4k on Cinelerra - RC Groups
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Nov 19, 2016, 02:50 PM
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4k on Cinelerra


The answer is yes. Cinelerra can play 3840x2160 in a 2560x1600 window at 30fps without any hardware acceleration, on the 7 year old AMD. For all those years, it seemed hopeless, but it had the power long before 4k cameras were around. It doesn't work so well in a 3840x2160 window, but the lion kingdom can't afford a 4k monitor. It requires some diabolical hacks, without which it only did 15fps for all those years.


XMovie used a file -> BGR8888 bitmap -> window pipeline back when computers could barely play 720x480. The only way to watch a movie was on XMovie. When computers got fast enough, XMovie went away & Cinelerra got away with using file -> YUV888 intermediate -> BGR8888 bitmap -> window to play everything up to 1920x1080. Once again, the limit of computing power has been reached & the intermediate copy needs to be skipped again.


It was surprising that file -> YUV888 intermediate -> OpenGL was slower than file -> BGR8888 bitmap -> window. OpenGL was always slower than software on this system, but it used a 10 year old graphics card.


The idea of optimizing it occurred while adding a colorspace converter for the new HDR codecs & remembering all the codecs still contain the scaling routines for XMovie to play on low end machines 17 years ago. There's also the fact that virtual machines, faster CPUs, & vanishing interest in PC video has made hardware acceleration in Linux go away & the old software BGR8888 bitmap has become the standard video device.


20 years ago, you had to blit to 8 bits, 16 bits, & 24 bits in both endians. Nowadays, BGR8888 is guaranteed to always work & the codecs know if it's BGR8888, it's always going directly to the window so it needs to scale at the codec level. We also know 99% of the time, video is shown with no processing or cropping. Of course, the moment it has any effects or cropping, it has to revert to the slow intermediate frame & there are probably a few operations it can't do at all.


Despite the fact that all quadcopters now have 4k cameras, all action cams do 4k, & gootube famously added 4k support years ago, it's hard to find anyone using it for anything but test footage. There was a period 2 years ago when everyone uploaded 4k video to gootube, but now they've reverted to 1080. There's still no DSLR which can do it full frame.
Last edited by Jack Crossfire; Nov 19, 2016 at 09:04 PM.
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