iOS App can play MP4 video but no sound

Development
1

Please help!

my iOS app cab play mp4 video but no sound (the same video can be played with sound on Android app and web)

Please help!

2

Is there any parameter should be set in ios.yaml to enable the sound?

or,
is there any extra parameter should be set to specify the MP4 format in IOS openEDX app?

Please help!

3

Do I need to store the video in m4V format for IOS devices?

4

(fixed)

For anyone if having same issue

Reason: The MP4 Codecs should be changed from H.264 to AAC, H.264