TL;DR version: what's the most power-efficient H.264 MKV player for a retina MBP 15" (late 2013, Intel GPU only)? A way to play MKV files under QuickTime would be ideal (Perian doesn't work). Also check the edit at the end!

I regularly watch MKV files with H.264 1080p video on my retina MBP 15" (late 2013, Intel GPU only), and up until now, I did so using the latest version of VLC. Unfortunately the battery drains pretty quickly with this setup and I decided to investigate alternatives. In trying to be a little scientific, I created a spreadsheet listing the CPU time used (checked in Activity Monitor) for each alternative that I tested. For all testing, I played the first 1 minute of a video clip of my choosing, with H.264 1080p video and DTS audio, as well as transcoding it to M4V format using MP4Tools, and in the process transcoding the audio to AAC 2-channel. Tests were performed with the computer plugged in to AC.

First up is stock VLC version 2.1.2 (the latest available as I write this), playing the MKV video. It used 28.89 seconds of CPU time to play the 1 minute clip. Next up, I enabled, under Preferences -> Input / Codecs, the option Video Decode Acceleration under Hardware Acceleration. This improved things slightly to 22.82 CPU seconds. Doing the same tests with the transcoded M4V file yielded similar results (29.76 and 22.44 CPU seconds, respectively).

I also tried MPlayerX, version 1.0.21 (1718). I found no settings for hardware acceleration, so I can't tell whether it's being used or not. Either way I got a better result, adding up the CPU time used by all the mplayer processes and the GUI process: 15.92 CPU seconds with the MKV file and 15.74 CPU seconds with the M4V file.

QuickTime playing the M4V file set the bar for everyone else, presumably using hardware accelerated decoding: 4.51 CPU seconds for the main GUI process (assuming no auxiliary decoding processes to use up more CPU time; at least I was unable to find any.)

Using iStat Menus to monitor the CPU usage % in real time correlates well with the measurements above: QuickTime hovers around 5% usage, while VLC hovers around 40-55% using software decoding.

I also tried investigating Plex but gave up in the middle of it, because my use case often involves using the computer at the same time as the video is playing, and Plex doesn't seem to be made for that -- by default it uses a full screen mode, and even under windowed mode, it captures the mouse.

AFAIK MKVs can't be played with QuickTime; I have the latest Perian (which has been discontinued, and probably has compatibility problems with Mavericks), and when I try playing this video, it gets stuck for a long time at a screen with a progress bar (with no visible progress) and "Converting..." written underneath.

Now for the questions themselves:

Has something come up to fill the Perian void that I'm not aware of, that could be used to play MKV files on QuickTime?

Failing that, are there other players that I should investigate that might get closer to QuickTime in efficiency?

Edit: I have now tried Movist (available at the Mac App Store). It allows me to choose whether to use QuickTime or FFmpeg to decode videos, and also has a hardware acceleration checkbox. Unfortunately, trying to use QuickTime to decode an MKV file fails just like QuickTime Player does. Software decoding of the M4V file, whether with QuickTime or FFmpeg, performs worse than the alternatives mentioned above (between 30.73 and 37.03 CPU seconds, depending on the setting). Hardware decoding, on the other hand, fared better than everything else except QuickTime Player: 9.22 CPU seconds for the MKV file using FFmpeg, 8.12 CPU seconds for the M4V file using QuickTime and 9.04 CPU seconds for the M4V file using FFmpeg.

So while I'm not 100% satisfied, Movist is my new player of choice for MKV files, using the FFmpeg decoder and hardware acceleration. Still, the question remains: can I play MKV files in QuickTime in Mavericks, since QuickTime is clearly the most optimized software among the ones I analyzed?

How can I play MKV files from QuickTime in Mavericks?

I used to use Perian but it hangs and the other third party players are very inefficient as QuickTime is the most optimized software among the ones I analyzed.

TL;DR version: what's the most power-efficient H.264 MKV player for a retina MBP 15" (late 2013, Intel GPU only)? A way to play MKV files under QuickTime would be ideal (Perian doesn't work).

Failing that, are there other players that I should investigate that might get closer to QuickTime in efficiency?

TL;DR version: what's the most power-efficient H.264 MKV player for a retina MBP 15" (late 2013, Intel GPU only)? A way to play MKV files under QuickTime would be ideal (Perian doesn't work). Also check the edit at the end!

Failing that, are there other players that I should investigate that might get closer to QuickTime in efficiency?

Edit: I have now tried Movist (available at the Mac App Store). It allows me to choose whether to use QuickTime or FFmpeg to decode videos, and also has a hardware acceleration checkbox. Unfortunately, trying to use QuickTime to decode an MKV file fails just like QuickTime Player does. Software decoding of the M4V file, whether with QuickTime or FFmpeg, performs worse than the alternatives mentioned above (between 30.73 and 37.03 CPU seconds, depending on the setting). Hardware decoding, on the other hand, fared better than everything else except QuickTime Player: 9.22 CPU seconds for the MKV file using FFmpeg, 8.12 CPU seconds for the M4V file using QuickTime and 9.04 CPU seconds for the M4V file using FFmpeg.

So while I'm not 100% satisfied, Movist is my new player of choice for MKV files, using the FFmpeg decoder and hardware acceleration. Still, the question remains: can I play MKV files in QuickTime in Mavericks, since QuickTime is clearly the most optimized software among the ones I analyzed?