Video Server Technology (VST) applications routinely open a TCP/IP connection to a host running VST on the MVCP port, normally 5250. The application sends MVCP commands to control VST.

The port value is set in the file /usr/vtr/config/control-in.conf. For example, to set the port to 5250, use the following line in the file:

mvcp tcp 5250

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Note: Do not change the port value from 5250 unless it is absolutely necessary.

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You can, however, manually control VST by opening a telnet connection to a host running VST and then issuing MVCP commands to control it. For example:

152% telnet server 5250
Trying 130.62.156.178...
Connected to server.
Escape character is `^]'
100 VTR Ready

To exit the telnet session, type the following command:

BYE

A unit is a virtual VTR. It can play and record video and audio just like a VTR.

The UADD command, which you can use to create units, returns the name of the unit as shown in the following example:

% UADD MFCODEC_0 * SHAR
202 OK
U1

U1, in this case, controls the MFCODEC_0 video board, which includes both an input video port and an output video port.

UCLS unit-name

Multiple Connections to a Unit

Once a unit has been created, it can be controlled by a number of MVCP connections by opening it:

UOPN unit-name

When multiple MVCP connections are made to one unit, the unit is not deleted until all of the connections have deleted it.

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Caution: Opening a unit owned by a Sony or VDCP port using MVCP commands (for example, UOPN) causes unpredictable behavior.

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To load and unload a clip into a unit, use the following commands, respectively:

LOAD unit-name clip-name OUT CRTE


UNLD unit-name

The OUT option means that the clip, clip-name, can only be played, not recorded onto. Other valid values include IN, which means the clip will be recorded onto, and BOTH, which means the clip can be played or recorded onto.

CRTE creates the clip. Without a CRTE argument, the clip does not exist in the clip cache.

If you do not know the name of a clip, you can list all of the clips by issuing the clip list command:

CLS

The in and out edit points specify where the source video is to begin and end playing, and where the beginning and ending recording points are on the record deck, usually the SGI Media Server.

When a clip is played, by default the edit in point is used as the starting point for play.

To set edit points, use the CEDP command:

CEDP clip-name in-point out-point

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Note: The media outside of the in and out points is not actually erased; it will not be played.

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You can play and record on units without cueing them. There is, however, a good chance that the beginning of the playing or recording will not be clean; the frame count might be off by several frames or the audio might be garbled.

You can avoid these problems by cueing the units for playing or recording.

To cue a clip for playback, enter the following:

CUE unit-name

To cue a clip for recording, enter the following:

CUER unit-name

The following optional CUE and CUER arguments specify the segment of media to play, the direction of play, and how many times the segment is played:

CUE unit-name in-point out-point direction number-of-passes

Values for direction include FWD (forward), BWK (backward), F/B (play forward and then play backwards), and B/F (play backward and then play forward).

There is a variety of sequencing operations you can use, including the following:

For information about command sequencing, see the mvcp(5) man page.

To play a clip, use the following procedure:

You can also play the clip in other modes, such as the following:

For more information about the arguments for each of these commands, see the mvcp(5) man page.

VST c onfiguration variables are called controls. The two major categories of controls are the following:

To set or get the configuration variables for a specific unit, you have to select the subset of controls you want to set by using STOR (storage) or MED (media). For example:

SET unit-name MED vtr.media.video.input.compression.type dvcpro
GET unit-name MED vtr.media.video.output.*

These commands set the video compression type to DVCPRO 25 and return all of the video output controls for the specified unit.

To display the configuration of video and deck control ports, use the port list command:

PLS

To identify which audio port to use by a given MFCODEC unit, use the SET command for a unit as shown in the following:

SET unit-name MED vtr.media.audio.input.channel_map.channel_pair “1231” SET unit-name MED vtr.media.audio.input.channel_map.source “EEEA”
SET unit-name MED vtr.media.audio.input.channels 4

Alternately, you can configure a unit in /usr/vtr/config/device-defaults/*. For example, in MFCODEC_1 you would enter:

vtr.media.audio.input.channel_map.channel_pair “1231”
vtr.media.audio.input.channel_map.source “EEEA”
vtr.media.audio.input.channels 4

To record video using the SGI Media Server, you must set the compression type using vtr.media.video.input.compression.type. The valid values follow:

To record a clip, use the following procedure:

You can edit clips on two levels of granularity:

You can use the MVCP SET command with the following controls to display your company logo, or any image, when the video port is not playing a clip:

vtr.media.output.idle_mode idle-mode
vtr.media.video.output.image.type image-type
vtr.media.video.output.image.name image-name

Place image files in directory /usr/vtr/data/images.

The commands to execute a playlist can be performed over a single MVCP control connection. Some control implementations may find it easier to use a unique MVCP control connection for each unit. The commands and the order in which they are sent is identical in either case.

When executing a play list, you can display the state of the list execution. Using MVCP this can be accomplished by polling, but a more efficient solution is to utilize unit monitoring. Unit monitoring provides asynchronous events describing the change in state of a unit, such as execution state, loaded clips, or timecode location. Details of unit monitoring can be found in the section “Monitoring”. Typically, a separate MVCP connection will be initiated for monitoring.

In the play list algorithm in the preceding paragraph, a unit monitor could be started after the units are created to trace unit execution. This would allow a control application to trace which clip was being played and the timecode location of the unit in the clip. Note that the information provided by unit monitoring describes the unit state and locations. The actual video frame timecode leaving the server port will be some fixed number of frames behind that time due to codec delays. This delay is format-dependent and can be found in Table 9-1. The table shows the difference between the time reported by the unit and the actual video frame at the server port at that time. For instance, with DVCPRO 25 on record the unit status reports three frames behind the frame on the input of the server, and on play the unit status reports seven frames ahead of the frame on the server output port.

This section explains the following ways to monitor the system:

USTA unit-name


ULS

MON [unit-name] [/ event-type]

STLS [component-name [statistics-type]]

STLS * *

STST [component-name [statistics-type]]

STST *MFCODEC*

ERR 

UERR unit-name