[VictorBoyko]

I'm really tired of Apple TV and its, let's say, limited ability to play digital content.

I'm thinking of byuing a Powerbook 12" (i love the dimensions!) and connecting it to my screen via DVI-HDMI.

Tell me please, will the PB 12" 1.5GHz be capable of playing the 720p movies in .MKV format (player VLC)? Or it's processing power is less?

[Simon]

With the 1.5 GHz G4 I'd expect some stuttering. A C2D MacBook or Mac mini OTOH should have no problems.

[mduell]

Assuming it's H.264 video in that MKV, no way. AppleTV is way more capable of video playback (albeit less compatible without hacks) than a G4 laptop. In my own testing with a 12" 1.25Ghz, it couldn't even keep up with simplified H.264 (CAVLC, etc) at 640 pixels wide and modest bitrates.

Use Handbrake to transcode all your pirated downloads with the Apple TV preset. Or get any Intel Mac for your HTPC.

[reader50]

Here are some test numbers from my G5 Quad at 2.5 GHz. All were done with fullscreen playback on a 1920 x 1200 monitor. Playing at normal size only saved ~1% on 720p, so video scaling is a minor factor.

A 720p (h264) MKV uses 70-88% of one CPU under VLC. Load fluctuates with the bitrate, though not linearly. Using different files, I get 88% peak load at 7.7 Mbps (6.2 video), 70% is minimum load at 5.6 Mbps (4.1 video). Allowing another 5% for other processes like the windowserver and kernel, you get 75% to 93% of 2.5 GHz. So required PPC GHz for 720p playback is 1.88 - 2.33 GHz.

A 1080p (h264) MKV uses 135-170% (150% typical) based on bitrate and scene complexity. Using multithreaded video decode of course. Adding 5% overhead, this calculates to 3.5 GHz to 4.4 GHz (3.9 GHz typical) of multicore PPC CPU capacity. So a dual 1.8 G5 will just manage to play low bitrate 1080p, a dual 2.0 G5 will play most, and you need a dual 2.3 G5 or better to play them all.

QuickTime trailers use less challenging (for playback) compression settings, at the expense of larger file sizes. So I did the same tests on a few QT 720p trailers. It works out to 1.3-1.6 PPC GHz required for smooth playback.

Since all PowerBooks have 1 core, you'll experience a lot of stuttering while playing 720p. That's if you turn on aggressive frame dropping to maintain sync. Without dropping frames, playback will fail.

If you used HandBrake as mduell suggests, you could transcode 720p to low settings with huge file sizes. It might play back on a 1.5 PowerBook, but your internal HD size & speed will become a problem. And you'd better not use the PowerBook to do that transcoding - it will die of old age before it finishes your library.

[mduell]

Originally Posted by reader50 

Here are some test numbers from my G5 Quad at 2.5 GHz. All were done with fullscreen playback on a 1920 x 1200 monitor. Playing at normal size only saved ~1% on 720p, so video scaling is a minor factor.

A 720p (h264) MKV uses 70-88% of one CPU under VLC. Load fluctuates with the bitrate, though not linearly. Using different files, I get 88% peak load at 7.7 Mbps (6.2 video), 70% is minimum load at 5.6 Mbps (4.1 video). Allowing another 5% for other processes like the windowserver and kernel, you get 75% to 93% of 2.5 GHz. So required PPC GHz for 720p playback is 1.88 - 2.33 GHz.

A 1080p (h264) MKV uses 135-170% (150% typical) based on bitrate and scene complexity. Using multithreaded video decode of course. Adding 5% overhead, this calculates to 3.5 GHz to 4.4 GHz (3.9 GHz typical) of multicore PPC CPU capacity. So a dual 1.8 G5 will just manage to play low bitrate 1080p, a dual 2.0 G5 will play most, and you need a dual 2.3 G5 or better to play them all.

QuickTime trailers use less challenging (for playback) compression settings, at the expense of larger file sizes. So I did the same tests on a few QT 720p trailers. It works out to 1.3-1.6 PPC GHz required for smooth playback.

How is this at all relevant to G4 laptops? They're completely different architectures.

Originally Posted by reader50 

If you used HandBrake as mduell suggests, you could transcode 720p to low settings with huge file sizes. It might play back on a 1.5 PowerBook, but your internal HD size & speed will become a problem. And you'd better not use the PowerBook to do that transcoding - it will die of old age before it finishes your library.

Hard drive speed isn't going to be a problem, there's no way a G4 can keep up with the bitrates a hard drive can pump out.

If he's going to do any transcoding, he should do it for the Apple TV he already has.

[reader50]

Originally Posted by mduell 

How is this {G5 test results} at all relevant to G4 laptops? They're completely different architectures.

I seem to recall some early tests on G4 vs G5, which showed their performance to be much the same on a per-clock basis. Obviously, the G5 bus architecture is very different, but the test results suggest playback is bottlenecked by CPU. So unless someone does some G4 testing with contradictory results, I think my numbers and projections are in the ball park.

Real G4 test results would be welcome. The G5 numbers are there because that's what I have to test on.

[mduell]

Originally Posted by reader50 

IReal G4 test results would be welcome. The G5 numbers are there because that's what I have to test on.

As I did in my original post: In my own testing with a 12" 1.25Ghz, it couldn't even keep up with simplified H.264 (CAVLC, etc) at 640 pixels wide and modest bitrates. Which is a quarter the resolution that your "PPC equivalence" suggests a 1.mumble Ghz PPC should be able to play.

Looking back at the files I tested, the 1.25Ghz G4 couldn't even handle 480 pixel wide (iPhone res) H.264 smoothly.

[Guy Kuo]

I had my 12" 1.25Ghz G4 PowerBook connected to a 1080P TV as my treadmill computer. HD playback was not possible without severe frame stuttering. However, it could do full screen DVD playback (SD scaled up to fill screen). That however kept its cooling fan running full blast. Web browsing was also slow compared to that which I'm used to on my MacBook Pro's.

I can however, ditto the recommendation of a MacBook. A used MacBook replaced my PowerBook at the treadmill and is MUCH superior in speed and keeping cool. It also is a fine SlingBox client.