[x264-devel] x264 Development Newsletter vol. 29

[Jason Garrett-Glaser]

This is the twenty-ninth x264 development newsletter. This is a
regular email containing updates on fixes and improvements in the most
recent x264 push, along with updates on what's coming next.  Previous
versions can be found in the mailing list archives.

A hotfix was pushed this time on March 11 to fix clobbering of
mutexes/cvs in the sliced threads patch from last time.  This didn't
affect stable.

Fixes:

Fix a sliced threads ratecontrol bug: qp was swapped with qscale in
the ratecontrol distribution code, causing less accurate results and
possible NaNs.

Fix input colorspace checks.

Fix NAL HRD calculation with intra refresh.

Fix shared library generation on MSVC/ICL.

Improvements:

Add --extra-rcflags to configure and correct handling of the RC variable.

Update config.sub/config.guess, which adds support for detecting some
new arches (armv8, etc).

Force -m32/-m64 for i386/x86_64 compiling, making multilib compilation
more convenient.

Fix disabling of mtree with 2-pass encoding and zones.

Add level 5.2 support.

Add dedicated ads function for faster chroma weight cost calculation,
plus x86 asm.

Add a constant-MB API that allows callers to assist x264 by telling it
in advance which macroblocks remain unchanged since the previous
frame.  This may be extended over time to add other features, such as
external motion vectors.  This can give a significant performance
increase in the case of mostly-constant video where this information
is known, i.e. in VNC applications.

Upcoming:

Google Code-In is done, but a bunch of NEON assembly still needs review.

x262 is under development: a best-in-class MPEG-2 encoder built using
the x264 framework.  It works well enough to be vaguely usable now,
but is still highly experimental and needs more work -- developers
welcome!

xvp8 is under development: a best-in-class VP8 encoder built using the
x264 framework.  It supports I-frames with i16x16 blocks now and is
being extended to support more of the spec.

Jason Garrett-Glaser

The x264 Team