mvAudio(3dm)							  mvAudio(3dm)

NAME    [Toc]    [Back]

     mvSetPrimaryAudio,	mvGetPrimaryAudio - Set/get the	movie instance with
     control over the audio hardware

SYNOPSIS    [Toc]    [Back]

     #include <dmedia/moviefile.h>
     #include <dmedia/movieplay.h>


     void mvSetPrimaryAudio(MVid movieid);

     MVid mvGetPrimaryAudio(void);

DESCRIPTION    [Toc]    [Back]

     mvSetPrimaryAudio(3dm) tells the Movie Playback Library to	favor a
     particular	movie's	audio sampling rate for	playback. The preferred	audio
     sample rate of a movie is the sample rate of the movie's first audio
     track.  You may designate a movie as primary regardless of	whether	or not
     it	is currently playing.

     The default value for the primary audio movie is MV_PRIMARY_AUDIO_NOTSET.

     When the primary audio movie is set to something other than
     MV_PRIMARY_AUDIO_NOTSET, the movie	library	will use a "rude" policy for
     setting the system	audio hardware sampling	rate.  When this is the	case
     and whenever the primary audio movie is playing, the Movie	Playback
     Library will set the audio	hardware sampling rate based on	the preferred
     audio sample rate of the primary audio movie.

     When the primary audio movie is MV_PRIMARY_AUDIO_NOTSET, the movie
     library use a "polite" policy for setting the system audio	hardware
     sample rate.  The Movie Playback Library opens an output ALport for each
     movie that	has at least one audio track and is currently bound to a
     window (see mvBindOpenGLWindow(3dm)).  When the primary audio movie is
     MV_PRIMARY_AUDIO_NOTSET and such a	movie starts playing (see
     mvPlay(3dm)), the Movie Playback Library checks to	see if the system has
     any other currently open output ALports (see alGetParams(3dm)).  These
     other ALports could belong	to other movies	currently opened by the	same
     process (or process group), movies	open in	other applications, or other
     processes that use	output ALports.	 If there are no other currently open
     output ALports, the Movie Playback	Library	will set the audio hardware
     sample based on that movie. If there is at	least one other	currently open
     output ALport, the	Movie Playback Library will use	linear sample rate
     conversion	(when necessary) to ensure that	the movie's audio will play
     using the current audio hardware sampling rate.

     The Movie Playback	library	does not follow	this protocol for movies bound
     directly to a movie library audio port (MV_PORT_AUDIO) with
     mvBindMovieToPorts(3dm) with the ownsRate set to DM_TRUE.	When these
     movies start playing, a "rude" policy is used.  See the section on



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mvAudio(3dm)							  mvAudio(3dm)



     MV_PORT_AUDIO in mvPort(3dm) for details.

     Once you designate	a primary movie, it owns the audio hardware until you
     designate another with a subsequent call to mvSetPrimaryAudio(3dm), or
     you close the movie by calling mvClose(3dm).  If you close	the primary
     movie, the	primary	movie will revert to MV_PRIMARY_AUDIO_NOTSET.

     To	remove primary audio status from a particular movie, but not assign to
     another movie, you	may call mvSetPrimaryAudio(3dm)	with the value
     MV_PRIMARY_AUDIO_NOTSET.

     mvGetPrimaryAudio(3dm) returns the	movie ID which currently has primary
     audio status, or MV_PRIMARY_AUDIO_NOTSET if no movie has primary audio
     status.

     Only one movie may	have primary audio status at any given time.

SEE ALSO    [Toc]    [Back]

     ALintro(3dm), alGetDefaults(3dm), alOpenPort(3dm),	alSetParams(3dm),
     mvBindWindow(3dm),	mvIntro(3dm), mvPlay(3dm), mvPort(3dm).


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