Playing 'snd ' Resources
nothing more than a handle to an existing 'snd ' resource. An 'snd ' resource
contains the information necessary for the Sound Manager to create a channel linked to the required synthesizer, together with the sound commands
that are to be sent to that synthesizer to play the desired sound. The 'snd '
resource may or may not contain sound data. If it does, as in the case of a
sampled sound, that data can be either compressed or uncompressed. As long as
the resource is created correctly, SndPlay will play it. The following code example illustrates how to play back an 'snd ' resource.
Playing an 'snd ' resource with SndPlay // Assuming inclusion of MacHeaders
#include <Sound.h>
// constants
#define kAsync TRUE // play is asynchronous
#define mySndID 9000 // resource ID of 'snd'
// prototype your routine like this prior to calling it
void CallSndPlay(void);
void CallSndPlay()
{
Handle mySndHandle; [TOKEN:12079] handle to an 'snd ' resource SndChannelPtr mySndChan; [TOKEN:12079] pointer to a sound channel
OSErr myErr;
// prototype for user defined error handling routine
mySndChan = nil; // Initialize channel pointer for error checking
// Read in 'snd' resource from resource file
// check for a nil handle
if ( mySndHandle != nil ) {
myErr = SndPlay ( mySndChan, mySndHandle, kAsync); if ( myErr )
DoError( myErr);
}
}
When your application uses SndPlay and passes NULL as the pointer to a sound channel, it does not need to concern itself with any memory allocation or
deallocation. The Sound Manager automatically opens a sound channel (in the application's heap) and then closes it when the sound is completed.
For more complete control of the sound channel, your application can open a
the sound is completed, your application closes the channel with
can use low-level Sound Manager routines in the simple case of calling the sampled sound synthesizer to play back a buffer of sampled sound. The buffer
can be either compressed or uncompressed. This example assumes that the
sampled sound is uncompressed and that the sound header whose address is
passed as an argument has already been filled out correctly.
// Assuming inclusion of MacHeaders
#include <Sound.h>
// prototype your buffer routine like this prior to calling it
void DoBufferCmd (SoundHeaderPtr);
void DoBufferCmd(SoundHeaderPtr mySHPtr)
{
SndChannelPtr mySndChan; // pointer to a sound channel
// prototype your DoError routine like this
mySndChan = nil; // Sound Mgr allocates channel
mySndCmd.cmd = bufferCmd; // the command is bufferCmd
mySndCmd. param1 = 0; // not used here
mySndCmd. param2 = (long)mySHPtr; // pointer to SoundHeader // allocate a sound channel
myErr = SndNewChannel(& mySndChan, sampledSynth, initMono, NULL); if ( myErr )
DoError( myErr);
// queue bufferCmd in the sound channel
if ( myErr )
DoError( myErr);
// dispose of the channel when finished
if ( myErr )
DoError( myErr);
}
following sections. Note that the procedure does not do proper error handling;
it is intended primarily to illustrate the proper order in which you should call