Commit graph

10 commits

Author SHA1 Message Date
Vivia Nikolaidou
dd00dab5e9 ccutils: Add padding also for ccp data
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5423>
2023-11-08 10:06:45 +00:00
Vivia Nikolaidou
78bc3d53dd ccutils: Keep upstream padding payload
A payload of 0x80 0x80 means that it's padding. It's not a good idea to
throw this away though, because of the cc_valid field.

According to CEA 10-B section 25.2.1, if cc_valid is zero, the run-in
clock and start bit should not be generated. In practice, this means
that any closed captions will be erased and the end-user TV will show
that captions are not available for this stream. This might have
undesired consequences, e.g. we were just showing a long line of
captions and we disable it before the user has had time to read it, or
you can't enable closed captions during silence/music intervals.

We cannot reliably detect whether there's a currently-silent closed
caption stream or just nothing, but we have this information coming from
upstream, so we can at least not discard it.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5508>
2023-11-06 13:44:36 +00:00
Matthew Waters
21b232ce30 closedcaption: write 0x00 padding instead of 0x80 in cc_data/cdp
Depending on the exact output format, 0x00 may be a better default for
padding than 0x80.  0x00 is the recommended padding value when used in
CDP (and cc_data) but is not when used in s334-1a.  See CTA-708-E 4.3.5
amd SMPTE 334-1-2007 5.3.2.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4578>
2023-05-10 00:52:01 +00:00
Matthew Waters
262be30b6f ccutils: generate valid padding in field 1 when needing to generate field 2
Fixes CC in Field 2 but not in Field 1 errors.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4490>
2023-04-26 20:43:13 +00:00
Matthew Waters
be72fbc334 cccombiner: fix output-padding=false for a cea608 field 1 only stream
If we have data that needs outputting but we have to output padding to
meet the alternating field requirements of cea608, then output that
padding anyway.

Also includes a test

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4124>
2023-03-08 11:11:05 +00:00
Matthew Waters
e2ff6b61ce cccombiner: initial implementation of using CCBuffer helper
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3211>
2022-11-10 00:52:14 +00:00
Matthew Waters
088597b430 closedcaption: move CC buffering to helper object
Move most of the interesting code from ccconverter to this new helper
object.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3211>
2022-11-10 00:52:14 +00:00
Matthew Waters
06a20f9243 closedcaption: move cdp->cc_data into shared location
So it can be used by both ccconverter and cccombiner

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3211>
2022-11-10 00:52:14 +00:00
Matthew Waters
fde92ec43f closedcaption: move cc_data->cdp to shared file
Used by both ccconverter and cccombiner

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3211>
2022-11-10 00:52:14 +00:00
Matthew Waters
067185e7da closedcaption: move cdp framerate table to common file
shared by both cccombiner and ccconverter

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3211>
2022-11-10 00:52:14 +00:00