[M4IF Technotes] multiple audio tracks into an mp4 file

[Nico Oorts]

Hi all,
With the mp4tool (JC Dufourd), I try to make a .mp4 file which contains 
multiple audiotracks. I make a scene with an audiosource. This 
audiosource has an url to the OD which contains the elementary stream. 
After some time I replace the audiosource by another which has also an 
url to an OD and ES. The result is an .mp4 which contains the tracks (I 
can check this with some tools and size), but play only the first track. 
Some ideas why this does not work?
Thx
Nico Oorts
Research team
VRT