From ModMyiFone - Wiki
by: fireraining
Many friends ask me how to put DVD movie and video on iPhone, so I took a few days to write a guide to teach you how to do that with freeware. Before we start the guide, here is something about iPhone supported video format that we should know:
Video formats supported:
H.264 video, up to 1.5 Mbps, 640 by 480 pixels, 30 frames per second, Low-Complexity version of the H.264 Baseline Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats;
H.264 video, up to 768 Kbps, 320 by 240 pixels, 30 frames per second, Baseline Profile up to Level 1.3 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats;
MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48 kHz, stereo audio in .m4v, .mp4, and .mov file formats
Mac user
what you need is Handbrake:
Step1. Install handbrake and run it. The latest version is 0.8.5. In the “Source” section, click “browser” button to load the DVD file from your DVD-Rom or hard drive:
Then click “Open”.
Step2. You can select the desire audio and subtitle in the “Video Audio & Subtitle” section. If you don’t know much about video encoder, just leave it as original, the default setting works great.
Because iPhone’s resolution is 480*320, DVD movie resolution is 720*480, if you want to customize the resolution; you can click “picture settings” to open the crop panel. Type in the value you want.
Then click close to return to the main interface, click “Start” to rip the DVD to MP4.
If you center on more powerful functions such as movie length trimming, video cropping, selecting DVD chapters/titles, joining/merging more than one DVD chapter/title, selecting audio track and subtitle, or want to rip DVD's for viewable on more mobile devices on Mac, you can try Wondershare, here is its official website.