[FFmpeg-user] libx265 a lot slower

Alexander Strasser eclipse7 at gmx.net
Thu Aug 20 18:28:44 EEST 2020

On 2020-08-19 15:06 +0200, Moritz Barsnick wrote:
> On Mon, Aug 17, 2020 at 22:53:12 +0200, Cecil Westerhof wrote:
> > Maybe I am just dumb and I use the wrong questions, but when I
> > searched I got a lot of hits that explained I needed tot switch
> > because the space needed would be halved
> Well, if you're driving a compact, and someone writes "you need to
> switch to a Jeep, because it can pull your trailer out of the mud", do
> you buy a Jeep? ;-)
> I'm trying to say: Try to understand the benefits and the
> disadvantages, and check against your requirements.
> Do you need less space? Are you willing to sacrifice encoding speed? Is
> H.265 the right codec for your type of videos? As Mick Finn pointed
> out, H.265 is more designed for higher resolutions and bit depths
> (IIUC). Can your target players even decode H.265? (Does the Jeep even
> fit into your parking spaces? Do your feet reach the pedals?)
> There's no matter of "must", "need to" - just of considerations. I
> believe whatever you read, implied some other details, or forgot to
> tell about them.
> BTW, if someone does magic hacking, or even more optimized GPUs emerge,
> x265/H.265 *may* become "faster" than x264/H.264. It isn't right now.
> > (what is not true, I did see 'only' a 2/3)
> It depends on the material. I'm sure there are tons of comparisons out
> there.
> > and a few explained that you could not use h265
> > everywhere, so you should evaluate if it was a good idea to switch.
> Absolutely! Even if I could encode my material to H.265, I probably
> wouldn't, except when targetting a very specific player (modern smart
> phones?). My PVR/STB, my TV, ..., cannot decode it. Possibly even my PC
> doesn't have enough compute/GPU power to decode it in full HD.
> > In none of the hits I saw anything about a performance hit. Especially
> > not a hit up to a factor three.
> They should. ;)

Maybe also an interesting question to ask (I try to extend the car

Do the cars available to you master the inclusion of new tech in a
way that compares favourably to existing cars?

Are you fine with the new feature - cost balance comparing to
other cars? Are you willing to accept higher space and fuel
usage of the big jeep for its extra features?

Or without cars: Is there an encoder available to you that creates
significantly smaller same quality output in less space while not
taking ages to encode?

Of course there are other similar questions to ask and it may depend
on your use case. E.g. like Moritz mentioned which devices do you
target or what is the enconding situation?
(E.g. how much delay/energy usage can you accept?)


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