[alsa-devel] New sound device question

Laurent Epinat l.epinat at free.fr
Sun Dec 26 21:11:32 CET 2010


Thanks for the answer

Le 26.12.2010 12:20, Clemens Ladisch a écrit :
> Laurent Epinat wrote:
>> I try to developpe a usb sound driver for a Alesis Multix 8 USB2.0
>> http://www.alesis.com/multimix8usb20
>> The output interface is allready fonctional, but the Input not :-(
>> Because there is 2 end point for it. The first one is on Isochronous
>> mode and the other is on Bulk mode
>> I don't know how to declare the second endpoint in the quirks_table.
> There is no predefined quirk for such an endpoint; you'd have to write
> your own code.
>> Where can I get a good documentation or help about the alsa USB sound
>> structure.
> At the moment, the only documentation is the source code.
>> The only informations I have about the devices, are dump from windows
> What is the bulk endpoint used for?

I don't know exactly,
I think the Isochrone endpoint is used for control and the bulk one is 
the data, because the size is bigger and the interval is short than the 
isochrone one

on the device you can record 10 inputs channels at the same time

Interface Descriptor:
    bLength                 9
    bDescriptorType         4
    bInterfaceNumber        1
    bAlternateSetting       1
    bNumEndpoints           2
    bInterfaceClass       255 Vendor Specific Class
    bInterfaceSubClass      0
    bInterfaceProtocol      0
    iInterface              0
    Endpoint Descriptor:
       bLength                 7
       bDescriptorType         5
       bEndpointAddress     0x81  EP 1 IN
       bmAttributes            5
         Transfer Type            Isochronous
         Synch Type               Asynchronous
         Usage Type               Data
       wMaxPacketSize     0x0040  1x 64 bytes
       bInterval               4
    Endpoint Descriptor:
       bLength                 7
       bDescriptorType         5
       bEndpointAddress     0x86  EP 6 IN
       bmAttributes            2
         Transfer Type            Bulk
         Synch Type               None
         Usage Type               Data
       wMaxPacketSize     0x0200  1x 512 bytes
       bInterval               1

> Regards,
> Clemens


More information about the Alsa-devel mailing list