GPU vs CPU measurements

Tests

On 1minute 1080p file

Base measurements

Original impl

46.866s / 45.314s

x264enc -> nvh264enc

30.006s

After removing overlay

Original impl

34.834s 35.933s

x264enc -> nvh264enc

6.099s 6.008s

Added upscale

Upscaling 1080p->4k

Bitrate 16->80mbit

Original impl

2m42.928s

x264enc -> nvh264enc

17.390s

Moved all video to gpu

15.469s 15.564s 15.484s

added crude overlay

54.255s (29.196s of measured drawing time (runs on CPU))

i.e.:

about 10s is overhead from passing memory to GPU and GPU applying the overlay
about 29s is overhead from crude CPU drawing without caching that can be improved

Note the overlay is now generated after scaling - i.e. CPU measurements were in 1080p genration, GPU is in 4K

Test on raw GoPro video

Video length: 39m30s
Resolution: 1080p
Full GPU impl
no overlays

Time: 8m45.467s (4x speedup!)