[alsa-devel] Hercules P32 DJ: severe sound distortion during MIDI transfers
Guido Trentalancia
guido at trentalancia.com
Fri Mar 22 15:54:03 CET 2019
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?
I have found reports on the web about similar problems (with other audio interfaces) with kernels>3.0.0.
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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