[x265] Fwd: Encoding question

[Mario *LigH* Rohkrämer]

Tom,

I guess you can imagine similar "Let's Play" videos of FPS with a  
partially translucent HUD. They will also have some (semi-) static  
elements near the border of the frame, but uncovered moving content in the  
middle.


Sebastian,

the x264 encoder recently merged an experimental AQ mode 3 with bias  
towards dark areas to the release branch; x265 did not yet adapt AQ mode 2  
with completely satisfying results, but when its development continues, an  
adaption of mode 3 may also be interesting. Not yet a solution for your  
issue, but maybe "soon™" ;-)

Encoding of partially covered motion is a pretty tough issue. MPEG-7 tries  
to model layers of shapes, but that's the next generation... For current  
encoders, "more bitrate" may be one of the best recommendations.

Disclaimer: IMHO. There will probably be more experienced people than me...


Am 20.01.2015, 02:03 Uhr, schrieb Tom Vaughan  
<tom.vaughan at multicorewareinc.com>:

> Hi Sebastian,
>
> We don’t currently support the ability to adjust the quantization in
> specific areas of the picture.  If you share samples of what you’re  
> seeing
> it would help us understand the challenge better.
>
>
>
> Best regards,
>
> Tom
>
>
>
> *From:* x265-devel [mailto:x265-devel-bounces at videolan.org] *On Behalf
> Of *Sebastian
> Sylwan
> *Sent:* Monday, January 19, 2015 11:27 AM
> *To:* x265-devel
> *Subject:* [x265] Fwd: Encoding question
>
>
>
> Hi,
>
>
>
> This is my first message to the list, so please forgive me if it is not
> fully appropriate for it.
>
>
>
> I am experimenting with encoding video whose final application is to be
> merged with static images around it. I have reached an appropriate level  
> of
> compression, but I am seeing some quantization issues at the edge of the
> frames, that would probably be perceptually ok, if they weren't adjacent  
> to
> a static image that is supposedly blended to the video. This is really  
> only
> noticeable in the darker areas of the image, and in regions that are
> static, and the artifact is mostly noticeable since there is a tinting
> towards green (and a slight brightening).
>
>
>
> I was wondering if there is a way to tell the encoder to quantize less
> aggressively around the edges (or in any specific area). Alternatively,
> also biasing the quantization towards the darker regions of the image may
> work. Since the artifacts seem to build overtime, I wonder if there is a
> drifting of a DC component also happening.
>
>
>
> Any suggestion appreciated. Of course I could increase the bitrate, but  
> the
> rest of the image is ok.
>
>
>
> Thank you.
>
>
>
> S


-- 

Fun and success!
Mario *LigH* Rohkrämer
mailto:contact at ligh.de