HDR10 support

When ingesting TS streams, HDR10 is detected by parsing SPS. If the HDR10 info is included in the TS streams, the VUI part of SPS will contain colour_primaries with value 9, matrix_coeffs with value 9 and transfer_characteristics with value 16. If ew-vodingest detects exactly HDR10 info with these values, it will do following things:

• Add new hdr field to video variant in content_info.json. This field currently supports only one value hdr10. The video variant info will look like this:

  "variants": [
    {
      "media_type": "video",
      "subtype": "hevc",
      "name": "video_hevc_886kbps",
....
      "hdr": "hdr10",

• Add compatible brand “chd1” to ftyp box of video file .cfmv

[ftyp]
 - majorBrand: mp42
 - minorVersion: 512
 - compatibleBrand: chd1

Beside the VUI part of SPS, the following SEI NAL units may be present in the TS streams: Mastering display colour volume (SEI payload type 137) and Content light level information (SEI payload type 144). But this signal is optional, ew-vodingest doesn’t rely on them to detect HDR10. If these SEI NAL units are present, ew-vodingest will just add them to the hvcc box of video file .cfmv

For MP4 input, ew-vodingest does exactly the same behaviours, but the behaviour which add above SEI NAL units to hvcc box has not been tested.