Robert Osfield wrote:
Hi Jason,
On Thu, Feb 26, 2009 at 9:10 PM, Jason Daly <jd...@ist.ucf.edu> wrote:
OpenAL is an obvious possibility for this. The OpenAL-Soft implementation
at http://kcat.strangesoft.net/openal.html supports almost all of the
platforms that OSG supports, and there are also hardware implementations of
OpenAL for some sound cards (mostly Creative Labs). There is also a
dedicated OSX implementation.
You wouldn't necessarily need to go so far as to integrate osgAudio yet.
Simple streaming from ffmpeg could probably be implemented with just a few
lines of OpenAL code.
Do you have any links to a tutorial that illustrates what these few
lines of code might be?
No, but off the top of my head:
// Opening the device looks like this:
ALCdevice * device = alcOpenDevice(NULL);
ALCcontext * context = alcCreateContext(device, NULL);
alcMakeContextCurrent(context);
alcProcessContext(context);
// Set the distance model to NONE, so there is no distance
// attenuation
alDistanceModel(AL_NONE);
// Initialize the listener's state
ALfloat orientation[6];
alListener3f(AL_POSITION, 0.0, 0.0, 0.0);
alListener3f(AL_VELOCITY, 0.0, 0.0, 0.0);
alListenerf(AL_GAIN, 1.0);
memset(zero, 0, sizeof(ALfloat) * 6);
alListenerfv(AL_ORIENTATION, zero);
...
// Setting up playback with a double-buffered streaming mechanism looks
like this:
ALuint buffers[2];
ALuint source;
alGenBuiffers(2, &buffers);
alGenSources(1, &source);
alBufferData(buffers[0], AL_FORMAT_MONO16, audioData, dataLength, 48000);
alBufferData(buffers[1], AL_FORMAT_MONO16, audioData, dataLength, 48000);
...
// This is how you keep the buffers full
alGetSourcei(source, AL_BUFFERS_PROCESSED, &processed);
if (processed > 0)
{
// Swap the buffers
buffer[0] = buffer[1];
// Fill the "back" buffer again
alBufferData(buffers[1], AL_FORMAT_MONO16, audioData, dataLength,
48000);
}
OK, maybe it's more than a few lines, but it's pretty straightforward.
If I had more time, I'd contribute it myself. I'm sorry that I can't
spare the time right now.
--"J"
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