Paul B Mahol wrote > On Thu, Jan 28, 2021 at 10:23 PM Mark Filipak (ffmpeg) <
> markfilipak@ > > > wrote: > >> Synopsis: >> >> I seek to use minterpolate to take advantage of its superior output. I >> present some performance >> issues followed by an alternative filter_complex. So, this presentation >> necessarily addresses 2 >> subjects. >> >> Problem: >> >> I'm currently transcoding a 2:43:05 1920x1080, 24FPS progressive video to >> 60FPS via minterpolate >> filter. Apparently, the transcode will take a little more than 3 days. >> >> Hardware: >> >> There are 4 CPU cores (with 2 threads, each) that run at 3.6 GHz. There >> is >> also an NVIDIA GTX 980M >> GPU having 1536 CUDA cores with a driver that implements the Optimus, >> CUDA-as-coprocessors architecture. >> >> Performance: >> >> During the transcode, ffmpeg is consuming only between 10% & 20% of the >> CPU. It appears to be >> single-threaded, and it appears to not be using Optimus at all. >> >> Is there a way to coax minterpolate to expand its hardware usage? >> >> Alternative filter_complex: >> >> minterpolate converts 24FPS to 60FPS by interpolating every frame via >> motion vectors to produce a 60 >> picture/second stream in a 60FPS transport. It does a truly amazing job, >> but without expanded >> hardware usage, it takes too long to do it. >> >> A viable alternative is to 55 telecine the source (which simply >> duplicates >> the n%5!=2 frames) while >> interpolating solely the n%5==2 frames. That should take much less time >> and would produce a 24 >> picture/second stream in a 60FPS transport -- totally acceptable. >> >> The problem is that motion vector interpolation requires that >> minterpolate >> be 'split' out and run in >> parallel with the main path in the filter_complex so that the >> interpolated >> frames can be plucked out >> (n%5==2) and interleaved at the end of the filter_complex. That doesn't >> make much sense because it >> doesn't decrease processing (or processing time) and, if the fully >> motion-interpolated stream is >> produced anyway, then output it directly instead of interleaving. What's >> needed is an interpolation >> alternative to minterpolate. >> >> Alternative Interpolation: >> >> 55 telecine with no interpolation or smoothing works well even though the >> n%5==2 frames are combed >> but decombing is desired. The problem with that is: I can't find a >> deinterlace filter that does >> pixel interpolation without reintroducing some telecine judder. The issue >> involves spacial alignment >> of the odd & even lines in the existing filters. >> >> Some existing filters align the decombed lines with the input's top >> field, >> some align the decombed >> lines with the input's bottom field. What's desired is a filter that >> aligns the decombed lines with >> the spacial mean. I suggest that the Sobel might be appropriate for the >> decombing (or at least, that >> the Sobel can be employed to visualize what's desired). >> >> Sobel of line y: ______/\_____________/\_________ (edges) >> Sobel of line y+1: __________/\_____________/\_____ >> Desired output: >> line y: ________/\_____________/\_______ (aligned to mean) >> line y+1: ________/\_____________/\_______ (aligned to mean) >> I could find this: >> line y: ______/\_____________/\_________ >> line y+1: ______/\_____________/\_________ (aligned to top line >> edges) >> and I could find this: >> line y: __________/\_____________/\_____ (aligned to bottom >> line edges) >> line y+1: __________/\_____________/\_____ >> >> > Sorry, but I can not decipher above stuff. Does anybody else can? He wants an "inbetween" scanline (and perhaps resampled to a full frame) for the target frame . Y=0 and Y=1 represent scanlines from 2 different times (fields from 2 different times). He wants something in the middle, such as Y=0.5. ie. A retimed in-between frame , perhaps using optical flow The other option he had been using was blend deinterlacing , a vertical blur between Y=0 and Y=1, which combines both times, but obvious problems with blurring and ghosting (The best option, hands down, is a judderless display, so you don't have all these artifacts or blurring. Very inexpensive nowadays) -- Sent from: http://ffmpeg-users.933282.n4.nabble.com/ _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".