Aaugh! Sound devices changed again!

[jdow]

On 2015-09-02 05:20, Ian Malone wrote:
> On 2 September 2015 at 12:27, Tom Horsley <horsley1953 at gmail.com> wrote:
>> Every single fedora release, and sometimes even just from
>> an update where there wasn't a full release, the sound
>> devices get renumbered or renamed. The last time I
>> tried to play a movie and send the sound to the optical
>> output connected to my receiver, this worked:
>>
>> pacmd set-card-profile 1 off
>> mplayer -vo gl_nosw -ao alsa:device=hw=1.1 -ac hwdts,hwac3, -monitoraspect 16:9 -fs "$@"
>>
>> I tried it last night for the first time in a while, and
>> it doesn't work. I've had to fiddle this script over and
>> over again every time sound devices change.
>>
>> When are we going to get immutable names for sound devices?
>> If they can do it for ethernet ports, surely they can
>> do it for sound cards, right? (Though come to think of it
>> the "immutable" ethernet port names change in every release
>> as well :-).
>>
>
> cat /proc/asound/cards
>   0 [PCH            ]: HDA-Intel - HDA Intel PCH
>                        HDA Intel PCH at 0xf6420000 irq 82
>   1 [NVidia         ]: HDA-Intel - HDA NVidia
>                        HDA NVidia at 0xf6080000 irq 36
>
> The text in [] can be used as an alsa device name. You can still add
> the "," for sub devices.

There is a basic problem here. Cheap USB audio devices tend to behave "cheap". 
They have no distinguishing features between the dongles. And they are not 
always found in the same order when you reboot the machine despite their USB 
address not changing. I have seen this with USB sound dongles, MIDI dongles, and 
DVB dongles (as used for ultra cheap SDRs.)

The only solution is to develop a tool that can change serial numbers or other 
identification in the dongles, if an eeprom facility is present, or relying on 
the user never changing the USB address. In the latter case the name could be 
followed by " 0/2/4/6" or "0246" for the USB address path though root hub and 
intermediate hubs to the final device.

Sounds kludgey? Yup. But it can work. Meantime it's not useful to purchase two 
or three of the same dongle in many cases. Purchase completely differnet 
dongles. They may have different names and can distinguish themselves that way.

{^_^}