./ffmpeg -f lavfi -i yuvtestsrc=duration=1:size=1200x1440 \
                -s 1200x720 -f null -vframes 100 -pix_fmt $i -nostats \
                -cpuflags 0 -v error -

32-bit mul, power8 only.

~6.4x speedup:

rgb24
 214278 UNITS in yuv2packedX,   16384 runs,      0 skips
  33249 UNITS in yuv2packedX,   16384 runs,      0 skips
bgr24
 214616 UNITS in yuv2packedX,   16384 runs,      0 skips
  33233 UNITS in yuv2packedX,   16384 runs,      0 skips
rgba
 214517 UNITS in yuv2packedX,   16384 runs,      0 skips
  33271 UNITS in yuv2packedX,   16384 runs,      0 skips
bgra
 214973 UNITS in yuv2packedX,   16384 runs,      0 skips
  33397 UNITS in yuv2packedX,   16384 runs,      0 skips
argb
 214613 UNITS in yuv2packedX,   16384 runs,      0 skips
  33310 UNITS in yuv2packedX,   16384 runs,      0 skips
bgra
 214637 UNITS in yuv2packedX,   16384 runs,      0 skips
  33330 UNITS in yuv2packedX,   16384 runs,      0 skips