Why the Current iPod nano Won't do Video

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Date: Thursday, January 5th, 2006, 00:08
Category: iPod

In my ZDNet blog article “Top 10 things Apple could announce at Macworld Expo” I speculated in #3 (1GB iPod nano) that “Apple will also add video support to the nano line via a firmware upgrade to boost sales of TV shows and video content.”
While this sounded good at the time, reader Eugenia Loli-Queru proceeded to burst my bubble. It appears that the 75MHz, single DSP nano, doesn’t have the juice to decode real video. The iPodlinux Video Player only plays raw AVI files.
For more on Eugenia’s technical explanation on why, click through…


In my ZDNet blog article “Top 10 things Apple could announce at Macworld Expo” I speculated in #3 (1GB iPod nano) that “Apple will also add video support to the nano line via a firmware upgrade to boost sales of TV shows and video content.”
While this sounded good at the time, reader Eugenia Loli-Queru proceeded to burst my bubble. It appears that the 75MHz, single DSP nano, doesn’t have the juice to decode real video. The iPodlinux Video Player only plays raw AVI files.

This is technically impossible. What you don’t seem to know is the fact that the iPod Video has TWO cpus. One generic CPU running at ~75Mhz (which is the same as in the Mini/Nano/ipods) and one very specialized video DSP at ~150 MHz that is able to decode h.264 video in real-time. The video playback only uses that DSP and not the main CPU. No other iPod model has this DSP in it, and so video playback is not possible on them.
Yes, the Linux port on iPod Nano can playback video, but ONLY by using the 75 MHz CPU (running very low resolution video clips) and *not* QVGA h.264 videos which require a LOT of CPU power to decode.
Additionally, all iPod video clips are encoded at 320×240 for 4:3, while the Nano’s screen has almost half that resolution. Re-scaling videos to fit on screen in real-time not only takes away more CPU power but it will also look like crap because of the “fast” re-scaling algorithm that they will have to use to make it happen using just 75 MHz of the generic CPU.
So, no, you can’t just “upgrade the firmware” and metamorphosize your iPod Nano to an iPod Video. Just because it has a pretty color screen too doesn’t mean that it has the capabilities to be “compatible” with Apple’s videos. At best, you can just install Linux on it, and run non-h.264 videos specially encoded at very low resolutions and low frame-rates (e.g. DivX or h.263 at 176×144 at 10fps and 64kbps sound, similar to what some phones do today with the 3GP codec).
I do believe that the next generation Nano *will* be a full QVGA video player with the needed DSP in place, but the current Nano can’t become it.

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