[FFmpeg-devel] [PATCH 2/2] libx265: Enable 12-bit encoding

Stephen Hutchinson qyot27 at gmail.com
Sun Aug 23 03:03:41 CEST 2015

On 8/22/2015 3:26 PM, James Almer wrote:
> The warnings were removed from the master branch of libx265 three days
> ago, and X265_BUILD in that branch is 71.
> libx265 1.8 will be tagged from the stable branch in the coming days,
> which is not up to date with master (X265_BUILD is 68) and of course
> means it still has the 12bit warnings. It however looks like no changes
> related to 12bits encoding were added to master since then, so even with
> warnings 1.8 should be good.
> Hopefully they will backport the warning removal commit if that's the
> case before tagging the new release.

Agreed. I really only picked 60 because of the commit message in
http://hg.videolan.org/x265/rev/a7b2a1cfd10e, mostly about what
minimum version needs to be checked to avert compilation failure.
But the experimental warnings would still be there.  The change
actually happened at API version 59, though (said commit was the
second-to-last commit prior to 1.7 being tagged).  60 would simply 
guarantee that it's there, but if the user is checking out 1.7 directly, 
I guess that might not be necessary.

> I don't really think checking for 60 is enough to get working 12bit
> non-experimental encoding. 68 will probably be a safer bet.
> And regardless of which we end up checking for, this change will break
> support for libx265 1.7, which is not a good idea at the very least until
> 1.8 is released.

To test, I checked out 1.7 from the 1.7 tag. Dropping the check in
the patch to 59 so I could use 1.7, compilation still succeeds.  The 
requirement for -strict experimental would be necessary to pair with the 
warnings in libx265, but it doesn't appear to actually break.

Otherwise, waiting for 1.8 would be preferable since hopefully the 
warnings wouldn't be necessary.

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