[M4IF Technotes] MediaControl node problem

[Christian Weigel]

Renaud Cazoulat wrote:
> Hi,
> 
> > Maybe it's a bug in mp4tool. What did envivio different by creating 
> > the scene? I found that the scene time of the envivio 
> sample scene is 
> > 20min whereas the time of "my" envivio scene was just as 
> long as the 
> > video. Could there be some problem with the time bases resulting in 
> > these problems?
> 
> Could be, indeed. If you want to "pause" a stream, you must 
> be sure that it is *not* linked to the same OCR as the BIFS 
> scene (otherwize you would pause the scene itself!) At least 
> this could be an explanantion why the envivio content does 
> not show the same durations for the scene and for the video 
> (despite it could be the same but that makes more sense to 
> have a longuer scene duration in this case)

The more I study the spec the more I believe that this is really the
problem. Unfortunately I'm not so familiar with time stamps and time
bases. I tried to use an additional OCR stream as time base for the
video ES but without success. Maybe someone could give an example for a
typical ObjectDescriptor with aggreated ES descriptor and especially
SLConfigDescriptor (of course in text description) describing a scene
with scene description stream and a video or audio media object embedded
in this scene where the streams are not linked to the same time base.
Regards
Christian Weigel