On Friday 24 September 2010 11:59 AM, Rajeev R. K. wrote:
I think the culprit here is the permissions system. Usually, Systems like PackageKit assign permissions to various devices to allow normal user access without having to manually add users to various groups. If you remember the good old days, we used to add users to the 'audio' group to allow them to play audio, and to the 'tty' group to allow them to access serial ports, etc. On Modern distro's when a user logs in, the permissions of the relevant devices are updated to allow that user to access it, using filesystem ACL's. That way, as long as your login is at a local console, you get access to all physically connected hardware IO devices, subject to certian rules..
This is why your programs are playing audio as long as you are logged in somewhere or the other, but refuse to play when you are logged out. It's nothing but a simple permission denied issue.
I agree. This is also one reason why 'audacity' is good at editing audio files but bad at recording live from audio input jacks in user mode. It does not give access of the sound devices to the user, even when logged in. The sound recorded is blank.