The P800 can handle MP4 video (DiVX MPEG); the MP4 video file must conform to MPEG-4 Simple Visual Profile Level 0. This standard was developed for the wireless industry and sets the maximum MPEG-4 resolution to 176x144 at 15 frames per second. The total bitrate must be between 100-150 Kbit/sec. Anything else and the P800 won’t play it.
The best, cheapest, simplest and easiest method I have been able to find to get your video down to size is as follows:
Required:
To get your favourite DVD onto your P800:
This will give you a screen resolution of 352 x 288 at 25 fps. You’ll be looking at a file size of roughly 1mb per minute of video so 600mb for 60 minutes. For this the best bit of software I have found out of the 10 odd programs I downloaded was DVDx 2.2 and better still it is free. You can download it from here
http://www.digital-digest.com/dvd/downloads/dvdx.html. I simply used all the defaults for MPEG-1 (VCD), you can use MPEG-2 (SVCD) Letterbox 480 x 576, but this will result in a final size of 120 x 144 to play on your P800, plus your MPEG-2 file size doubles! Remember to select ‘whole’ in our output setting else you will only get the first 10000 frames.

The only software I could find for PC that did both MP4 conversion plus resolution downsizing was MPEGABLE X4 Live by http://www.mpegable.com it can be downloaded at http://www.mpegable.biz/download/mpegableX4liveSetup-wrapped.exe
The software is limited to a 30-day trail after which it will cost you 29 Euros or about £21. Having tried every piece of MP4 video encoding software I could find this one is definitely the bollocks.
The other software available if you use Adobe Premiere is Ligos LSX-MPEG 2.01 Plug-in which supports MP4 SVP Level 0, but it costs USD$129. http://www.ligos.com
Assuming you’ve sprung for the £21, or are attempting to convert all your DVD within 30 days the settings for MPEGABLE X4 are as follows:
1. Select your source AVI MPEG-1 VCD file you created, and output file if default not okay.
2. Open the advanced settings tab
3. Set the Total Bitrate to 125 Kbits/sec and Audio Bitrate to 16 Kbit/Sec.
4. Under advanced/reprocessing set target frame rate to 15.0, downsize factor to x2. (this will reduce the 352 x 288 MPEG-1 to the require 176 x 144) select x4 if you are encoding MPEG-2 SVCD.
5. Under advanced/audio set channels to mono, precision to 16 bit and sample rate to 22050 hz. Setting output audio to stereo (on a two minute sample) very little to the end file size so if your watching via the headphones - why not (I’ve only ever used mono so far).
6. Under advanced/interoperability select simple profile.
7. Select Encode – it is very quick!

The output MP4 will now play on your P800!
Star Trek Original Series Episode 1 - 50 minutes 20 sec
AVI MPEG1 352x288 = 502MB (10,284 KB per minute of Video)
MP4 176X144 = 45.5MB (932KB per minute of Video)
The Crow – 1 hour 37 minutes
AVI MPEG1 352x288 = 971MB
MP4 176x144 = 88.1MB (so I am off to buy me a 128MB duo)
As yet I haven’t tried to encode any other video source for the P800, however the trick would be to ensure your source video is at least MPEG1 352x288 so you can convert it easily using X4 Live. X4 supports downsizing factors of X2 and X4 so the only trick is to get the end result to 176x144 15fps or lower and remember total bitrate can’t exceed 150 Kbits/sec.
Happy encoding!