When a gstreamer pipeline transits to playing state, it sets the
base_time of all elements to the internal time of the current clock. At
that point, the pipewire stream has not yet started and the
gstpipewireclock returns last_time which is initialized to 0 in
gstpipewirestream. This leads to a incorrect base_time in the gstreamer
element and various synchronization issues.
The use-case for last_time is not really clear to me. My basic guesswork
is: If a stream is no longer streaming the internal clock should pause
at that time and return last_time. So this patch keeps this behaviour
in place and only ensures that a valid time is returned when the stream
is not yet started and last_time was not purposely initialized with a
value != 0.
A gstreamer pipeline that can be used to replicate the issue is:
GST_DEBUG="pipeline:5,GST_CLOCK:6,pipewiresrc:6" gst-launch-1.0 \
pipewiresrc name=video target-object=<some video target> ! \
video/x-raw,format=UYVY ! fakesink \
pipewiresrc name=audio target-object=<some audio target> ! \
audio/x-raw ! f akesink 2>&1 | \
grep PTS
Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
GST_SECOND * t.rate.num can turn into a negative gint, resulting in
assertions like:
_gst_util_uint64_scale_int: assertion 'num >= 0' failed
Just use the 64bit version instead.
Use the pipewire ticks again as the clock source.
This was disabled because the v4l2 sources created bad ticks for the
graph. Now that this is improved we can enable the ticks again.
This has the advantage that simple audio playback does not drift
anymore. The only remaining problem would be timestamp drift or
discontinuities, which we don't handle here yet.
Make a method to get the current time to compare agains the pw_time-now
field. This is currently CLOCK_MONOTONIC but make this into a method
so that we can more easily change it later.
This was introduced in 4faa28fd96 in order to correctly map the time
from the stream. From d52df30c88 on, however, the clock switched to
monotonic time, which does not need the extra-offset.
Disable `clock_reset()` for now but leave it in place so we can easily
reenable it once we use the stream time again.
This fixes video recording in Cheese and similar apps.
Closes https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/3149
