|Microsoft DirectX 9.0|
This topic applies to Windows XP Service Pack 1 only.
A DVD-Video disc can have up to eight audio streams, numbered zero through seven, each with up to six discrete channels. Audio streams specify a standard movie soundtrack, a director's comments soundtrack, alternate language soundtracks, or other audio features. Only one audio stream at a time can be enabled. Discs are generally authored with default audio streams, but an application can enable the user to see all the streams that are available for a given title, and select the one in the language they prefer.
Unfortunately, there is no way to determine the content of an audio stream programmatically; an audio stream may contain a simple soundtrack, director's comments, or other audio. So, for instance, there may be three audio streams listed as English language, but one may be director's comments, another may be a simple soundtrack in English, and the third may be a multi-speaker soundtrack.
Here are the basic steps to display a list of audio streams for user selection:
(Note that audio and subpicture streams are numbered from zero, whereas titles, angles, and parental levels are numbered from one.)
The following code fills a list box (lboAudioStream) with a list of available languages:
lboAudioStream.Clear For i = 0 To oVidWebDVD.AudioStreamsAvailable - 1 If oVidWebDVD.IsAudioStreamEnabled(i) Then lboAudioStream.AddItem oVidWebDVD.AudioLanguage(i), i End If Next i lboAudioStream.Selected(oVidWebDVD.CurrentAudioStream) = True
The following code changes the audio stream when the user clicks on the list box:
Private Sub lboAudioStream_Click() oVidWebDVD.CurrentAudioStream = lboAudioStream.ListIndex End Sub