Playlist

Playlist	Prev	Next

Using the playlist

Description

Overview

The playlist features lets you specify a list of video clips that have to be played automatically one after the other.

There are 2 ways to use the playlist:
statically: you specify a static set of clips, then play this set of clip like it was a single clip (the trackbar moves across the whole set of clips)
dynamically: you can dynamically add/remove clips while the playlist is playing by invoking PlayList (pl_Add...). In this case the trackbar is active for the current clip being played.

- all the playlist actions are performed by using the Playlist function, detailed below.

- the playlist content can be retrieved by the GetPlaylist function, that returns a list of strings separated by CR/LF

- the current index in the playlist is returned by the PlaylistIndex property (if opened dynamically)

- when the end of the playlist is reached, the OnPlayerEndOfPlaylist event occurs.

- it is possible to know if the playlist is currently playing by testing IsPlaylistActive.

The Playlist function

The playlist function accepts 2 parameters:

- a first parameter that specify the action
- a 2nd parameter that specify the video clip (used only for pl_Add and pl_Remove).

The first parameter can take one of the following values:

pl_Add: adds the video clip (specified as 2nd parameter) to the playlist
pl_Remove: removes the video clip (specified as 2nd parameter) from the playlist
pl_Clear: clears the playlist
pl_Loop: enables the loop mode (the playlist restart from the beginning when the end is reached)
pl_NoLoop: disables the loop mode
pl_Play: starts playing the playlist
pl_Stop: stops playing the playlist after the end of the current clip
pl_Next: starts playing the next clip (immediately)
pl_Previous: starts playing the previous clip (immediately)
pl_SortAlpha: sorts the playlist in the alphabetical order
pl_SortRevAlpha: sorts the playlist in the reverse alphabetical order
pl_Random: enable the "random" mode: the clips will be played in a random order.
pl_Sequential: disables the "random" mode: the clips will be played sequentially.
pl_SpecifyPositions: let specify a start position and/or a stop position

Remark: while the static playlist is playing, you can't control it with the playlist settings anymore, it behaves like a single video clip.

Building the playlist

Simply invoke Playlist (pl_Add, "... path of the video clip...") as many times as required. Pass and empty string for the "VideoClip" parameter when it is not required (it is required only for pl_Add and pl_Remove). E.g.:

videograbber.Playlist (pl_Clear, '')
videograbber.Playlist (pl_Add, 'vg000004.avi')
videograbber.Playlist (pl_Add, 'vg000002.avi')
videograbber.Playlist (pl_Add, 'StaticImage1.BMP')
videograbber.Playlist (pl_Add, 'vg000003.avi')
videograbber.Playlist (pl_Add, 'vg000005.avi')
videograbber.Playlist (pl_Add, 'vg000001.avi')
videograbber.Playlist (pl_Add, 'StaticImage2.JPG')

Starting the dynamic playlist

Be sure to set all the required options (like pl_Loop, pl_SortAlpha or pl_Random), then invoke pl_Play. E.g.:

videograbber.Playlist (pl_Clear, '')
videograbber.Playlist (pl_Add, 'vg000004.avi')
videograbber.Playlist (pl_Add, 'vg000002.avi')
videograbber.PlayerDuration = 50000000 // specifies 5 seconds of display time for StaticImage1.BMP
videograbber.Playlist (pl_Add, 'StaticImage1.BMP');
videograbber.Playlist (pl_Add, 'vg000003.avi')
videograbber.Playlist (pl_Add, 'vg000005.avi')
videograbber.Playlist (pl_Add, 'vg000001.avi')
videograbber.PlayerDuration = 80000000 // specifies 8 seconds of display time for StaticImage2.JPG
videograbber.Playlist (pl_Add, 'StaticImage2.JPG')
videograbber.PlaylistIndex := 0
videograbber.Playlist (pl_SortAlpha, '')
videograbber.Playlist (pl_Loop, '')
videograbber.Playlist (pl_Random, '')
videograbber.Playlist (pl_Play, '');

Starting the static playlist

videograbber.Playlist (pl_Clear, '');
videograbber.Playlist (pl_Add, 'vg000004.avi');
videograbber.Playlist (pl_Add, 'vg000002.avi');
videograbber.Playlist (pl_Add, 'vg000003.avi');
videograbber.Playlist (pl_Add, 'vg000005.avi');
videograbber.Playlist (pl_Add, 'vg000001.avi');
videograbber.PlayerFileName = 'PLAYLIST'
videograbber.OpenPlayer()

Specifying a custom video size and/or frame rate to the static playlist

By defaut the static playlist plays all the clips at the same video size (640x480) and at the same frame rate (29.97 fps)

- to customize the frame rate, set a FrameRate value > 0

- to customize the video size, invoke UseNearestVideoSize (width, height, false) before invoking OpenPlayer

E.g.:

...
VideoGrabber.PlayList (pl_Add, "vg0000006.avi")
VideoGrabber.PlayerFileName = 'PLAYLIST'
VideoGrabber.FrameRate = 25.0
VideoGrabber.UseNearestVideoSize (720, 480, false)
VideoGrabber.OpenPlayerPlayer()

You can later reset the video size by invoking:

UseNearestVideoSize (0, 0, false)

and the frame rate by setting:

FrameRate = 0

Pausing the playlist

Simply invoke PausePlayer.

Stopping the playlist

- to stop the playlist at the end of the current clip, invoke Playlist (pl_Stop)
- to close the playlist immediately, invoke ClosePlayer

specifying start/stop positions for each clip

Invoke VideoGrabber.PlayList (pl_SpecifyPositions,...) and immediately after OpenPlayerAtTimePositions or OpenPlayerAtFramePositions (this will not open the clips but just register the positions)

VideoGrabber.PlayList (pl_Add, 'myvideoclip1.wmv');
VideoGrabber.PlayList (pl_SpecifyPositions, 'myvideoclip1.wmv');
VideoGrabber.OpenPlayerAtTimePositions (50000000, 120000000, true, true);

VideoGrabber.PlayList (pl_Add, 'myvideoclip2.wmv');
VideoGrabber.PlayList (pl_SpecifyPositions, 'myvideoclip2.wmv');
VideoGrabber.OpenPlayerTimePositions (30000000, 130000000, true, true);

VideoGrabber.PlayerFileName := 'PLAYLIST';
VideoGrabber.Openplayer();

In this example the first clip will play 7 seconds (from 7 seconds to 12 seconds) and then the second will play 10 seconds (from 3 seconds to 13 seconds)
to let the clip play until the end specify -1 as stop position)

Using static images or animaged GIFs in the playlist

Static images (like BMP, JPG files) can be opened alternatively with video clips in the dynamic playlists.
To specify the display time for static images, assign the PlayerDuration with the desired value BEFORE the PlayList (pl_Add...) statement (the display time is expressed as 100ns units, e.g. 7 seconds = 70000000).

E.g.:

VideoGrabber.PlayerDuration = 30000000; // will set 3 seconds for myvideoclip1
VideoGrabber.PlayList (pl_Add, 'myvideoclip1.wmv');
VideoGrabber.PlayerDuration = 40000000; // will set 4 seconds for myvideoclip2
VideoGrabber.PlayList (pl_Add, 'myvideoclip2.wmv');
...
VideoGrabber.PlayList (pl_Play, "");