I was having transcoding issues I was able to resolved thanks to the great help of the developers and people in general in this forum.
But now I noticed all my mpeg-4 videos and VC-1 videos are delayed, the sound is heard first and after approximately 2 seconds the image follows, most of my videos have subtitles and they are in sync with the audio.
I checked all the settings in the device and emby app but I've been unable to find any solution.
It's important to clarify the videos are not transcoded, therefore I'm unable to attach log files for this issue.
On my android phone (Alcatel 4047A) this delay is absent.