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Handbrake 1.5.1 | re-encode large x265 into smaller x265?

J

Jim Lahey

macrumors 68030
Original poster
Apr 8, 2014
2,754
5,734
Hello folks. Does anyone know if Handbrake is able to shrink an existing x265 into a smaller x265 using a higher RF value? I originally assumed it was possible but on each attempt I keep getting a nondescript error that doesn't actually explain anything to the novice. I had hoped it was possible to take a very large HEVC video file and shrink it down, but it appears not. Am I missing something or is this common knowledge? No setting that I try seems to make any difference. The encoding always fails immediately.

Thanks.
 
HDFan said:
How do you define "smaller" - smaller in frame size or file size?
Click to expand...

Sorry, I wasn’t clear. File size. It works if I try to downscale from 2160p to 1080p, but keeping the same resolution results in instant failure, even if I select something materially different such as the bit-depth. Seems that basically once something is encoded as x265 that‘s your lot and it can’t later be compressed at the same resolution? If so then that’s fine but just looking for confirmation as I didn’t have much luck with web searches. Mainly wondering if there’s a setting or workaround that I don’t yet know about.
 
It works for me with RF 51 :)
I’ve also tested by setting the average bitrate of the output to half of the input, resolution unchanged (1080p), video encoder H.265 (x265) or H.265 (VideoToolbox), the second one producing a slightly larger file with the same setting.
 
bogdanw said:
It works for me with RF 51 :)
I’ve also tested by setting the average bitrate of the output to half of the input, resolution unchanged (1080p), video encoder H.265 (x265) or H.265 (VideoToolbox), the second one producing a slightly larger file with the same setting.
Click to expand...

Thanks for the info. I will have to do some more fiddling about.
 
Seems the only way I can get this to work is by using VideoToolBox as the encoder. I should have been more specific in that I'm trying to encode 2160p HDR files so maybe my CPU just isn't up to it? Any downsides to using VideoToolBox with average bitrate instead of x265 constant quality RF?
 
bogdanw said:
HDR10 encoding https://handbrake.fr/docs/en/latest/technical/hdr10.html
Constant Quality vs Average Bit Rate https://handbrake.fr/docs/en/latest/technical/video-cq-vs-abr.html
Apple VideoToolbox https://handbrake.fr/docs/en/latest/technical/video-videotoolbox.html
Click to expand...

Thanks but I had already come across those articles earlier today. The VideoToolBox literature doesn’t do much to explain the outcomes vs. vanilla x265, but I appreciate it will depend on many factors. Honestly though I think I’m just going to give up on this until I have a faster computer ?
 
Depending on your mac, VideoToolBox uses the iGPU (integrated GPU in the Intel processor) or the GPU.
Depending on the app that uses the VideoToolBox method of encoding, it could be faster than encoding done by the CPU.
 
bogdanw said:
Depending on your mac, VideoToolBox uses the iGPU (integrated GPU in the Intel processor) or the GPU.
Depending on the app that uses the VideoToolBox method of encoding, it could be faster than encoding done by the CPU.
Click to expand...

I tried some VideoToolBox encoding and it was at least 100% faster than regular x265 but the constant quality option isn’t available in this mode which gives me pause. The whole process is still extremely slow and probably not worth the effort at this stage. I will probably readdress the situation when I have an Apple Silicon Mac at some point in the hopefully not too distant future ?
 
Last edited:
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