Yesterday night, after the first wave of AC-3 support drop from iOS multimedia players, the MKV playback support scene has turned out (article) to be very dire: previously excellent MKV players (for example, BUZZ Player) were rendered practically useless by the combination of the drop of AC-3 and other problems – for example, BUZZ Player's inability to play any MKV file with a DTS or AC-3 audio file, that is, practically, 99% of the MKV's you may have. In addition, PowerPlayer (which also had to drop AC-3 support) is still suffering from major stuttering with DTS MKV's and is completely unable to play any MKV file containing an AC-3 track, even if the file also has a (compatible) AAC audio track. Finally, it's still not known when AVPlayer(HD), a player having excellent and flawless MKV support, is back to AppStore (article on removal) and in what way will it be modified. (Nevertheless, the last version of AVPlayer(HD), if you were lucky to buy it before it was removed from the AppStore, works just great and will continue to do so.)
If your iDevice is jailbroken, you can have two additional players: XBMC and RushPlayer+. XBMC is, basically, great but is really let down by still (as of yesterday's version) not having iPad 3 Retina screen support (forget using it on the iPad 3, except for playing back lowish-resolution videos!) and RushPlayer+, while it offers excellent MKV playback, isn't exactly feature-packed.
All in all, there is a need for a decent MKV player more than ever. Fortunately, a relatively newcomer (it received MKV hardware playback support less than a month ago - article from back then) to the MKV scene, the AppStore-based HD Player Pro, has just received an update.
A screenshot of the update list is exactly the same as that of version 5.0 (the hidden row at the bottom announces TV out support):
(click for a larger image. Also note that I've also annotated the update list of 1080 MKV Player, also quickly reviewed last night. In that article, I referred to this update note.)
What has changed?
I've thoroughly tested the new version and found out that the wired TV (HDMI / VGA) out bug, only existing during hardware MKV playback I've described in my previous article, has been fixed – this is great news.
And what didn't?
Unfortunately, there is still no way of switching audio tracks with MKV's having more than one (an example) and the player still crashes with MKV files containing native Blu-Ray subtitle tracks (an example test file). Unfortunately, files with the much more common VobSub subtitles aren't supported either: the player just crashes upon encountering an MKV file with VobSubs inside (an example). Completely disabling hardware acceleration via Settings > Acelerate MKV, FLV makes these files at least (software-)playable - as a slideshow only, of course. (By the way, speaking of playing back MKV's with VobSubs inside, AVPlayerHD can't do it either using hardware acceleration - it falls back to software decoding, rendering Full HD content a useless slideshow. The jailbroken XBMC and RushPlayer+, on the other hand, have no problems with the hardware playback of this kind of footage; XBMC can even render the subtitles. RushPlayer+, while it certainly sees the tracks being present, can't.)
Neither can the player render MP4 (M4V / MOV) files with embedded VobSubs (an example) either, unlike ProPlayer (the recommended player for MP4 + embedded VobSub playback).
All in all, the statement in the AppStore's official feature list of the app, “HD Player Pro is the only player on iOS that renders subtitle correctly (especially SSA subtitle)” is not entirely true: some types of (common) subtitles are much better handled by some other players; for example, the just-discussed VobSub embedded tracks. (Of course, its SSA handling is indeed excellent. However, if you do jailbreak, XBMC also offers great SSA support.)
What about AC-3? Has it been removed?
As far as AC-3 support is concerned (the one dropped from BUZZ Player and PowerPlayer – see the intro paragraph above), it's (still?) present in the current version. (It's not known whether it'll be removed. Make sure you backup before upgrading to future versions.) The player plays all the four MKV's I've used for testing in yesterday's article just fine and is, consequently, a great choice for you if your device isn't jailbroken.