CODEWITHSUNDEEP
audiovolumeopenal
brigadir
brigadir

Reputation: 6942

How to set channel gain in OpenAL?

I tried

alBufferf (myChannelId, AL_MAX_GAIN (and AL_GAIN), volumeValue);

and got error 0xA002.

Upvotes: 0

Views: 1697

Answers (2)

RJFalconer
RJFalconer

Reputation: 11652

As Isaac has said, you probably want to be setting gain on your a sources:

alSourcef (sourceID, AL_GAIN, volume)

To avoid recieving mysterious error codes in future, you should get into the habit of polling for errors after calls you think may fail / calls you are trying to debug.

This way, you'd know immediately that "0xA002" is "AL_INVALID_ENUM".

To do this with OpenAL you call "alGetError()" which clears and returns the most recent error;

ALenum ALerror = AL_NO_ERROR;
ALerror = alGetError();
std::cout << getALErrorString(ALerror) << std::endl;

You'll need to write something like this to take an error code and return/print a string

std::string getALErrorString(ALenum err) {
    switch(err) {
    case AL_NO_ERROR:       return std::string("AL_NO_ERROR - (No error)."); break;
    case AL_INVALID_NAME:       return std::string("AL_INVALID_NAME - Invalid Name paramater passed to AL call."); break;
    case AL_INVALID_ENUM:       return std::string("AL_INVALID_ENUM - Invalid parameter passed to AL call."); break;
    case AL_INVALID_VALUE:      return std::string("AL_INVALID_VALUE - Invalid enum parameter value."); break;
    case AL_INVALID_OPERATION:  return std::string("AL_INVALID_OPERATION"); break;
    case AL_OUT_OF_MEMORY:      return std::string("AL_OUT_OF_MEMORY"); break;
    default:            return std::string("AL Unknown Error."); break;
    };
}

You can lookup exactly what the error code means for a specific function call in OpenAL Programmer's Guide .

For example, on page 39 you can see AL_INVALID_ENUM on alSourcef means "The specified parameter is not valid".

Upvotes: 1

Isaac Nequittepas
Isaac Nequittepas

Reputation: 392

0xA002 is an ILLEGAL ENUM ERROR in linux.

You got that because it's impossible to modify the gain of a buffer. There's no such thing.

What you can do is set the AL_GAIN attribute either to the listener (applying it to all sources in the current context) or to a particular source.

Upvotes: 0

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