Ubuntu Desires Lower Audio Latency For Gaming

[unix_epoch]

Isn't there an API for this thing? Having to configure text files each time I want to change just doesn't cut it, IMO. This is stuff that should be configurable at runtime. Things like that is what make me believe that ALSA should be called LSA instead.

IIRC the last page I linked to is also the libasound API docs. There would be a decent GUI for configuring ALSA, if people hadn't decided to ignore ALSA's entire infrastructure and build sound servers instead. I almost wrote one for a car PC I was building, but the car it was going into was totaled (and there were some issues with ALSA's LADSPA plugin support adding unpredictable latency) so it never happened.

[unix_epoch]

Different people have different needs. Onboard sound cards and my discrete sound card support 192 kHz. That $235 sound card has some crappy parts if it supports only 96 kHz.
HW mixing can be advantage in some cases, but it isn't option in many cases. If I would have to buy new sound card tomorrow I would still buy sound card without HW mixing because there is no reasonable priced card with HW mixing
which provides high quality sound to my headphones, which is most important to me. Using two sound cards is unacceptable because it isn't possible to connect one headphones to two sound cards at same time.

Your onboard sound card's "192kHz" probably rolls off significantly above 20-30kHz, with a much higher noise floor. Pay no attention to the sample rate. Unless you are working with ultrasound, the most important factors are measured frequency response, noise floor, jitter, and distortion. For final playback, 44.1k should be enough according to http://people.xiph.org/~xiphmont/demo/neil-young.html.

You can use two sound cards at the same time by passing the line output of one to the line input of the other, then your headphones into the headphone output of the second. Finally, unmute the Line In on your second sound card's mixer.

[thofke]

As this is a thread about latencies, if anybody is interested in frame latencies in Doom 3, please see my thread in the Gaming section:
Frame latency analysis on Doom 3

[ShadowBane]

My PA latency is currently bouncing between 7 and 9 ms, never going above 10. If the average on ubuntu is 25ms they are doing something wrong.

(you can check your latency with 'pacmd list-sinks', it will print out a bunch of info about each sink, including the current latency.)

[Detructor]

No, they cannot. You're confusing the dmix device with the hardware device.

uhm, dmix is part of ALSA. So yes, it (ALSA) can do software mixing. Also dmix is (usually) enabled by default (unless the sound card is able to do hardware mixing or you are using a very weird system with very strange options on the compiler side. I've never seen a linux system with ALSA that was not able to softwaremix without a soundserver. And I've seen quite some systems).

[RealNC]

uhm, dmix is part of ALSA. So yes, it (ALSA) can do software mixing. Also dmix is (usually) enabled by default (unless the sound card is able to do hardware mixing or you are using a very weird system with very strange options on the compiler side. I've never seen a linux system with ALSA that was not able to softwaremix without a soundserver. And I've seen quite some systems).

I already mentioned that in the post.

What on earth are you arguing about?

[Paradox Uncreated]

If they want lower latency for games, and also less-jitter (better performance) they need to enable low-latency desktop.
That alone will improve latency to probably around 1ms. And makes games graphics so much better aswell.

With a professional firewire audiocard, I have actually run audio at 0.33ms latency with a custom kernel. This does not seem to work on standard HDA chips though, but 1ms will do. And 0.33ms latency uses a great amount of CPU. So, for the time being, until audio-subsystem is optimized for low latency, 1ms will be good enough, and if you want to ensure minimal cpu usage, just set it to 5ms latency, for normal "close" pc-speakers or monitors, and it will be fine aswell.

That does not mean I don`t want lower, but at the current time being, I would recommend that. Ultimately 0.2ms latency, should give a "close to hardware" feeling.

PS: Ubuntu might need realtime group, to a higher priority, to run 0.33ms latency.

Peace Be With You.

[Detructor]

I already mentioned that in the post.

What on earth are you arguing about?

you wrote it in a way that made it seem as if dmix was some sort of virtual device, unrelated to alsa.