Strange behavior with transcoding on n Apple TV 4K (and iPad pro)
I recently update my plex environment:
New powerful Server and new client which is now Apple TV 4K.
Server is a Intel Skylake CPU i7500T (quad core with latest QSV features), transcoding is enabled and is working well. Server version is 126.96.36.19925
Here my findings and problems:
1) I have plenty of ts files recored from satellite TV. These files are ts container which include h264 streams 1080i50 at bandwidths between 5-15 MB/s in average.
So once I moved the ts files to the plex server I discovered the ATV 4K to behave like this: I start the playback with Audio is on but no video coming through, in other words only a black screen with audio. From my previous experiences I remembered that ts files are tricky since they have some not video related overhead information inside (that happened to me few years ago with a Raspberry PI setup). So I re-coded (using mkvmerge) the ts files to mkv files (with slightly smaller file size in result).
Same thing happens, no change in behavior compared to the original ts file.
It is important to mention that mkv files from makemkv are not problematic, they start to play just as normal as expected (with transcoding).
2) I took my older iPad Air 1 and played the same files as above. And surprise: No issue playing this files, so both mkv and the original ts file play well. Transcoding I noticed is set to 4MBs 720p. So with the older iPad not being so powerful this is a thing which understandable. Pushing it manually to a higher bandwidth is not working for all bandwidths, 8 MBs 1080p seems to be possible (it is not a network bandwidth thing, as later turned out when playing the iPad pro in parallel).
3) With knowing that I returned to the ATV 4K. First step was to modify the bandwidth manually and it turned out to be a successful step. Playback starts with audio and video. I repeated it also with ts and mkv file, both behave the same (means actually now with newer versions of plex server and client there is no issue with ts files).
I started with lower bandwidth but on the ATV 4K it seems to be possible even at 20MBs 1080p settings. What is not possible to use the „automatic convert“ setting or the „direct stream“.
One interesting thing is also: Once playing the from scratch with Audio and black screen even to enter the bandwidth setting and just select to the already checked marked 20 MBs 1080p setting is sufficient to „tweak“ the client on ATV 4k to play.
4) iPad pro (2015 9.8“) experience: I did all the same experiments as I did with the ATV 4K and the results are the same. It surprised me as it behaved different to the iPad Air 1.
Conclusion: My setup has a problem with ts or corresponding mkv files with more powerful clients and is confused somehow by the transcoding settings, assuming that it selected by intention the 20MBs 1080p setting. Re-Confirming the settings simply solve the problem, but cause a „bad user experience“.
The setup has not problems with mkv files in general, since other files play. Maybe this is related to higher bandwidth or something else different (profile of the decoding or something).
I tried to workaround with the settings in the client app:
a) modify the automatic quality between on and off
b) Play smaller files at original quality (only ATV 4K)
No success. Anybody ideas?
It is no bandwidth issue or server not powerful enough issue since at he end 3 streams ran in parallel, two via wifi and one over ethernet.
Finally I must say that it would be desirable to just direct play the file on apple devices. And the Infuse App demonstrates that this is possible (at least for the ATV 4K). I accept transcoding or even understand the need of transcoding for mobile devices via wifi but not for a wired (network) player.
Many thanks for reading this long text.