Friday, May 06, 2005

QuickTime 7 and the real power of H.264

In previous articles we talked about the hardware requirements of QuickTime 7 for H.264 HD. H.264's implications for high definition content are very exciting, but perhaps not quite as exciting as its implications for web delivery of lower resolution content.

Behold the power of H.264 in QuickTime 7:

This image is a screen capture of a QuickTime 7 stream of CNBC's report on Tiger. What's interesting is the fact that it's a 640x480 stream with a high frame rate, with a bit rate of only 676 Kbps.

Contrast this to what QuickTime 6 users get:

Now, the bitrate of this clip is approximately 30% lower than the H.264 clip, but still, even at the same bitrate it would be extremely difficult for any QuickTime 6 codec to achieve anywhere near to close the quality of the H.264 clip with the same resolution and frame rate.

It's fortunate for Apple that the iPod and iTunes are so popular, since every installation of iTunes includes QuickTime. I look forward to when QuickTime 7 for Windows is released. Once that happens, the iPod will mean a big boost for the adoption of H.264, which I hope translates into a quick transition to a time when video streams on the internet are actually enjoyable to watch.

Wednesday, May 04, 2005

iMac G5 May 2005: An excellent update

Apple yesterday released the new iMac G5. Although many of the updates are fairly small, there are a ton of them, and Apple has either kept the price the same (at the low end) or decreased the price (at the high end). Some of the updates include:

1) CPU speedbumps. The top speed is now 2.0 GHz, still with the G5 970FX.
2) 256 -> 512 MB RAM. This one's especially nice since the 512 MB is one stick, leaving the second DIMM slot free for additional RAM.
3) Increased hard drive space. The minimum size now is 160 MB, and the top end gets 250, with the option to upgrade to 400 GB.
4) 8X dual-layer DVD+/-RW SuperDrive. This is likely the Panasonic UJ-845.
5) GeForce FX 5200U -> Radeon 9600. ATI's Radeon 9600 is certainly not a stellar performer, but it is a definite improvement. Games will be faster, and so will Core Image/Core Video/Motion. However, just as importantly it's a big marketing win for Apple. People respect the 9600 name much more than the 5200, even if the 9600 is still relatively low end.
6) 64 MB -> 128 MB GPU memory. This is a nice bonus for video games at higher resolutions, and for some people (who like a lot of open windows) the extra memory may be important for Exposé on the 20" iMacs.
7) Gigabit Ethernet. For most of us this is unimportant, but it will be useful for some institutional settings and for some looking at the iMac for video work, etc.
8) Integrated Bluetooth 2.0. We benefit because we all get Bluetooth now, and we have Bluetooth 2.0 compatibility for the future. Apple benefits because it simplifies the stocking of iMac models.
9) Airport Extreme. Quite frankly, I'm surprised Apple decided to do this, but see #8. I'm not complaining.
10) International power supply. You can now buy a US iMac and use it in China, without having to get an expensive adapter.
11) Mac OS X 10.4 Tiger. This is expected and welcome to home users, but may prove problematic for some institutional purchases. It will be some time before everyone upgrades to Tiger because of new bugs that have not unexpectedly cropped up. Many in this situation would rather not purchase a lot of machines only capable of running an OS they haven't had time to test.
12) Ambient light sensor. When the new iMac is sleeping, its pulsating sleep light fades when low light conditions are sensed "so you and your iMac G5 can both catch some Zs".

Overall, this is an excellent update. In fact I was so bowled over by the new update I ordered one for myself:

20" iMac G5 2.0 GHz
512 MB RAM (to be upgraded to 1.5 GB)
400 GB SATA drive
Wireless Bluetooth keyboard and mouse

My new machine is shipping next week. :)

Sunday, May 01, 2005

True requirements for H.264 HD playback

In the previous post we mentioned Apple's listed hardware requirements for QuickTime 7 HD H.264 playback and suggested that most G4 Macs will have problems with this material. While true, it seems that Apple's latest dual G4 Power Macs can handle at least 720p24 material (but not 1080p material) at full frame rates.

Thanks to those people with dual G4s who posted their results. Going by these reports and by reports at Ars, it seems that Apple has taken a conservative approach and may be overestimating the hardware requirements slightly.


So far the lowest end hardware reported that can sustain 24 fps for the 720p material is a dual 1.0 GHz G4 Power Mac or 1.6 GHz G5 iMac. (The few reports of dual 867 Power Macs so far state that they cannot maintain the full frame rates.) Apple lists support for neither the 1.6 GHz iMac nor any G4 Macs. Apple recommends at least a 1.8 GHz G5. However, one report of a 1.67 GHz PowerBook states that it comes very close, at least for 1280x544 material at 24 fps, so even if the 1.8 GHz G5 970GX doesn't make its way into the next PowerBook, a 1.8 GHz G4 7448 with its doubled L2 cache and 200 MHz bus might just be enough.

Both my Cube G4 1.7 GHz and my PowerBook G4 1.0 GHz get about 12 fps (half the native frame rate) with the 720p Batman Begins trailer. At 12 fps, the video is watchable, but stutters somewhat. It interesting that despite the 700 MHz clock speed advantage, if anything the Cube sometimes does slightly worse than the PowerBook. While the PowerBook has a better GPU, it's possible the difference lies in the bus speed, which is 33% faster on the PowerBook. Fortunately, there are no audio dropouts whatsover on either machine, at least when using 10.4 Tiger, despite the reduced video frame rates. This is even true for 1080p. The audio is fine, even if the video is unwatchable.


The lowest end hardware reported so far that is able to play back 1080p material is a dual 1.8 GHz G5 Power Mac, which is lower than Apple's recommendation of a dual 2.0 GHz Power Mac.

Note, however, that Apple hardware recommendations are based on 30 fps material. Most of the clips on Apple's website are 24 fps. Furthermore, Apple's "720p" material often isn't full 1280x720. The Batman Begins 720p trailer is 1280x544 for instance. Similarly, Apple's "1080p" material often isn't full 1920x1080. The Batman Begins 1080p trailer is 1920x816. It is possible that Apple is being conservative in its hardware recommendations to ensure playback is smooth even in the worst case scenarios, ie. 1280x720 @ 30 fps, and 1920x1080 @ 30 fps.

It will be interesting to see how Windows x86 hardware fares with this material, but Apple has not yet released QuickTime 7 for Windows yet. Apple says it's coming soon though.