Improve media player engine (FFmpeg 1.1.3 and DirectShow)

We develop a media player CherryPlayer [login to view URL] Player engine uses FFmpeg for software decoding and DirectShow EVR for audio/video output. We are searching for a coder that can do next improvements in player engine work: 1. Improve work of "audio tracks switching" during video playback between internal audio tracks and external AC3 tracks. This feature has been implemented in first version of player engine, but with some bugs. For example if video has a few internal audio tracks then engine selects to play the longest track between available that sometimes is NOT default track. This logic need to check and rewrite. Additionally switching between audio tracks should work more smoothly then it works now. 2. Add support playback multi-video files like m2ts with ability to switch between videos. For now player engine selects the longest video stream and longest audio stream to play video and so we have sometimes played incorrect default video with audio from another video. This feature connected to p.1. 3. Player engine supports internal video subtiles but with some bugs that need to fix. Also need to add support of external subtitles (SRT etc). 4. Add support codecs installed in system and Windows Media codecs. 5. We use ffmpeg 1.1.3. We would like to update FFmpeg either to last available FFmpeg 2.1.1 that has some API changed or to 1.1.7 that should have the same API. This task includes ONLY fixes to player engine work and does NOT include UI fixes. Only experienced coders please make a bid!