On 3/15/2016 4:46 AM, Ganesh Ajjanagadde wrote: > Concretely, it is nearly as fast as av_lfg_get (which only returns 32 bits), > and has a much smaller cache (128 bits). Thus, the timings should also > be more stable. > > This is needed because av_lfg_get<<32 | av_lfg_get is far slower, and > likely less random as measured by BigCrush - most LFG's perform > quite poorly on the BigCrush suite: > http://www6.tw.freebsd.org/distfiles/testu01.pdf. > In particular, FFmpeg's seems to be Ran055 in the paper, see pg31.
This doesn't explain how it benefits our uses of PRNGs. We are a set of multimedia libraries, not a general utilities library. Most of our use is for noise generation or unit tests, neither of which benefits much/at all from this. For encrypted streams, we pass in keys via options (e.g. MP4 CENC), mostly. - Derek _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
