lavfi/vf_libplacebo: support blending multiple inputs

Subsequent inputs require frame blending to be enabled, in order to not
overwrite the existing frame contents.

For output metadata, we implicitly copy the metadata of the *first*
available stream (falling back to the second stream if the first has
already reached EOF, and so on). This is done to resolve any conflicts
between inputs with differing metadata. So when e.g. input 1 is HDR and
output 2 is SDR, the output will be HDR, and vice versa. This logic
could probablly be improved by dynamically determining some "superior"
set of metadata, but I don't want to handle that complexity in this
series.

0 files changed, 0 insertions, 0 deletions