Alsa buffering accumulation
  • Vote Up0Vote Down Jean-Marie FavreauJean-Marie Favreau
    Posts: 8Member
    Dear all,

    I'm using airtime for an FM radio in France. Our computer is not producing any streaming, we are just using the sound card as output of our airtime, through alsa. Everything works fine, except an accumulation of buffering in alsa produces a delay between airtime and the output, with more than one minute after 9 days. 
    Does anyone is aware about this problem, and does it exists an alternative to alsa, or a tuning of its parameters to solve that?

    Thank you in advance for your ideas!

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  • Vote Up0Vote Down Voisses TechVoisses Tech
    Posts: 1,423Member
    Your Answer is here
    https://forum.sourcefabric.org/discussion/17812/soundcards-how-to-use-input-and-output-from-your-soundcard-with-almost-zero-latencyoverunderruns

    I always write my post with a preamble so most time out can start at the second post on the thread

    and the steps to get it working are
    1.Get the index of your card
    2.make a small modification to the ls_script

    and you are good to go

    LET ME SAY THIS THE SOUNDCARD IN MOST COMPUTERS ARE CRAPPY
    YOU DO NOT NEED A SOPHISTICATED CARD .

    Behringer UCA202  Audio Interface IS CHEAP AND DOES WELL.INVEST IN SOME TYPE OF AUDIO INTERFACE IS WELL WORTH IT.THIS GIVES YOU TWO INPUT IN AND TWO OUT(2x2)
     


    So here is what seems to be the problem
    1.The current code is designed to use the default card
    2.The default card is assumed to be hw:0,0
    3.the wallclocks are normally the same for the script as the soundcard cause overruns when the stream are pumped to the output and underruns when the inputs are too slow to be input in the script.
    This is why you are more likely to  to see Overruns on Output and Underruns on Input
    4.whilst the script only has output if you look in the utils.liq you will see whatever card you select as the output will be assumed to be the preferred output will automatically become the Input even if you dont use it
    Now if you use pulse audio it will work but if for any reason it stops,like you had to restart the ls_script,which includes changing the stream from the UI.you have to restart the computer cause you will lose the default sink

    Alsa offer the best choice because you can use all the Linux sound program (including Jack) like Meterbridge ,Ardour ,you name it.

    Let me know if you have difficulty.






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    Post edited by Voisses Tech at 2016-01-05 03:57:29
    Anyone reading this a find it funny about my grammar , I make no apology ,Go get a translator.
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