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I'm just trying to increase the resolution of the video, while keeping the same quality and bitrate. You can do this with h264 very easily. Just change the resolution of the output file while keeping the bitrate the same, and it renders in the same amount of time keeping the same file size, even if the image is 10 times bigger now.

However with h265, every increases causes increase in render time and in file size.

  • That is to be expected. a) At the same quality, 10 times the pixel mean 10 times the bitrate (not necessarily, as both encoder know blocking). b) 10 times the pixel mean more rendering time (in my experience, x265 scales far better with higher resolution than x264 does, so the increase isn't necessesarily linear to the increase in pixels). Tried it myself by upscaling to 3840x5400: FFmpeg eats up all the RAM it can get (28GB on my 32GB setup) and fps drop to 0.0 on x265 after a few frames - on x264 it crashes on start. Also, please post your syntax and perhaps the stats of your input-file. – flolilo Jun 27 '17 at 12:51
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    I'm confused. You're saying, "You can do this with h264 very easily. Just change the resolution of the output file while keeping the bitrate the same" — but when you re-encode and change the resolution, keeping the same bitrate, you're of course going to sacrifice quality. You can't change the resolution without re-encoding. Or are you doing something else? If so, please clarify. And anyway, what are you really attempting to do here? – slhck Jun 27 '17 at 13:02

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