iPhone ringtones' format are slightly different than other ringtones' format. First of all the format is based on MPEG-4 but renamed to have an M4R extension (R for ringtone) and secondly the sound spectrum is quite different from other mobile phones.
The existence of different file extensions for naming audio-only MP4 files has been a source of confusion among users and multimedia playback software. Since MPEG-4 Part 14 is a container format, MPEG-4 files may contain any number of audio, video, and even subtitle streams, making it impossible to determine the type of streams in an MPEG-4 file based on its filename extension alone.
In response, Apple Inc. started using and popularizing the .m4a file extension. Software capable of audio/video playback should recognize files with either .m4a or .mp4 file extensions, as would be expected, as there are no file format differences between the two. Most software capable of creating MPEG-4 audio will allow the user to choose the filename extension of the created MPEG-4 files.
The same is true for .m4r which essentially is the same as an .m4a file but with a different extension. The dedicated extension ensures that when an .m4r file is dragged to iTunes for example - the ringtone is automatically recognized and installed - ready to be synced with the iPhone.And we can convert vedio(include youtube vedio) to m4r iPhone ringtone.
Frequency response: 20Hz to 20,000Hz
Audio formats supported: AAC, Protected AAC, MP3, MP3 VBR, Audible (formats 1, 2, and 3), Apple Lossless, AIFF, and WAV
User-configurable maximum volume limit
iPhone Ringtone belongs to truetone type ringtone which is simply an audio recording, typically in a common format such as "MP3", AAC, or WMA, and represents the latest evolution of the ring tone. Truetones, which are often excerpts from songs, have become popular as ring tones. iPhone Ringtone can be up to 30 seconds.
Convert various audio and video formats to M4R ringtone formats and offer waveform for precise trim and fade in&out effect available