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Is HD about GPU or CPU?

SpaceMagic

SpaceMagic

macrumors 68000
Original poster
Oct 26, 2003
1,744
9
Cardiff, Wales
Hey all,

I'm just looking at 1080p content and noticing how jerkily annoying it is. Now I was wondering, how would one go about improving this playback? Is it:

1) CPU .. my 1.8Ghz not enough?
2) GPU .. my Nvidia 5200 not good enough (probably!)?
3) More ram?
4) A mixture of all three?

If I was to buy one.. would it be new computer (thus new CPU) or new GPU? If so what do you recommend? (1.8 G5 PCI-X and 8x AGP)

Cheers,

SpaceMagic
 
At this point, playback of 1080p HD seems to be processor intensive. I think you might have an iMac G5 1.8Ghz or PM 1.8 Single Proc. If you have any Dual Processor Mac, PPC or Intel, you will be able to play 1080 content as proven by many. The new Mac mini CD can play 1080, but not the Core Solo without stuttering. So as you can see, one needs two processors to play 1080p cleanly.
 
Apple's specs for HD playback:

For 852x480 (480p) video at 24 frames per second:

QuickTime 7 for Mac OS X:
1.25 GHz PowerMac G4 or faster Macintosh computer
At least 128MB of RAM
64MB or greater video card
QuickTime 7 for Windows:
2.0 GHz Intel Pentium 4 or faster processor
At least 512MB of RAM
64MB or greater video card
Windows 2000 or XP

For 1280x720 (720p) video at 24-30 frames per second:

QuickTime 7 for Mac OS X:
1.8 GHz PowerMac G5 or faster Macintosh computer; 1.83 GHz Intel Core Duo or faster
At least 256MB of RAM
64 MB or greater video card
QuickTime 7 for Windows:
2.8 GHz Pentium 4 or faster processor
At least 512MB of RAM
64MB or greater video card
Windows 2000 or XP

For 1920x1080 (1080p) video at 24 frames per second:

QuickTime 7 for Mac OS X:
Dual 2.0 GHz PowerMac G5 or faster Macintosh computer; 2.0 GHz Intel Core Duo or faster
At least 512MB of RAM
128MB or greater video card

I have a MBP, 1.83GHz, and it plays 1080p well, but certainly not flawlessly. Fast CPU & a good deal of VRAM seem to be very important.
 
I don't even know why they publish 480p requirements. That's maximum DVD quality..if I wanted to see a DVD, I'd pop it in.

My other question is, why not 1080i? I work at circuit city, and see 1080i all day, and i love it. It wouldn't be nearly as intensive as 1080p, and still enjoyable. Not that my TiBook could handle it, but still!

EDIT: I just remembered, most internal DVD players don't do progressive scan. 480p WOULD be a step up! :eek:
 
Jschultz said:
...
EDIT: I just remembered, most internal DVD players don't do progressive scan. 480p WOULD be a step up! :eek:
Click to expand...

DVDs are encoded as an interlaced signal, so they are only 480i anyway. 480p is done by upscaling, even on progressive scan DVD players.
 
Jschultz said:
I don't even know why they publish 480p requirements. That's maximum DVD quality..if I wanted to see a DVD, I'd pop it in.

My other question is, why not 1080i? I work at circuit city, and see 1080i all day, and i love it. It wouldn't be nearly as intensive as 1080p, and still enjoyable. Not that my TiBook could handle it, but still!

EDIT: I just remembered, most internal DVD players don't do progressive scan. 480p WOULD be a step up! :eek:
Click to expand...

Why not 1080i? Because, the vast majority of '1080p' material out there is only 24 fps. 1080i is 60 'fields' per second, and so doesn't scale to 24fps as cleanly. At that framerate, progressive scan looks way better than interlaced, and for source material that was progressive 24fps in the first place, 1080p/24 would look better than 1080i/60. (Played back on a native 1080i monitor, of course 1080i looks better, though. I'm only talking about playing back on a computer screen.)

(In addition, 1080i is 60 'fields' per second, 1920x540. Or, the equivalent of 1920x1080 at 30 fps. So it's actually slightly more work than 1080p/24. The HD standard '1080p' is 1920x1080 at 60 full frames per second. Based on the specs for current H.264 media, only a G5 Quad could handle 1080p/60 right now. Also note that even a single G5 1.6 or Core Solo 1.5 could handle UNCOMPRESSED 1080p/60, if you have a fast enough drive system; it's the H.264 decompression that takes so much power.)
 
Right now it's mostly CPU based. The newer ATI X1xxx Series Radeons and the NVidia 7800 have h.264 decoding capabilities built into them. Sadly, those abilities aren't enable on either Mac or Windows yet.
 
Eidorian said:
Right now it's mostly CPU based. The newer ATI X1xxx Series Radeons and the NVidia 7800 have h.264 decoding capabilities built into them. Sadly, those abilities aren't enable on either Mac or Windows yet.
Click to expand...

Yeah it's daft. As apple force h.264 down our throat's - their new hardware which features encoding/decoding acceleration via the GPU isnt even being utilised. At the rate apple updates gfx drivers, I'd say 10.5 before we even see the feature implemented.. :( :(
 
MacRumorUser said:
Yeah it's daft. As apple force h.264 down our throat's - their new hardware which features encoding/decoding acceleration via the GPU isnt even being utilised. At the rate apple updates gfx drivers, I'd say 10.5 before we even see the feature implemented.. :( :(
Click to expand...

It's Called Core video and it works.
 
This might sound pretty stupid. But.

How do I Convert some of my DVD's and stuff to H.264? I have a Intel Duo Core iMac 2Ghz and QT Pro 7.

What is it i need to do?
 
It's the same level of 'hardware' decoding that modern GPUs use on DVDs. It's not a full 100% hardware H.264 decoder, like you would see in, say, the iPod. It's a 'hardware-assisted' decode, like the hardware-assisted DVD decoding that is so common nowadays.

To test, I just tried the 30-day trial on my son's Windows PeeCee. He has an ATI X1300 (the minimum listed video chip,) with a crappy Celeron-D 2.8 Ghz processor. This is WAAAY under the minimum specs according to Apple for 1080p content, and BARELY acceptable for 720p content.

I tried BBC Motion Gallery samples from Apple's HD Gallery. In QuickTime, it plays 720p at maybe an average 20fps, dropping below that a couple times, but never below 12fps. In 1080p, it averages maybe 10-12fps. If the magic ATI program truly does do all decoding in the video chip, it should be able to handle it perfectly, right? Sorry, no. It does get faster, averaging maybe 16-18 fps, but it still can't handle full 24fps. It HELPS, it doesn't take over. With the magic ATI decoder, it can play the 720p clip flawlessley, though.

It might be enough, though, to enable a Core Solo to do it. But, sadly, the new Mini uses Intel graphics, not ATI or nVidia. That means it's using the processor for all video tasks anyway. (It also means that upgrading the processor can remove video chip-speed limitations, since you're effectively upgrading the CPU and GPU both. So the 1.5 Solo to 2.16 Duo upgrade should make a SIGNIFICANT difference in gaming. More than just the simple clock-speed alone should imply, since you're then getting a 'second dedicated' processor for video-chip functions, if you want to think of it that way.)
 
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