[x265] [PATCH] Added support for multiple references

[Olivier Lapicque]

Yeah, it seems like it should be more like:
MaxDecPicBuffering = 1 (Current) + MaxNumNegativePics (=MaxForwardRefs) + MaxNumPositivePics (=MaxBackwardRefs)

With assuming
MaxNumNegativePics = maxNumReferences (really MaxNumForwardReferences)
MaxNumPositivePics = limited by gop structure (reordering)

For a standard GOP structure with non-reference B-frames (coded order=Pbbb):
MaxDecPicBuffering = 1 (Current) + maxNumReferences + 1 ( 1P available as backward reference, limiting NumPositivePics to 1) = 2+maxNumReferences

For 1-deep B-pyramid where the middle-B is a reference (display order=bBbP, coded order=PBbb):
MaxDecPicBuffering = 1 (Current) + maxNumReferences + 2 (1P + 1B available as backward references, limiting NumPositivePics to 1) = 3+maxNumReferences

Olivier

From: x265-devel [mailto:x265-devel-bounces at videolan.org] On Behalf Of Steve Borho
Sent: Wednesday, September 25, 2013 3:36 PM
To: Development for x265
Subject: Re: [x265] [PATCH] Added support for multiple references



On Wed, Sep 25, 2013 at 5:27 PM, Olivier Lapicque <olapicque at nvidia.com<mailto:olapicque at nvidia.com>> wrote:
Shouldn't it be X265_MAX(m_numReorderPics[i] + 2, _param->maxNumReferences+1) ?
Unlike H.264, the picture is added to the DPB before being decoded (so the current picture always takes up one slot in the DPB)

I was just staring at that line myself.  It would probably be more clear to add the +1 after the X265_MAX.  What I wasn't sure about was whether m_maxDecPicBuffering is supposed to also include the max B frame count as well.

--
Steve

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