No *.mp4 video with MP3 sound playable on iPhones?

[pxstein]

I sent a *.mp4 video to buddies.

Much to my surprise some of them can play the video but hear no sound.
I turns out that exactly these guys use an iphone.
Android users do not have a problem with sound.

So can it be that MP3 codec is not working on iPhones?

Which audio codec should I use instead which works on both: Android and iPhones?
I could re-encode the video.

[Cornucopia]

It would be stupid for iPhones to not support mp3 audio inside the mp4 container, as it is quite compatible & a legit option. However, I wouldn't put it past Apple to lock out non-preferred options.

Use AAC. It is both more efficient (= better quality for less bitrate) and more expected as the compatible audio codec for mp4.


Scott