jerkiness in video on using phonon on windows

Lilesh Ghadi lilesh.ghadi at
Fri Nov 20 15:25:08 GMT 2009


We are subclassing QIODevice to pass audio-video data to a custom parser 
(a Directshow filter implementation) using Phonon. Phonon creates a 
graph that includes the custom parser and corresponding audio-video 
decoders and rendering filters. The custom parser internally separates 
audio and video, which is then decoded and rendered.
When this sequence is played, jerkiness is observed periodically (spaced 
every 2-3 seconds). By video jerkiness, I mean that previous frame is 
again rendered causing a break in continuous viewing. It is important to 
note that there is no break in audio.

When the same file with the custom format is drag-n-dropped in to 
Graphedit, it automatically creates a pipeline and renders audio-video 
data satisfactorily (meaning no jerkiness and in audio-video 
synchronization). From this, we have concluded that the directshow 
filters by themselves do not have any bug and perform correctly.

We are unable to figure out why this behaviour is observed on using 
phonon in windows. Any help/suggestions in this matter will be appreciated.


Lilesh Ghadi 
Lead Technologist | MunduTV 
Tel: +91-9820482055 

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