[LAU] Re: Jack Frames/Period setting with Firewire

> #2. Generic Kernel is useless for Audio.
    install lowlatency kernel &/or liquorix kernel.

This is no longer true. Generic kernels contain more or less the entire
RT-PREEMPTION patch set these days, and will function at least well as the
so-called low-latency kernel. If you want to do better, you need the "RT"
kernel provided by your distro, not the "low latency" one.

On Tue, Apr 8, 2025 at 8:07 AM Juan P C <[email protected]> wrote:

> #1. most computers cannot do better than 7 or 8 miliseconds AD-DA
> latency...
> Buffer size is different in different interfaces: PCI, USB, FireWire...
> ADC & DAC chips have more latency if are 1st gen "older",
>
> USB: 256x2 is much better vs. 128x5
> has the same audio latency measured with an oscilloscope,
> but CPU works relaxed with 256x2 = less Xruns.
>
> #2. Generic Kernel is useless for Audio.
> install lowlatency kernel &/or liquorix kernel.
>
> #3. RME hdsp 9632 pci alsa driver works ok up to 2013,
> since 2013, source code has small "Cosmic Ray Bit Flips",
> RME Alsa driver has weird glitches,
> because Alsa driver is Not activated permanently,
> driver activates every-time i pay an audio file, and deactivates when
> audio stops,
> the first 7 seconds of audio buffer are corrupted.
>
> but Jack is Activated continuously,
> it does Not matter.
>
> #4. when using low latency:
> requires CPU running Fast all the time "Performance" mode,
> install cpupower-gui
> or similar
> and
> CPU-X
> to verify CPU speed.
>
> some Linux Generic Kernels, when are "On Demand"
> does Not allow Single core CPU to reach 100%, are limited to 50%.
> "to save battery power."
>
> #5. Pulse audio requires manual configuration to change sample rate to
> 48KHz or more,
> and Bit Depth from 16 to 24 or more.
> if you play a 48KHz-24-Bits file using PulseAudio,
> PulseAudio will convert to 44.1KHz,-16-Bits
> same:
> some versions of VLC only play at 44.1KHz has a Bug,
> even if PulseAudio .config is set ok.
>
> #6.
> i have the temptation to buy a Digidesign 003
> would be interesting to test.
>
> Digi002 had terrible sound, requires too much modifications.
> Digi001 had nice sound, transparent, PCI but does Not have Alsa driver.
>
> ________________________________________
> From: Florian Paul Schmidt <[email protected]>
> Sent: Tuesday, April 8, 2025 2:02 AM
> To: linux-audio-user-cunTk1MwBs/[email protected]; Jay Thomas
> Subject: [LAU] Re: Jack Frames/Period setting with Firewire
>
> On April 7, 2025 8:36:15 PM GMT+02:00, Jay Thomas <[email protected]>
> wrote:
> >Hello
> >
> >I am having difficulty setting Frames/Period for Jack at 128 to keep the
> >system from having stuttering audio quality.  The highest I can go is 64
> >but that is not high enough to resolve the stuttering issue.   Jack
> >complains of ALSA not being able to set the parameters: "ERROR: ALSA:
> >cannot set hardware parameters for capture"
> >
> >The driver being used is snd-fireworks.  This module has a config
> parameter
> >called resp_buf_size that can be set to 4096 maximum.  So when I set this
> >parameter to 4096, I still have trouble setting the Frames/Period in Jack
> >to 128.  It would seem that one would expect that 4096 would be good
> enough
> >since I am using an AudioFire device with 16 channels being sent over the
> >FW bus.  1 sample = 4 bytes.  4 bytes x 16 channels x 128 = 4096.  So this
> >figure of 4096 bytes is enough to hold 128 samples of 16 channels of
> audio.
> >
> >Is there another driver module configuration parameter that I need to
> >change instead of the snd-fireworks parameter such that ALSA will be able
> >to set the requested buffer size that propagates down from Jack config?
> >
>
> Hi, sorry for top-posting.
>
> A buffer needs to hold at least two periods for jackd. And two times 64 is
> 128.
>
> Regards,
> FPS
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