A few other things...
In my testing of encoding a single frame where I only examined
processing of the first few CUs this search method always found the
lowest cost but cost values never followed a consistent curve with a
single low point. Without further testing or deeper knowledge of the
angle intra modes I wouldn't guarantee the lowest cost will always be found.
Also, unfortunately my system is old and doesn't support sse4 and that
is the only level of assembler supported for intra mode predictions so I
was only able to develop and test for the c primitives. I need to
upgrade...
Yes, there was a small performance increase that seemed larger when
encoding a single frame than a short video. Neither produced consistent
results on my system but the new search method was slightly faster most
of the time when encoding a single frame and always faster when encoding
a short video.
On 08/01/2014 09:50 PM, Steve Borho wrote:
On 08/01, dave wrote:
I am submitting a patch to implement the faster intra search suggested by
Steve Borho here:
https://mailman.videolan.org/pipermail/x265-devel/2014-July/004873.html
nice!
The patch is implements the faster search in slicetype.cpp. The same
approach can also be used in analysis.cpp but it's a little more than a
simple cut and paste though it shouldn't take long.
yep
TEncSearch.cpp also calls intra_pred_allangs for which this is the faster
alternative but at first look, TEncSearch.cpp is more complex. Depending on
what is desired, either this search could greatly simplify this part of
TEncSearch.cpp or it might not be applicable to what TEncSearch.cpp is
doing. I will be looking into it.
it should also apply here; this function is a little more complicated
because it keeps a "best N" list of modes, and then performs
rate-distortion measurements (encodes each option and records the actual
distortion and bit cost) to select the final intra mode. The same 'fast
scan' mode could be used to build the 'best N' list. But I imagine most
presets that use this RDO version of intra will not want a fast scan.
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