[alsa-devel] Hercules P32 DJ: severe sound distortion during MIDI transfers
Guido Trentalancia
guido at trentalancia.com
Fri Mar 22 17:06:22 CET 2019
> On the 22nd of March 2019 at 16.05 Guido Trentalancia <guido at trentalancia.com> wrote:
>
>
> I suppose the Fedora 29 kernels are included in the range I tested as broken, i.e. 4.12 -- 5.0.
I have checked and can now confirm the above, as Fedora 29 kernel is version 4.18.16, therefore included in the same range I tested as broken.
> So, there is something triggering it on my system and not the other, maybe the USB system as pointed out by Clemens.
>
> I'll make some research on the two USB systems...
>
> I would also like to try USB Audio driver from kernel 3.0.1.
>
> What else do you suggest?
>
> Guido
>
> Il 22 marzo 2019 15:58:23 CET, Takashi Iwai <tiwai at suse.de> ha scritto:
> >On Fri, 22 Mar 2019 15:54:03 +0100,
> >Guido Trentalancia wrote:
> >>
> >> As already explained, I have tested the following kernels:
> >>
> >> - kernel 5.0.2 -----> BROKEN
> >> - kernel 4.17.10 --> BROKEN
> >> - kernel 4.12.9 ---> BROKEN
> >>
> >> So, it's been around for very long.
> >>
> >> What do you suggest doing?
> >
> >But which kernel is used for another user who can use without the
> >problem? I suppose they use the recent kernel with Fedora?
> >
> >> I have found reports on the web about similar problems (with other
> >audio
> >> interfaces) with kernels>3.0.0.
> >
> >Such a regression should have been reported earlier, otherwise it
> >becomes more and more difficult to catch up...
> >
> >
> >thanks,
> >
> >Takashi
> >
> >
> >> Regards,
> >>
> >> Guido
> >>
> >> Il 22 marzo 2019 15:47:36 CET, Takashi Iwai <tiwai at suse.de> ha
> >scritto:
> >>
> >> On Fri, 22 Mar 2019 14:44:48 +0100,
> >> Guido Trentalancia wrote:
> >>
> >> Hello Takashi.
> >>
> >> I have carried out the test that you proposed...
> >>
> >> My reply follows your quoted text.
> >>
> >> On Fri, 22/03/2019 at 11.12 +0100, Takashi Iwai wrote:
> >> On Fri, 22 Mar 2019 11:04:01 +0100,
> >> Guido Trentalancia wrote:
> >>
> >> Hello Takashi,
> >>
> >> I am using the latest version of everything,
> >including kernel and
> >> ALSA
> >> userspace library / tools.
> >>
> >> The other user has exactly the same hardware and has
> >tested same
> >> firmware
> >> (both 1.36 and latest
> >> 1.46), but with Fedora 29 and it is working.
> >>
> >> Perhaps Fedora 29 has a different version of the
> >ALSA library, I
> >> will find
> >> out, try to downgrade, test again and report back.
> >>
> >> Yes, that'd be really helpful. If aligning the software
> >doesn't fix
> >> the issue, it's either because of the hardware or the
> >difference of
> >> usage patterns.
> >>
> >> I have tested exactly the same ALSA userspace library and
> >plugins
> >> distributed by Fedora 29 and it does NOT work !
> >>
> >> As already explained, the usage pattern is exactly the same
> >between me
> >> and the user which is not experiencing this severe problem.
> >>
> >> Also, the hardware is the same: Hercules P32 DJ (with
> >exactly the same
> >> firmware version 1.46 which is the latest).
> >>
> >> So, the conclusion is that it must be a kernel bug ! I was
> >expecting
> >> this, as already pointed out in previous messages.
> >>
> >> Did you test the
> >> very same kernel, too? Without that confirmation, no
> >> one can conclude that at all...
> >>
> >> If the kernel makes difference, you can try identify which kernel
> >> version starts showing the problem, and at best, do git
> >bisection.
> >>
> >> thanks,
> >>
> >> Takashi
> >>
> >> Can you please help me fix this bug since you wrote the
> >driver and/or
> >> are maintaining it ?
> >>
> >> Thanks,
> >>
> >> Guido
> >>
> >> thanks,
> >>
> >> Takashi
> >>
> >> Guido
> >>
> >> Il 22 marzo 2019 10:53:11 CET, Takashi Iwai
> ><tiwai at suse.de> ha
> >> scritto:
> >>
> >> On Fri, 22 Mar 2019
> >> 10:17:17 +0100,
> >> Guido Trentalancia wrote:
> >>
> >> It cannot be a firmware bug, as you say,
> >because:
> >>
> >> - it does NOT happen on Windows!
> >>
> >> It doesn't mean that the device behaves
> >correctly as
> >> advertised.
> >>
> >> - it does NOT even always happen on Linux:
> >other users
> >> (with different kernel
> >> / ALSA library) are not experiencing the
> >same problem;
> >> - it happens with several firmware
> >versions, including the
> >> latest one (1.36
> >> and 1.46).
> >>
> >> So it is either a bug in ALSA kernel
> >driver, USB sound
> >> driver (more likely) or
> >> ALSA library.
> >>
> >> Now, you are in charge of the USB sound
> >driver, can you
> >> please double check??
> >>
> >> If it doesn't happen for other users with the
> >very same device,
> >> you'd
> >> need to identify what's the difference
> >> between your case and
> >> others.
> >> For example, if the difference of alsa-lib
> >matters, you can try
> >> the
> >> very same condition.
> >>
> >> This kind of bug can't be easily debugged
> >without the actual
> >> hardware, unfortunately.
> >>
> >> Takashi
> >>
> >> Regards,
> >>
> >> Guido
> >>
> >> Il 22 marzo 2019 09:55:52 CET, Takashi Iwai
> ><tiwai at suse.de
> >> ha scritto:
> >>
> >> On Thu, 21 Mar 2019 23:27:46 +0100,
> >> Guido Trentalancia wrote:
> >>
> >> I wonder if this might be due to a
> >bug in the
> >> "USB Audio Driver for Alsa"?
> >>
> >>
> >https://git.kernel.org/pub/scm/linux/kernel/git/t
> >> orvalds/linux.git/tree/sound/usb
> >>
> >>
> >https://git.kernel.org/pub/scm/linux/kernel/git/t
> >> iwai/sound.git/tree/sound/usb
> >>
> >> More likely a buggy firmware of your
> >USB audio device
> >> :)
> >>
> >> From the driver implementation POV,
> >both audio and
> >> MIDI devices are
> >> handled by individual endpoints, hence
> >they shouldn't
> >> conflict.
> >>
> >> Or another possibility would be some
> >USB host side
> >> issue like the
> >> bandwidth. But
> >> it's a MIDI stream that is very low
> >data rate, so this
> >> sounds also unlikely...
> >>
> >> thanks,
> >>
> >> Takashi
> >>
> >> Guido
> >>
> >> On the 20th of March 2019 at
> >21.47 Guido
> >> Trentalancia
> >> <guido at trentalancia.com wrote:
> >>
> >> Hello.
> >>
> >> I am hitting a very serious
> >bug (ALSA kernel
> >> driver or ALSA library)
> >> when using the Hercules P32 DJ
> >audio
> >> interface.
> >>
> >> The sound is severely
> >distorted during MIDI
> >> transfers.
> >>
> >> To reproduce:
> >>
> >> + start playing something in
> >a first
> >> console:
> >>
> >> console1# AUDIODEV=hw:2,0 play
> >audio.wav
> >>
> >> + the audio plays fine
> >>
> >> + now start "amidi" in a
> >second console
> >> while the above track is still
> >> playing
> >>
> >> console2#
> >> amidi -p hw:2,0,0 -d
> >>
> >> + the sound is now severely
> >distorted
> >> (basically noise, with some
> >> hard-
> >> to-distinguish features
> >resembling the
> >> original track) until "amidi"
> >> is
> >> interrupted !
> >>
> >>
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