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I'm new to audio programming so excuse me if I'm not using the right terms...

I have two streaming buffers that I want to have playing simultaneously completely synchronized. I want to control ratio of blending between the streams. I'm sure it's as simple as having two sources playing and just changing the their gain, but I read about people doing some tricks like having 2 channels buffer instead of two single channels. Then they play from a single source but control the blending between the channels. The article I read wasn't about OpenAL so my question is: Is this even possible with OpenAL?

I guess I don't have to do it this way but now I'm curious and want to learn how to set it up. Do I suppose to setup alFilter? Creative's documentation sais "Buffers containing more than one channel of data will be played without 3D spatialization." Reading this I guess I need a pre-pass on a buffer level and then having the source output blended mono channel signal.

I guess I'll ask another question. Is OpenAL flexible enough to do tricks like this?

I decode my stream manually so I realize how easy it will be to do the blending myself before feeding the buffer but then I won't be able in real time to change the blending factor since I already have a second or so of the stream buffered.

Aleks
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1 Answers1

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I have two streaming buffers that I want to have playing simultaneously completely synchronized. I want to control ratio of blending between the streams. I'm sure it's as simple as having two sources playing and just changing the their gain

Yes, it should be. Did you try that? What was the problem?

ALuint source1;
ALuint source2;
...

void set_ratio(float ratio) {
    ratio=std::min(ratio,1);
    alSourcef (source1, AL_GAIN, ratio);
    alSourcef (source2, AL_GAIN, (1-ratio));
}
RJFalconer
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