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Dropped frames and lower speeds on usb3 camera

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#1 m_abukhalid

m_abukhalid

    Mariner 2

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Posted 02 August 2021 - 11:18 PM

Hello all,

 

I just got a qhy5iii290m as an upgrade as I am about to switch to an oag setup and was testing the frame rate on it as I would like to use it for planetary as well. Based on the qhyccd website, the camera should be able to achieve 135fps at native resolution of 1920x1080. I have tested this on my mini pc (N5000 processor with 8 gb of ram and samsung 970 evo nvme drive) as well as my Ryzen 9 desktop (128gb ram and samsung 980 pro nvme) . For the setup I basically installed the all in one driver, updated with the ascom 6.5 driver, and let her rip. In both tests I used the same usb cable and got similar results in sharpcap and firecapture.

 

minipc: 5-10% dropped frames and a maximum of 40fps

desktop: 0% dropped frames and a maximum of 51fps

 

Did anyone, who is using this camera, get to 135fps with it? The only setting I can find to tweak is the usb speed, but ~50fps seems to be the limit. I am trying to understand why Im seeing the dropped frames on the mini pc even with a 1ft usb cable... I disconnected all other usb devices but that didnt fix it. Advice/Opinions appreciated.

 



#2 m_abukhalid

m_abukhalid

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Posted 02 August 2021 - 11:44 PM

I reinstalled the driver and rebooted my machine and Im now seeing up to 135fps on my minipc if I set the colorspace to mono8. But I get about a 7% dropped frame rate and sharpcap crashes in about a minute. I wonder if the N5000 chipset might be underpowered for this application...



#3 grubba

grubba

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Posted 03 August 2021 - 12:10 AM

USB 3 has a maximum bandwidth of 640MB/s. A single, full uncompressed 1920x1080 (16-bit) frame is ~4MB, which implies a maximum of 160fps. When you set to 8-bit, you are halving the bandwidth, which should bring you to 320fps maximum. This, assuming a non existing ideal scenario. Have you tried their own EZCAP_QT software (bypassing any ASCOM stuff)? My hunch is on poorly written middleware. And yes, I doubt the N5000 could handle well an uncompressed full HD stream.


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