[LAU] make alsa device hw:1,0 be hw:0,0 somehow

[Paul Davis]

Oh, one other thing. Using PortAudio will *not* reduce latency. JACK
does not add any latency.

On Sun, Oct 4, 2015 at 6:46 PM, Paul Davis <paul at linuxaudiosystems.com> wrote:
> This can be hard to do. Why can't you tell software to use hw:1 ?
>
> Most system BIOS setup utilities can be used to disable onboard sound.
> Getting Linux to reorder them is also possible but can be complex
> depending on the types of devices (PCI, USB etc)
>
> On Sun, Oct 4, 2015 at 2:57 PM, ansible <bburdette at gmail.com> wrote:
>> I compiled supercollider to play through portaudio rather than jack, as it
>> usually does, in an attempt to reduce latency and hassle.  It works for
>> audio device hw:0,0, but it doesn't work for hw:1,0.  My problem is that on
>> my device hw:0,0 has horrible latency - 70ms - while hw:1,0 has 9ms latency,
>> much better.
>>
>> So what I'd like to do is reorder the audio devices, or disable the onboard
>> audio, and have my current hw:1,0 be the hw:0,0 device.  Hopefully then
>> supercollider will work with it and I'll have those coveted low latency
>> numbers.  This is on arch linux on a bananapi armv7 computer.
>>
>> So here's the output from aplay -l:
>>
>> ```
>> [bananapi at lemaker ~]$ aplay -l
>> **** List of PLAYBACK Hardware Devices ****
>> card 0: sunxicodec [sunxi-CODEC], device 0: M1 PCM [sunxi PCM]
>>   Subdevices: 1/1
>>   Subdevice #0: subdevice #0
>> card 1: Pro [Sound Blaster X-Fi Go! Pro], device 0: USB Audio [USB Audio]
>>   Subdevices: 1/1
>>   Subdevice #0: subdevice #0
>> [bananapi at lemaker ~]$
>> ```
>>
>> According to the [alsa wiki][1], I should be able to reorder the devices
>> using a .conf file. See 'set the default sound card'.  It gives the example
>> of this:
>>
>> ```
>> /etc/modprobe.d/alsa-base.conf
>>
>> options snd_mia index=0
>> options snd_hda_intel index=1
>> ```
>>
>> Ok so I made a file like that, but I only know the name of the usb driver,
>> not the onboard sound driver.  lsmod reveals the following:
>>
>> ```
>> [bananapi at lemaker ~]$ lsmod
>> Module                  Size  Used by
>> snd_usb_audio          96225  0
>> snd_hwdep               5757  1 snd_usb_audio
>> snd_usbmidi_lib        18033  1 snd_usb_audio
>> cdc_acm                20518  0
>> spidev                  6217  0
>> spi_sun7i              17802  0
>> sunxi_cedar_mod         9808  0
>> mali_drm                2608  0
>> drm                   209226  1 mali_drm
>> mali                  111427  0
>> disp_ump                 861  0
>> ump                    52415  2 mali,disp_ump
>> ap6210                584133  0
>> ip_tables              12937  0
>> x_tables               17443  1 ip_tables
>> ```
>>
>> If I do "modprobe -r snd_usb_audio", then snd_hwdep and snd_usbmidi_lib both
>> disappear too, so they are all for the same device I think.  That leaves
>> nothing for the driver name for the onboard audio.
>>
>> The alsa wiki says that the driver names should be in "cat
>> /proc/asound/modules" but I don't have that directory on my system.
>>
>> So anyway I made an alsa-base.conf file as directed, which looks like this:
>>
>> ```
>> [bananapi at lemaker ~]$ cat /etc/modprobe.d/alsa-base.conf
>> options snd_usb_audio index=0
>> options sunxicodec index=1
>> [bananapi at lemaker ~]$
>> ```
>>
>> After creating that file and rebooting aplay just returns this.
>>
>> ```
>> [bananapi at lemaker ~]$ aplay -l
>> **** List of PLAYBACK Hardware Devices ****
>> card 0: sunxicodec [sunxi-CODEC], device 0: M1 PCM [sunxi PCM]
>>   Subdevices: 1/1
>>   Subdevice #0: subdevice #0
>> [bananapi at lemaker ~]$
>> ```
>>
>> So this alsa-base.conf has the effect of making only the onboard audio
>> available instead of reordering.  I most likely have the 'sunxicodec' name
>> wrong for the onboard audio, I'm just guessing at that, and have no idea
>> what the driver name for that is, if there even is one.  I'm kind of
>> suspecting the audio device is part of a monolithic driver for the whole
>> system-on-chip, is that possible?
>>
>>   [1]:
>> https://wiki.archlinux.org/index.php/Advanced_Linux_Sound_Architecture
>>
>>
>>
>> --
>> View this message in context: http://linux-audio.4202.n7.nabble.com/make-alsa-device-hw-1-0-be-hw-0-0-somehow-tp97402.html
>> Sent from the linux-audio-user mailing list archive at Nabble.com.
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