The Louth Video Disk Communications Protocol, which is defined by Louth Automation, provides full-featured control of the VCP-Recorder using RS-232, RS-422, and TCP/IP. The VCP-Recorder's Louth processor supports back-to-back play and record (subject to restrictions imposed by the video I/O port capabilities) and archival management.
This chapter provides a step-by-step description of installing Louth in the following sections:
At the time of this writing, all Louth Video Disk Communications Protocol commands defined as of the 2/22/95 protocol revision are supported except for the following:
Local Disable Local Enable Video Compression Rate Audio Sample Rate Audio Compression Rate Audio IN Level Audio OUT Level Video Compression Parameters Select Output Select Input Record Mode SC Adjust Horizontal Position Adjust Compression Settings Request |
An automation controller is connected to a VCP-Recorder server using one or two serial ports per video port to be controlled. If the VCP-Recorder server supports simultaneous play and recording, two serial port connections are required if you want to be able to play and record at the same time.
Origin/DIVO and O2/O2Video support simultaneous playing and recording. Vela is playback only.
O2 serial ports run only in RS-232 mode. Consequently, to connect the Louth ADC-100 automation controller to the serial ports of the O2, you do one of the following:
Insert a 422/232 protocol converter between the Louth and the O2.
Use a special cable that uses the A (negative) and ground line from the RS-422 to provide a RS-232-compatible connection.
The Origin/Onyx2 serial ports can run in either RS-232 or RS-422 mode. The configuration file (louth.conf) specifies which mode to use.
See the serial(7) man page for information about the RS-232 and RS-422 ports.
There are two steps to configure the Louth ADC-100 automation controller:
On the Louth ADC-100, configure the VCP-Recorder system as a standard video disk. Table 2-1 shows how to specify the device parameters for the video disk.,
Table 2-1. Louth Device Parameters
Device Parameter | Setting |
|---|---|
AUDIO/VIDEO SWITCHING DATA | All zero |
DEVICE NAME | User-specified |
VIDEO INPUT PORT IN DISK | Video port to use for recording |
VIDEO OUTPUT PORT IN DISK | Video port to use for playing |
REPORT DISK SPECIFIC WARNINGS | Enabled |
STOP DISK PLAY/RECORD ON INIT | Enabled |
ENABLE SEGMENT PLAY/RECORD WITHIN ID | Enabled |
UPDATE EVENT DURATIONS FROM DISK | Enabled |
CONFIGURE INSTANT PLAY PREROLLS | Enabled, 0 seconds 4 frames |
CONFIGURE DISK PREROLLS | 3 frames |
NUMBER (=) OF FRAMES TO SEND PLAY EARLY | 3 frames |
ENABLE BACK TO BACK PLAY | Enabled |
DISK PORT IS AIR PROTECTED | As appropriate |
MODIFY IDS FOR EVENTS WITH SEGMENTS | As desired |
ENABLE RECORDING OF RECORD EVENTS | As appropriate |
ENABLE BACK TO BACK RECORD | Enabled |
RECORDING QUALIFIERS | As appropriate |
REPORT ITEMS AUTOMATICALLY DELETED OR RECORDED | As desired |
DELETE ITEMS AUTOMATICALLY RECORDED FROM DISK AFTER PLAY OUT | Usually disabled |
AUTOMATICALLY DELETE FROM DISK WHEN FULL | As desired |
DISK SPACE TO KEEP FREE (MINUTES) | As desired |
DISK HAS ARCHIVE | Enabled if MediaHub available |
BACKUP PLAY FROM ARCHIVE SUPPORTED | Disabled |
CLOSE DISK PORT WHEN NOT IN USE | Disabled |
DISK SERIAL COMM. PORT NUMBER OF SAME VID DISK | As appropriate |
CACHE RECORD DISK SERIAL COMM. PORT NUMBER | 0 |
The port number specified in the Louth device parameters corresponds to a port-number-to-port-name mapping in the Louth configuration file (louth.conf).
To each controlled video port, you must add a “signal” configuration line which specifies how to map port numbers to port names. For example, to specify that video port 1 corresponds to the video port known as DIVO_4, add the following line:
signal 1 DIVO_4 |
Each video port configured on the Louth system needs a similar signal line.
To configure the serial ports used by the Louth ADC-100 automation controller, edit the /usr/vtr/config/louth.conf file on the VCP-Recorder server. For each serial connection, add the following line to this file:
control type serial_port speed [parity] video_por frame_rate preroll |
where
type is one of the following:
rs232 for a RS-232 control connection.
rs422 for a RS-422 control connection. The RS-422 connection is available on Origin and Onyx2 servers, only.
serial_port is the serial port number (for example, 1 or 2).
For example, serial port 2, which may be referred to as tty2 in the hardware inventory (see hinv(1M)) or as /dev/ttyd2 by some software programs, is specified simply by the number 2.
speed is the speed of the connection. The speed must be 38400.
parity is one of the following:
0, indicating no parity
1, indicating odd parity
2, indicating even parity
The parity must be specified as odd as required by the Louth protocol.
 | Note: Two serial port connections are required if you want to be able to play and record simultaneously. In this case, you must add two lines to the /usr/vtr/config/louth.conf file, one for each port. |
video_port specifies the default video port number to be controlled by this control port.
A `-' may be used to specify that there is no default port. Otherwise, the numbered port specified here is automatically opened when the system is initialized and must match the port number configured in the DEVICE PARAMETERS for the control port on the Louth system.
frame_rate specifies the frame rate to be used when converting between HH:MM:SS:FF and frame numbers.
This should match the frame rate of the media being played or recorded by the port.
preroll specifies the number of frames of “disk preroll” used and must match the value configured in the DEVICE PARAMETERS for the control port on the Louth system.
“Disk preroll” is how far in advance the control system sends commands to the VCP-Recorder. Normally, the control system tells the VCP-Recorder protocol processor what value has been configured, but occasionally this value is delayed. Specifying the value in the Louth configuration file on the VCP-Recorder ensures that the correct value is always used.
The following example defines an RS-232 control connection that uses serial port 2 and specifies odd parity:
control rs422 2 38400 1 1 29.97 3 |
Defines control port using RS-422 serial protocol on serial port tty2. The standard bit rate of 38400 and odd parity are used. The default video port is port 1 with a frame rate of 29.97 frames/sec, and there are 3 frames of disk preroll.