jerkiness in video on using phonon on windows

Ian Monroe ian.monroe at
Mon Nov 23 16:02:12 GMT 2009

On Fri, Nov 20, 2009 at 9:25 AM, Lilesh Ghadi <lilesh.ghadi at> wrote:
> Hi,
> 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.

phonon-ds9 is more or less unmaintained. What little personal
experience I have with it has been unpleasant, so it doesn't surprise
me that you'd have trouble like this.

You could think about implementing your parser as a phonon effect and
then implement it in phonon-ds9 itself. If its already a directshow
filter... it would make logical sense to work with ds9 directly. Your
code would need to be released under the LGPL then. But again, no
expert here. :)


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