Copyright © 2011-2023 MultiMedia Soft How to use the TracksBoard to visually compose songs

Audio Sound Editor API for .NET , through the TracksBoard class, allows visually composing new sound and/or music files by mixing together audio incoming from two main audio sources:

 

 

An important concept about this feature is the fact that all sound items composing the session are layered, meaning that they can be added, removed or modified before being mixed for playback or for export into a destination file.

 

The TracksBoard can be added at runtime to the container form by invoking the TracksBoard.Create method which instances the window containing the user interface, very similar to the one rendered by the WaveformAnalyzer class; as any other window, it can be later destroyed through the TracksBoard.Destroy method, moved/resized through the TracksBoard.Move method, refreshed through the TracksBoard.Refresh method and shown/hidden through the TracksBoard.Show method.

 

 

Differently from the WaveformAnalyzer object, the TracksBoard is based upon the concept of "tracks" instead of "audio channels". The aforementioned TracksBoard.Create method will automatically create a new "session" with an initial number of tracks: this number can be incremented through the TracksBoard.TrackAdd method and decremented through the TracksBoard.TrackRemove method: it's important to note that a track can be only removed when empty and not when still containing one or more items.

 

The concept of audio channels is in any case still available, indeed each item added to the session can be assigned to a specific speaker and this will become effective when the mixing will occur, before starting playback through the PlaySound method or before starting the exporting to file phase through the TracksBoard.ExportToFile method. The total number of speakers managed by the session can be set through the TracksBoard.SpeakersNumSet method.

 

A session and all of its existing tracks and items can be saved for later use through the TracksBoard.Save method and loaded through the TracksBoard.Load method.

 

During a playback session started through the PlaySound method, the vertical line named play head line shows the current playback position: this line can be moved through the mouse by clicking a position outside of existing items; the position of the play head line can be also modified programmatically through the TracksBoard.PlayHeadPositionSet method and the current playback position can be retrieved through the TracksBoard.PlayHeadPositionGet method.

 

Modifications to the session performed through the mouse, like moving an item or changing the position/amplitude of a volume point, are disabled during playback.

 

The current duration of the session can be obtained through the TracksBoard.CurrentDurationGet method; once a session is no more needed it can be discarded from memory through the TracksBoard.FreeMemory method.

 

 

Other operations available for tracks added to the session are the following:

 

 

 

On the screenshot below you can see an example of session with 4 tracks, each containing one or more "Items". On the final mix, each item can be rendered on a different audio channel.

 

 

All of the items can be selected or dragged through the mouse by holding down the left mouse button: items cannot overlap on the same track so, if you should need to have more items on the same timeline, each of them should be placed on a different track.

 

 

As seen on the screenshot above, the Tracksboard user interface is made up of a window containing a set of different entities:

 

 

Settings of each of the entities described above can be customized through the following set of data structures:

 

 

All of these setting can be saved for later use through the TracksBoard.SettingsSave method and loaded through the TracksBoard.SettingsLoad method.

 

Zoom operations are supported programmatically through the TracksBoard.ZoomIn, TracksBoard.ZoomOut and TracksBoard.ZoomToFullSound methods or through the mouse by moving the scrollbars handles. In case you should need to display a specific range of the session, the TracksBoard.DisplayRangeSet would be the way to go. Once zoomed, the visible range of the session can be scrolled programmatically through the TracksBoard.Scroll method or through the mouse by moving the scrollbars thumbs; the zoom-in capability is limited to the number of peaks available for rendering the waveform of items added to the session so, when using the horizontal scrollbar, the zoom-in operation is automatically interrupted when there are not enough peaks to proceed further.

 

 

After a zoom or scroll operation the current displayed range can be obtained through the TracksBoard.DisplayRangeGet method.

 

When an item is selected through the mouse, it immediately appears surrounded by a tracker of a different color and a dotted rectangle extended to time rulers is displayed; further elements become visible; most of these elements can be dragged through the mouse:

 

 

As mentioned at the beginning of this tutorial, the following kind of items can be added to the session:

 

 

In all cases, items added to the session will be identified by a unique identification number created by aforementioned methods. Once added, several modifications can be applied to each item through the following method:

 

 

Operations below can be optionally delayed in order to save some CPU and avoid too many refreshes of the waveform when invoked in sequence: in this case they will become effective after invoking the TracksBoard.ItemCompose method:

 

 

 

A certain amount of methods is dedicated to volume points management:

 

 

If the value of the bAutoApplyVolumeAutomation field of the TRACKSBOARD_ITEM_SETTINGS structure should be set to "true", methods listed above could be immediately applied; in case it

should be set to "false", they could be invoked together and not immediately applied, allowing to save some CPU: in this case the TracksBoard.ItemVolumePointsApply method could apply their settings all at once.

 

 

Methods listed above come with a bAutoRefresh parameter which allows deciding if the modification should be applied immediately or applied later when one of these methods should be invoked with the the bAutoRefresh parameter set to "true" or through a call to the TracksBoard.ItemVolumePointsApply method.

 

 

Existing volume points can be enumerated through the TracksBoard.ItemVolumePointCountGet method; in case one of the volume points should have been selected through the mouse, it could be obtained through the TracksBoard.ItemVolumePointSelectedGet method.

 

Each volume point can have its own friendly name originally assigned by the  method: the current friendly name can be obtained through the TracksBoard.ItemVolumePointFriendlyNameGet and modified through the TracksBoard.ItemVolumePointFriendlyNameSet method.

 

As mentioned above, the TracksBoard.ItemVolumePointRemove method removes a specific volume point: in case the duration of the item should be modified by dragging one of its resize handles or through a call to the TracksBoard.ItemSoundFileLoadRangeSet method, volume points falling outside of the visible range of the item would be automatically removed.

 

 

A set of callback delegates is provided for keeping the container application up to date respect to operations happening on the user interface of the TracksBoard:

 

 

A further set of events is dedicated to operations performed directly on items available inside the session:

 

 

 

 

A couple of examples of usage of the TracksBoard class in Visual Basic.NET and Visual C# can be found inside the following samples installed with the product's setup package:

- TracksBoard

- SoundEditor (for defining a volume automation)