This is the first batch of a series implementing faster media source resolution required to workaround an Unreal Engine race condition present in some games, and deterministic stream ordering that decodebin / parsebin cannot provide, which is required to expose the streams in native order, for compatibility in several other applications.
I pushed the full series as a branch here: https://gitlab.winehq.org/rbernon/wine/-/commits/mr/wg-source-part-one
Note that this full series is also a first step in the direction of having a simpler demuxer interface, which will be required in the future for compatibility with applications that build MF or DirectShow pipelines directly and expect the relevant components to behave as a demuxer and expose compressed media types. For now it only delays the use of wg_parser to whenever the media source is started, and matches the non-ordered streams using their media types and tags. This is a best effort solution but I don't think we can do much better for the moment.