Hello.
I saw another similar thread, but let me confirm my problem.
After installing the HDMI module(for phantom3) in Phantom 4, using an HDMI external monitor lags the real-time image (both tablet and external monitor).
Especially after pushing the shutter of still image, the monitor image lags for about 3 seconds.
Although I remember that there was no problem before.

Using firm version now.
RC 1.8.0
aircraft 　1.2.602
app 4.0.2

Is this problem improved if I do a firmdown grade? Is it only RC?

>Is this problem improved if I do a firmdown grade?

If it is yes then how to operate RC firm down grade on DJI Go4 .

so you use a p3 hdmi on the p4? that there is prob your issue

Somewhere I thought I read that rolling back from version 1.8 to 1.6 addressed this?  Might be worth a try.

From the DJI Store, the HDMI module is the same unit for the P3 and P4:   "This module allows for HDMI output from the Phantom 3 Professional/Advanced or Phantom 4 Series remote controller, similar to that of the HDMI output on the Inspire 1."

Not sure if it works better with Apple or Android either, but I'd wager on Apple working better if I were a betting man.

Rolling back to V1.6 may help:-

Connect display device (with good wifi connection) to RC and power both up (aircraft off).

Run DJI Go, on initial screen (where it displays aircraft type etc) at top right hand corner you will see a 'graduation hat' icon (or perhaps three lines if DJI Go 4). Hold your finger on that for about 5 seconds and release. You should now see a black screen appear with an option to roll back RC firmware. Make sure RC is well charged, takes about 5 minutes or so. Power down when complete. Restart all and check all working, you may need to relink RC to aircraft.

Everyone, thank you for your reply.

I checked the following topics.
WEAK transmission signal caused by HDMI output module

My issue is exactly this.

There are three people using this module around me, but the same problem is occurring.
My table-pad is ipad pro, but this issue will also happen with other Android tabreds.

DJI, I hope to improve the firrm soon.

I will downgrade and check it.

Did downgrading work?

My p4 got better by downgrading.
I hope next firmwaire is improveed.

Just for everyone's information, the signal fed to the viewing devices is MPEG, and by its very nature, the stream takes time to decode, because certain items are not defined until several frames after they are shot. I have 3 television sets in close proximity, and it is not unusual for one or more to be lagging behind another. Switch one off and then one again and it can end up in front instead of behind. Changing firmware on the aircraft is unlikely to affect this issue, the main culprit is the display device. Try Googling 'mpeg decoder delay' and you will see what I mean.

Geebax Posted at 2017-2-27 00:48
Just for everyone's information, the signal fed to the viewing devices is MPEG, and by its very nature, the stream takes time to decode, because certain items are not defined until several frames after they are shot. I have 3 television sets in close proximity, and it is not unusual for one or more to be lagging behind another. Switch one off and then one again and it can end up in front instead of behind. Changing firmware on the aircraft is unlikely to affect this issue, the main culprit is the display device. Try Googling 'mpeg decoder delay' and you will see what I mean.

I have a suspicion that there is an incompatibility between RC V1.8 and the HDMI module (And perhaps many Android devices), there seem to have been many cases  where a rollback to V1.6 has at least reduced if not resolved display issues (Primarily Android). An extract from the release notes (aircraft firmware 1.1.310 last April) indicates an 'enhancement' to encryption between aircraft and RC to improve 'security', this was April last year. I read this as them having introduced encryption, or changed the encryption method. This also required the RC to be updated to allow both to communicate, I am trying to remember which RC version, I think it may have been V1.58. My thinking is that this 'enhanced' encryption places greater demands on the display devices.

The release note for RC V1.8 (Introduced October last year) suggests only two changes, one for the earlier GL300A RC when recording 2.7k video. And another to 'enhance RC to mobile device connection', and that is the bit that I think may be causing problems, this is my personal opinion only and I could be wrong. But it seems too coincidental.

RC 1.8 + Android + HDMI module = WEAK video feed, Nvidia SHIELD K1 issue .
iOS devices are prefered.Downgrade RC to 1.6 resolves that problem.
DJI is leaving us with no chance for upgrade, it's not fair.

AEROKAMERA Posted at 2017-2-27 06:55
RC 1.8 + Android + HDMI module = WEAK video feed, Nvidia SHIELD K1 issue .
iOS devices are prefered.Downgrade RC to 1.6 resolves that problem.
DJI is leaving us with no chance for upgrade, it's not fair.

"DJI is leaving us with no chance for upgrade, it's not fair."

Hopefully they will be working on a fix in the background for some future release. But as it stands I'm not convinced that RC V1.8 is of any real benefit, perhaps to those with the GL300A RC (earlier P3 models ?).

What happens if you just do a reinstall of 1.8 once the HDMI is installed?  Could it also write something to the HDMI module in the refresh process to make it work as it should?

Rolling back points to something bad with the software. no?   Maybe the HDMI has a portion of the older version within it and it conflicts with 1.8 unless reinstalled.  Dunno, DJI isn't forthcoming on the matter.

Aardvark Posted at 2017-2-27 07:18
"DJI is leaving us with no chance for upgrade, it's not fair."

Hopefully they will be working on a fix in the background for some future release. But as it stands I'm not convinced that RC V1.8 is of any real benefit, perhaps to those with the GL300A RC (earlier P3 models ?).

RC1.8 is not, you're right  (I'm on GL300C) but further ones, who knows

fansa84fe8a4 Posted at 2017-2-27 07:22
What happens if you just do a reinstall of 1.8 once the HDMI is installed?  Could it also write something to the HDMI module in the refresh process to make it work as it should?

Rolling back points to something bad with the software. no?   Maybe the HDMI has a portion of the older version within it and it conflicts with 1.8 unless reinstalled.  Dunno, DJI isn't forthcoming on the matter.

You could be correct, I don't have an HDMI module to test. I don't seem to remember reading any threads to confirm that it works.
Try it and see, it only takes a few minutes to roll back if it doesn't work

Aardvark Posted at 2017-2-27 08:47
You could be correct, I don't have an HDMI module to test. I don't seem to remember reading any threads to confirm that it works.
Try it and see, it only takes a few minutes to roll back if it doesn't work

I'll have one shortly.  I'll let you know how it goes on my GL300C box.

I might just try a reinstall of 1.8 once I get it on the RC unit as the HDMI itself has probably sat around since 1.0 came out.  

Steve-76 Posted at 2017-2-23 06:58
so you use a p3 hdmi on the p4? that there is prob your issue

I thought they were both the same module

Okay, I just did the installation of the HDMI module to a GL300C box for a P4.  Went okay, other than a tight fit of the stacked module inside the white box.

Odd part was I thought I was up to date on 1.80 but I see now that it is showing 1.60+ in GO.  Don't get why it shows 1.60+ either.  It is asking for an update maybe to 1.80 but think I'll hold off until I try 1.60+ out first.  Seems to be working okay so far.

Another odd thing is see is there is some ....V....  in the middle of the HDMi screen and it is tilted down a bit to the left.  I thought gimbal alignment was bad, but this is a fixed image and doesn't have a way to un-tilt it.  Gimbal tilts horizon but the ...V... remains tilted.  Not annoyingly so, but yet it is tilted.  Image looks good though through the Royole Moons which are maybe twice the width of the Gylphs with their two 1920x1080 screens, one for each eye.

fansa84fe8a4 Posted at 2017-2-27 14:54
Okay, I just did the installation of the HDMI module to a GL300C box for a P4.  Went okay, other than a tight fit of the stacked module inside the white box.

Odd part was I thought I was up to date on 1.80 but I see now that it is showing 1.60+ in GO.  Don't get why it shows 1.60+ either.  It is asking for an update maybe to 1.80 but think I'll hold off until I try 1.60+ out first.  Seems to be working okay so far.

My understanding is that there are many different hardware modules updated during firmware update (as can be seen in text file produced during update). I think that the 1.60+ indicates that it is above V1.60, but that not all the hardware modules have  been fully updated to V1.80 (HDMI module ?). So a further update would likely just update any outstanding modules needing done.

Okay, playing with version 1.8 on the RC GL300C and the HDMI module with both old GO 3 and newer GO 4 on an iPad Air 2 I observed the image breaking up on the iPad, but the HDMI to the googles was clean and no breaking up.  Something is wrong here.  The brief breaking up occurred several seconds after pressing the Movie record red button and was a black portion of the screen, sometimes green bar, and image often changed to B&W and back to color.  even turning off the Movie camera record showed up several seconds later with the black bars a few seconds apart.

I'll try and go back to version 1.60+ on the RC after I recharge the batteries and try it again.

Something is askew here DJI...