This is basically a frame counter provided by the driver and it's
advancing at the speed of the HDMI/SDI input. Having this available on
each buffer allows to know what constant-framerate-based timestamp each
frame is corresponding to and can be used e.g. to write out files
accordingly without having the local pipeline clock timestamps used.
https://bugzilla.gnome.org/show_bug.cgi?id=779213
15:18:47 gstdecklinkaudiosrc.cpp:745:45: error: cannot initialize a parameter of type 'int64_t *' (aka 'long long *') with an rvalue of type 'gint64 *' (aka 'long *')
15:18:47 (BMDDeckLinkMaximumAudioChannels, &self->channels_found);
15:18:47 ^~~~~~~~~~~~~~~~~~~~~
15:18:47 ./linux/DeckLinkAPI.h:970:87: note: passing argument to parameter 'value' here
15:18:47 virtual HRESULT GetInt (/* in */ BMDDeckLinkAttributeID cfgID, /* out */ int64_t *value) = 0;
15:18:47 ^
On some hardware the first few frames are bogus and not very useful.
Their timestamps are off, they have no timecodes, or there are spurious
black frames / no-signal frames. After a few frames this stabilizes
though.
https://bugzilla.gnome.org/show_bug.cgi?id=774850
Based on this we calculate the actual capture time, which should get us
rid of any capturing jitter by averaging it out.
Also add a output-stream-time property which forces the elements to
output the stream time directly instead of doing any conversion to the
pipeline clock. Use with care.
https://bugzilla.gnome.org/show_bug.cgi?id=774850
The hardware timestamps have no relation to when frames were produced,
only when frames arrived somewhere in the hardware. Especially there is
no guarantee that audio and video will have the same hardware timestamps
although they belong together, and even more important: the rate with
which the hardware timestamps increase is completely unrelated to the
rate with which the frames are captured!
As such we can as well use the pipeline clock directly and stop doing
complicated calculations. Also as a side effect this allows now running
without any pipeline clock, by directly making use of the stream times
as reported by the driver.
https://bugzilla.gnome.org/show_bug.cgi?id=774850
We have no idea which timestamps they are supposed to have so the only thing
we can do at this point is to drop them. Packets without timestamps happen if
audio was captured but no corresponding video, which shouldn't happen under
normal circumstances.
https://bugzilla.gnome.org/show_bug.cgi?id=747633
When the mode of decklinkvideosink is set to "auto", the sink claims to
support the full set of caps that it can support for all modes. Then, every
time new caps are set, the sink will automatically find the correct mode for
these caps and set it.
Caveat: We have no way to know whether a specific mode will actually work for
your hardware. Therefore, if you try sending 4K video to a 1080 screen, it
will silently fail, we have no way to know that in advance. Manually setting
that mode at least gave the user a way to double-check what they are doing.
https://bugzilla.gnome.org/show_bug.cgi?id=759600
Not from the decklink clock. Both will return exactly the same time once the
decklink clock got slaved to the pipeline clock and received the first
observation, but until then it will return bogus values. But as both return
exactly the same values, we can as well use the pipeline clock directly.
Otherwise we might start the streams before the audio or video streams are
actually enabled, and then error out later because they are enabled to late.
We enable the streams when getting the caps, which might be *after* we were
set to PLAYING state.
