Etiquette, expectations, entitlement...
@autoexec_bin | #magiclantern | Discord | Reddit | Server issues
Quote from: Onion on Today at 03:53:32 PMSo the 1080p 60fps output doesn't use 3x3 pixel binning?
Quote from: names_are_hard on May 25, 2024, 07:26:36 PMAnd yeah, because here you can treat each frame / file as a separate decompression job, you can trivially parallelise the overall task. 8 cores? Use say, 6 threads, and decode whatever frame someone requests, and the next 5.
Quote from: vastunghia on May 25, 2024, 06:53:45 PMSo it looks like this could be a bottleneck after all, at least to some extent. And in particular as long as one keeps asking for single frames in sequence, one at a time (as DVR seems to do, naturally assuming that the bottleneck is hard drive read speed, and not CPU), instead of asking for a bunch of them, and then proceed to the next bunch.
Quote from: names_are_hard on May 25, 2024, 05:03:23 PMBut then you have to do the real step: profiling.
Quote from: vastunghia on May 24, 2024, 09:41:51 PMCould be helpful to make MLVFS log single frame read requests with their corresponding timestamp, to try and understand the time sequence with which DVR asks for frames. And check if frame requests are repeated during the third playback, when all seems to be cached already. May give it a try as soon as I have 10 minutes.
Quote from: names_are_hard on May 25, 2024, 05:03:23 PMDecompression is normally much faster than compression and parallelises well. I would expect this not to be a bottleneck, and if it is, I'd expect it to be easy to fix. Easy to measure with a profiler.
QuotePerformance of Lossless JPEG decoder is mostly limited by Huffman decoding. Actually, we need to read bitstream (bit after bit), to recover Huffman codes and data bits. Huffman decompression is essentially serial algorithm, so one can't implement it on GPU, that's why everything is done on CPU.
Page created in 0.062 seconds with 11 queries.