Linux
iSight Audio
Drivers
This project is no longer active!
Please contact arne@datafloater.de if you want to take maintainership
Please contact arne@datafloater.de if you want to take maintainership
Hi, los newos maintainer here (danalien)...
Since 2005-08-15, I've been been wanting to update this page a bit,
but hadn't had much spare time to do so. Been busy, a lot these days.
Happens when you got work to finish...
But since I'm leaving for aKademy'05 on the 24th of august, and my schedule
for september is allready booked up - This project will have to wait to oktober
at the very least.
cheers.
BTW, I fonud this link the other day: http://developer.apple.com/[...]/iSightProgGuide/index.html about the iSight.
[last updated: 2005-08-18 @ 21:58 GMT+1]
This page provides information about the
Apple(TM) iSight(TM) camera and the
protocol used by the internal microphone of this camera. Final goal is
to write an alsa audio
driver for it.
Note: The video part of the iSight is already supported by libdc1394 and by unicap.
All information on this page is gathered from the firmware version of the first released iSight cameras. At the time of this writing, firmware version 1.0.2 is available, but can only be updated with a computer running MacOS. Firmware update with a Linux computer will hopefully be implemented in the future.
The registers of interest are:
enables the microphone at a frame rate of 44100 Hz. The audio stream is transmitted on isochronous channel 0 afterwards.
Still I do not know how to set the isochronous channel. As I have no access to an Apple computer, there I currently can not investigate this. One way to find out how to set the channel would be to allocate channel 0 before starting the camera with iChatAV. The log should then show a different sequence than the one shown here and we can hopefully see how the channel is set.
Note: The video part of the iSight is already supported by libdc1394 and by unicap.
All information on this page is gathered from the firmware version of the first released iSight cameras. At the time of this writing, firmware version 1.0.2 is available, but can only be updated with a computer running MacOS. Firmware update with a Linux computer will hopefully be implemented in the future.
iSight ConfigROM
The iSight has 4 unit directory entries in the ConfigROM:- Directory 1 ( starting
at offset
0x43c) refers to the video functionality of the iSight. The spec ID0xa02dand the software version0x102indicate that this device is compliant to IIDC 1394 Digital Camera Specification Version 1.30. - Directory 2 ( starting
at offset
0x45c) refers to the audio functionality. The spec ID for this function is0xa27, the software version is0x10. The spec ID does not refer to any standard that I know of. Any further information on Apple's spec ID and software version numbers would be greatly appreciated ( contact me ).
The offset of0x8000( specified in quadlets ) at the key0x40( offset0x470) points to the status and cotrol registers of the audio functionality. - Directory 3 ( starting
at offset
0x474) has the spec ID0xa27and the software version0x11. I do not know the meaning of this function.
- Directory 4 ( starting
at offset
0x49c) has the spec ID0xa27and the software version0x12. I do not know the meaning of this function either.
Status and control registers
The log shows the communication between the iSight and iChatAV upon startup of the application. It was taken with the help of nosy, a simple firewire sniffer for Linux.The registers of interest are:
- Address
0xf0020000: This seems to be the ISO Enable/Disable register. A Value of0x80000000is written to start the isochronous operation, a value of0x0is written to stop the isochronous operation. - Address
0xf0020300: A value of0x00010001is written to this register when the microphone is turned on.
- Address
0xf0020500: A value of0x22is writen to this register when the microphone is turned on. I do not know the meaning of this register.
f0020500 00000022
f0020000 80000000
f0020300 00010001 enables the microphone at a frame rate of 44100 Hz. The audio stream is transmitted on isochronous channel 0 afterwards.
Still I do not know how to set the isochronous channel. As I have no access to an Apple computer, there I currently can not investigate this. One way to find out how to set the channel would be to allocate channel 0 before starting the camera with iChatAV. The log should then show a different sequence than the one shown here and we can hopefully see how the channel is set.