candyer says,

iPhone 4 Supported Video Formats

* H.264 video up to 720p, 30 frames per second, Main Profile level 3.1 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 per channel, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats;
* Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames per second, audio in ulaw, PCM stereo audio in .avi file format

iPhone 4 Supported TV Formats

* Support for 1024 by 768 pixels with Dock Connector to VGA Adapter
* 576p and 480p with Apple Component AV Cable
* 576i and 480i with Apple Composite AV Cable (cables sold separately)

iPhone 4 Supported Audio Formats

* AAC (8 to 320 Kbps)
* Protected AAC (from iTunes Store)
* HE-AAC
* MP3 (8 to 320 Kbps)
* MP3 VBR
* Audible (formats 2, 3, 4, Audible Enhanced Audio, AAX, and AAX+)
* Apple Lossless
* AIFF
* WAV

Convert videos or rip DVD movies for the iPhone 4

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