The existing implementation made an attempt to remove duplicate
captions if increasing the framerate, but made no attempt to
handle reducing the framerate, nor did it rewrite the caption
payloads to have the appropriate cc_count (e.g. the cc_count needs
to change from 20 to 10 when going from 1080i59 to 720p59 and
vice-versa).
Make use of the new ccfifo mechanism to ensure that caption data
is properly preserved.
Signed-off-by: Devin Heitmueller <dheitmueller@ltnglobal.com>
Signed-off-by: Limin Wang <lance.lmwang@gmail.com>
When transcoding video that contains 708 closed captions, the
caption data is tied to the frames as side data. Simply dropping
or adding frames to change the framerate will result in loss of
data, so the caption data needs to be preserved and reformatted.
For example, without this patch converting 720p59 to 1080i59
would result in loss of 50% of the caption bytes, resulting in
garbled 608 captions and 708 probably wouldn't render at all.
Further, the frames that are there will have an illegal
cc_count for the target framerate, so some decoders may ignore
the packets entirely.
Extract the 608 and 708 tuples and insert them onto queues. Then
after dropping/adding frames, re-write the tuples back into the
resulting frames at the appropriate rate given the target
framerate. This includes both having the correct cc_count as
well as clocking out the 608 pairs at the appropriate rate.
Thanks to Lance Wang <lance.lmwang@gmail.com>, Anton
Khirnov <anton@khirnov.net>, and Michael Niedermayer <michael@niedermayer.cc>
for providing review/feedback.
Signed-off-by: Devin Heitmueller <dheitmueller@ltnglobal.com>
Signed-off-by: Limin Wang <lance.lmwang@gmail.com>
Motivated by a desire to use vf_libplacebo as a GPU-accelerated
cropping/padding/zooming filter. This commit adds support for setting
the `input/target.crop` fields as dynamic expressions.
Re-use the same generic variables available to other scale and crop type
filters, and also add some more that we can afford as a result of being
able to set these properties dynamically.
It's worth pointing out that `out_t/ot` is currently redundant with
`in_t/t` since it will always contain the same PTS values, but I plan on
changing this in the near future.
I decided to also expose `crop_w/crop_h` and `pos_w/pos_h` as variables
in the expression parser itself, since this enables the fairly common
use case of determining dimensions first and then placing the image
appropriately, such as is done in the default behavior (which centers
the cropped/placed region by default).
In some circumstances, libplacebo will clear the background as a result
of cropping/padding. Currently, this uses the hard-coded default fill
color of black. This option makes this behavior configurable.
