[Febs]

linuxstb posted this message on the Rockbox forums, giving a good explanation of where video stands and what you should and should not expect from video on iriver players:

Originally Posted by linuxstb

This post doesn't belong in this iPod Video forum - the mpegplayer now in CVS is implemented purely using the CPU, and not using the iPod Video's Broadcom chip. Hopefully this thread will be moved, so I'm posting a little status update here.

I own an ipod Color, and the Photo/Color and Nano share the same LCD driver, which is why those targets have received the first optimisations. I also own an ipod 5g, and will be working with that as well.

All ipods (with colour LCDs) have a more or less identical main CPU (the PortalPlayer chip), which means that out of those targets, the Nano is most likely to get working video support first - a full-screen video on the Nano is only 176x128, compared with 224x176 for the Photo/Color and 320x240 for the Video. So there is both less data to decode, and less data to write to the LCD.

Currently, the player can play back a 176x128 MPEG-2 file at around 24fps on the ipods - so this means either full-screen on the Nano or smaller than full-screen on the Photo/Color and 5g. Full-size videos on the Photo/Color and 5g play much slower than that. The aim is to get this up to at least 25fps (PAL framerate) and hopefully 29.97fps (NTSC framerate) for full-size video on all targets.

The PortalPlayer chips inside the ipods have two 75Mhz ARM cpu cores. Currently the video player (and Rockbox in general) is just using one. The hope is that if one core can cope with full-speed video decoding (and writing to the LCD), the other core can be brought into use to handle the audio decoding, buffering the data from disk, and whatever else a video player needs.

Things are not looking as bright on the Coldfire-based targets (iriver H300 and iaudio X5) - full-screen video is around 9fps on the H300 at the moment when running the CPU at the full 124MHz. And there is no second core to use for audio - the main CPU will need to handle everything. But these are early days - all the audio codecs were also worryingly slow when first run on the Coldfire. I personally will probably not be working on the Coldfire version (I don't own a H300 or X5), so developers are needed...