icey 2.4.7

Added

• icy::av::parseDeviceUrl(source) — single source of truth for libavdevice URL schemes (avfoundation:, v4l2:, dshow:). Returns the resolved AVInputFormat* and the post-prefix filename. Throws if a recognised scheme has no matching backend on this build.
• MediaCapture::openFile routes recognised device URLs through the existing openStream(filename, iformat, opts) path, so callers can open the OS camera directly without an ffmpeg/relay subprocess.

Fixed

• internal::init() now calls avdevice_register_all() under HAVE_FFMPEG_AVDEVICE. The prior comment was wrong: codec/format auto-registration arrived in FFmpeg 4.0+, but libavdevice still requires an explicit register call for av_find_input_format("avfoundation"|"v4l2"|"dshow") to resolve. parseDeviceUrl also performs a one-shot std::call_once registration so device URLs work even before any MediaCapture is constructed.
• MediaCapture::run no longer treats AVERROR(EAGAIN) from av_read_frame as fatal. Live demuxers (notably avfoundation) return it whenever their internal frame queue is momentarily empty; the prior code tore the capture down at the first hiccup, which surfaced as the capture pipeline emitting only the initial three buffered frames before going silent.

Changed

• Bumped the pinned libdatachannel from v0.24.1 to v0.24.2.