
      required output format (RGBA on SGI VW 540 only)
      
    - Using the video control panel, select the required genlock source
      for the video output jacks (in the Timing tab). If you use an SGI
      VW 540 with digital video option, please make sure that both
      digital output jacks are set to the same genlock source and that
      the 'Serial Digital 1 Out' jack is set to 'Jack carries Program' 
      and the 'Serial Digital 2 Out' jack is set to 'Jack carries Alpha'
      (in the corresponding Misc tabs).

    - you do not need to framelock the graphics to a reference signal,
      but anyway if you do so, it does not matter.
      

4. Running viz

There are several command line parameters for starting up viz with
video output on the SGI VW 320 and 540 (not required for video-in only):

-V      ... use videoout  (both modes)
-G      ... genlock graphics to reference-in jack
            (not needed in video synchronous mode)
-S ##   ... use video synchronous mode
            ## ... buffer size in frames (2 <= ## <= 50)
            
Examples:

- Standard mode

    command     : viz -V -G  
    description : reference-in jack is connected to a analog sync source

    
- Video Synchronous mode

    command     : viz -V -S 25
    description : video out is running with 25 frames (1 sec.) delay
    

5. Known bugs and caveats

There are no known bugs.
Using RGBA is slightly slower then using RGB.

