Le sextidi 16 prairial, an CCXXIV, Jesper Taxbøl a écrit : > I am working on a threaded video reader to spread the decode workload on > some more cores and gain some speed. My source is included below: > > The thing is that I dont see a time improvement when starting two processes > instead of one. On a 80mb mp4 file it takes 6 seconds to decode the video, > while doing two in parallel takes 12 seconds. I can see that two cores's > are used 100 percent. Im on a fast SSD disk so I dont think im IO limited. > > What could be the case. Is it the same decoder taht is doing all the work? > Do I perhaps need to instantiate a context or something?
The decoders for the most common codecs, including the ones you are probably using in your MP4 files, are already threaded in FFmpeg. Unless you have a lot of cores, a single instance of the decode probably already uses them all completely. Running several instance in parallel will only add context-switching overhead. Please remember that top-posting is not accepted on this list; if you do not know what it means look it up. Regards, -- Nicolas George
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