Messages in this thread |  | | Date | Sat, 10 Feb 2001 23:32:55 +0100 | From | Pavel Machek <> | Subject | Re: Inadmissible sound dropouts on 2.2.18 |
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Hi!
> I found that 2.2.18 probably rudely drops samples (lets ocassionally one sample > be played several times) on the Gravis Ultrasound output device. I use 2.2.18 > and the native kernel drivers. I wrote this program that should produce a clean > sine tone. Instead I hear a sine interspaced with crackling. The crackling > repeats at 100Hz I guess. There runs nothing CPU-consuming. The sound process > takes 5% CPU. It's funny Linux drops sound samples just at 5% of CPU load. I > got AMD K6-2 3D 400Mhz at 400Mhz, 4*100MHz, running stably between 20-35 deg C > of case temperature. I got PCI / AGP board FIC VA-503+. There are three serial > ports, none of them was transceiving at that time. There is one ISA > NE2000 NIC
And receiving?
There are tools for measuring latency problems. Look at kernel archives.
> The crackling is not dependent on the buffer size you can set up in the C code. > The crackling is dependent on the frequency of the sine. It's clearly audible > (read: annoying) at 10kHz, audible at 1kHz, inaudible at 100Hz. So I think > they are sample dropouts - the card stops playing and repeats one sample until > kernel gets the breath and whips itself up to supply next audio > data.
Or it is just Graivs driver bug...
> There are no custom changes in the drivers - no buffer tweaking, nothing. The > Gravis plays modules, midules and mp3 with nearly no problems (apart from when > Loreena Mc Kennith sings too high and too loud, I hear something that looks like > MP3 frames bounds, but I can't surely tell who's responsible for this - if the > Fraunhofer Institute or Linux Kernel)
;) Or maybe problem is in your application. Can you generate sample file than "play" it with cat samples > /dev/dsp? You can do it on different machines to learn if it is gravis or something else.
Pavel PS: I think it is your app that is buggy. You write to soundcard, then you do _lots_ of floating point computation, then you write again.... If your computtation takes too long, you'll hear cracking... Of course. You wrote latency critical app!
-- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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