Re: [LAU] Fwd: Re: Raspberry Pi and real-time, low-latency audio

From: Carlos sanchiavedraz <csanchezgs@email-addr-hidden>
Date: Wed May 08 2013 - 15:04:49 EEST

2013/5/5 Carlos sanchiavedraz <csanchezgs@email-addr-hidden>:
> 2013/5/3 Carlos sanchiavedraz <csanchezgs@email-addr-hidden>:
>> Hello all,
>>
>>
>> 2013/4/23 Carlos sanchiavedraz <csanchezgs@email-addr-hidden>:
>>> 2013/4/22 Nicola <nicola.di.marzo@email-addr-hidden>:
>>>> Il 22/04/2013 09:46, Carlos sanchiavedraz ha scritto:
>>>>
>>>>> 2013/4/19 Nicola <nicola.di.marzo@email-addr-hidden>:
>>>>>>
>>>>>> Il 19/04/2013 19:54, Jeremy Jongepier ha scritto:
>>>>>>
>>>>>>> On 04/19/2013 11:11 AM, Nicola wrote:
>>>>>>>>
>>>>>>>> That's great, "keep it simple" i should say...that's why i think it's
>>>>>>>> brilliant!
>>>>>>>
>>>>>>>
>>>>>>> Keep an eye on http://ampbrownie.com/ then, it's an effort to make it
>>>>>>> even
>>>>>>> simpler.
>>>>>>

>> [...]

(On last few days I sent two more responses but... only to Nicola
instead to the list, so here they are. Things that happen.
And I add one more step)

>>
>> I gave it another shot.
>> This time around I started with a stock Wheezy Raspbian
>> (2012-12-16-wheezy-raspbian) and executed inside the Ambrownie config
>> script.
>>
>> Step 1, raspi-config, went well except for an error when trying to
>> expand the memory. Well, I think it is because it is fixed to expand
>> an sd card at /dev/mmcblk0 and I'm using an usb stick at sda. This is
>> no problem for the moment.
>>
>> Step 2, updating and installing specific packages from autostatic and
>> others, went well or it seemed so. I connect through "ssh -X" and
>> executed Qjackctl to make first config, but every time I tried to
>> start Jack it throws an error that it cannot start. Tried different
>> configs but no luck.
>> I didn't connect any soundcard yet.
>>
>> I would like to know if anybody tried this script with success.
>>
>> Regards.
>>
>> --
>> Carlos sanchiavedraz
>> * Musix GNU+Linux
>> http://www.musix.es
>
> A few steps ahead more.
>
> I red again the wiki and got to start Jack with the onboard soundcard
> just as it says: jackd -d dummy.
>
> Then I tried to start jack with the UA25EX. I pluged the usb/power
> cable to a laptop this time, instead of using the mobile usb charger
> as before, and RPi doesn't reboot. Great.
> Now I tried to start jack on RPi through Qjackctl on the laptop with
> ssh -X. Jack crashed every time. I tried on RPi itself and same thing.
> Then I checked jack log, ps -A and realized that pulseaudio was
> running and jack couldn't have access to the device. I made a quick
> search and then I made two things:
>
> 1) created a config file to prevent pulseaudio to restart every time
> It is killed: ~/.pulse/client.conf with "autospawn=no" inside.
>
> 2) kill pulseaudio with "pulseaudio -k" when I run jack, and
> configured same thing on Qjackctl preferences to execute it before
> starting jack.
>
> So now I have an RPi that can start jack using UA.
> But now there is the next problem: jack starts ok but when I try to
> connect any program (sooperlooper i.e.) or just system-in to
> system-out ports the driver crashes (that what messages say), lights
> on UA switch off and, oddly enough, jack still running.
>
> That's it for the moment.
>
>
>
>
>
> --
> Carlos sanchiavedraz
> * Musix GNU+Linux
> http://www.musix.es

One step more, this time with success.
Given the situation mentioned before I tried to step back a little.

First, I tried only to run jack using jackstart script again. A few
tweaks and could make jack to work, but sound had glitches and
crackles whatever config I tried.

Second, I stepped back a little more.
I executed again Ampbrownie setup.sh with option 2 (update and install
additional packages). During this it changed jackd2 to jack1
uninstalling it. This could be installed before as a dependence of
some of the apps I installed in addition to those that setup.sh script
install (maybe sooperlooper or rakarrack, not sure).
Then, I noticed during rebooting that USB is only 1.1, so I changed
the hardware switch on the back of the UA from advanced driver to
normal.

One more reboot and... Voila! Sounds was almost perfect and delay
acceptable, practically RT, connecting in to out and using Rakarrack
with some basic effects.

Don't know if this success is due to some newer versions it appears to
have been updated on repos that are newer than those installed on
first run of setup.sh, or maybe some of the modifications mentioned
flicked the switch.

I made a backup with dd, of course, and I'm moving towards setting up
RPi as a Jam/Improv/Live headless station: boot an then run Rackarrack
as a multifx connected to Sooperlooper/Freewheeling as a looper, using
an external audio card and a MIDI-USB pedalboard. And then improving
step by step until reaching the limit on RPi processing and
overclocking.

In the future I have more plans in mind, but for now that's it.

BTW, I managed to connect a second usb device without RPi rebooting
because of problems with power with two USB power adapters.
So now I have:
- 1 USB power adapter to the RPi,
- 1 USB stick for the system partition on USB port1,
- 1 4 USB hub on USB port 2 (where external audio card and MIDI-USB
pedalboard is connected)
- 1 USB power adapter to the second mini-USB port on the MIDI-USB
pedalboard that helps to feed it and to stable the overall setup.

I think both USB power adapters are mobile adapters, I think 0,7A and
0,5A, so maybe with just one USB power adapter at 2A for the RPi I
could connect all this and a qwerty keyboard and something else, which
now I can't. That or just a powered USB hub, but that is more
expensive.

Hope it helps.
Thanks all and Regards.

-- 
Carlos sanchiavedraz
* Musix GNU+Linux
  http://www.musix.es
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Received on Wed May 8 20:15:02 2013

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