Re: Multichannel audio playback
David Wright wrote:
> On Wed 28 Apr 2021 at 18:21:27 (+0000), Rodolfo Medina wrote:
>
> > Now it works:
> >
> > $ ecasound -a:1,2,3 -i:sndfile,3canali.wav -o alsaplugin,2,0
> > **************************************************************************
> > * ecasound v2.9.1 (C) 1997-2014 Kai Vehmanen and others
> > **************************************************************************
> > (eca-chainsetup) Chainsetup "untitled-chainsetup"
> > (eca-chainsetup) NOTE: Real-time configuration, but insufficient privileges
> > ... to utilize real-time scheduling (SCHED_FIFO). With small buffersizes,
> > ... this may cause audible glitches during processing.
> > (eca-chainsetup) "rt" buffering mode selected.
> > (audioio_sndfile) Using libsndfile to open file "3canali.wav" for reading.
> > (eca-chainsetup) NOTE: using existing audio parameters -f:s16_le,3,48000
> > ... for object 'sndfile' (tried to open with -f:s16_le,2,44100).
> > (eca-chainsetup) Opened input "sndfile", mode "read". Format: s16_le,
> > ... channels 3, srate 48000, interleaved (locked params).
> > (eca-chainsetup) Opened output "alsaplugin", mode "write". Format: s16_le,
> > ... channels 2, srate 48000, interleaved.
> > - [ Connected chainsetup: "untitled-chainsetup" ] ------------------------
> > - [ Controller/Starting batch processing ] -------------------------------
> > - [ Engine - Driver start ] ----------------------------------------------
> >
> > - [ Engine - Processing finished ] ---------------------------------------
> > - [ Controller/Batch processing finished (0) ] ---------------------------
> > - [ Controller/Processing stopped (cond) ] -------------------------------
> > - [ Engine exiting ] -----------------------------------------------------
> > (eca-control-objects) Disconnecting chainsetup: "untitled-chainsetup".
>
> > Let's try to go to problem 2).
>
> It's difficult to know what you've actually done from this description.
> I know nothing about the UMC404HD apart from the two downloaded PDFs,
> 8849567252510.pdf and download_259085.pdf. I know nothing about Ecasound.
>
> Let me first reveal my ignorance by asking: does Ecasound run on your
> computer, or on the Behringer?
The Behringer is a USB-attached sound card. It happens to have
four inputs and four outputs. This is not particularly unusual.
> I'm going to assume the former, that you're playing a file on the
> computer in Ecasound, which then enters the Behringer via the USB
> connection.
Correct.
> How are these loudspeakers connected to the Behringer: which type of
> connectors are used, in which sockets, and what's the pinout at each
> end of the cables? What type of input do these loudspeakers expect
> to be driven by: presumably not an unbalanced 50W into 8Ω!
Completely irrelevant. The Behringer produces four single
channel outputs at line level suitable for an amp or preamp. We
can assume that the original questioner has things hooked up
properly.
> > Actually, the Behringer seems to behave in
> > stereo mode.
>
> Do you mean that all three channels have been mixed into two channels,
> and this is what you hear on your loudspeakers 1 and 2?
>
> Isn't that what these lines might indicate:
>
> > (eca-chainsetup) Opened input "sndfile", mode "read". Format: s16_le,
> > ... channels 3, srate 48000, interleaved (locked params).
> ↑
> > (eca-chainsetup) Opened output "alsaplugin", mode "write". Format: s16_le,
> > ... channels 2, srate 48000, interleaved.
Yes, this means that ecasound is writing 2 channels, which is
what the question is all about.
The questioner wants ecasound to write 4 channels, which could
be:
ecasound using the wrong ALSA output
or
ALSA not presenting an acceptable 4 channel output, so ecasound
falls back.
-dsr-
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