I cannot seem to disable the Cache recording with the Spark. I'm using Samsung Galaxy S4, DJI RC, Spark.
Using RC for most functions.

Due to the video / image lag, betweent the Spark and the phone, I am trying to streamline / make the connection more efficient.

First, understand the OTG cable will not work. I have tried all I can figure with it (see below). Wish it would.
Under "General Settings"
I have selected moving the "Radio button" to the left (which I beleive should be off), in "Record Audio with Video Cache", "Cache to SD card", .
I have tried various settings with "Largest Video Cache Capacity" (Zero is not an option. Various settings with "Adaptively reduce cache resolution".
I have cleared the video cache. Deleted all the images created in the gallery from Spark.
However after every flight, when checking the phone (with everything else turned off), there are lots of images on the phone, in album named "Cached"

My setup:
Device                                 Version
Go4 App                                 4.3.14
Spark                                     1.00.1000
RC                                         1.00.0600
Camera                                  00.00.18.02

Phone setup
Samsung Galaxy S4                SCH-I545
Android OS                             5.0.1
Airplane Mode
WiFi on
Stripped out many other apps. Cannot strip everything as this phone must be able to be used for other things in a pinch.

For those that say the OTG cable will work: I have tried. This phone will not allow selection of Host. It will only allow"Installer" or "MTP" or "PTP". OS allows USB Host, but Samsung has disabled the hardware and rooting might be the only way to enable it, which is not an option.
Therefore I'm just trying to make the communication through the WiFi better to avoid the lag.

First:
Check the pictures in Cache, check if any video streams are on it (record 10 seconds of video, dont need to fly the bird for this)
What size are the pictures, are there any videos at all "cached"

Usually the video folder is called
DJI_RECORD
The cache folder are just pictures, cached in the Go4App, in case you do pictures when the bird is on

size is 960x720px
You can check that IN the flight records, (minimum on droid tablets ;-) by clicking on either the picture or the placeholder on the very right, in the "flight data" page

Second:
OTG, is the RC charging your phone?
Because the RC ist the HOST, here.
Not your phone.
In case you phone is charging the RC: turn the cable connection
But anyway, get away from 4.3.xx Go4s
They are made/optimized for Droid 8 and 9 and carry too much other DJI in them
You neither need the abilty to fly a mavic 2, nor a mavic air. Also older apps need less performance! (S4 has just 2GB Ram!!)
This makes the 4.1.15  a good choice. (apkmirror for DJI apps)
However, the easyness of "official" OTG support makes the 4.2.21 (just plug it in, charge the phone, Go4 auto-starts) "best choice" (imho)

Good luck

S-e-ven Posted at 3-3 10:21
First:
Check the pictures in Cache, check if any video streams are on it (record 10 seconds of video, dont need to fly the bird for this)
What size are the pictures, are there any videos at all "cached"

S-e-ven yes the videos and stills are in the aforementioned directories. Yes, cached. Many articles, I have read, state to turn off the cache, however I don't see how.
What else will I lose if I downgrade to 4.1.15?
Not sure what you are referring to with offical OTG support in 4.2.21 as the OTG limit is from the phone, not the DJI app.

S-e-ven, if the OTG is plugged into the RC and usb extension into S4, then the RC tries to charge the S4.
If the OTG is plugged into the S4, and extension plugged into the RC, then no charging is noticed.
No change is seen in the image lag.

Since last summer, otg is official a feature for the Spark.
Before it was working, but needed a bit of lining up the process.

In my understanding, WE (Spark User) DONT NEED ANY 4.3.xx app.
And my experience, Droid 7, 8, 9, proves that to me
4.1.15, 4.2.21, both are running fine
(You can have both on the phone, the DJI 4.2.21 AND the 4.1.15 mod 2.0 , which has some mavic flightmodes available. They do install aside each other)
And both of these app have less balast, your phone has to deal with:
As newer the app, as bigger it is in the Rom, as more Ram it needs and better the newest, then a Droid 5.

But back to the otg:
Can you test with another device/Android, first?
Since I am pretty sure that I have read reports about S4 and OTG working, in the past 20 month.
If that works, check your connection direction
Check the cable!
For testing, you may just have a OTG adapter, to connect to your original Charger cable (Data!)
Hint: My phones didn't like the one or the other cable, which worked perfect to the computer!

Plug FIRST the data cable IN your phone
Start RC, wait till LED is solid red
plug the micro from the adapter, adapter and data cabel plugged together, into the RC
Phone will start charging

Are you getting so far?

djiuser_NCXRokNslVsT Posted at 3-3 10:28
S-e-ven yes the videos and stills are in the aforementioned directories. Yes, cached. Many articles, I have read, state to turn off the cache, however I don't see how.
What else will I lose if I downgrade to 4.1.15?
Not sure what you are referring to with offical OTG support in 4.2.21 as the OTG limit is from the phone, not the DJI app.

Oh:
To the cache settings: set it first to the lowest, 1GB I think.

S-e-ven Posted at 3-3 10:47
Since last summer, otg is official a feature for the Spark.
Before it was working, but needed a bit of lining up the process.

Yes, I just did exactly you what you stated, about the cables. The phone is charging from the RC.

BTW I uninstalled the Go  Ap and am trying to install the older versions.

So far the apk of DJI Go v4_4.1.15 - 30274
and
DJI Go v4_4.1.15 -  10274   will not install on the phone.
I have toggled for installation from unknown sources. The files are stored on the phone and I am using file explorer to access them.
When I select install, they just go through the motions but at the end state "file not installed" no other error message.
I think I ran into this before.

specific / exact file name "dji.go.v4_4.1.15-3027412_minAPI19(armeabi-v7a)(nodpi)_apkmirror.com.apk"

I have finally installed the aforementioned. It would only install from the apkmirror site, not from my downloaded file. Oh well, i tis installed.

Results:
A) The same image lag, even worse.
B) If I hook up the OTG cable, no matter which direction, the phone (S4) powers off immediately.
C) It takes avery, very long time for the Application to load.
D) So far I prefer the 4.3.14 version, as this seems not to give any imrovement.

If I recall correctly, caching is forced in latest versions.
Sync your flightlogs, uninstall GO 4 version.
Delete /DJI/dji.go.v4 folder.
Install older 4.1.15 version.
Open old GO 4 version without connection at all.
Open Camera view, disable cache.
Force close GO 4 app.
Open GO 4 app and connect to AC once.
Turn everything off and force close app again.
Now update GO 4 app in Store.
Start up again, snap some video and shots.
Check cache location.
Sorted?

(I'll try to search for the thread which describes this procedure)

Haggi Posted at 3-3 14:01
If I recall correctly, caching is forces in latest versions.
Sync your flightlogs, uninstall GO 4 version.
Delete /DJI/dji.go.v4 folder.

Found it..
Slightly different description, but result should be equal.

https://forum.dji.com/thread-169810-1-1.html

The lag has been measured at 5 to 6 seconds between when the camera is moved to when the screen image shows it. That is terrible.

Haggi Posted at 3-3 14:01
If I recall correctly, caching is forced in latest versions.
Sync your flightlogs, uninstall GO 4 version.
Delete /DJI/dji.go.v4 folder.

Haggi, "Now update GO 4 app in Store."
are you saying to then upgrade to the newest 4.3.14 version?

djiuser_NCXRokNslVsT Posted at 3-3 14:41
Haggi, "Now update GO 4 app in Store."
are you saying to then upgrade to the newest 4.3.14 version?

Yes, I do ;)

Haggi Posted at 3-3 14:47
Yes, I do ;)

Ok, I did it all. Found the stated method to turn off cache. Did it. Then rebooted. Then linked to RC and Drone. Same lag as before.
Rebooted again. I no longer see the option to turn off cache (as the article mentions).
So now I'm running 4.3.14 yet OTG does not work and video lag is terrible.
Also found the phone is still collecting chache images.
I thought, perhaps I missed a step, so I repeated EVERYTHING three more times.
Exact same results.

S4 is still caching images.
Video lag is still terrible.
Oh, and to top it off... Even though I sysced up my flight logs, before all this, now my flight logs are gone!!!
I tried sysncing up again and my experience points are there  but everything else is gone.
This s*cks !!!

Another easy way is to use an  8GB sd card and set cache to record to sd, start a recording and let the card fill up , when full u will be prompted no cache recording