LiVES Multitrack Window - mini tutorial

The LiVES user interface consists of two parts: the clip editor which allows preparation of multiple clips, and is useful for VJ's; and the multitrack editor which brings those clips together, and is more useful for video artists.

The clip editor is well described in the excellent tutorial by Marco de la Cruz.
This guide is about the multitrack window.

There are currently two ways to enter multitrack mode in LiVES. The first is to record some events by pressing 'r' before playback, and then after playback, those events can be shown in the multitrack window.

The second way is to have some clips loaded and then press ctrl-m or menu Edit/Multitrack.

Here we will deal with the latter method.

[Note: If you see Tip: - this is for more advanced users, e.g. on second reading of this document.]

Screen Layout

Once you enter multitrack mode, you will see the screen is split vertically into 3 areas. At the top is the "manipulation area", below this is the "timeline area", and at the bottom is the "message area".

The manipulation area is split horizontally into three regions:
- the preview window
- the "polymorph" window
- the context window

as shown here:

Fig. 1: The manipulation area.

The preview window shows playback and effect previews.

The polymorph window, as its name suggests, changes depending on what you are doing. Its modes include:
- clip mode (as seen above) : shows all clips loaded in LiVES, and allows them to be dragged onto the timeline. You can enter this mode any time by pressing 'c' (or from the View menu)

- in/out mode : if you double click on a block, the polymorph window will go into in/out mode. You can adjust the start and end points of a block using the in/out spinbuttons. If a block is selected (by double clicking on it) then you can enter this mode by pressing 'i' (or from the View menu)

- effect mode : if the last action was to apply an effect, and that effect has parameters, then the polymorph window will go into effect mode. In this mode, you can set effect parameters and preview frames. Frame previews are shown in the preview window. You can return to this mode by editing an effect (TODO).

The context window shows information relevant to the current action. Look at this window if you are confused. It might help...maybe...

The timeline area contains the timeline header, which is a horizontal ruler marked in seconds. It has a cursor which scrolls during playback, or can be set by clicking in the timeline header. If you click and drag here, you can set a time region (see below).

It also contains the track area. Here you can see your video tracks and (TODO !) audio tracks.
Each track has a checkbox for "selected/unselected", then a name and a layer number, then a blank area which can be filled with video or (TODO !) audio.

Selected/unselected is used for setting the track part of a region (see below).

Layers go from layer 0 at the top, (the "front") downwards - towards the "back". Layer 0 is always the "front" layer, layer 1 is "behind" this, layer 2 "behind" that, etc. You can add layers at the front or back, literally as many as you like. Normally you will only see the front layer, unless you apply a transition or a compositor (see below).

Fig. 2: The timeline area.

At the top of the timeline area are two spinbuttons. These show the region start and end points (see below for more explanation of regions).

The message area is the same as in clip editing mode, and shows information about your actions. You can call up the entire message log from the View menu.

Fig. 3: the message area.

Inserting clips and applying an effect

You can insert a clip by dragging a clip from the polymorph window onto a timeline track. If the polymorph window is not in clip mode, you can press 'c' to get there. Drag a clip from the top and release it onto the timeline.

Tip: Alternately, you can use the keyboard. ctrl-page-up and ctrl-page-down will cycle through clips. ctrl-left and ctrl-right will move the timeline cursor. ctrl-up and ctrl-down can be used to change the current track. ctrl-i will insert the current clip at the current cursor position in the current track.

In standard insert mode, the insert point must be blank (i.e. free of other video). If the clip is too long, as many frames as possible will be inserted. In future there will be more types of insert mode (TODO).

If you have "snap" mode on, any inserted or moved clips will be moved as far left as possible. You can switch on "snap" mode from the menu bar. In future there may be different types of "snap" modes.

If you inserted a clip, you can always "undo" it from the Edit menu. Then switch on snap mode, and insert again.

You can also set the "mouse mode". We will come on to that later, for now, leave it as "move".


Fig. 4 mouse mode and snap mode.

Fig. 5 Selecting a clip.

Fig. 6 dragging to the timeline

Fig. 7 dropped on the timeline with "snap" on

When you have inserted a clip, it becomes a "block". Blocks are the smallest unit in the LiVES multitrack editor.
A block can vary from 1 frame to any number of frames. Currently, all frames in a block must come from the same clip.

Tip: There are two types of blocks in LiVES - ordered blocks and unordered blocks. Ordered blocks have incrementing frame numbers, and these are what you get if you insert a clip from the clip area. Unordered blocks have frame numbers which jump around. Unordered blocks can be produced by the event recorder. There is not yet much support for unordered blocks in LiVES, but there may be in the future.

Now we have inserted a block, we can apply an effect to it. First we must select the block by double clicking on it. If you do this, you will see the block gets marked with an "X" and the polymorph window will enter in/out mode.

Fig. 8 double clicking on a block selects it

Fig. 9 the polymorph window in in/out mode

With the polymorph window in in/out mode, the start and end points can be adjusted using the spinbuttons. The start and end points can be anchored in time using the anchor start/end buttons.

Tip: blocks can be split and deleted by right clicking on them.

With the block still selected we will apply an effect to it. Go to the effects menu, and select "apply effect to block". We will choose the "colour correction" effect because it has parameters.

When you click on an effect with parameters, the polymorph window will go into effect mode. You will also see a frame preview in the preview window.

Fig. 10 after applying an effect with parameters (colour correction)

We will first set the parameters at the start of the effect. We can do this by sliding the small slider under the parameters all the way to the left.

Fig. 11 slide the time slider to the left

Tip: notice the timeline cursor moves with the effect time slider. You can also move the timeline cursor which will set the effect time slider.

You can then adjust the parameters, and preview them by pressing the "preview frame" button.

Fig. 12 setting the parameter values

Fig. 13 the "show frame preview" button.

When you are happy with the values, you can press the "Set values at time" button.

Fig 14. set values at time

We will now set the values at the end of the effect. Slide the effect time slider all the way to the right. Then adjust and preview the values, and when you are happy click on "set values at time" again.

Tip: you can move between parameter values, and delete parameter settings using the buttons to the right of the effect time slider. You can also set values at any time between start and end of the effect.

If you now move the slider back and forth, you should see the values changing smoothly. This is known as "parameter interpolation". You can preview at any point by pressing "show frame preview".

If you now play back the layout (by pressing 'p'), you should see the colours in the clip changing !

You can add more effects on top of the colour correction, and undo effects using the Edit/Undo menu.

In future there will be ways of deleting, reordering, and editing effects (TODO).

Creating a transition

We will now create a transition. First we will move our block down to layer 1. You can do this simply by dragging and dropping the block onto the track below. If you still have "snap" on, it will snap to the left of that track. Also, if you have the menu option "Effects/move effects with blocks" checked, any block effects will be moved with the block.

Fig. 15: the block is moved to layer 1

Now we will add a second block to layer 0. Make sure the blocks overlap (this is easier if you have "snap" on). Drag a second clip into layer 0.

Fig. 16: adding a second block

We will now create a region. In LiVES, a region is a combination of a time region with 1 or more selected tracks. First we will select our two tracks. You can either click on the checkbuttons on the left of the tracks, or use the menu option Selection/Select all video tracks.

Tip: you can also select tracks using the keyboard. ctrl-space will select/deselect the current track, and ctrl-up-arrow, ctrl-down-arrow will move the current track up and down.

Fig. 17: two tracks are selected

We will now complete the region by selecting a time region. First we will choose to select the overlap. We can do this by switching on the menu option: Selection/Snap to overlap. This will cause selection of the overlap area between the selected tracks.

Now click on the timeline header inside the overlap, and the region will expand to cover all of the overlap.

Fig. 18: completed selection of a region.

We can now apply a transition to our region. Go to the menu option Effects/Apply effect to region, and choose "transitions". For this tutorial, we will use the "chroma blend" transition. This will give us a cross-fade between the two tracks.

We will first cross-fade from layer 0 into layer 1.

When you select "chroma blend", the polymorph window will go into effect mode. As above with an effect, slide the time slider all the way to the left. Then select "transition in". Transition in means that all of the front layer (in this case, layer 0) is visible.

Fig. 19: setting the transition in at the start

Don't forget to press "set values at time" !

Now, slide the effect time slider to the right, and click on Transition Out. Transition Out means that all of the rear layer (in this case, layer 1) is visible. Then click on "set values at time" again.

Fig. 20: setting the transition at the end

Now when you play back, you will see frames transition from layer 0 to layer 1.

OK, but what if we want to transition the other way, from layer 1 to layer 0 ? Simple. Slide the time slider to the left, select Transition Out, and then "set values at time". Then slide the time slider to the right, click on Transition In, and "set values at time". That's it !

Applying a compositor

Now we are going to apply a compositor. A compositor takes 2 or more tracks and mixes them down to a single track. The output is always on the frontmost layer of the compositor (in future, this will be adjustable - TODO).

We will start by laying out three clips on three tracks in the timeline. [You can first clear the timeline by pressing ctrl-e, ctrl-m.]

Now we need to add a third track. You can do this by pressing ctrl-t (add frame behind) or ctrl-shift-t (add frame in front), or from the tracks menu. You can drag a clip onto each track.

Fig. 21: LiVES with 3 video tracks

Now we need to create a region to apply our compositor to. First select all three tracks, either by checking the boxes on the left, or from the menu option Selection/Select all video tracks.

Fig. 22: three video tracks selected.

Now select a time region by dragging on the timeline header. If Selection/snap to overlap is on, only the overlap region will be selected.
For this demo, we will have Selection/snap to overlap off.

Fig. 23: three tracks selected and a time region

Now click on Effect/Apply effect to region, and pick "compositors". At the time of writing there is only one compositor, called "compositor".
Select this. The polymorph window will go into effect mode.

Now, this is where it becomes a little tricky. You need to know where the timeline cursor is, and also which track is the "current track".

If you look in fig. 23, the current track is layer 2 (because it is a different colour to the rest). You can change the current track by clicking on its label, or by using ctrl-up and ctrl-down.

You can also move the timeline cursor by using key combinations ctrl-left-arrow and ctrl-right-arrow, or by clicking on the timeline header. You can use ctrl-j (jump) or menu option "Edit/Jump to next block boundary" to jump to the edge of a block.

Depending on whether there is a frame present or not at the current time/track coordinate you will see one of two things. If a frame is present, you will see frame settings (x start, y start, x scale, yscale, alpha) and the background colour control. If no frame is present, you will see only the background colour control. Try moving the timeline cursor and current track so you can see both things.

Fig. 24: compositor parameters when no frame is present

Fig. 25: compositor parameters when a frame is present.

If a frame is present, you can also click and drag on the preview window to set the xstart, ystart, xscale, yscale and alpha values.

Fig. 26: preview window can be used to "draw on" for the compositor.

Don't forget to click on "set values at time" when you want to set some values.

Tip: parameters xstart, ystart, xend, and yend and alpha, are set independently for each track in the compositor. Clicking on "set values at time" only sets these parameters for the current track.

These parameters are also interpolated, so for example, you can make a clip move around, or fade in and out.

Saving and rendering

You can save your layout at any time from the file menu.

You can render your layout from the Render menu, or by pressing ctrl-r. The rendering is added as a new clip. You can decide whether rendering returns you to the clip editor, or leaves you in multitrack mode using the Preferences/Rendering Multitrack settings.

Other things

This is just a brief introduction to the multitrack window in LiVES. There are many other features, for example:

- mouse mode select : changing mouse mode to "select" allows you to select a region simply by clicking and dragging with the mouse on the timeline area.

- close gaps : with a region selected, you can close any gaps in it by pressing ctrl-g or from the Selection menu
- close first gaps : you can also close only the first gaps by pressing ctrl-f or from the Selection menu

Gap closing is done by moving blocks left

- split selected tracks : you can split all selected tracks at the timeline cursor

- select all : pressing ctrl-a selects the whole timeline (just like in the clip editor) [but beware of Selection/select overlap]

Note also that the multitrack window is still in development.