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Ubuntu Desires Lower Audio Latency For Gaming

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  • dajomu
    replied
    Klang

    Isn't Klang supposed to fix the latency issue?
    http://www.phoronix.com/scan.php?pag...tem&px=MTE1MDc

    Leave a comment:


  • Detructor
    replied
    Originally posted by RealNC View Post
    That results in the game taking exclusive control of the card. Nothing else will be audible. Which is a disaster. Unless you talk to the dmix device. In that case, you're back to high latency.
    you are talking about OSS. With ALSA multiple programs can access the sound card.

    I never understood that soundserver idea anyway. You've to configure more for the same solution. Softwaredevelopers have to code more and add special cases for every friggin soundserver. And to top it off, you get 0 advantage from it over direct ALSA. Nada. In fact, you now have a high latency aswell. Well done.

    Also, now you can't even remove PulseAudio anymore without losing the sound control in Ubuntu anymore. (alsamixer is nice, but you always need to open a terminal for it, instead of just using a slider in the top menu bar like it should be)

    And you introduced another level of error into the system.
    Last edited by Detructor; 11-02-2012, 06:07 AM.

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  • unknown2
    replied
    Originally posted by RealNC View Post
    Mixing can run at high priority. Load doesn't affect it much.
    If running at high priority can solve the problem, then ubuntu developer will not "Desires" Lower Audio Latency For Gaming.
    and this post will not exist at all.

    Besides, software mixing running at high priority will probably preempt the game unexpectedly. The "jitter" will be transferred from the sound to the game - network packet drop, video frame skipping.


    Why don't you try to watch a HD movie when your CPU is under full load by low priority programs? Is the movie still ok?

    If linux kernel's scheduler is good at realtime, you should not be affected, right?

    Originally posted by RealNC View Post
    No, it's not.
    Try to archive low latency with cheap card+user level software mixing is very difficult. There is no free lunch.

    The miserable history of linux audio proves that kernel mixing/hardware mixing are superior solution (low cpu usage and good latency)


    Originally posted by RealNC View Post
    That happens when you try to monitor the output from the card; it raises latency.
    try googling yourself about Windows 7 audio latency, this is not the only post
    Last edited by unknown2; 11-02-2012, 05:36 AM.

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  • hansdegoede
    replied
    Latency numbers seem to be completely made up

    Hi,

    I'm the author of the current SDL pulse-audio backend (not the original author, but I rewrote it to fix several issues with the original), see:
    http://hg.libsdl.org/SDL/rev/5b99971a27b4

    The numbers posted in this article seem completely made up to me. In my experience (back when I was working on this), When using SDL
    based games (I did most of my testing with ioquake3) one could set the latency lower when using the pulse-audio backend then when
    using the alsa backend (with pulseaudio disabled of course). This is due to pulseaudio using high res timers to schedule sending data
    to the cards buffers rather then relying on the often somewhat "crude" (wrt granularity) interrupts from the soundcard.

    Now if you look at the patch you will notice it is using the new (back in 2009) PA_STREAM_ADJUST_LATENCY flag, if their testing did
    not include this flag, and instead was relying on pulseaudio's defaults, or if they were going something -> alsa -> alsa-plugin-pulseaudio
    rather then directly talking to pulse, then yes 25 ms makes a lot of sense. But then they have just been doing it wrong.

    Back in 2009 I good get excellent latencies using SDL with its pulse-audio backend, provided the game *actually asked* SDL for such a
    low latency ...

    Regards,

    Hans

    Leave a comment:


  • RealNC
    replied
    Originally posted by unknown2 View Post
    Gaming software always has a very high CPU usage.

    For software mixing problem, high CPU load always means bad latency for software mixing solution.
    Mixing can run at high priority. Load doesn't affect it much.

    Having a dedicated hardware for sound mixing is always a good idea.
    No, it's not.

    Take a look on Windows:

    Windows XP: hardware mixing
    Windows 7: change to software mixing which cause serious latency problem http://www.youtube.com/watch?v=iujDVsg_2xY
    That happens when you try to monitor the output from the card; it raises latency.

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  • unknown2
    replied
    Originally posted by unix_epoch View Post
    "ALSA is useless" "HW mixing fixes that" "HW mixing is useless" Wat?!

    You posed a problem. A solution was offered. You rejected it without justification.

    Also, the dmix buffer size can be adjusted.
    +1

    Gaming software always has a very high CPU usage.

    For software mixing problem, high CPU load always means bad latency for software mixing solution.

    Having a dedicated hardware for sound mixing is always a good idea.

    Take a look on Windows:

    Windows XP: hardware mixing
    Windows 7: change to software mixing which cause serious latency problem http://www.youtube.com/watch?v=iujDVsg_2xY
    Windows 8: http://msdn.microsoft.com/en-us/libr.../br259116.aspx they realize their mistake and go back to hardware mixing again

    I wonder those PA developers will follow the stupid Microsoft again?
    Last edited by unknown2; 11-02-2012, 04:47 AM.

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  • RealNC
    replied
    Originally posted by unix_epoch View Post
    "ALSA is useless" "HW mixing fixes that" "HW mixing is useless" Wat?!
    Where exactly did you see "ALSA is useless" being said?

    You posed a problem. A solution was offered. You rejected it without justification.
    Justification was given. If you want more: this "solution" requires me to buy a new sound card. I already have one for which I paid good money for. If that's what it would take for gaming on Linux, no thanks. I'll keep using Windows for this, since it works awesome there without hardware mixing (which just proves how useless it is).


    Also, the dmix buffer size can be adjusted.
    Is there a "defaults.pcm.dmix.*" option for this? I'd like to try it and see whether audio skipping becomes a problem with smaller buffers.
    Last edited by RealNC; 11-02-2012, 04:39 AM.

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  • unix_epoch
    replied
    Originally posted by RealNC View Post
    That results in the game taking exclusive control of the card. Nothing else will be audible. Which is a disaster. Unless you talk to the dmix device. In that case, you're back to high latency.
    Originally posted by christian_frank View Post
    to be more specific , this is only the fact for non hw mixing cards ...which sadly seem to be very popular nowadays ..i love my hw mixing soundblaster
    Originally posted by RealNC View Post
    HW mixing is useless though. It was nice on my 486. That Gravis Ultrasound rocket the boat. But today, mixing can be done on the CPU so easily, it's not worth having it in HW.
    "ALSA is useless" "HW mixing fixes that" "HW mixing is useless" Wat?!

    You posed a problem. A solution was offered. You rejected it without justification.

    Also, the dmix buffer size can be adjusted.

    Leave a comment:


  • gQuigs
    replied
    Originally posted by ShadowBane View Post
    This is 2012, almost 2013. The mixer being able to change the volumes of applications is useful and rather standard these days.
    That seems like the only benefit for the *average* user, but pretty much no *average* user is ever going to modify per-application volume in this way. A "hack" to allow the volume control applet to directly modify volumes exposed from applications would let us get this benefit, while keeping the stack just ALSA.

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  • ShadowBane
    replied
    Originally posted by AJSB View Post
    2. That's not exactly true....i run pura ALSA and i still can adjust per application volume...each game has i'ts one volume, VLC, IIRC same goes to Flash, etc.etc....do, no need for PA for that....
    This is 2012, almost 2013. The mixer being able to change the volumes of applications is useful and rather standard these days.

    Leave a comment:

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