[x265] [PATCH] Introduce CLI/param options to control min and max VBV fullness

[Aruna Matheswaran]

On Thu, Sep 10, 2020 at 2:59 AM Alex Giladi <alex.giladi at gmail.com> wrote:

> Hi Aruna,
> I don't understand the relationship between the patch and compression
> efficiency / compliance:
>     +    Increasing the minimum required fullness shall improve the
> compression efficiency,
>     +    but is expected to affect VBV conformance. Experimental option.
> 1. Does the result produce streams which may violate HRD constraints?
>

[AM] No, Alex. The default buffer fullness limits are set in a manner that
rate-control shall account for HRD prediction errors and the encodes will
not encounter HRD violation. Relaxing the limits too much via the CLI
options may not give space for rate-control to compensate prediction errors
and might result in HRD violation. It is highly content-dependent.

2. How does this option affect compression efficiency?
>
[AM] Though the default hard coded HRD fullness limits are good in
maintaining VBV conformance overall, it might impose unwanted rate-control
constraints in some titles. Tuning these limits slightly to adapt to the
source title is expected to improve compression efficiency without
violating HRD conformance.

>
> Best,
> Alex.
>
>>
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>


-- 
Regards,
*Aruna Matheswaran,*
Video Codec Engineer,
Media & AI analytics BU,
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