I had the same problem with CoreAVC. Turns out DirectvobSub post processing was causing it.
In MP Config, if I had DirectvobSub (autoloading) in post processing, some MKVs & .ts files wouldn't play. If I removed it, they'd play, but I couldn't get subs, & some movies like The DaVinci Code need subs. So I tried the other version of DirectvobSub & the same thing happened. By chance, I happened to leave DirectvobSub in post processing, but unchecked the checkbox beside it. Now all my videos play & I can switch the subs on & off. I don't think the one MKV file I have with internal subs will show the subs, but that's probably something with Haali.
It's not HAALI, removed it, installed Gabest. No success. I'll try the vobsub tip, but no internal subs is not an option.
Weird that MPC does work with HAALI, CoreAVC and DirectVobSub. And what's weird too, is that MediaPortal works fine with these files if I use the PowerDVD x264 codec.
I used to have 0.2.3.0 on WinXP SP2 & it played everything perfectly, including internal subs in MKV files. I had a lot of junk that I installed when first setting up the HTPC, so I decided to wipe everything & start over.
After installing WinXP SP3 & MP 1.0 RC2, a couple of weeks & a lot of frustration, I got it this far. Lesson learned: if it ain't broke, don't fix it.
I'll look into the MKV internal sub problem & let you know if I find anything out.
I tried disabling DirectVobSub. No success either. Still no picture with the 'problem' mkv's. You're right about the "if it ain't broke" part, but somehow I always have the urge to update anything that's updateable. I just can't help myself
I update my setup to latest MediaPortal release (1.0.0.0 RC2), but the problem remains basically the same:
mkv ok in WMP and MPC (with VMR7 or VMR9 selected), with either: ffdshow (CCCP), CoreAVC (1.8.0.0) or PowerDVD Ultra 8.0
mkv ok in MediaPortal with just PowerDVD Ultra 8.0
mkv nok in MediaPortal, just gives me a black screen with CoreAVC, except in pause mode where the frame (image) is shown ok
I use latest Catalyst 8.8, Reclock (1.8.0.8) as audio renderer sending events to Powerstrip to set correct refresh rates (works fine), and AC3Filter 1.51a as audio codec. I have selected "DirectVobsub Auto Loading" in MP Movie PostProcessing.
When I change the renderer to EVR on Media portal Configuration, within MP works ok (but unusable due to tearing as I have WinXP with SP3) with CoreAVC, but I get a black image with PowerDVD (the reverse situation).
I don't know what else to try, so I attached the log files of MP, with VMR9 and CoreAVC playing a mkv file and pause it twice then I quit.
You could use GraphStudio for example instead of GraphEdit and compare the data in the input and output pins of the reader, codec etc. between the graph of Media Player and the graph of Media Portal. Maybe you find some discrepancies there?