Hi, On 06/08/17 04:01, Edmund Grimley Evans wrote: > As far as I know, the best way to implement run-time detection of > hardware capabilities is with getauxval(AT_HWCAP) and > getauxval(AT_HWCAP2). > > There is some kind of NEON detection in ffmeg. See, for example: > > https://sources.debian.net/src/ffmpeg/7:3.3.3-1/libavutil/arm/cpu.c/ > > That code appears to use /proc rather than getauxval. Is there a good > reason for that?
I guess you would have to ask upstream to get an answer to this question. > In case someone reading this has access to hardware (or a simulator) > without NEON but is not familiar with ffmpeg, what is a quick and easy > way of checking whether ffmpeg is working? I think the runtime is working, but this is the testcase from the SIGBUS bug which you can use: ffmpeg -f lavfi -i testsrc=s=32x32:d=0.1 -strict -2 -c:v libx264rgb -f avi libx264rgb.avi -y -hide_banner -nostdin ffmpeg -strict -2 -i libx264rgb.avi -t 1 -c:v rawvideo -c:a pcm_s32le -f nut /dev/null -y -hide_banner -nostdin Since the SIGBUS bug occurs in NEON code, if the runtime detection is working, this will _only_ fail on machines with NEON and work on non-NEON machines. Thanks, James
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