Re: Meaning of "volume"?

I think it's gain.  There are too many parameters on how you would
determine "how loud is the audio" (e.g. a VU meter is one standardization)
- unless you clearly standardize how you want to do that, there could be
significant differences.


On Mon, Oct 14, 2013 at 10:38 AM, Harald Alvestrand <harald@alvestrand.no>wrote:

>  A discussion erupted this week at the office over the meaning of this
> construct:
>
> dictionary MediaSourceStates {    SourceTypeEnum <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#idl-def-SourceTypeEnum>       sourceType <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaSourceStates-sourceType>;    DOMString            sourceId <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaSourceStates-sourceId>;    unsigned long?       width <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaSourceStates-width>;    unsigned long?       height <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaSourceStates-height>;    float?               frameRate <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaSourceStates-frameRate>;    float?               aspectRatio <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaSourceStates-aspectRatio>;    VideoFacingModeEnum <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#idl-def-VideoFacingModeEnum>? facingMode <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaSourceStates-facingMode>;    unsigned long?       volume <http://dev.w3.org/2011/webrtc/editor/getusermedia.html#widl-MediaSourceStates-volume>;
> };
>
>
>
> In particular the last field, which has the definition:
>
> volume of type unsigned long, nullable The current audio track's volume
> (as a percentage). A volume of 0 is silence, while a volume of 100 is the
> maximum supported volume. Returned for audio sources.
>
> For all the other properties of MediaSourceStates, it's reasonably obvious
> that they are relatively static properties that are controlled mainly by
> setting constraints.
>
> There's also a "volume" constraint in "Constraint Registrations":
>
> volume    unsigned long or MinMaxConstraint    Constrain the audio source
> to the exact desired volume or volume range.
>
> The two interpretations at the office were:
>
> - Volume is "audio level" - how much sound is currently coming out.
> - Volume is "gain" - how much the system will amplify (or dampen) the
> sound on the track.
>
> For the constraint, it's obviously "gain". But is the MediaSourceState
> what it's currently set to, or is it the amount of sound coming down the
> channel?
>
> (We have another discussion about the fact that we *need* a way to see how
> loud the audio is. But let's first figure out if this particular piece
> should be interpreted one way or the other.)
>
>     Harald
>
>