I am trying to play a midi file i've downloaded by using SndStreamCreate.
I've stored the file in a database and have a pointer to the midi data.
I'm not sure what the original sample rate was for the sound file, but when i
try to play the midi using the code below, i get nothing but a bit of a crackle.
Can anyone shed some light on how to play a midi file please..
I've used the following code.
typedef struct
{
Boolean active;
UInt8 *currP;
UInt8 *endP;
}AudioDataBlockType
static void PlayMidi(void)
{
Err err;
SndStreamRef stream;
AudioDataBlockType dataBlock;
dataBlock.currP = theMidiData; // pointer to the start of the midi data
dataBlock.active = true;
dataBlock.endP = endOfMidi; // pointer to the end of the midi data
err = SndStreamCreate(&stream, sndOutput, 8000 /*Hz*/,
sndUInt8 /*8-bit signed*/, sndMono,
StreamCallback /*callback*/, &dataBlock /*callback
data*/,
1024 /*requested block size*/, false /*not a PNO*/);
err = SndStreamStart (stream);
}
And i'm using the following call back function...
static Err StreamCallback (void *userData, SndStreamRef stream, void *buffer,
UInt32 frameCount)
{
AudioDataBlockType *dataBlockP;
UInt8 *outP, sample;
Int16 fc;
dataBlockP = (AudioDataBlockType *)userData;
outP = (UInt8 *)buffer;
if (!dataBlockP->active)
{
MemSet(buffer, frameCount * sizeof(Int8), 0);
return errNone;
}
for (fc = (Int16)frameCount - 1; fc >= 0; fc--)
{
sample = 0;
if (dataBlockP->active)
{
sample = *(dataBlockP->currP++);
if (dataBlockP->currP >= dataBlockP->endP)
{
dataBlockP->active = false;
}
}
*(outP++) = sample;
}
return errNone;
}
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