This function is set with gst_audio_base_sink_set_custom_slaving_callback()
and is called during playback. It receives the current time of external and
internal clocks, which the callback can then use to apply any custom
slaving/synchronization schemes.
The external clock is the sink's element clock, the internal one is the
internal audio clock. The internal audio clock's calibration is applied to
the timestamps before they are passed to the callback. The difference between
etime and itime is the skew; how much internal and external clock lie apart
from each other. A skew of 0 means both clocks are perfectly in sync.
itime > etime means the external clock is going slower, while itime < etime
means it is going faster than the internal clock. etime and itime are always
valid timestamps, except for when a discontinuity happens.
requested_skew is an output value the callback can write to. It informs the
sink of whether or not it should move the playout pointer, and if so, by how
much. This pointer is only NULL if a discontinuity occurs; otherwise, it is
safe to write to *requested_skew. The default skew is 0.
The sink may experience discontinuities. If one happens, discont is TRUE,
itime, etime are set to GST_CLOCK_TIME_NONE, and requested_skew is NULL.
This makes it possible to reset custom clock slaving algorithms when a
discontinuity happens.
This function is set with gst_audio_base_sink_set_custom_slaving_callback() and is called during playback. It receives the current time of external and internal clocks, which the callback can then use to apply any custom slaving/synchronization schemes.
The external clock is the sink's element clock, the internal one is the internal audio clock. The internal audio clock's calibration is applied to the timestamps before they are passed to the callback. The difference between etime and itime is the skew; how much internal and external clock lie apart from each other. A skew of 0 means both clocks are perfectly in sync. itime > etime means the external clock is going slower, while itime < etime means it is going faster than the internal clock. etime and itime are always valid timestamps, except for when a discontinuity happens.
requested_skew is an output value the callback can write to. It informs the sink of whether or not it should move the playout pointer, and if so, by how much. This pointer is only NULL if a discontinuity occurs; otherwise, it is safe to write to *requested_skew. The default skew is 0.
The sink may experience discontinuities. If one happens, discont is TRUE, itime, etime are set to GST_CLOCK_TIME_NONE, and requested_skew is NULL. This makes it possible to reset custom clock slaving algorithms when a discontinuity happens.