Update ffmpeg for assert fix in avi
Fix 16-bit DVD LPCM decoding

Fixes Issue #392
Fix playback of DVD LPCM with other source filters or other decoders.
Avoid negative file positions in the BD demuxer
Manually sync to the seek target position if required

libbluray can only seek to random access points on the disc, so
we may need to fix the position manually in this case.
Seek after the 4-byte extra TS headers on BD.

This avoids an extra resync pass and improves seeking performance.
Read into a fixed size buffer instead of all at once.
Log seeking corrections
Revert "Propose a RGB mediatype with negative height on connect."

This reverts commit 3e494f88c377600ca5ef17df529fcc954dea764d.

This change caused RGB output to fail with VSFilter and produced
flipped output with AviSynth DirectShowSource