Min Chen wrote: > Sent: Thursday, September 30, 2021 10:29 AM > To: FFmpeg development discussions and patches <ffmpeg- > de...@ffmpeg.org> > Subject: Re: [FFmpeg-devel] [PATCH v2 3/4] libswscale/x86/rgb2rgb: add > uyvytoyuv422 avx2 > > Hello, > > >+pb_shuffle_low: times 4 db 1, 3, 5, 7, 9, 11, 13, 15, -1, -1, -1, -1, > >+-1, -1, -1, -1 > Why we times 4? > AVX2 provided instruction VPBROADCASTQ to load these constant into SIMD > register. > > Moreover, the plane U/V also apply same algorithm to get improve. > > Regards, > Min Chen > Hi Min Chen,
Much appreciated your helpful suggestions. Correct! It's not necessary to use time 4 here. It's funny that I did try to avoid using it here when writing the codes and get no way because I ignored the VBROADCASTI128 instruction. About the UV extracting, I have estimated the new method before making a decision to keep using the masterpiece of the previous author. The former is better, and pand instruction has a better reciprocal throughput, or issue latency. Best regards, Jianhua _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
