Nazar78
 Captain
Flight distance : 5106037 ft
Singapore
Offline
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Hello,
Which device are you using? The DJI GO 4 is a power hunger app to each update. Here's the two common lags that I noticed:
1. FPV lapses like you mentioned, sometimes up to 30secs+ during recording.
2. Command lag e.g. try to toggle the gimbal quickly up and down during recording with the 5D button when you noticed the FPV lapses. You will notice the physical gimbal movement is not immediate, adding more lags to the FPV.
I've tested on several device and I have come to a conclusion that heat from the handheld device running this app is causing all these lags. Once overheating, the device will start throttling the CPU/GPU frequencies including auto turning off CPU cores depending on your device thermal protection. It sometimes kicks in even if the device is still not too hot. Until the app codings has been properly optimized, the only way I can prevent this is to tweak my device but unfortunately this requires root. If you are able to root your device do continue reading else I'm sorry I can't be much help.
Here's what I did for my few years old Samsung Note 3 with stock 5.0 ROM but custom kernel. Any custom kernel should work if they provide the support and you can edit using any kernel editor or init.d run-parts shell scripts which most custom kernel supports.
1. Set the internal I/O scheduler to NOOP. Readahead cache buffer to no larger than 512KB, high values will introduce more latency. Same goes to the external sdcard if you have set the DJI GO 4 app to cache it there. This helps with the FPV and video cache as it reduces CPU utilization.
2. Less voltage = less heat. Tune down the voltage for all frequencies -5mV each step then stress with any benchmark app in between until you get a stable sweet spot, no overclocking, had mine -50mV all across. This requires custom kernel.
3. Increased the frequency thermal protection temperature limit till about 90-95°C and importantly ensure it doesn't auto turn off any CPU cores. This requires custom kernel.
With the above tweaks I still get thermal throttling but at a minimal level so the frequency especially for CPU doesn't dip down too low often. I've flown few times with the latest 4.1.10 in max screen brightness on a 33°C sunny day and so far no lags whatsoever.
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