[x265] Who washed my video? x264 vs x265 'placebo' comparison

[Derek Buitenhuis]

On 2/23/2014 10:22 PM, Tom Vaughan wrote:
> Does the MKV contain video that was ripped straight from the Blu-ray Disc?
> The video in the MKV is only 14 Mbps... I would have expected a higher bit
> rate (and more detail) if this was not re-encoded.  It would be best to
> start with the highest quality source possible.

This is a red herring argument. The vast, *vast* majority of actual use cases
will be recompressing existing content. Also, 14 mbps is hardly low. I would
almost argue it's not interesting to compress from ridiculously high quality or
lossless sources, except to test pure improvement changes (i.e. devs).

> Notice that prova.h264 is twice the size (12 MB) of prova.h265 (6 MB).  This
> explains some of the difference in quality.  It's hard to hit a bit rate
> target with such a short clip.  You may need to use CRF, experimenting with
> different values until you get close.  I think that your test method is
> valid, and the results are very interesting, but you have to make sure that
> you end up with identical bit rates.

Answered by Niccolò elsewhere.

> To be fair, we want to compare encoded frames to the original incoming
> frames.  We don't want to consider "more compression artifacts" to be "more
> detail".

So you completely discount the notion of psychovisual optimization... ?

> There are definitely some areas where your x264 encode preserved
> more detail, such as in the waves on the water, or the green areas in the
> landscape.  I noticed that even at half the bit rate, the x265 encode
> provides much more accurate edge definition of objects in motion and far
> lower noise than the x264 encode.  Notice how you can see the individual
> feathers in the close-up shots of the birds flying.

As noted in Niccolò's email, it's not half the bitrate.

I must say, as a viewer, similar complexity > blur, always. You see this sort
of thing almost all the time in PSNR-optimized ratecontrol, and it's sad.

[...]

- Derek