The CRF scales for x264 and x265 do not correspond. x265 CRF 28 is supposed to be equivalent to x264 CRF 23. But x265 is not yet as mature in its development as x264, so take that CRF equivalence with a pinch of salt.
That said, you can try to establish your own calibration between the current versions of the encoding libraries in your ffmpeg by running ...
ffmpeg -i input -c:v libx264 -intra output
For H265, seems no alias or preset has been set yet
ffmpeg -i input -c:v libx265 -x265-params frame-threads=4:keyint=1:ref=1:no-open-gop=1:weightp=0:weightb=0:cutree=0:rc-lookahead=0:bframes=0:scenecut=0:b-adapt=0:repeat-headers=1 output
H265 code stolenborrowed from here.
A container is what the name implies, a container for video data and audio data (and other misc. data).
This might go a little bit under your know-how but just to make it easy to understand:
A video is made up by frames which are made up by pixels. A codec like h265/HEVC is there to take this pixel information and process it in a way that makes it a lot ...
Just because you can get a hamburger at different restaurants doesn't mean they'll taste and look the same.
Apples and oranges
x265 and NVENC are two different encoder implementations that can output the same format, HEVC. What settings, options, and algorithms they use is up to the authors as long as the output conforms to the specs.
Choose the right ...
h.265 is obviously more compressed than h.264 and was built for UHD and 4K. Though 1080 files still look great and are even smaller when encoded with h.265 than h.264. Some computers may have trouble with the new codec since it is so new. But, without being too technical, you can think of h.265 and being the new h.264.
In strict mathematical terms, no.
In terms of maintaining an acceptable image quality, yes. If you use CRF 18 and a preset like ultrafast now, you should be able to get a smaller acceptable file with preset veryslow later on.
Your source is neither YUV nor Y4M, going by the extension (and also the FFmpeg error you received). x265 is referring to a raw uncompressed bitstream by those extensions, not simply the pixel format. A .h264 is a raw H.264-encoded bitstream.
To use ffmpeg only, start the cmd like this:
ffmpeg -f h264 -i video.h264 -c:v libx265 ....
To use the x265 ...
As it seems both videos have a bitrate of 118 (117) megabits per second.
This means - regardless off any other parameter - your video will take up 118 mb for each recorded second.
But as you already noted, a video with double the FPS should have double the data, so if you originaly exported the 4k60 video with 118, you can export the 4k30 video with 57mb/s ...
From Why does 10-bit save bandwidth (even when content is 8-bit)?
When encoding with the 10-bit tool, the compression process is
performed with at least 10-bit accuracy compared to only 8-bit
otherwise. So there is less truncation errors, especially in the
motion compensation stage, increasing the efficiency of compression
tools. As a ...
Wrong container format (MP4)
I omitted the information about the container format. I used MP4 in preliminary tests in an effort to increase compatibility with portable devices.
It did not cross my mind that this would be the cause for the missing audio in PowerDVD 17 Ultra player. So the container has been changed to MKV. It did not, however, change ...
That command isn't well-formed. First, you specify copy, then specify a raw HEVC format with HEVC encoding and then RTSP as an output format.
ffmpeg -f image2pipe -vcodec mjpeg -i - -vcodec libx265 -f rtsp rtsp://10.31.5.126:1935/app2/myStream
If you want to know when x265 is going to be in a usable state you will have to ask the developers about that. Though I'm pretty sure they don't know either.
If you want to know when h265/HEVC will be starting to get actually used I'd say earliest end of 2014 though more realistically in mid 2015.
Why? At the moment the devices most profiting from this new ...