2016-10-24 13:02 GMT+02:00 YIRAN LI <[email protected]>: > > > 2016-10-24 19:49 GMT+11:00 Carl Eugen Hoyos <[email protected]>: >> >> 2016-10-24 7:26 GMT+02:00 YIRAN LI <[email protected]>: >> >> > I'm researching the impact multi-thread decoding may have on memory >> > usage. >> > Does anyone know if enabling multi thread decoding will use more memory >> > ? >> >> Multi-threaded decoding can be more memory-consuming than single-threaded >> decoding, FFmpeg developers do not agree whether this is unavoidable or a >> disadvantage of our implementation. >> >> > (so that more threads used, more memory required?) >> > >> > I tried to decode an H.264 encoded 4K video using command: >> >> > ffmpeg.exe -v error -i a.mp4 -threads 0 -f null - 2>error.log >> >> How did you encode the H.264 input file? >> Test with eight reference frames and yuv 4:4:4. > > Thanks Carl, does that mean multi-thread decoding doesn't work > for all H.264 videos?
That is not what I wrote but I believe that for inter-dependency codecs like h264, this is always true. > I'm at home so I can only do the test tomorrow, but could you tell > me, if you know, if more threads used in decoding will generally > consume more memory? I believe I already answered this but I suspect it depends on your definition of "generally" and "more" (even if FFmpeg would not allocate additional resources for multi-threaded decoding which I believe it does, the operating system would have to anyway). > If decoding speed is not that important, is > there any other reason to use multi-thread decoding? Again, this depends on your definition of "decoding speed": Multi-threaded (h264) decoding has a huge overhead / scales very badly, so some will argue that to increase decoding speed (for many videos), you have to use single-threaded decoding for h264. Carl Eugen _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
