The "Video signal type present" information is written to the output
video file when it is created, and later is used by the decoder to
properly decode the compressed video data. The saved attributes
are:
- format type (PAL, NTSC, etc.)
- color primaries (BT709, SMPTE170M, etc.)
- transfer characteristics (BT709, SMPTE170M, etc.)
- color matrix ((BT709, SMPTE170M, etc.)
These modifications allow the client to specify these attributes
and, if specified, makes sure they are written to the output file.
Currently the emscripten JavaScript environment for C/C++ programs
cannot do multithreading, and doesn't have a sysctl implementation
to get hardware CPU count. Hardcode to 1.
Using the Linux OS settings works, so not adding a platform file.
To build with emscripten (tested 1.30.0):
emmake make OS=emscripten ARCH=asmjs
The resulting libopenh264.so is LLVM bitcode which can be further
linked into an emscripten project for final JavaScript output.
