Abekas A-60 Framestore

A60

A60MENU

Usage

The Abekas A-60 can be controlled by either the Remote Console or by logging into it via rsh. It is a digital framestore that can load 750 frames, then play those frames back at high speed so that they can be recorded in real time. Unfortunately, it takes ~20 minutes to load up those frames through a slow Ethernet connection. Thus, its use is deprecated now that we have the new nonlinear editing setup on both the SGI with Premiere and on the PC with Avid MCXpress.

The A-60 can be controlled either via remote login (see below) or by the remote unit pictured above. The remote unit works in conjunction with a visual display, which should be routed to one of the monitors if you want to see what's going on. See the A60 manual for details on how to use the console.

Connection

The A60 is physically located in the machine room.

The A60 is directly connected to the A20 via a parallel SDI cable, since that's how they used to be connected and we had the cable lying around. The main SDI backbone is serial, so they each have a parallel->serial converter box in front of the output and a serial->parallel converter in front of the input. Note that parallel SDI cable lengths are extremely limited, so those converter boxes can't move far away from the Abekas boxes. They're all located in the same rack in the machine room.

At one point in the past the A20-A60 connection was the only way to get from streaming video to frames on disk. Now we have more convenient ways to do this, with multiple transcoders and the digitizing capabilities of the nonlinear editing systems which are directly connected to the main filesystem.

Additional notes

Logging in remotely

To use the A-60 through the Ethernet, you can rcp (or rsh or telnet) to it from crossbar or moviola. If you try this from another machine it will probably hang. See Troubleshooting section for details.
You can either type "rsh a60" to start an interactive session, "rsh a60 < scriptfile" to have it read commands from a file, or "rsh a60 command" to execute a single command.
The A-60 accepts several commands, including "goto framenum", "play", and "stop". See the manual for the full list.

Frames must be converted to YUV format and rcp'd over to the A60 to load it. The program "toyuv" converts from SGI to YUV image format. The sequence below will convert and load two frames into the first two slots on the A-60.
```
% toyuv myfile0.rgb /tmp/myfile.yuv
% rcp /tmp/myfile.yuv a60:0
% toyuv myfile1.rgb /tmp/myfile.yuv
% rcp /tmp/myfile.yuv a60:1
```

On the A-60, a filename is simply an integer between 0 and 759. If you have a whole sequence of frames to copy over, you could write a little perl script with an incrementing frame counter to make your life easier.

An example of a simple script is at ~beers/bin/image/rgb2ab60 or ~munzner/bin/toa60.perl. A complex script that involves fades and uses segments on the A-60 is at ~munzner/bin/ab.perl. Again, such shenanigans are now deprecated since we have real nonlinear editing capabilities.

Troubleshooting

There are many manuals that say "Abekas". Make sure you're using the A-60 ones instead of the A-20 ones. You probably don't need to look at the giant technical reference manual. The smaller one tells you how to use the console and the Ethernet interface.

To recover from a hang, type
```
% rsh a60 reset
```
from a machine that is known to work (crossbar, moviola, or anything running Irix 5.3). Hangs can happen if you try rsh-ing from a nontweaked Irix 6.x machine, or if you twiddle the ball on the remote console while rcp-ing frames, or do something else that confuses it.
The Abekas is old enough that it's confused by an MTU (large packet size) optimization that many OS's now do by default. Here's how to configure an Irix 6.x machine so that this will work. Since this leads to performance decreases, John has only configured crossbar and moviola this way:
- Prior to Irix 6.5, there was line in /var/sysgen/master.d/bsd,
```
int tcp_mtudisc = 1;
```
  Change the 1 to 0, run autoconfig -f, and reboot.
- As of Irix 6.5, you can use systune(1) to view/change this parameter. When done with systune, the change is stored in /var/sysgen/stune

Return to Main Video Menu
videolab@graphics.stanford.edu
Last modified: Fri Jan 28 14:23:35 PST 2000