Experiments With GraphEdit©

Before you do any changes to the filter graph you should inform yourself about the filters actually being in use.

The first place to look is within the DVBViewer at View/Filters - all used filters are listed there. Unfortunately some of them are not labeled with a meaningful name. Left-clicking one of them opens its property page if available.

For a comprehensive overview of all registered filters in the system you should try GraphEdit from Microsoft. Since it is part of the DirectX SDK, which is a very large file, it is better to search for a download site providing a stand-alone version; you may try http://doom9.org/ (rar-compressed) or http://www.stokebloke.com/video/wmv2avi.php.

GraphEdit shows a filter graph as a diagram and provides an easy way to build an own graph. Here is an overview of the features offered by GraphEdit:

• After selecting Graph/Insert filters a hierarchically arranged list with all available filters appears. In the “Directshow Filters” section you will find - among others - the available MPEG decoders listed with filename and path; this information is needed in order to un-register filters that cause problems (more about it later). Look for names such as ATI, Cyberlink, DVD Express, Elecard, MainConcept, InterVideo, Ligos, nVidia, Sonic, Ulead.

• File/Render Media File lets GraphEdit respectively the filter manager automatically build the graph that is necessary for playing a file. As file you may select any media file. The individual filters are connected like the components of an audio system by their output and input pins. The automatic media file rendering shows, what is used as standard in the system. Clicking on the Play button lets GraphEdit respectively the filter chain play the file.

  • File/Connect to Remote Graph connects to the running graph of the DVBViewer and displays it.

  • By selecting File/Render URL you may let GraphEdit build a filter graph for TV reception via the SkyStar2 card and to function as a TV set! Proceed as follows:

    • Launch DVBViewer and tune the desired channel.

    • Open the channel-list, go to the Edit tabsheet and note the Video- and AudioPID displayed there.

    • Terminate DVBViewer, launch GraphEdit and select File/Render URL

    • Input the following address: b2c2src://VideoPid-AudioPID.mpg (VideoPID and AudioPID stand for the values you have noted). Now a corresponding graph will be build and can be used for playback.

  • Graph/Insert Filter lets you insert other filters into the graph. After disconnecting the filters with Edit / Disconnect all, you may re-connect the filters manually pin by pin and build in a different decoder, for example - just drag the mouse pointer from an output pin to the desired input pin. In this way you can find out, how different components affect the playback.

Unfortunately some filters are indicated in GraphEdit by meaningless numbers. In this case it helps to store the entire graph via File/Save as XML and to open the file, which contains additional information, with a text editor. For further details please refer to the GraphEdit help file.