If we receive video buffers with non-perfect timestamps, the
caption buffers' timestamps might fall in the interval between
the end of one video buffer and the start of the next one.
Make our criteria for dropping that the caption buffer has
a timestamp older than the end of the previous video buffer,
not older than the start of the new one, unless of course
this is the first video buffer.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1207>
And only update the caps and stream-start event accordingly. This
ensures that we'll always forward sticky events that arrive after the
caption pad was created, and especially updates to existing sticky
events like the segment event.
Also create a proper stream id based on the upstream stream id for the
stream-start event, and make sure that all the sticky events we know are
already on the caption pad at the time it is added to the element.
We pass-through the video as is, only putting a GstMeta on it from the
caption sinkpad.
This fixes negotation problems caused by not passing through caps
queries in both directions.
Also handle CAPS/ACCEPT_CAPS queries directly for the caption pad
instead of proxying.
GST_VIDEO_BUFFER_FLAG_INTERLACED and GST_VIDEO_BUFFER_FLAG_TFF
flags are needed when processing SCTE 20 closed captions for an interlaced
stream, when we need to convert back to analog, in which case we need to match
the caption to the top or bottom field
Fixes the following error.
gstccconverter.c:677:7: error: variable 'len' is used uninitialized whenever 'if' condition is false
[-Werror,-Wsometimes-uninitialized]
if (flags & 0x40) {
^~~~~~~~~~~~
gstccconverter.c:698:10: note: uninitialized use occurs here
return len;
^~~
gstccconverter.c:677:3: note: remove the 'if' if its condition is always true
if (flags & 0x40) {
^~~~~~~~~~~~~~~~~~
gstccconverter.c:572:12: note: initialize the variable 'len' to silence this warning
guint len;
^
= 0
Prior to this, cccombiner stopped consuming video buffers when
data wasn't arriving on its caption pad. In a live situation,
when aggregator is timing out we should still output whatever
video buffers are present, even if no caption buffers can be
aggregated with them.
It is necessary to implement this vmethod, as when the src pad
is marked as reconfigure, the base class will reset to src caps,
and the default update_src_caps simply queries the caps allowed
downstream without taking into account the caps set by
gst_aggregator_set_src_caps.
As a side-effect we can now actually store the line offset in the
line21dec element, and have to perform fewer transformations in the
decklink elements (which were also buggy as they assumed a single byte
triplet per meta).
It depends on the framerate how many cc_data byte pairs are allowed per
frame, and the framerate is also needed for converting into the CDP or
MCC format as the framerate is part of the header metadata.
