x264(mkv) GPU playback on new MBA 13?

I have a new MBA 13 on loan. When I play a 720p MKV x264 file the CPU runs at 40-50% all the time using VLC.

Is there any way to use GPU accelleration for playback so that it lowers CPU use?

I tried playing a 1080p Quicktime trailer and that seemed to use less CPU?

I don't believe VLC uses hardware accelaration (Windows version does. Apple hardware APIs are available but it's not been added to VLC for Mac yet). That's why you're seeing higher use in that over Quicktime.

Does the CPU usage matter? If it's a battery life issue I doubt there's much in it between GPU and CPU power consumption

I thought it might use less power using the GPU, but maybe not?

Toranaga said:

I have a new MBA 13 on loan. When I play a 720p MKV x264 file the CPU runs at 40-50% all the time using VLC.

Is there any way to use GPU accelleration for playback so that it lowers CPU use?

I tried playing a 1080p Quicktime trailer and that seemed to use less CPU?

Click to expand...

I just tried an x264-encoded video on my iMac, first in Quicktime in its m4v container, then in VLC in an mkv container, and the cpu load was identical, running under 8% typically, spiking around 12% rarely. So something is off with either your videos or your software. Do you have the latest version of VLC? Are you SURE that the video encoding is x264 rather than VC-1? You may want to try MPlayer X as an alternative (free on the Mac App Store), or Lunettes, an ongoing effort to modernize and optimize VLC for OS X.

What CPU does your iMac have? When I play on my iMac i7 the CPU load is very small, but that CPU is also WAY faster than the C2D in the Air. I will do some further testing i guess...

Toranaga said:

What CPU does your iMac have? When I play on my iMac i7 the CPU load is very small, but that CPU is also WAY faster than the C2D in the Air. I will do some further testing i guess...

Click to expand...

Before my response here, I should mention that I used "x264" incorrectly, and it's frequently confused with h.264, myself included. I had to do some followup reading to clear my mind on this, and here's my understanding: x264 is an encoder, and h.264 (aka AVC) is a codec. As an alternative, x264 can also encode to VC-1, a competitor to h.264. Apple's public hardware-decoding API is for h.264 and does NOT support VC-1.

That said… I have an i3 (mid-2010 iMac), but that's not really the point. Point is, I'm having identical results with an h.264 (AVC) video in an m4v container played in Quicktime vs the exact same video remuxed to an mkv container and played in VLC. That tells me that VLC is accessing the same publicly-available APIs for hardware decoding of h.264 video that Quicktime is using. You need to determine if your videos use VC-1 or h.264 (AVC). Ignore any reference to x264… it's irrelevant.

Ok, so I just tried playing some mkv's on my iMac i7 and a remember wrong i guess. Task monitor shows 15-18% when playing a 720p mkv!? And up to 40% CPU use for 1080p. But the strange thing is that the CPU useage graph at the bottom never rises above one green dot even though it says 40%??
So I am thinking it is only using one core or what is up??

Also on the MBA the icon in the dock for task monitor show two cpu useage bars, but my iMac only shows one??

Toranaga said:

Ok, so I just tried playing some mkv's on my iMac i7 and a remember wrong i guess. Task monitor shows 15-18% when playing a 720p mkv!? And up to 40% CPU use for 1080p. But the strange thing is that the CPU useage graph at the bottom never rises above one green dot even though it says 40%??
So I am thinking it is only using one core or what is up??

Also on the MBA the icon in the dock for task monitor show two cpu useage bars, but my iMac only shows one??

Click to expand...

This is all irrelevant. If you want to improve the performance, you first need to determine if your videos' codecs are h.264 (AVC). If they are not, you need to transcode them. If they are, you either need to switch to a player that supports Apples public APIs for hardware decoding of h.264, or re-encode your videos at a lower bitrate.

I just figured out the CPU usage thing. Turns out that full load on my Air would be 200% and on my iMac it would be 800%. So when the iMac shows 40% use for playing a 1080p mkv it is actually using like 5% of total CPU power.