x264enc: Add timecode into SEI from buffer meta
x264 as a library doesn't support this yet, so we depend on gst-plugins-bad's H264 parser library to parse the encoded data and inject the new SEI for us.
x264 as a library doesn't support this yet, so we depend on gst-plugins-bad's H264 parser library to parse the encoded data and inject the new SEI for us.