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Re: Get current volume for a source
by Jason Daly
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The Big Uno wrote:
> Hello all,
>
> I am trying to implement a VU Meter style widget by pulling the
> currently playing volume of a given source. Note that this is not the
> gain of the source; I want the number to be either the raw value of the
> sound frame at the time I call the function, or the raw value * current
> gain set for the source. Does anyone have an idea on what function I
> could call for this?
>
> I would like to get this value for just a certain source, not the entire
> OpenAL environment. The VU meters I am making are going to be on a
> per-channel level, with each source logically mapped to a certain
> channel. Think of the giant mixing boards with a VU meter for each
> input source for an idea of what I am trying to do here.
>
The only way to do this is to retain your own copy of each source's
buffer data after you pass it to OpenAL, and then get the current
position of each source as you update your meter. You can either call
alGetIntegerv with AL_SAMPLE_OFFSET or AL_BYTE_OFFSET, or you can call
alGetFloatv or alGetDoublev with AL_SEC_OFFSET, whichever you prefer.
> (On a side note, I am actually using JOAL - Java wrappers for the OpenAL
> functions - which I believe is currently using the OpenAL 1.0
> specification. The JOAL methods map quite closely to the underlying
> OpenAL API, which is why I am asking here and not on the JOAL forums.
> If you can get me the OpenAL function, that would be good enough for me.)
>
Oh, then you're out of luck. The AL_*_OFFSET queries are 1.1 features.
As far as I know, there isn't any reliable way to do what you want in
OpenAL 1.0.
--"J"
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Openal@...
http://opensource.creative.com/mailman/listinfo/openal
> Hello all,
>
> I am trying to implement a VU Meter style widget by pulling the
> currently playing volume of a given source. Note that this is not the
> gain of the source; I want the number to be either the raw value of the
> sound frame at the time I call the function, or the raw value * current
> gain set for the source. Does anyone have an idea on what function I
> could call for this?
>
> I would like to get this value for just a certain source, not the entire
> OpenAL environment. The VU meters I am making are going to be on a
> per-channel level, with each source logically mapped to a certain
> channel. Think of the giant mixing boards with a VU meter for each
> input source for an idea of what I am trying to do here.
>
The only way to do this is to retain your own copy of each source's
buffer data after you pass it to OpenAL, and then get the current
position of each source as you update your meter. You can either call
alGetIntegerv with AL_SAMPLE_OFFSET or AL_BYTE_OFFSET, or you can call
alGetFloatv or alGetDoublev with AL_SEC_OFFSET, whichever you prefer.
> (On a side note, I am actually using JOAL - Java wrappers for the OpenAL
> functions - which I believe is currently using the OpenAL 1.0
> specification. The JOAL methods map quite closely to the underlying
> OpenAL API, which is why I am asking here and not on the JOAL forums.
> If you can get me the OpenAL function, that would be good enough for me.)
>
Oh, then you're out of luck. The AL_*_OFFSET queries are 1.1 features.
As far as I know, there isn't any reliable way to do what you want in
OpenAL 1.0.
--"J"
_______________________________________________
Openal mailing list
Openal@...
http://opensource.creative.com/mailman/listinfo/openal
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