Hi Developpers.
I was directed there by a more advanced user ( http://linuxmusicians.com/viewtopic.php ... 0&start=15 ).
I'm sorry if I didn't reach to find information elsewhere, so feel free to sincerely say I post here in a wrong place so that I don't hope more.
First allow me to introduce the enviromnent I'm stuck in:
New in Computer Aid Music and linux, I have distant friends I'd like to jam with over the web and I found a gentle App called Jamulus for this aim. I have no analog input in my laptop but the embeded mic. But I have an external USB audio box with a bass/guitar input, a line input too, and a single line/phone out.
Unfortunately the Jamulus app requires sampling rate to be 48kHz and pops up a warning then quits when I set up jack to use the external audio box even though I set up jack to use 48000Hz. When set this way I see jack fallback to 44100 in qjackctl main window, confirmed in verbose messages mode.
When using the internal audio chip in jack, the app launches ok and jack shows 48000, but this is not useful to jam.
I try to understand what my problem is. I got usb dumps from my laptop and an other one from my dad windows pc with Thesycon usb dumper, but both are difficult to understand.
I also tried to use the supported way by the manufacturer (windows, the korg px5d usb-asio driver, and the bundled app Ableton - is called a DAW): there, when using korg driver it seems only 44k1 is available. When using instead MME/DirectX driver I can select any 6 rates between 22k05 and 96k including 48k, and I can hear the test sound in the headphone and set quality and I/O buffers for latency according to CPU usage simulation. I didn't yet try other things like Asio4All nor the Jamulus windows version nor even all that with wine.
Please tell me if I have any chance to freely jam with my linux laptop (I kept the dumps if useful, and I also found the box's usb-chip datasheet - it is said usb 1.1 and usb-app 1.0 compliant, and search through the datasheet shows even 96k capabilities).
Thank you in advance.
Hardware sampling frequency
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linuxdsp
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Re: Hardware sampling frequency
From a look at the manual and a look around the internet, it seems the PX5D can only do 44100 sample rate (even though the chip can, in theory, go to 96K, it seems likely that korg hasn't implemented this option - either in the hardware, and it seems not to be present in their drivers). So, when you ask Qjackctl to start JACK at 48K, (Qjackctl is just a graphical front end for JACK) - it passes the requested parameters to JACK (Qjackctl doesn't / can't tell what your soundcard / interface can do) and JACK fails - most likely because it can't configure the audio interface for the requested 48K.
In Windows, if you use the MME driver, it will perform software sample-rate conversion (at the expense of CPU and latency) - so the interface is still running at 44100 but appears to other software as if it is running at any of the other selected rates - the driver is doing the conversion, although obviously at 'higher' rates than 44100 you don't get any of the benefits you would do if the hardware were running natively at that higher rate since it is still locked to 44100.
I'm not aware of any equivalent mechanism for running JACK (reliably) with software sample-rate conversion, which means that unless your application can be configured to work at 44100 you are unlikely to be successful with this interface (on linux) - you will most likely find that trying to jam live via the internet is totally unsatisfactory anyway - for many of other reasons..
In Windows, if you use the MME driver, it will perform software sample-rate conversion (at the expense of CPU and latency) - so the interface is still running at 44100 but appears to other software as if it is running at any of the other selected rates - the driver is doing the conversion, although obviously at 'higher' rates than 44100 you don't get any of the benefits you would do if the hardware were running natively at that higher rate since it is still locked to 44100.
I'm not aware of any equivalent mechanism for running JACK (reliably) with software sample-rate conversion, which means that unless your application can be configured to work at 44100 you are unlikely to be successful with this interface (on linux) - you will most likely find that trying to jam live via the internet is totally unsatisfactory anyway - for many of other reasons..
Re: Hardware sampling frequency
Thank you for your reply dsp.
I understand I will not even try with wine which would make overall things worse introducing added latency... if it ever works. My only way is now to make my own point of view about jamming over the web by switching to pure windows. If it works there (I still believe it works by the simple existence of a dedicate app), I maybe visit linux again at the added cost of another generic usb box with native 48k in linux and plug the PX5D in it the good old TRS/XLR way (good idea? any advise?).
Although, I'll have a look at the app developer site if a reply is* there to give any hope for 44k1 support (it maybe difficult as it seems to me the 48k is a minimum de facto standard to which maybe everybody would comply in a client-server app - too much burden for the server to handle various sampling rate, maybe, just in my mind, to sync all that stuff).
Thank you very much again for the time you spent for me.
Bye bye
*[edit]: there was, far better said I would be able: https://sourceforge.net/p/llcon/feature-requests/44/
[edit later]: I tried with windows and the korg asio driver is stuck to 44k1, no way to use Jamulus. Asio4all won't allow 44k1 neither. This hardware is 44k1 locked by korg. Now desperately trying to have alsa help.
I understand I will not even try with wine which would make overall things worse introducing added latency... if it ever works. My only way is now to make my own point of view about jamming over the web by switching to pure windows. If it works there (I still believe it works by the simple existence of a dedicate app), I maybe visit linux again at the added cost of another generic usb box with native 48k in linux and plug the PX5D in it the good old TRS/XLR way (good idea? any advise?).
Although, I'll have a look at the app developer site if a reply is* there to give any hope for 44k1 support (it maybe difficult as it seems to me the 48k is a minimum de facto standard to which maybe everybody would comply in a client-server app - too much burden for the server to handle various sampling rate, maybe, just in my mind, to sync all that stuff).
Thank you very much again for the time you spent for me.
Bye bye
*[edit]: there was, far better said I would be able: https://sourceforge.net/p/llcon/feature-requests/44/
[edit later]: I tried with windows and the korg asio driver is stuck to 44k1, no way to use Jamulus. Asio4all won't allow 44k1 neither. This hardware is 44k1 locked by korg. Now desperately trying to have alsa help.