The root cause is that alsa-lib is not thread safe for the same handle.
There are two threads in the gstreamer accessing alsa-lib not serilized.
The race condition happens when one thread holds the old framebuffer app_ptr
position in the kernel, another thread advances the framebuffer app_ptr.
when the former thread is scheduled to run again, it overwrites the app_ptr
to old value by copying from kernel.Thus,the app_ptr in the upper
alsa-lib(pcm_rate) become one period size more advanced than the lower
alsa-lib(pcm_hw & kernel).
gstreamer uses noblock and poll method to communicate with the alsa-lib.
The app_ptr unsync situation as described above makes the poll return immediately because
it concludes there is enough space for the ring-buffer via the low-level alsa-lib.
The write function returns immediately because it concludes there is not enough
space for the ring-buffer from the upper-level alsa-lib. Then the loop of poll
and write runs again and again until another period size is available for
ring-buffer.This leads to the cpu 100 problem.
delay_lock is used to avoid the race condition.
Fixes: https://bugzilla.gnome.org/show_bug.cgi?id=690937
The _1_0 suffixed environment variables override the
non-suffixed ones, so if we're in an environment that
sets the _1_0 suffixed ones, such as jhbuild, we need
to set those to make sure ours actually always get
used.
These override the variants without version suffix. Makes
'make check' work properly in environments that set the
suffixed variant for 1.0, such as jhbuild.
jhbuild already sets $GST_PLUGIN_PATH_1_0 which overrides $GST_PLUGIN_PATH. Set
both for the tests to see the locally built elements. Fixes 'make check' in
jhbuild.
A return value of FALSE here indicates that we don't have control-values. In
0.10 we were returning the default value of the property. Now we don't fill an
array with defaults in the ControlBinding, but leave it up to the element to
handle this case.
We need to mark our clock as using some other clock source. Alsa source uses the
clock type to decide if it can use alsa driver timestamps or not.
Fixes https://bugzilla.gnome.org/show_bug.cgi?id=690465
Use new ringbuffer ERROR state to make all the various
threads bail out correctly when the subclass posts an
error. It's a bit iffy to communicate this properly
between the different bits of code.
https://bugzilla.gnome.org/show_bug.cgi?id=690197
In SKEW mode, use next_sample == -1 to check for the first sample
when starting to read samples so it resyncs the ringbuffer and
timestamps are ok.
Suggestion from Teemu Katajisto <teemu.katajisto@digia.com>
https://bugzilla.gnome.org/show_bug.cgi?id=648359
The codec data blob we get from matroskademux with the SSA/ASS
init section is supposed to be valid UTF-8. If it's not, just
continue with the bits that are valid UTF-8 instead of erroring
out. We don't actually parse the init section yet anyway..
https://bugzilla.gnome.org/show_bug.cgi?id=607630
Don't loop forever if an USB audio device gets disconnected
while in use. Post an error message instead. This is not
enough yet though, we still need to make the base class
and/or the ring buffer bail out.
https://bugzilla.gnome.org/show_bug.cgi?id=690197
