Video latency (lag) what is yours and what's your set up?

CactusJackSlade · Dec 6, 2015

Coming from several rigs using 5.8 Ghz FPV on Immersion video transmitters and Fatshark receiver goggles where the video signal was virtually instantaneous I was fairly disappointed in the P3P video lag which I'd estimate at about .3 to .4 seconds.

I'm using a Samsung Tab S2 9.7" - Is this amount lag normal? I saw several mentions of others using this tablet with "excellent" and "very good" results. I guess I have not read specifically what the lag time was on others using this tablet.

There are lots of threads on this subject but I have yet to hear if anybody is getting "instantaneous" results with the P3P and any tablet?

If video lag is unavoidable with the DJI downlink on the P3P what is your lag (approx) and what tablet are you using? Are you satisfied with your setup and lag?

Thanks in advance!

CJS

Snapring · Dec 6, 2015

I used to get lag with my Galaxy Tab 10 and decided to change to the Ipad Air 2 based on comments on this forum. It solved the lag issue. I had a friend watching me fly last week and he kept moving his arms when the camera was looking at us because he couldn't believe how instaneous the video was.

CactusJackSlade · Dec 6, 2015

Wow, that's some interesting news, I'm trying to find if there are any tweaks that will help with this issue. The lag makes it a bit scary.

Anybody else using a Galaxy Tab S2?

Darmie · Dec 6, 2015

I read these forums and others before I invested in a tablet. There was no question of going with the ipaid air 2.

When you look at the specs, the ipad air 2 offers the fastest chip and the fastest graphics across the board. A8X 1.4X faster than A7, Graphics 2.5X faster.. Now that the Pro is out that maybe a game changer but where the hell you going to mount it? I heard on a podcast that they use a black pearl monitor. I guess with a monitor, there is 0 lag. The feed doesn't go out ect. Now keep in mind they are using an ispire that has HDMI out.

JoBe · Dec 6, 2015

Darmie said:
I read these forums and others before I invested in a tablet. There was no question of going with the ipaid air 2.

"ipaid air 2" is funny. Freudian slip? Lol.

I'm saving for an Air 2, but use a Mini 2 now. I don't notice much lag, and have even done that same hand waving thing in front of the camera but from on the ground. It's not instant, but way less than .3 seconds without a doubt.

Wacker2611 · Dec 6, 2015

My Nexus 7 had hardly any lag , now I've got a Shield which appears to have no lag whatsoever.

Darmie · Dec 6, 2015

Yep, going to leave it in there, for when you buy an Ipad, you feel like you paid alright.

JoBe said:
"ipaid air 2" is funny. Freudian slip? Lol.
.

CactusJackSlade · Dec 6, 2015

Darmie said:
I read these forums and others before I invested in a tablet. There was no question of going with the ipaid air 2.

When you look at the specs, the ipad air 2 offers the fastest chip and the fastest graphics across the board. A8X 1.4X faster than A7, Graphics 2.5X faster.. Now that the Pro is out that maybe a game changer but where the hell you going to mount it? I heard on a podcast that they use a black pearl monitor. I guess with a monitor, there is 0 lag. The feed doesn't go out ect. Now keep in mind they are using an ispire that has HDMI out.

Yeah, I read all these forums too.... and a couple guys said the Tab S2 was "excellent".... but maybe lag is not a big deal or I'm holding out the possibility that I just need to find the right settings (Already spend half a day reading/tweaking etc).... all to no avail so far

tcope · Dec 6, 2015

I think the lag on the Nvidia Shield is about .5 or .3 seconds.. the same as you mention. I don't see this as being an issue at all. Jump to the 1 minute mark.

shockwave199 · Dec 6, 2015

With my air2 and hardware decoder off in the Go app, there was more lag so I keep the decoder enabled and it's very much better. I also keep the bit rate at the lowest. Even on the big screen of the air2, the low bit rate feed is really just fine. I have not done a clock test to really know but I'd put my latency at .2, the closest you can get to real time. It will never be latency free, but the air2 provides the best results I think.

Oso · Dec 6, 2015

tcope said:
I think the lag on the Nvidia Shield is about .5 or .3 seconds.. the same as you mention. I don't see this as being an issue at all. Jump to the 1 minute mark.

That paper Phantom at the start of the video was epic. A P4 prototype for sure. Thanks sir for posting it.

bobmyers · Dec 6, 2015

tcope said:
I think the lag on the Nvidia Shield is about .5 or .3 seconds.. the same as you mention. I don't see this as being an issue at all. Jump to the 1 minute mark.

Simon has competition!

aka1ceman · Dec 6, 2015

I never tried my Tab 2, but my Samsung Tab 4 works flawlessly as far as lag. It's only a split second with Litchi and the Go. (The Tab 2 was free with my wife's new Samsung phone)

CactusJackSlade · Dec 7, 2015

tcope said:
I think the lag on the Nvidia Shield is about .5 or .3 seconds.. the same as you mention. I don't see this as being an issue at all. Jump to the 1 minute mark.

Thanks for posting.... my lag is slightly longer.... coming from FPV flying this lag is very long. Maybe it's just the standard for this type of interface on most tablets?

For me this amount of lag is (or can be) an issue because I tend to fly fast and close to objects (trees, canyon walls etc) so latency is important to me. I mean at 20mph (29 feet per second) you could smack something with this kind of latency. (.3 to .4 sec as I do).

Perhaps I will just need to adjust my flying style and be a lot more conservative when coming up on hazards.

CactusJackSlade · Dec 7, 2015

shockwave199 said:
With my air2 and hardware decoder off in the Go app, there was more lag so I keep the decoder enabled and it's very much better. I also keep the bit rate at the lowest. Even on the big screen of the air2, the low bit rate feed is really just fine. I have not done a clock test to really know but I'd put my latency at .2, the closest you can get to real time. It will never be latency free, but the air2 provides the best results I think.

There is an option in the GO app to enable/disable a hardware decoder? I can't seem to find it?

Oso · Dec 7, 2015

CactusJackSlade said:
There is an option in the GO app to enable/disable a hardware decoder? I can't seem to find it?

Here's a screen shot, but I think that hardware decode may only available in the iOS version of GO. I'm not certain about that however. It may have been added to the Android version by now.

Adammmmm · Dec 7, 2015

CactusJackSlade said:
Thanks for posting.... my lag is slightly longer.... coming from FPV flying this lag is very long. Maybe it's just the standard for this type of interface on most tablets?

For me this amount of lag is (or can be) an issue because I tend to fly fast and close to objects (trees, canyon walls etc) so latency is important to me. I mean at 20mph (29 feet per second) you could smack something with this kind of latency. (.3 to .4 sec as I do).

Perhaps I will just need to adjust my flying style and be a lot more conservative when coming up on hazards.

These are not fpv racers. Don't you think the quad racers would use 720p video link also if there was no lag? I use a Samsung tab S. Almost identical to the tab s2 and I have minimal lag. Still more than my quad racer but almost nothing. But I certainly would not fly it like a quad racer. Also, people saying their iPads are better, if they compared them to decent android tabs they are not better at all. however unlike apple, Android make some really cheap tablets which have a purpose, just not for flying a drone. Your tab s2 is perfect and as good as it gets for your phantom. Just turn on hardware decoding. Shut all other apps down or reboot first.

Wacker2611 · Dec 7, 2015

Oso said:
Here's a screen shot, but I think that hardware decode may only available in the iOS version of GO. I'm not certain about that however. It may have been added to the Android version by now.

View attachment 37337

The android app defaults to hw encoding if it's available. However, Litchi does give you a sw/hw option that you can choose yourself.

Adammmmm · Dec 7, 2015

Wacker2611 said:
The android app defaults to hw encoding if it's available. However, Litchi does give you a sw/hw option that you can choose yourself.

Ah OK. I use litchi only. Didn't realise go app didn't have an option. However, in developer options of Android you can force hardware decoding always.

John Locke · Dec 7, 2015

CactusJackSlade said:
Coming from several rigs using 5.8 Ghz FPV on Immersion video transmitters and Fatshark receiver goggles where the video signal was virtually instantaneous I was fairly disappointed in the P3P video lag which I'd estimate at about .3 to .4 seconds.

CJS

Immersion uses analog video broadcasting to an analog receiver in the fatshark goggles. There is no compression encoding done in the camera that needs to be uncompressed or decoded on the ground. Hence you get zero lag with immersion technology. However you can't go 1 mile+ either like Lightbridge can.

Lightbridge compresses the video in the camera using the industry standard h.264 compression algorithm. This is done in hardware so it's fast at encoding. Lightbridge broadcasts this compressed video to the ground controller where it needs to be uncompressed, or decoded. If this decoding can be done in hardware it's faster. If it's done with software using the general purpose CPU, you will have more lag, or latency.
My latency is about 150ms using my iPad mini 2 with GO and hardware decoding enabled.

Lightbridge 2 is supposed to reduce lag down close to 50ms while broadcasting a 1080 video stream to the controller, better than today's 720 stream. I assume this is using the newer h.265 compression algorithm. Hopefully we'll see Lightbridge 2 in upcoming Phantom 4 and Inspire 2 craft in 2016.