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Re: Optimal cores for Apple 2160p60 4K HEVC Surround preset?

Posted: Tue Jun 30, 2020 12:28 am
by mduell
8Ringer wrote:
Mon Jun 29, 2020 8:35 pm
is is possible to get that perforamnce bump with a single encode? Or is x265 encoding really just limited to not fully using all 24 threads? And before you snipe back (as I know you're going to do), the fact that there is 12% more performance left on the table with 2 encodes proves that the CPU isn't out of execution resources as you glibly stated above, mduell. Are there tweaks that can be done os is this the best I can hope for? If thats it, then thats fine, just curious if I can optimize my workflow and wring all the things out of these CPUs. While 12% is nothing in the scheme of things, if its on the table I'd like to leverage it if I can.
Sure, what are you trying to optimize for:
FPS? Pick a faster preset.
CPU usage? Try both slower and faster presets to see where it ends up. Try removing the advanced options you've picked, or picking a different aq-mode.
Seeing a significant benefit from x265 over x264? Upgrade to 4K content.

If the CPU doesn't have the right execution resources available at the right time, your encode isn't going any faster. Doing 2 encodes at the same time is going to shift those demands, since now you've got another decode thread running.

Re: Optimal cores for Apple 2160p60 4K HEVC Surround preset?

Posted: Tue Jun 30, 2020 3:41 am
by 8Ringer
I'm not trying to optimize for anything except maximum thread usage during the encode stage. The preset, as I've set it up at least, walks the line between encoder speed and quality so changing it isn't something I'm particularly interested in doing, and I'm happy with the encoding speed. Compared to the i5-3450 rig I was using previously, this machine is a rocketship.

I'm using x265, in particular, because its generally a good bit more efficient than x264 and lower average bitrate was something I was hoping to achieve to avoid transcoding in my Plex environment when streaming remotely, lower bitrate equals more streams I could squeeze out of my paltry upload bandwidth. The decoding burden on the other end isn't an issue as any device I'm streaming to supports native x265 decode. x264 encodes much faster (and curiously saturates all 24 threads even if HT isn't helping all that much, ~12% faster with HT enabled), but the tradeoff is larger filesize and higher bitrate for a given quality. The majority of my content is 1080p but I'll be upgrading to 4K eventually, I just don't have a 4K tv, or anything 4K compatible so its not been a priority yet.

I mean, if I'm just hitting the limit of thread scaling for this CPU combination then thats fine, and I'm cool with the performance, but a small part of me just dislikes leaving performance on the table if I can avoid it.

My other thought is getting a pair of e5-2637v3 or 2643v3s and chucking them in as the base clocks are so much higher it could potentially bring a good chunk of performance. My current CPUs stay quite cool under full load, so theres plenty of cooling headroom, but the 2620s are pretty limited due to how they're configured and Xeons just don't overclock so thats out of the question. But then again, spending $300 on a pair of CPUs just to eke out more encoder performance sorta is a waste realistically, as those likely come with a power efficiency penalty, even at idle.

Re: Optimal cores for Apple 2160p60 4K HEVC Surround preset?

Posted: Tue Jun 30, 2020 4:12 am
by 8Ringer
Also, I realize me filling this thread with data and exposition when its really about something else is sort of a tangent, I'll make another thread later on rather than continue in here.