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To me they have a implementation issue, at least on my systems. They use the GPU for media library playback decoding (shown in pic) but not timeline playback (other pic). Of course this depends on PD pref settings for HA. This behavior appears strange to me.
Interesting, and nice catch !
Is this issue specific to H.265 ? Or are you seeing it with H.264 as well ?
Of course, the GPU load might be lower with H.264 hardware decoding. Perhaps try to playback a 4K H.264 file in the timeline to push the needle a bit more.
The next test would be to do a rendering with the software encoder to see if the hardware H.265 decoder gets utilized at all not for this case. The GPU load % might be low if you render in software at full resolution. Maybe try to render a 4K clip to a low resolution in software, and see if the hardware decoder gets used. Again, it would be good to do this test with both H.264 and H.265 .
I have done this a long time ago with H.264 and on older GPU hardware (pre-nvEnc), and older PD. Back then, PD was definitely utilizing the hardware decoder at all times. This was easily noticeable without even looking at any GPU tool because simply turning on/off the "use hardware deocding" setting box in PowerDirector would shorten software rendering times.
It would be good to see if this setting box still has the same effect on rendering times for H.264 on current GPUs, and whether it has any effect on H.265 . I can do the former test, but I can't do the later since I returned my GTX960 at this time, so I don't have any GPU with H.265 hardware decode capability.
Hopefully, it's just another bug on the Cyberlink side for H.265 . But it's also possible that the nVidia API for the H.264 and H.265 hardware decoders is different, and the H.265 decoder can only decode straight to the display, as would be the case when playing back a clip, and not to a buffer in RAM, which would be needed for timeline playback, or for rendering. I hope that's not the case.I haven't seriously programmed any graphics since my DOS days hacking the VGA card in assembly 20+ years ago, so I don't have any idea about the modern Windows graphic APIs.
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