Video File Source

How to use the Video File Source robot skill

Video File Source plays video files as a camera in ARCx. Play one recording or a whole playlist, once or on repeat, and every vision skill (Face Tracking, Color Tracking, Glyph Recognition, OpenCV Filter Flow and the rest) sees it exactly as it would a live camera. It is the easy way to tune a detector on the same footage over and over, demonstrate a project without the robot's camera, or run a robot's vision against recordings.

The videos can be files on the ARCx computer's drive, or embedded in the project file so the project carries them to another computer.

The video source is named after the robot skill's window title, so rename the window to give it a meaningful name, and add the skill more than once for more than one source.

The window

Part	What it does
Previous	Back to the start of the video, or within its first 3 seconds, to the video before it.
Play / Pause	Play, or pause on the current picture. A paused video keeps sending its picture, so the vision skills keep seeing it.
Stop	Stops playing. The video source stops sending pictures.
Next	The next video in the playlist.
Repeat	Click to step through Repeat off, Repeat one, Repeat all and Shuffle.
Speed	Playback speed, from a quarter to eight times normal.
Playlist	The videos in the playlist. Click one to play it. Embedded videos have a box icon; a missing file is greyed out.
Status line	Which video is playing, its picture size and frame rate.
Seek bar	The time into the video and its length. Drag to jump to another time.
Log	Videos started, skipped and finished.

The playlist

The playlist is set up in the configuration. Each video can be switched off without removing it, renamed (scripts refer to videos by name), and given a start and end time to play only part of it.

There are three ways to add videos.

• Type the full path of a video on the ARCx computer and press Add.
• Browse lists the folders and videos on the ARCx computer, which is not necessarily the computer the browser is on. Tick videos and add them, or add every video in a folder.
• Upload & embed sends videos from the computer the browser is on and embeds them in the project.

A video on the drive can also be embedded afterwards with the box button on its row, which stores a copy in the project.

Any format FFmpeg reads plays: MP4, MKV, WebM, MOV, AVI, WMV, FLV, MPEG, TS, 3GP and more.

Drive or embedded

	Drive	Embedded
Where the video is	A file on the ARCx computer	Inside the project file
Project file size	Unchanged	Grows by the size of the video
Opening the project on another computer	The file must be at the same path there	Plays as it is
Changing the video	Replace the file	Upload it again

Embedded videos are stored as they are, without compressing them again, beside the skill's settings in the project file. While the project is open each one is copied to a temporary folder that the player reads from; the folder is deleted when the skill is removed or ARCx closes. An AI reading the skill's configuration sees the playlist and the names and sizes of the embedded videos, never the video bytes, and can change the playlist and settings without disturbing them.

Uploads and embeds are copied into the skill straight away but only kept if the configuration is saved; Cancel throws them away.

Repeat and timing

Repeat	What happens when a video ends
Off	The next video plays; after the last one the playlist has finished.
Repeat one	The same video plays again.
Repeat all	The next video plays, and after the last one the first.
Shuffle	A random video plays. Every video plays once before any plays again, and the order is shuffled again each time round.

When the playlist has finished (Repeat off), the When Finished setting either stops the video source or keeps sending the last picture, so the vision skills still have something to look at. The When Finished script runs either way.

Videos play in real time, at their own frame rate times the speed. When the vision skills take longer than a frame, the frames that are already late are stepped over without being decoded, so a recording keeps its real timing instead of turning into slow motion. Max FPS limits how many pictures a second reach the vision skills, which saves CPU on high frame rate videos.

Configuration

Playback

Setting	What it does
Repeat	Off, Repeat one, Repeat all or Shuffle.
When Finished	With Repeat off, stop or hold the last picture after the last video.
Speed	1 is normal speed, 0.5 half, 2 double (0.1 to 8).
Play With Project	Start playing when the project opens.
Max FPS	The most pictures a second passed on to the vision skills. 0 passes every frame.
Window Frame Delay (ms)	How often this window's picture is refreshed. It does not change what the vision skills receive.

Scripts and variables

When A Video Starts runs each time a video starts playing, and When Finished runs when the playlist has finished with Repeat off.

The skill keeps these global variables, named after the Variable Prefix (VideoFile by default). Empty the prefix to set no variables, and give each copy of the skill its own prefix when a project has more than one.

Variable	What it holds
$VideoFileName	The name of the video playing.
$VideoFileIndex	Which video is playing, counting from 1.
$VideoFileCount	How many videos are in the playlist.
$VideoFilePosition	How far into the video it is, in seconds.
$VideoFileDuration	How long the video is, in seconds.
$VideoFileIsPlaying	true while a video is playing (not paused, stopped or finished).

Scripts can also play, pause, seek, change the speed and repeat mode, jump to a video by name or number, and add files to the playlist with the skill's control commands, which are listed in the script editor's ControlCommand view.

Good to know

Videos play as pictures only; their sound is not played. FFmpeg comes with ARCx on Windows. On Linux and macOS, playing video files needs an OpenCV built with FFmpeg.

Control Commands for the Video File Source robot skill

There are Control Commands available for this robot skill which allows the skill to be controlled programmatically from scripts or other robot skills. These commands enable you to automate actions, respond to sensor inputs, and integrate the robot skill with other systems or custom interfaces. If you're new to the concept of Control Commands, we have a comprehensive manual available here that explains how to use them, provides examples to get you started and make the most of this powerful feature.

Control Command Manual

This robot skill has 19 control commands, listed below. Send them from a JavaScript or Python script, from Blockly, or from another robot skill.

The first value is always the window title, which is the name in the title bar of the robot skill on your workspace. It starts out as Video File Source, which is what every example below uses. If you rename the robot skill, or add a second copy of it to the project, use the title as it appears on that window instead.

ControlCommand() can be shortened to CC(), and both spellings work in JavaScript and in Python. The examples are JavaScript; Python is the same call, except that true and false are written True and False.

AddFile

Add a video file on the ARCx computer's drive to the end of the playlist, by its full path.

Syntax

ControlCommand("Video File Source", "AddFile", (String)path)

Parameters

#	Name	Type	What to pass
1	path	Text	Your text, in quotes

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "AddFile", "path");

ClearPlaylist

Remove every video from the playlist, including embedded ones.

Syntax

ControlCommand("Video File Source", "ClearPlaylist")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "ClearPlaylist");

GetCurrentItem

The name of the video playing, or empty.

Syntax

ControlCommand("Video File Source", "GetCurrentItem")

Returns: String

Example

var result = ControlCommand("Video File Source", "GetCurrentItem");

GetDuration

How long the video playing is, in seconds (0 when unknown).

Syntax

ControlCommand("Video File Source", "GetDuration")

Returns: Double [5.0e324 to 1.7e308]

Example

var result = ControlCommand("Video File Source", "GetDuration");

GetPlaylist

The names of the videos in the playlist, in order.

Syntax

ControlCommand("Video File Source", "GetPlaylist")

Returns: Array of String

Example

var result = ControlCommand("Video File Source", "GetPlaylist");

GetPosition

How far into the video it is, in seconds.

Syntax

ControlCommand("Video File Source", "GetPosition")

Returns: Double [5.0e324 to 1.7e308]

Example

var result = ControlCommand("Video File Source", "GetPosition");

GetStatus

One line saying what the player is doing.

Syntax

ControlCommand("Video File Source", "GetStatus")

Returns: String

Example

var result = ControlCommand("Video File Source", "GetStatus");

IsPlaying

Whether a video is playing (not paused, stopped or finished).

Syntax

ControlCommand("Video File Source", "IsPlaying")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "IsPlaying");

Next

Play the next video of the playlist.

Syntax

ControlCommand("Video File Source", "Next")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "Next");

Pause

Pause. The paused picture is still sent, so the vision skills keep seeing it.

Syntax

ControlCommand("Video File Source", "Pause")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "Pause");

Play

Play. Resumes when paused, starts the playlist when stopped or finished.

Syntax

ControlCommand("Video File Source", "Play")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "Play");

PlayItem

Play a video of the playlist, by its name or its number counting from 1.

Syntax

ControlCommand("Video File Source", "PlayItem", (String)nameOrNumber)

Parameters

#	Name	Type	What to pass
1	nameOrNumber	Text	Your text, in quotes

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "PlayItem", "nameOrNumber");

Previous

Go back to the start of this video, or within its first 3 seconds to the video before it.

Syntax

ControlCommand("Video File Source", "Previous")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "Previous");

Seek

Jump to a time in the video playing, in seconds.

Syntax

ControlCommand("Video File Source", "Seek", (Number)seconds)

Parameters

#	Name	Type	What to pass
1	seconds	Number	A number, without quotes

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "Seek", 0);

SetRepeat

Set what happens when a video ends: Off, RepeatOne, RepeatAll or Shuffle.

Syntax

ControlCommand("Video File Source", "SetRepeat", (String)mode)

Parameters

#	Name	Type	What to pass
1	mode	Text	Your text, in quotes

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "SetRepeat", "mode");

SetSpeed

Set the playback speed: 1 is normal, 0.5 half, 2 double (0.1 to 8).

Syntax

ControlCommand("Video File Source", "SetSpeed", (Number)speed)

Parameters

#	Name	Type	What to pass
1	speed	Number	A number, without quotes

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "SetSpeed", 0);

ShowOriginal

Show the original video in the window.

Syntax

ControlCommand("Video File Source", "ShowOriginal")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "ShowOriginal");

ShowProcessed

Show the processed video, with the vision skills' boxes and labels, in the window.

Syntax

ControlCommand("Video File Source", "ShowProcessed")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "ShowProcessed");

Stop

Stop playing. The video source stops sending pictures.

Syntax

ControlCommand("Video File Source", "Stop")

Returns: Boolean [true or false]

Example

var result = ControlCommand("Video File Source", "Stop");

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This list is read out of the robot skill itself each time its package is uploaded, so it matches the published version (v2).