Ever since HitFilm 3 was released, I've been dealing with this problem.
When I take any sort of footage, run it through HitFilm and want to render it using Constant Bitrate in 60FPS, regardless of the other settings, I see massive bitrate drops during playback. Like it plays back beautifully and suddenly the footage goes completely dithered for a split-second, then back to the normal quality.
I need to use Variable Bitrate to avoid it, however Variable seems to have some of the same tendencies albeit much, much less visible.
Here's an example. Granted it's a fairly poor example but gives you an idea what I'm talking about; http://www.gfycat.com/ShrillWelcomeGalapagoshawk - Obviously this is heavily compressed due to being a .webm, however what I'd like to point out is the sudden massive dither / blur that happens a few seconds in, twice in a row. That is VERY pronounced when viewing it back in 1080p at a 100k+ bitrate.
And it happens every single time, despite of the original source, whether it's a game recording fresh off ShadowPlay, something rendered pre-hand in Sony Vegas or otherwise. As long as I use Constant Bitrate, it happens.
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