[pulseaudio-discuss] Command Line Language

Max Kempter kxam at gmx.net
Tue Dec 5 09:10:02 PST 2006


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:
usr at CST-G2L2:~$  arecord | pacat -p -s -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)

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.

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.

If I try 
arecord test.wav  
It works and I record the mic capture.

If I try 
aplay test.wav | pacat -p -s -d out 
Also no problem, I recive the audio at alsa-sink „out“.


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}!


Next, every time I load a source/sink, with load-module, I have to read this message:

 >>> 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
Which mixer it means? Alsamixer?

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)?


If I send a RTP-Stream via „rtp-send source=mic loop=1“ I don`t get the mic signal to my output sink or to my output.monitor. 
>>>load-module module-rtp-send source=mic loop=1

>>> ls (only importent things)
Default sink name: output
Default source name: mic

7 module(s) loaded.

     index: 4
        name: <module-alsa-source>
        argument: <device=plughw:0,0 fragments=2 fragment_size=128 
        rate=48000 format=alaw channels=1 source_name=mic>
        used: 1
        auto unload: no
    index: 6
        name: <module-alsa-sink>
        argument: <device=plughw:0,0 >
        used: 0
        auto unload: no
    index: 14
        name: <module-rtp-send>
        argument: <source=mic loop=1>
        used: -1
        auto unload: no

1 sink(s) available.
  * index: 0
        name: <output>
        driver: <modules/module-alsa-sink.c>
        volume: <0:  90% 1:  90%>
        latency: <5166 usec>
        monitor_source: <1>
        sample spec: <s16le 2ch 48000Hz>
        channel map: <front-left,front-right>
        owner module: <6>
        description: <ALSA PCM on plughw:0 (NVidia nForce2)>
2 source(s) available.
  * index: 0
        name: <mic>
        driver: <modules/module-alsa-source.c>
        latency: <1500 usec>
        sample spec: <aLaw 1ch 48000Hz>
        channel map: <mono>
        owner module: <4>
        description: <ALSA PCM on plughw:0,0 (NVidia nForce2)>
    index: 3
        name: <output.monitor>
        driver: <modules/module-alsa-sink.c>
        latency: <0 usec>
        sample spec: <aLaw 1ch 48000Hz>
        channel map: <mono>
        monitor_of: <2>
        owner module: <15>
        description: <Monitor Source of ALSA PCM on plughw:0 (NVidia nForce2)>
0 sink input(s) available.   #--> WHY IS HERE NO SINK?????
1 source outputs(s) available.
    index: 12
        name: 'RTP Monitor Stream'
        driver: <modules/rtp/module-rtp-send.c>
        state: RUNNING
        source: <0> 'mic'
        sample spec: <aLaw 1ch 48000Hz>
        channel map: <mono>
        resample method: src-sinc-fastest
        owner module: <14>
0 cache entries available.
0 autoload entries available.


When you look at the loaded modules, you see in each module at the third row after the index the parameter "used". I guess 1 is for used; 0 for not used; -1 for used by a stream ?????


The next one is about the troughput speed:
If I add the latency of source module and the latency of the rtp-send module together the result is the time from the beginning of signal to the point when my packets send out of my ethernet device !?


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


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!?

thanks in advance


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