Play 4K video on iPhone (2018)


I have the following setup:

  • iPhone XR (since Friday ^^)
  • Synology DS215j with 512 MB RAM
  • AVM Fritz!Box 7490 router with WiFi AC
  • the room in question is about 5 meters away from the router with no walls in between
  • latest Infuse

Now I wanted to stream a 4K file to my iPhone using Infuse. Of course I know I cannot expect a too great result because of the iPhone XR‘s relatively low resolution. My motivation is rather pragmatical: I don‘t want to downsize (convert) each and every 4K file I have for this use case.

In the end it simply didn‘t work. The loading indicator kept spinning very long and then the video run smoothly. But after some seconds the loading began again.

So here are my questions:

  1. So I assume the buffer can‘t be filled fast enough. But with WiFi AC standard it should be possible to do this, no?

  2. Or is the iPhone the problem?

  3. I guess the Synology should not be much of a problem because playing via ethernet cable works fine. Or is there an option to do the transcoding maybe on the NAS?

Thanks in advance.

Bye The_Unknown

If you run a speedtest on the phone what do you get? I can play 4k fine from my Synology to my XS Max, so it should work the same for the XR since the internals are basically the same (LCD screen, different battery, and no 3d touch are all I think are different).

Mhm, how can I test only the local WiFi? I can find Internet Speedtests?

I generally use an iperf docker container on my Synology and then an iperf app to test the Wifi speeds. I just did a test with the ‘WiFiPerf Endpoint’ app on my iPhone and then this command on my Synology (you need docker installed, and you might need to run it with sudo – change iPhone_IP with the IP the app shows you):

docker run -it --rm --name=iperf3-client networkstatic/iperf3 -c iPhone_IP

I got 240Mbps my first run and 410Mbps on my second run. Wifi is fickle.

Docket isn’t officially supported on lower end NAS models however there are native iperf Synology packages built by third parties.

I use this one with no issues

A google of your NAS will let you know what processor you’re using.

OK, I installed Jadahl iPerf. But how do I use it now on my iPhone? Can’t find any info on it?? I guess I need an app but can you recommend one that’s working?

I use Network Tools by Hurricane Electric

Ok, thanks for the tip. I used the app and got the following results:

IPerf results for host (TCP)

[8] 0.0- 1.0 sec 5898240 bytes 47.19 Mbits/s
[8] 1.0- 2.0 sec 6422528 bytes 51.38 Mbits/s
[8] 2.0- 3.0 sec 6160384 bytes 49.28 Mbits/s
[8] 3.0- 4.0 sec 6029312 bytes 48.23 Mbits/s
[8] 4.0- 5.0 sec 5636096 bytes 45.09 Mbits/s
[8] 5.0- 6.0 sec 5767168 bytes 46.14 Mbits/s
[8] 6.0- 7.0 sec 6553600 bytes 52.43 Mbits/s
[8] 7.0- 8.0 sec 6029312 bytes 48.23 Mbits/s
[8] 8.0- 9.0 sec 6422528 bytes 51.38 Mbits/s
[8] 9.0-10.0 sec 6422528 bytes 51.38 Mbits/s
[8] 10.0-11.0 sec 6291456 bytes 50.33 Mbits/s
[8] 11.0-12.0 sec 6291456 bytes 50.33 Mbits/s
[8] 12.0-13.0 sec 5767168 bytes 46.14 Mbits/s
[8] 13.0-14.0 sec 2359296 bytes 18.87 Mbits/s
[8] 14.0-15.0 sec 3014656 bytes 24.12 Mbits/s
[8] 15.0-16.0 sec 5767168 bytes 46.14 Mbits/s
[8] 16.0-17.0 sec 1835008 bytes 14.68 Mbits/s
[8] 17.0-18.0 sec 5242880 bytes 41.94 Mbits/s
[8] 18.0-19.0 sec 262144 bytes 2.10 Mbits/s
[8] 19.0-20.0 sec 1310720 bytes 10.49 Mbits/s
[8] 20.0-21.0 sec 1835008 bytes 14.68 Mbits/s
[8] 0.0-21.3 sec 102498304 bytes 38.48 Mbits/s

Seems to be a bit low, doesn’t it? Since some of the videos have 20 MByte/s (not Bit!), this cannot work. But WiFi standard AC should be capable of MUCH more. Maybe I misconfigured something :(?

Update: At least my router says that the iPhone is in 5 GHz and also in WiFi AC mode. Also the data rate seems to be very fast and enough for 4K. See attachment. Very strange.

Update 2: My router has an iOS app for measuring the WiFi speed. In fact concerning the communication between Router and iPhone and have constantly about 170 MBit/s. So streaming a film with 61 MBit/s bitrate (audio and video combined) should work without problems I guess.

So maybe the problem sits between the Synology NAS and the router.

OK, I think I found the problem :slight_smile: The problem was the connection of my Synology NAS. It was connected not directly to the router but over TP Link Powerline adapters. So these seem to limit the performance.

BIG thanks for pointing me in the right direction, guys!! Now the videos play well on my iPhone :slight_smile:


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