How to see 720p downloaded movie on iPhone 4

[Sumeetganguly]

Hi guys,
The 720p downloaded movie are usually .mkv format which is not supported by iPhone 4.
Please guide me, if I need to see a 720p movie on my handset (best quality) how should I transfer the movie on my iPhone 4
And also I don't want to see the black borders on top and bottom...
I want to watch the movie full screen till the edge with aspect ratio being affected.

Please help.

 

[solaris]

Depending on the audio and video codecs it might work to mux the streams into a QuickTime (.mov) container.