I tried the App "MX Player" to see, if that app would behave more like VLC or more like the native Video Player.
I don't know if I should laugh or cry, but this is what happened:
I started a movie using the freshly installed MX Player and was happy to see, that the subtitles were showing on the Kindle Display. I connected my Kindle with the Micro-HDMI-Cable to my TV and was also happy to see that the vertical black bar were NOT showing, but instead it was using the full resolution of my TV. I was totally excited. And then it hit me:
While the subtitles were showing on the Kindle screen, they were NOT showing on my TV!!! Otherwise both screens showed an identical picture, but the subs were missing.
So I tried out all kinds of options in the subtitles settings. To no avail.
Then I tried switching from using the Hardware accelleration to Software accelleration. The app offers three modes called SW, HW and HW+
And here comes the funny part:
When I switched from any of the two HW modes to the SW modes, suddenly my TV was showing the subtitles. And for a moment I was like "Yeah, I finally found the solution". And then it hit me: now my TV was showing the vertical bars again.
My conclusion from this test:
When you switch to software acceleration, MX Player behaves like VLC. You get the subtitles on your TV, but you have to live with the vertical black bars effectively reducing the resolution.
When you switch to any of the two hardware acceleration options, MX Player behaves like the native Video Player and gives you the correct 16:9 1920x1080p output on the HDMI-out. But for whatever reason the subtitles are only displayed on the Kindle screen and not on the TV any more.
My guess: by using the HW acceleration, the app automatically triggers the built-in feature of reducing the resolution from 1920x1200 to the standard 1920x1080 on the HDMI-out. Apparently amazon has built in that feature into the Hardware acceleration of the Kindle.
I don't know why this kills the subtitles. Either it is a bug in the app or for some reason the Hardware acceleration does not allow the blend-in of the subtitles over the video.
And when you switch to SW acceleration, the Kindle apparently thinks of the app like any other standard app and sends the full 1920x1200 resolution not only to its own screen but also to the HDMI-out.
It would be great to know, if superimposing subtitles is technically impossible when using the HW acceleration because the Kindle chips do not support that at all or if it could be achieved with the right algorithm.
Phone: HTC One X
ROM: Viper One X V3.5.2 - Bootloader: HBOOT-1.36.0000 S-ON unlocked - Recovery: TWRP 184.108.40.206
Radio: RADIO-5.1204.163U.30 - Android: 4.1.1 with HTC Sense: 4+
(2nd phone HTC One S with ViperOneS V2.2.0, HBOOT 1.06.0000, S-ON unlocked, TWRP 220.127.116.11 & Radio EU-1.11)
Sony CMDX-1000 > Nokia 7110 > Sharp GX-30 > Treo 680 & Nokia N95 > iPhone 3G > iPhone 4 > Desire Z > One X
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