[pulseaudio-discuss] Command Line Language

[Pierre Ossman]

Max Kempter wrote:
> hi,
> 
> here is max again.
> First of all I have to say that your answers are very helpfully, and week by week I`m nearer by my aim I want to do with PA.
> 
> I have some trouble with:
> -------------------------------------------------------------------------------------------------------------
> [/shell]
> usr at CST-G2L2:~$  arecord | pacat -p -s 192.56.1.3 -d out -v
> Opening a playback stream with sample specification 's16le 2ch 44100Hz'.
> Connection established.
> Stream successfully created.
> Buffer metrics: maxlength=132300, tlength=88200, prebuf=87320, minreq=880
> Recording WAVE 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono
> Time: 0.000 sec; Latency: 1234567890ms (goes up to endless)
> [shell/]
> 
> The pacat-source is connected with the sink „out“, but there is no level at volume meter at the reciver site.  Each 30 s I see a short amplitude at the level meter, the amplitude goes up to 0dB and after 0.5 s back to circa – 120dB.

pacat and arecord have different defaults. You need to pass additional
parameters to make sure the data is compatible.

> 
> I reach the the host I want to reach but the packets are empty (or it send the wrong things).
> 
> The second strange thing is that the Latency (I see it through -v option) goes up to endless, or till I push CTRL-C.
> 

This shouldn't happen though. Can you check the latency on "out" when
this happens?

> If I try 
> [/shell]
> arecord test.wav  
> [shell/]
> It works and I record the mic capture.
> 
> If I try 
> [/shell]
> aplay test.wav | pacat -p -s 192.56.1.3 -d out 
> [shell/]
> Also no problem, I recive the audio at alsa-sink „out“.
> 

Ehm... aplay doesn't send its stuff to stdout, so that is broken test
case. Your "out" is probably your default alsa device.

> ------------------------------------------------------
> 
> Let`s assume I load a source (eg mic) at Host1 and a load tunnel sink (eg out) from Host2, how can I route the source to the sink?
> I want to do this without the modules module-rtp-{send/recv}!
> 
> --------------------------------------------------------

I'm not familiar with module-rtp, so I can't tell you any more than
what's in the docs.

> 
> Next, every time I load a source/sink, with load-module, I have to read this message:
> 
> [/shell]
>  >>> load-module module-alsa-source device=plughw:0,0 rate=48000 source_name=mic
> 
> ALSA lib control.c:910:(snd_ctl_open_noupdate) Invalid CTL plughw:0,0
> alsa-util.c: Unable to attach to mixer plughw:0,0: File or Folder not found
> [shell/]
> Which mixer it means? Alsamixer?

alsamixer is an application. What the message means is that it cannot
find a mixer attached to that device. I don't think plug exports the
mixer interface, only pcm. So you should use hw:0,0 as the device.

> 
> My setup also works with this „error“ message, so it could be the best to ignore it? Or is it a problem with my kernel (2.6.16-2-686 stable)?
> 

You just lose hw volume control.

> ------------------------------------------------------
> 
> Which is the advantage of the module-null-sink? Is it for people who doesn`t have an audio device? 
> 

Amongst other things. It's also good for testing, and as a fallback when
you have to rescue streams.

> ------------------------------------------------------
> 
> And the last question is about the deamon parameter –high-priority=1 what is the effect about this option? Is it the process priority at machine!?

Yes. It will renice itself to -15 and (if possible) select FIFO scheduling.

Rgds
-- 
Pierre Ossman            OpenSource-based Thin Client Technology
System Developer         Telephone: +46-13-21 46 00
Cendio AB                Web: http://www.cendio.com

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