Drop frames in Quick Time

Question

In FCPx I exported a 4min video with stats: 1920x822, 30fps, mp4
And when I open it in quick time (X and 7) I've got drop frames during the playback. When I open whis video in VLC everythig is ok, very smooth video.
What the problem?
I've got iMac mid2011, 10.9.1 2,5GHz core i5, 12gb ram radeon 6750M 512 Mb.

Answer 1

What the problem?
Basically, the QT Players are, in some respects, less efficient than the VLC Player as many users have frequenty complained. Unfortunately, this is normal. QT players are, by default, programmed to drop frames if they cannot keep up with the "full" rendering of data at the encoded throughput data rate while other players may lower rendering quality, drop fields, or drop alternate lines in the rendering of progressive frames to "keep up." Such strategies allow multimedia players to work on a very wide range of platforms with varied CPU clocking rates. If this bothers you, you might try encoding or transcoding your conttent more efficiently by either reducing the encoding dimensions or limiting the encoding data rate setting. Unfortunately, many "modern" MPEG-4 AVC encoders have the potential to create files with data rates as high as 720 Mbps and some users tend to use unrealistic "quality" settings for the content they create. For instance, the average BD is encoded with a data rate on the order of 20 Mbps (MPEG-4 AVC) to 30 Mbps (VC-1) while the same 1080 video may perceptually look just as well using anamorphic encoding with data rates in the 5 to 13 Mbps range and 720p versions can frequently play very well in the 1.6 to 3.5 Mpbs range. Such encodeing strategies. In short, lower data rates allow smoother playback and smaller files at the potential expense of quality. The question then becomes, "Which aspect is most important to you depending on the targeted use of your files?"