[FFmpeg-user] When will ffmpeg use VP9 v1.5?
barsnick at gmx.net
Tue Nov 24 15:02:11 CET 2015
On Tue, Nov 24, 2015 at 14:31:58 +0100, D wrote:
> I played setting the values higher but it was neither faster nor slower.
> Average 4 cores utilization is still ~80%.
BTW, how do you define "utilization"? I believe in "top", 100% equals
one core's usage, so you should be able to achieve 400%. Below, you use
the term "100% on all 4 cores".
That said: I don't know much about libvpx, but this page:
and more explicitly this one:
says to use "-tile-columns" along with "-threads".
-tile-columns slightly affects output quality but it's the only
mechanism in VP9 to provide multithread encoding and decoding.
According to that, "-tile-columns" apparently defaults to 6. OTOH
"ffmpeg -h" says "-1", which corresponds to not explicitly setting it
to the encoder. And according to the encoder's sources:
> By default, the value is 0, i.e. one single column tile for entire
So 6 (correspnding to 2^6 columns) is likely not the default, but 0
(corresponding to 1 column), which is not beneficial to threading.
Disclaimer, again: I know nothing much about libvpx or VP9. ;-)
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