Conventional analog video delivered via composite signal is interlaced.
Interlaced video plays perfectly well on Discover Video players (DEVOS, Arcus) and on 3rd party players. However, iPhones do not officially support interlaced video.
According to the document of “HTTP Live Streaming” from Apple, there is a description,” Important: Interlaced video is not supported on iOS devices.”, which is written on the official document.
As of this writing:
Interlaced video does play on most iPads, and it does seem to play on iPhone 4, 4s,5, and 5c
Interlaced video does not play on iPhone 5s, iPhone 6, 6 Plus, or 6S Plus
Interlaced video does play on iPad 2, and 4, but not on iPad Air or iPad Air2
It appears to the chips used by Apple in these models.
If you want to show interlaced video (composite) on Apple iOS devices, convert it to progressive using a composite-to-HDMI converter.
We have had good success using VGA input with analog audio into the Mantis, and using an inexpensive HDMI-to-VGA converter (for example https://www.amazon.com/Rankie-Gold-Plated-Active-Adapter-Converter/dp/B00ZMV7RL2)