[FFmpeg-devel] [PATCH] cbs_h265: Detect more reference combinations which would overflow the DPB

[Mark Thompson]

On 21/02/2021 20:54, Michael Niedermayer wrote:
> On Wed, Feb 03, 2021 at 09:34:07PM +0000, Mark Thompson wrote:
>> In total, the number of short term references (from the selected short
>> term ref pic set), the number of long term references (combining both the
>> used candidates from the SPS and those defined in the slice header) and
>> the number of instances of the current picture (usually one, but can be
>> two if current picture reference is enabled) must never exceed the size
>> of the DPB.  This is a generalisation of the condition associated with
>> num_long_term_pics in 7.4.7.1.
>>
>> We use this to apply tighter bounds to the number of long term pictures
>> referred to in the slice header, and also to detect the invalid case where
>> the second reference to the current picture would not fit in the DPB (this
>> case can't be detected earlier because an STRPS with 15 pictures can still
>> be valid in the same stream when used with a different PPS which does not
>> require two DPB slots for the current picture).
>> ---
> 
>> Michael: does this fix your fuzz case for num_long_term_sps?
> 
> yes

Added appropriate annotation and applied.

Thanks,

- Mark