[LAU] Zita-ajbridge ?

[Fons Adriaensen]

On Sat, Jul 20, 2013 at 12:26:33PM -0400, Marc Lavallée wrote:
 
> > There is no need to resample anything.
> 
> Right... This is your use case for zita-resampler:
> "The development of zita-resampler was triggered by the need to
> resample multichannel files (HOA, 25-ish channels), while still keeping
> some CPU capacity for other tasks."

I mean: there is no need to resample if you want to use mplayer with Jack.
If the audio file's sample rate doesn't match that of Jack, mplayer will
do the resampling.


> So Mplayer is just reporting the output frequency of Jack?

Both actually:

==========================================================================
Opening audio decoder: [pcm] Uncompressed PCM audio decoder
AUDIO: 44100 Hz, 2 ch, s16le, 1411.2 kbit/100.00% (ratio: 176400->176400)
Selected audio codec: [pcm] afm: pcm (Uncompressed PCM)
==========================================================================
AO: [jack] 48000Hz 2ch floatle (4 bytes per sample)


> > > Another problem: when starting Jack with a 2 channels sound card,
> > > Mplayer can't output more than 2 channels. 
> > 
> > Again, mplayer can't know this. Your are probably running on
> > some other soundcard, not using Jack.
> 
> I confirm: when using Jack with the internal soundcard (with 2 output
> channels), Mplayer limit its number of output channels to 2, even if I
> specify the number of channels of my sound file (4) to Mplayer.

Because it wants to connect to four system:playback ports, and that fails.
And when the connection fails, mplayer deletes the output port. Which is
insane, but that's how it is.

Start Jack with two playback channels, and any program having at least
four jack inputs, e.g. ambdec. Then try

  mplayer -ao jack:port=ambdec -channels 4 YOUR_4_CH_FILE

and mplayer will have four output ports and connect them to ambdec's
inputs, even if your sound card has only two outputs.

The real problem is that mplayer doesn't allow you to specify the
connections, they could be in any order. So chances are 1 in 24 that
they will be correct in this case. Mplayer is one of the many apps that
claim Jack support but get it all wrong.

> - I installed the latest Jackd (version 1.9.10 from Grame): zita-j2a now works! :) 

What was your previous Jack version ?

>   after the "Starting synchronisation" message, there's now a
>   continuous sequence of numbers.

Probably because you still use -v. See the README for what they mean.

> Suggestion: a note in the documentation about the version of
> Jackd would help.

It shouldn't matter, unless it's *very* old. Zita-ajbridge requires
nothing special from Jack, apart from a working DLL. And that was
added at least five years ago.

Ciao,

-- 
FA

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It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)