Re: Dice firewire support

Re: Dice firewire support

[Takashi Sakamoto]

Hi Pascal,

On Fri, May 22, 2020 at 12:51:45AM -0700, bomelp@gmail.com wrote:
> Hi Takashi,
> 
> Sorry if i bother you about my mail.
> Actually, i try to enable a mytek  dsd-192 dac via its firewire port on a debian 4.9.12.
> I saw you worked on snd-dice module.Do you have a step-by-step documentation to help me do that ?
> 
> Best regards
> Pascal
> France

Although I don't test the device, Melvin Vermeeren added support for
Mytek Stereo 192 DSD-DAC in Linux kernel v4.18 firstly. It's not
available in your kernel.
https://www.alsa-project.org/pipermail/alsa-devel/2018-May/136194.html

If you can't work with the device just by loading snd-dice module in
recent Linux kernel, please contact to me or Melvin ;)


Regards

Takashi Sakamoto

Re: Dice firewire support

[Pascal Bomel]

Thank you so much Takashi.
Actually i have a debian 4.9.12 "stretch" release with 4.9.211 kernel
version (uname -v)
This kernel has snd-dice module inside isn't it ?
I am not very familiar with linux, that's why i appreciate your help.

Regards,

Pascal Bomel



Le ven. 22 mai 2020 à 12:10, Takashi Sakamoto <o-takashi@sakamocchi.jp> a
écrit :

> Hi Pascal,
>
> On Fri, May 22, 2020 at 12:51:45AM -0700, bomelp@gmail.com wrote:
> > Hi Takashi,
> >
> > Sorry if i bother you about my mail.
> > Actually, i try to enable a mytek  dsd-192 dac via its firewire port on
> a debian 4.9.12.
> > I saw you worked on snd-dice module.Do you have a step-by-step
> documentation to help me do that ?
> >
> > Best regards
> > Pascal
> > France
>
> Although I don't test the device, Melvin Vermeeren added support for
> Mytek Stereo 192 DSD-DAC in Linux kernel v4.18 firstly. It's not
> available in your kernel.
> https://www.alsa-project.org/pipermail/alsa-devel/2018-May/136194.html
>
> If you can't work with the device just by loading snd-dice module in
> recent Linux kernel, please contact to me or Melvin ;)
>
>
> Regards
>
> Takashi Sakamoto
>

Re: Dice firewire support

[Melvin Vermeeren]

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Hi all,

On Friday, 22 May 2020 11:07:06 CEST Pascal Bomel wrote:
> Thank you so much Takashi.
> Actually i have a debian 4.9.12 "stretch" release with 4.9.211 kernel
> version (uname -v)
> This kernel has snd-dice module inside isn't it ?
> I am not very familiar with linux, that's why i appreciate your help.

You can either upgrade to Debian buster, which has 4.19, or install a kernel 
from stretch-backports, which is also 4.19. Assuming you have amd64 hardware 
that would be https://packages.debian.org/stretch-backports/linux-image-amd64.
See also https://backports.debian.org/Instructions/ for more instructions.

Some background information below, from how I remember things. Do note that 
there were many details and I may be mistaken about some of them.

At the time of 4.18 there was some issue with the timing that caused non-bit-
perfect playback, resulting in audio artefacts that were hard to detect as it 
was near perfect. DSD over PCM (DoP) mode however made it very obvious this 
issue existed, as it would not work reliably at all. It was also noticeable 
when listening to a fixed Hz tone, it wasn't perfectly smooth.

I believe there was some significant refactoring going on with snd_dice at the 
cause, which caused some previously working things to stop working as snd_dice 
became more compliant with device's listed features and protocols.

Older versions "just sent a new stream" when frequency changed (iirc), which 
actually caused the DAC to sometimes not catch the signal and made it silent. 
You then had to restart jack (or ALSA stream) a few times. The new version 
used proper lock mechanism (AMDTP?) meaning it worked 100% of the time, except 
for the non-bit-perfect issue.

Since those days of experimenting I have been running snd_dice and 
snd_firewire_lib from sound-4.4-rc7-692-g2eb65d67afbf out of tree, with minor 
patches to make them compatible with modern kernels and overrides for the DAC.

Thanks for the mention Takashi, I appreciate it. Since I am running 5.5.17 
(buster-backports) kernel right now I will do some testing later today to see 
if there are still any issues in this version, the Mytek is still used daily.

Cheers,

-- 
Melvin Vermeeren

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Re: Dice firewire support

[Melvin Vermeeren]

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Hi Takashi,

On Friday, 22 May 2020 13:36:13 CEST Melvin Vermeeren wrote:
> Since I am running 5.5.17
> (buster-backports) kernel right now I will do some testing later today to
> see if there are still any issues in this version, the Mytek is still used
> daily.

I have just tested it with 5.5.17 and can confirm this issue still exists. It 
is not very noticeable when playing music but it instantly apparent when 
playing a 500hz tone for a few seconds. It sounds there is some small ticking 
in the background instead of a pure tone. Happens every few hundred 
milliseconds or so and is fully consistent, as if a timing or cycle issue.

Next I checked with current master v5.7-rc2-1808-g40e1763b6246 (snd_dice and 
snd_firewire_lib) with the same results. I believe the status is the same 
posted in 2018[1][2]. The old out-of-tree have served me well throughout the 
years, so I will probably keep using them for now. Perhaps this final issue 
will be found one day, if I can help you with anything please let me know.

[1] https://www.alsa-project.org/pipermail/alsa-devel/2018-June/136829.html
[2] https://www.alsa-project.org/pipermail/alsa-devel/2018-June/137160.html

Thanks,

-- 
Melvin Vermeeren

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