players: move more things into info structures for audio/video
dvdplayer: don't constantly hammer demuxer to get stream count

Note this could cause regressions in files where streams show
up during playback, but i think the demuxer signals such
situations now.
don't constantly hammer demuxer to get stream count

Note this could cause regressions in files where streams show
up during playback, but i think the demuxer signals such
situations now.
Merge pull request #3663 from elupus/dvdlocks

Some cleanups in gui/player callbacks