Senior Member
Join Date: Dec 2004
Location: Texas
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For anyone interested...
I took a few minutes and calculated the average bitrate of a new iTunes movie I downloaded (specifically, The Incredibles). This produced some VERY interesting results. Here is the calculation: Part1 -> Get the number of kilobits... 1.3GB = 1.3*1024*1024 = 1363148.8 kiloBYTES 1363148.8 kiloBYTES * 8 = 10905190.4 kilobits Part 2 -> Get the number of seconds... 1:55:12 * 3600 = 6912 seconds Part 3 -> Average bitrate... 10905190.4 kilobits / 6912 seconds = 1578 kbps AVERAGE (I am rounding to the nearest kilobit here). So..... This is a very interesting development since the videos are not downconverted on the iPod (i.e. the entire file size exists on the device), and playback works on both the device and TV out. That being said, Apple's published documentation for the 5G iPod said it could support a max of only 768 kbps for H.264 encoded video. Now I am including audio in the above calculation but still, this seems very *ahem*, interesting... Looks to me like a software cap was placed on the 5G iPod at launch. Or, to give Apple a LITTLE credit, perhaps the playback software was not optimized. What are your thoughts on this? Obviously, I am very happy that Apple has either 1) lifted their self-imposed cap, or 2) optimized the playback performance, so no huge complaints (hell, we didn't know what we were missing). Let me know if you think I am off in my analysis here. Thanks for your feedback! Cheers, Wraven |
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Veteran Member
Join Date: Mar 2005
Location: Near Indianapolis
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I would imagine they've just improved the software. I'm waiting a bit before I make my purchase decision now, though. If this doesn't have a negative impact on battery life on the original video model, I'll just get one of them refurbed and spend the money I save on a case and some downloads.
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Veteran Member
Join Date: May 2004
Location: Clayton, NC
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Hmmm... pretty interesting.
I've just now partially remembered something I read when H.264 was first introduced/announced/whatevered. Isn't there something special about H.264 that makes it scale down more easily to smaller devices? Maybe, if you're decoding H.264 and you know you're only going to need a certain, final, smaller resolution, you don't need to decode the full bandwidth. Like, somehow you can encode your movie to H.264, 640x480 and 320x240 in the same file, without just having two separate streams embedded; the similar information from the low and high res streams is factored-out. Somethnig like that maybe? Ugh. |
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owner for sale by house
Join Date: Apr 2005
Location: Charlotte, NC
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I think spotcatbug is spot on! The way most video encoders work is that they tell you the big stuff first, and then progressively refine the image. The idea is that if you have to push the image to the screen before having read the entire frame, you still get a best-effort image. So if the iPod simply stops refining the image at a certain point and skips the rest of the frame, that would work well for its built-in screen. It would be interesting to see how much better the image quality is on the TV-out, though.
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Senior Member
Join Date: Dec 2004
Location: Texas
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fcgriz,
Just a note - I think the 60% brightness increase on the new iPods is fairly significant. I just tried showing off The Incredibles on my 5G 60GB iPod to a buddy (outdoors, but in the shade), and the brightness was an issue. Just something to think about. Thanks for the feedback so far - that's really cool if what you wrote about H.264 is indeed the case spotcatbug. Thanks again! Cheers, Wraven |
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