Alexandre Janniaux authored Jan 18, 2023 and Steve Lhomme committed Jan 26, 2023

Use hxxx_helper to extract the SPS/PPS/VPS payload from the stream and
report it when it has been found.

It adds support for late-signalling of h264 and hevc codec specific data
to the mp4 mux, after pf_add has been called, which is needed for some
asynchronous encoders like VideoToolbox and MediaCodec that won't report
the format until they can also output the first I-frame, which means
after encoder_t::ops::encode_video has been called at least once.