FW: Trouble with Mixer Unit
FW: Trouble with Mixer Unit
- Subject: FW: Trouble with Mixer Unit
- From: "Mark Rowan" <email@hidden>
- Date: Fri, 11 Jun 2004 14:10:27 -0500
Hi all,
I am evaluating an AKM USB audio device (AK4571). It has a ROM-based
descriptor set that instantiates one mono upstream channel and a stereo
downstream audio path (the relevant descriptors included below). Also,
I'm double posting this to USB and CoreAudio lists.
One feature of the chip is a 'Mixer Unit' that allows monitoring of the
microphone input on both of the stereo output channels.
On a Mac (15" G4 Powerbook), the input and output streams work
separately (i.e. I can record from the mic and I can listen to playback
on the headphone out), but it appears the Mixer Unit is not working at
all. Are there any known problems with Mixer Units on Mac?
Using 'Audio MIDI Setup', I see where the input properties have a check
box for 'Thru', next to the 'Mute' select. This box is active (I can
check it on or off) for the AKM device, but it doesn't have any effect
on the audio output. Therefore, I wasn't sure if the 'Thru' box was
enabled by the Mixer Unit or not. I did notice that the 'Built-in
Audio' properties offered the same check box and other audio devices w/o
Mixer Units didn't enable the check box.
Using GarageBand, I could monitor the mic input if the armed recording
track was configured for monitoring, but my understanding of the 'Mixer
Unit' function was that I should be hearing a summation of input and
playback even with monitoring turned off. Leaving monitoring 'on'
should result in hearing the recorded track 'doubled', in effect getting
'live' and 'slightly delayed playback' both.
On a Windows machine the unit worked as intended immediately on plug-in,
no configuration or driver updates was needed.
Any insights appreciated.
Partial Descriptor list follows: (I tried posting all the descriptors
and got a 'message too large' error
This includes all the control and feature unit descriptors now
=========================================
Device Descriptor:
bcdUSB: 0x0110
bDeviceClass: 0x00
bDeviceSubClass: 0x00
bDeviceProtocol: 0x00
bMaxPacketSize0: 0x08 (8)
idVendor: 0x0556 (Asahi Kasei Microsystems Co., Ltd)
idProduct: 0x0004
bcdDevice: 0x0100
iManufacturer: 0x01
0x0409: "AKM "
iProduct: 0x02
0x0409: "AK4571 "
iSerialNumber: 0x00
bNumConfigurations: 0x01
ConnectionStatus: DeviceConnected
Current Config Value: 0x01
Device Bus Speed: Full
Device Address: 0x01
Open Pipes: 1
Endpoint Descriptor:
bEndpointAddress: 0x83
Transfer Type: Interrupt
wMaxPacketSize: 0x0001 (1)
bInterval: 0x40
Configuration Descriptor:
wTotalLength: 0x011C
bNumInterfaces: 0x04
bConfigurationValue: 0x01
iConfiguration: 0x00
bmAttributes: 0x80 (Bus Powered )
MaxPower: 0x31 (98 Ma)
Interface Descriptor:
bInterfaceNumber: 0x00
bAlternateSetting: 0x00
bNumEndpoints: 0x00
bInterfaceClass: 0x01 (Audio)
bInterfaceSubClass: 0x01 (Audio Control)
bInterfaceProtocol: 0x00
iInterface: 0x00
Audio Control Interface Header Descriptor:
bLength: 0x0A
bDescriptorType: 0x24
bDescriptorSubtype: 0x01
bcdADC: 0x0100
wTotalLength: 0x0065
bInCollection: 0x02
baInterfaceNr[1]: 0x01
baInterfaceNr[2]: 0x02
Audio Control Input Terminal Descriptor:
bLength: 0x0C
bDescriptorType: 0x24
bDescriptorSubtype: 0x02
bTerminalID: 0x03
wTerminalType: 0x0101 (USB streaming)
bAssocTerminal: 0x04
bNrChannels: 0x02
wChannelConfig: 0x0003
iChannelNames: 0x00
iTerminal: 0x00
Audio Control Output Terminal Descriptor:
bLength: 0x09
bDescriptorType: 0x24
bDescriptorSubtype: 0x03
bTerminalID: 0x04
wTerminalType: 0x0301 (Speaker)
bAssocTerminal: 0x03
bSoruceID: 0x08
iTerminal: 0x00
Audio Control Input Terminal Descriptor:
bLength: 0x0C
bDescriptorType: 0x24
bDescriptorSubtype: 0x02
bTerminalID: 0x01
wTerminalType: 0x0201 (Microphone)
bAssocTerminal: 0x02
bNrChannels: 0x01
wChannelConfig: 0x0000
iChannelNames: 0x00
iTerminal: 0x00
Audio Control Output Terminal Descriptor:
bLength: 0x09
bDescriptorType: 0x24
bDescriptorSubtype: 0x03
bTerminalID: 0x02
wTerminalType: 0x0101 (USB streaming)
bAssocTerminal: 0x01
bSoruceID: 0x05
iTerminal: 0x00
Audio Control Feature Unit Descriptor:
bLength: 0x08
bDescriptorType: 0x24
bDescriptorSubtype: 0x06
bUnitID: 0x05
bSourceID: 0x07
bControlSize: 0x01
bmaControls[0]:
03
iFeature: 0x00
Audio Control Feature Unit Descriptor:
bLength: 0x08
bDescriptorType: 0x24
bDescriptorSubtype: 0x06
bUnitID: 0x06
bSourceID: 0x01
bControlSize: 0x01
bmaControls[0]:
03
iFeature: 0x00
Audio Control Feature Unit Descriptor:
bLength: 0x0D
bDescriptorType: 0x24
bDescriptorSubtype: 0x06
bUnitID: 0x08
bSourceID: 0x09
bControlSize: 0x02
bmaControls[0]:
01 01
bmaControls[1]:
02 00
bmaControls[2]:
02 00
iFeature: 0x00
Audio Control Mixer Unit Descriptor:
bLength: 0x0D
bDescriptorType: 0x24
bDescriptorSubtype: 0x04
bUnitID: 0x09
bNrInPins: 0x02
baSourceID[1]: 0x06
baSourceID[2]: 0x03
bNrChannels: 0x02
wChannelConfig: 0x0003
iChannelNames: 0x00
bmControls:
00
iMixer: 0x00
Audio Control Selector Unit Descriptor:
bLength: 0x07
bDescriptorType: 0x24
bDescriptorSubtype: 0x05
bUnitID: 0x07
bNrInPins: 0x01
baSourceID[1]: 0x01
iSelector: 0x00
Mark Rowan
Griffin Technology
615.399.7000
www.griffintechnology.com
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