Xeon 8 core 16 threads lagging on a simple project

Hello. I have an old but powerful machine featuring dual cpus, however i currently use it in one cpu mode with a Xeon 2660 2.2ghz 8/16 threads. I also use an NVME PCI SSD and old Radeon hd7750. Also the latest software version. I need to create a video with the subtitles to the song. The project is simple, near empty: it is static 1080p picture, some text subtitle and a wav music file. No effects, whatever. However, despite it is lite, the audio playback chopps horribly, using only one thread of 16. When i stop the playback and do some operations with the video, each button press the system plays a millisecond of the audio. Is it normal and i my pc just to weak or is this a bug?

Try what is said here:

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Only one thread? Are you using the 32-bit version of Shotcut?

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I didn’t notice that fact. The fact is that very few include in the query, information about operating system and version of Shotcut. Many times I assume that the user uses the latest version and therefore the 64-bit one.

No, it IS 64bit. I have played a bit with proxy. In fact, when selecting a 360p proxy it does lags less, but still lags at start of the playback and when the are a lot of text on the video,
It is too strange, i find, it is just a plain text, why is it acting as a complex 3D scene with thousands of polygons? I have edited in Sony Vegas a way more complex video, actually a video from 1080p camera, not a simple picture with the text, on a 10 times weaker Core i3-370m laptop with Nvidia 310m graphics, and it was smooth.
It actually 100%s one core and 5-10% 5 others, 5 of 16. Is this normal?

What’s your gpu usage during? And what codec are you using, My first guess would be the 7750 isn’t capable of hardware accelerating the codec you’re using so it’s being done by the cpu which isn’t clocked high enough to do it well in software.

Is preview scaling also turned on? That’s where the big performance gain is.

The unfortunate news with Shotcut is that it edits better with a few fast threads than it does with a bunch of slow threads. The code isn’t currently designed to efficiently slice tasks across 16 threads. Usually 4-12 get high activity and the rest are close to idle. If those 4-12 are fast like 4GHz range, it helps a lot. Of course, at export time, you will enjoy your 16 threads a lot because the encoder will use them. :smile:

That said, I also have a dual Xeon and I have found it very responsive with preview scaling.

Shotcut does not use hardware-accelerated decoding for any codecs yet. So performance is all about the CPU.

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You’re correct, I had anticipated that nvenc would automatically decode the h264 stream but I’m not seeing any video decode usage. What I am seeing however is windows doing “something” causing it to be treated as a 3d application and using ~20% of my gpu with the proxies enabled

the drop to zero was where I paused shotcut to see if it was the source of the load.

Interestingly the load reached 30% when I turned scaling off(I wanted to see if scaling 1080>720 had any impact)

I also find my dual xeon very responsive but the x5690 chips I’m using right now hit 3.54GHZ while I have SC open and doing things

Yeah, that’s OpenGL being used to draw UI elements like the player window.


Yeah they’re sweet chips, but I’m thinking of jumping to 2690’s I just got one in a server someone abandoned XD

As far as the OpenGL I’d be curious to see how it’s handling drawing the UI using that 7750, that’s a very old radeon

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