Just to be clear … Hope I’ll not miss important information …
- The app is just GUI for system video player (lest call it “embedded system (HTML) video player”). Everything starts from this IMPORTANT thing. The app is not a native app … its HTML5 app.
- The app almost have no levers of influence to system (HTML ) video player. The app can work with embedded subtitles BUT with limited functionality. Embedded subtitles track can be selected by two symbols language code (ISO 6391). When two subtitles tracks have the same language code the second track must be transcoded to be showed. LG even hides API that can be used to work with embedded subtitles. LG even deleted the app from LG store after Ive tried to ask some extra details on public dev forum on LG website. Fortunately the app was returned to the store without any conditions from LG Inc. But subtitles API documentation was removed from developers documentation. Embedded subtitles color, position … size can not be controlled … at least in direct play mode.
- Video content (frames) can not be stretched to full screen (at least on last TV firmwares I have) … video content (frames) can not be moved out of screen borders. System (HTML) video player keeps aspect ratio own way and I can not affect to it. “Black bars” can not be removed.
- System (HTML ) video player does not throw media load error when subtitles API is used. Subtitles API is used almost always as the app uses it to hide embedded subtitles that are forced to be showed by default. Some old users may remember first test versions when forced subtitles used to be shown on screen always. That is way even when the app have failed to load media content it does not show error message and get back to details screen.
- Audio output can not be controlled. For eg the app can not mute output … or it can not control how to output audio DD or Dolby Atmos 7.1 output depends how player will handle it. The app will not have idea how TV will handle audio stream.
- Audio tracks can be selected without transcoding only on webOS 3.x and upper. As LG does not expose details of audio tracks … just audio track and that all. So it means that the app can match tracks from system (HTML ) video player and information that the app got from PMS only by track index. Probably it can lead that sometimes it select different audio track.
- Media format (media codec) support depends from webOS version … TV firmware version and etc. As system (HTML ) video player is used to play media content the app can not add new media codecs or add new media containers support. Everything depends from system.
- LG gives some developers tools for developers … SURPRISE … LOL)) Like webOS emulator. Usually I use webOS emulators to test the app but there is a compatibility break issue … even when the app works well on emulator it may not work on real TV the same way … quite strange thing … developers can not have all kind of possible variants of TV platforms.
- LG certify apps to TV platforms (dont mess with TV models). The same TV platform is used by several TV models. Ive no idea which TV model was certified by LG QA Team. It will affect to the app availability in LG Apps store for your TV model.
- Support 4k or not … playback buffering spinner … and etc and etc. As I have already mentioned before “the app almost have no levers of influence to system (HTML ) video player” … System (HTML) video player is used to play media content … It has no settings to anything else to improve “playback performance” and get rid of buffering/loading spinner. A few things have an influence here:
a) To improve performance “secured connection” on PMS side must be disabled or switched to “Preferred” instead of “Required”. PMS will use less CPU power to secure in/out network traffic it will also affect to TV. As TV will use less CPU power to decode incoming traffic. Its especially valid for high bitrate media and when TV model from low-end market.
b) Ethernet connection speed. Some models have only 100Mb Ethernet port or WiFi 2.4Ghz. Have no idea if TV have dedicated “CPU” to process Ethernet traffic or it uses main TV CPU to process Ethernet traffic. What about WiFi … Usually 2.4Ghz Wifi networks are quite overcrowded especially when you have too much neighbors. And as I remember because of nature how WiFi works … all networks on the same WiFi channel will work on lowest client speed. Its better to use WiFI 5Ghz in case your TV does support it. Ive TV model with WiFI 5Ghz and have no problem to play test 4K high bitrate media files without any problems.
c) 4K media files is not supported by non 4K TV models. Dont have enough power to handle it? Probably yes
PS
As you can see there so much BUT while trying to create app
I’m sorry for the mistakes in my poema as Im not a native speaker =)
