UbuntuHelp:UbuntuStudioControls
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This document provides instructions and explanation for Ubuntu Studio for the current version of Ubuntu Studio (Ubuntu Studio 9.10 Alpha-4 as of 8-15-09). For Ubuntu Studio Controls for Ubuntu Studio 8.04 LTS Hardy Heron please see UbuntuStudioControlsHardy for instructions and explanations. Ubuntu Studio Controls is a consolidated location where several audio/video system settings can be set including memlock and raw1394 (firewire) access.
目录
Ubuntu Studio Controls Panel
To find the Ubuntu Studio Controls panel navigate to System -> Adminstration -> Ubuntu Studio Controls.
You will be asked for your password.
Then the Ubuntu Studio Controls panel will be displayed with all options unchecked.
Enable memlock
Dedicating locked memory via the memlock setting to audio applications while using the -RT kernel can increase performance while reduce latency and xruns.
By default no memory is locked for audio applications.
To set memlock click to enable it and enter a percentage of available memory to lock for audio applications. This will modify the contents of the /etc/security/limits.conf file.
Jackaudio.org/faq suggests setting memlock to unlimited.
Florian Paul Schmidt's page suggests locking 50% of available memory.
The amount of memory you choose to lock could also be a function of how much memory you have available.
Enable raw1394 access
Enabling raw1394 (IEEE 1394 aka firewire) access enables users to access hard drives, cameras, camcorders and sound cards without root permission. This is accomplished by changing /etc/udev/rules.d/40-permissions.rules.
By default permission for raw1394 access is restricted to root privileges. Click the box next to Enable raw1394 access to , umm, enable raw1394 access.
N.B. This can be a security risk which is noted when you click to enable raw1394 access.
This message is somewhat misleading. The actual risks of user access to raw1394 are:
- It allows direct control of !FireWire-attached devices. (However, in order to do something really dangerous like overwriting device firmware or reading/modifying data from a !FireWire storage device, the user would need non-trivial purpose-made software.)
- It may allow read/write access to memory of other PCs which are plugged into the !FireWire bus together with this PC which runs raw1394. Whether such access is possible and to which extent depends on the remote PC's operating system and hardware platform.
- It may allow read/write access to memory of this PC if you have more than one !FireWire controller and plug them together to a single bus. This depends on settings of the ohci1394 kernel driver and on the hardware platform of this PC.
Enable nice
The nice setting allows manual control over how certain processes work together under the Linux scheduler system for assigning cpu cycles.
The nice settings range from -20 (lowest nice level, given the highest priority) to 19 (highest nice level, given the lowest priorities).
Setting the nice value lower (closer to -20) gives the audio processes high priority when the Linux scheduler assigns cpu cycles to said processes. This should result is fewer dropout when recording audio.
Saving Settings and Exiting
After moderating the settings click Apply and Close.
