Re: question on channel merger layout determination

I think this is just a bug in Gecko's implementation, and should be filed
in Bugzilla as such.  The spec says:

"There is a single output whose audio stream has a number of channels equal
to the sum of the numbers of channels of all the connected inputs."

That seems unambiguous to me (it uses "connected" inputs, not "active").

On Thu, Nov 6, 2014 at 7:46 AM, Joseph Berkovitz <joe@noteflight.com> wrote:

> Due to a random query about panning by Doug S, I recently ran into a
> behavior on Firefox that seems like a bug, but I want to make sure it’s not
> some kind of spec issue.
>
> On FF, if you feed a ChannelMergerNode with 2 mono inputs coming from
> GainNode outputs, and the GainNode assigned to the Right merger channel has
> a gain value of exactly zero, the ChannelMerger output no longer has a
> stereo channel layout: it acts as a mono-to-mono merger (i.e. it acts as if
> there was only input 0, and input 1 is considered “inactive”).  With a
> nonzero gain value, the merger acts normally.
>
> In Webkit and Blink, the merger acts consistently in stereo regardless of
> the upstream gain values.
>
> See http://jsfiddle.net/JBerkovitz/5byng2cj/ for an example. (I was
> attempting to build my own equal power panner but ran into this issue — of
> course there’s an easy workaround, which is to prevent gain values from
> assuming a value of exactly zero, but that’s not the point.)
>
> Does something need to be clarified in the spec about what an “inactive
> input” really means? I assumed it would mean an input that was simply not
> connected to anything, but this bug makes me wonder if there’s some
> ambiguity for implementors on this point. Or is this just an FF
> implementation bug (which I’m happy to file)?
>
> .            .       .    .  . ...Joe
>
> *Joe Berkovitz*
> President
>
> *Noteflight LLC*
> Boston, Mass.
> phone: +1 978 314 6271
> www.noteflight.com
> "Your music, everywhere"
>
>