Yup, I can reproduce this. First I launch iTunes and start something
playing. From the terminal I do
ps -A | grep iTunes
to get the process ID of iTunes, which is the first number listed. In my
case it was 63238. So if I do a
kill -s SIGSTOP 63238
not only does iTunes freeze, as expected, but all audio system-wide
dies. Likewise doing a
kill -s SIGCONT 63238
restores things. Not exactly model behavior for a single user process to
be able to take down a core system component.
CB
On 11/11/11 11:56 AM, Doug Lee wrote:
On Fri, Nov 11, 2011 at 08:57:42AM -0600, Chris Bagwell wrote:
On Thu, Nov 10, 2011 at 3:02 PM, Doug Lee<d...@dlee.org> wrote:
Not sure if this is a MacOS problem, a SoX problem, or both.
Tested on MacOS SnowLeopard (and Leopard I think, but I'm not sure of
that) with SoX 14.3.2 as installed via MacPorts.
Problem: I can block all sounds on MacOS by suspending a SoX play.
Steps to reproduce:
Verify that system sounds work: Cause a beep by hitting an invalid
key, play a file with another program, etc.).
Start playing a file (play file.wav) from a shell (I use tcsh).
Suspend play with Ctrl+Z.
Try to produce a sound with another program.
Result: No program, even the system itself (or VoiceOver, for those of
us who use that) can produce a sound until play is resumed.
That doesn't sound good. SoX doesn't have a SIGSTOP handler so
probably a thread related to coreaudio gets stuck on a mutex. Scary a
bad app locks down the whole audio subsystem.
I did a quick search for examples of other core audio apps source code
and I didn't see anyone else doing anything special for this case.
An interesting test would be to use "kill -s SIGSTOP %pid" of some
GUI-ish audio app and see if it locks up coreaudio the same way.
Anyways, it sounds like a SoX bug but I'm not quite sure how to fix it.
Chris
Actually, someone on the Mac list I also sent this to confirmed just
now that the problem can be demonstrated with just MacOS software:
Type this in Terminal, press Enter, then suspend with Ctrl+Z:
say "Hello, this is a sound system test. Suspending this suspends all system
sound."
Resume with "fg" to get system sound back.
So this is not SoX' fault after all.
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