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Motion JPEG (M-JPEG) up to 35 Mbps, 1280x720 pixels, 30 frames per second, audio in ulaw, PCM stereo audio in. MPEG-4 video up to 2.5 Mbps, 640x480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps per channel, 48kHz, stereo audio in. H.264 video up to 4K, 30 frames per second, High Profile level 4.2 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in.
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MP4 is just a container format, whether your video will play normally or not, depends on if its codec and other parameters are supported by iPhone as follows: Moreover, don't just assume that all MP4 videos are playable on iPhone. Just as I said above, video compatibility issue can be a common and frequently neglected reason for iPhone videos not playing. There are many reasons that can result in your iPhone doesn't play videos.
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Free Download Frequently Neglected Reason for Videos Wont Play on iPhone
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