How to Convert FLV to iPhone (FLV to iPhone 4S) on Mac
FLV videos are not natively supported by iPhone full series. But you are in the right place. This tutorial will show you how to convert .flv to iPhone (iPhone 4S) video on Mac OS X including Snow Leopard and Lion. The recommended FLV to iPhone Converter for Mac can convert video to iPhone (iPhone 4S) compatible video formats (MP4 or MOV), to play on iPhone, iPhone 3G, iPhone 4G, iPhone 4S, iOS4, iPod and other MP4 and MP3 player. It support iPhone OS 3.0, iPhone 4.0 (iOS 4).
Step 1: Free download and install FLV to iPhone (iPhone 4S) Converter for Mac
To make FLV videos playable on your iPhone (iPhone 4S), what you need is only a FLV to iPhone Converter. This FLV to iPhone Converter for Mac works on both Intel or PowerPC based Mac computers. Free download the right version first.
Download Video Converter for Mac (Intel version) Download Video Converter for Mac (PowerPC version)
After installing, run the Mac flv to iPhone 4/iPhone 4S converter, you will see the main interface as below.
Step 2: Add FLV video files to convert to iPhone (iPhone 4S)
Click File -> Add Video Files button to browse your computer hard drive and select FLV video files you want to convert. This FLV to iMovie video converter for Mac supports drag-drop and batch conversion, so you can import and convert several flv files to iPhone videos at a time.

Step 3: Select output format for iPhone 3G, iPhone 4, iPhone 4S
Click image button at right of each video item, set output file name and choose iPhone as output format from Format list. You could still make change to video parameters such as resolution, bit rate, audio quality, etc. But it's not recommended because the default settings usually the best. Change it only if you know what you are doing. Otherwise, the converted videos would not be played on your iPhone (iPhone 4S).

Step 4: Start to convert FLV to iPhone (FLV to iPhone 4S) on Mac.
Click "Start" to convert flv to iPhone, iPhone 3G, iPhone 4.0 (iOS 4) and iPhone 4S video on Mac, just leave it alone and do anything else you like.
Done. Next, it's the time to transfer the converted videos to your iPhone with iTunes or other third party iPhone transfer. Note: With Mac FLV to iPhone 4 Converter software's enhanced editing functions, you also can trim, crop, add effect on your video, merge several flv video clips into one file, and extract audio and image from FLV on Mac.
