[LAU] Zita-ajbridge ?

Marc Lavallée marc at hacklava.net
Sun Jul 21 13:14:00 UTC 2013


Fons Adriaensen <fons at linuxaudio.org> a écrit :
> Resampling means 'computing samples for another sample rate', and not 
> 'changing the sample format'. 

I thought that the sample format was the sample depth plus the sample
rate, but sample format and sample depth are the same. Definitions are
important.

> Neat trick, but if it works you are just lucky.

Gee. I just finished my script, and it works.

> ** There is no defined order when Jack provides a list of ports. **

What?? Now... Heinseberg law applying to Jack... :-)

> In most cases, Jack will list them in the order they were created,
> but you can't count on that.

I might just count on that. I like being lucky. :-)

> The only way to obtain a defined order is by interpreting the port
> names, which is what e.g. Qjackctl does: it does a lexicographical
> sort. Which is why it will show Ambdec's ports as 0w, 1x, 1y, 1z.
> AFAIK, mplayer doesn't do that.

Isn't Qjackctl just a wrapper (or controller) for jackd? Qjackctl shows
the ports in a different (lexicographical) order, but the order does
not change when starting jackd with Qjackctl.
 
> > Now my problem is to connect mplayer to a second instance of
> > ambdec; 

I'll try to use the aloop devices instead of mangling the channels
order with a bash script to create a remapping string for Mplayer. I
should be able to script the connections between the ambdec decoders and
the aloop devices, in order to use MPlayer with ALSA instead of Jack.

> I need it for lower frequencies, and since I use a triangle
> > (for basic horizontal decoding), I had to change the lower limit
> > for the number of allowed channels in the  source code of ambdec.
> 
> There's no need to do that, just set the matrix coefficients for the
> 4th channel to zero.

Nice! I'll fix my triangle decoder; it's cheaper than replacing all
my satellite speakers with full-range speakers, only for frequencies
below 120Hz.

> When Ambdec gets extended to 4th degree (order) and
> higher, it will also use ACN in the port names - there are
> no FuMA names for those. The only alternative would be to
> use port names that explicitly contain L and M.

I doubt I'll be using 4th degree anytime soon (my listening room is
very small), but there might be a need to create a new amb format using
the ACN ordering instead of the FuMA ordering. Or does it already
exists?

--
Marc


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