[LG Optimus 2x] Hironimo:
Mkv is just a container format. These days mkv videos usually contain h.264 avc video just as .mp4 videos do, and .mp4 videos can be played back smoothly up to 1080p resolution (however just with base profile).

NEON is indeed an expanded set of processor instructions, and Tegra2 does not support it.

However, NEON is only of use if you do the decoding on the CPU in software.

Since most video will be decoded in hardware on tegra2 devices, Nvidia chose to leave out the NEON instruction, since those need a lot of space on the chip.

However it is true that the next generation tegra 3 chip (which actually has a quad core cpu) should support the NEON instruction set, which helps speeding up handling some features in software.

However, since it is my understanding that Nvidia also plans to improve hardware video decoding on tegra 3 so it should support h.264 main or even high profile 1080p videos, it is not of the upmost importance.

Hardware decoding is more efficient (and thus will save battery life) than using NEON. So whenever having the choice, go for hardware decoding...

The reasony why high resolution .mkv files cannot be played fluently is just because the standard video player does not yet support the .mkv format, and only the standard video player supports using the hardware video decoding feature.

What actually happens when you play back a video file is that the software reads and understands the container format, which contains a raw video and audio stream. The player software then handse the video off to the hardware so it can do the decoding. The audio is also decoded - common formats possibly also in hardware.

The player controls the decoding and then feeds the decoded video to the screen and the audio to the speakers.

The standard player just does not understand the .mkv container format and thus cannot reach the embedded h.264 video.

So when you use another player that does suppot .mkv then it will usually do the decoding in software, which cannot do it fast enough for high resolution videos.

However, there is great news on this!

A new update is due to arrive soon, probably until the end of the month that will include support for mkv videos, and thus mkv can be played in hardware..

This update is already available in in korea for their version LG-SU660, and judging from this post from LG:

http://www.facebook.com/pages/LG-Optimus-Speed/192477164116791

those improvements will also come to the european P990 version.

See here a thread about the improvements of the korean version:

http://www.facebook.com/pages/LG-Optimus-Speed/192477164116791

Just to be sure, i'll provide them here again:

Faster internet browsing

Support .mkv

Hardware support for 720p h.264 4.1hp

60 frame xvid works

Little bit better LG home

Little bit faster for everything.

Apparently this also includes an improvement of the use of the tegra2 hardware to also allow high profile 720p video (before it just supported low profile). This 4.1hp video is for instance used on youtube, if my information is correct...

So to answer your original question:

You will be able to play back high resolution h.264 mkv files.

However, it will probably not be able to play all of them, because the tegra2 hardware only supports the base profile for 1080p.

So it actually depends on how the rip was made.

You can already make bd rips in 1080p that will play fine on a tegra 2 device.

For instance, if you use handbrake to encode videos, choose the MP4 container format and H.264 (x264) as video codec, and in the advanced tab in the text field, enter this line:

ref=2:bframes=0:subq=7:mixed-refs=0:weightb=0:8x8dct=0:cabac=0:weightp=0:me=umh:trellis=0:cqm=flat

This will create a video in base profile that should play fine on a tegra 2.

(Please note that some settings in that line are optimized for quality, not encoding speed. You can for instance alter the subq parameter to a lower value such as 6 and remove the me_umh option, which will result in faster encoding but worse quality).

This ofcourse requires you to have/own the bluray to create such a copy.

You are on your own for anything else...

Btw, i did not take part in the survey since the correct answer is more complex than just yes or no and ticking individual boxes.