[alsa-devel] Hercules P32 DJ: severe sound distortion during MIDI transfers
Guido Trentalancia
guido at trentalancia.com
Fri Mar 22 16:05:17 CET 2019
I suppose the Fedora 29 kernels are included in the range I tested as broken, i.e. 4.12 -- 5.0.
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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