[x264-devel] [PATCH] fix bug of weighted bipred according to Rec. ITU-T H.264 (10/2016) 8.4.3

[Lingjiang Fang]

On Thu, 21 Jan 2021 00:02:18 +0300
BugMaster <BugMaster at narod.ru> wrote:

> On Wed, 20 Jan 2021 10:59:39 +0300, BugMaster wrote:
> > On Wed, 20 Jan 2021 11:55:14 +0800, Lingjiang Fang wrote:
> >> On Wed, 20 Jan 2021 00:51:11 +0300
> >> BugMaster <BugMaster at narod.ru> wrote:
> 
> >>> ...
> >>> Hi.
> >>> 
> >>> I understand which part of H.264 spec you tried to fix. But was
> >>> you able to really trigger this bug (code path) in x264? I in my
> >>> quick test I couldn't because x264 does not use long-term refs
> >>> and I don't know when poc0 and poc1 would be equal for B-frame
> >>> (which frame-types pattern will cause this?).
> 
> >> thank you for your reply ^_^
> >> Yes, we will never trigger this bug under the current logic of
> >> x264, we notice this because we want do some enhancement to the
> >> reference management, so we need to fix it first.
> >> anyway, since the implementation doesn't follow the spec and it's
> >> easy to fix it, why not ^_^
> 
> > Ok, understood. But I have rewritten it another way:
> > https://code.videolan.org/BugMaster/x264/-/commit/60dc14afb103cbbbdd79d643c4746ca95ba86b22
> > So check that I didn't miss anything and your enhancement will be ok
> > with it.
> 
> I have created MR with this fix (with small changes):
thanks, your MR is much more clear
however, I wonder why you revert the small change of completing the
comment below :)
if( td == 0 /* || pic0 or pic1 is a long-term ref */ )

> https://code.videolan.org/videolan/x264/-/merge_requests/47
> 
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Regards,
Lingjiang Fang