where to select audio/video channels?

Christian Esken esken at kde.org
Mon Mar 6 21:09:16 GMT 2006

Am Montag, 6. März 2006 11:34 schrieb Matthias Kretz:
> Hi,
> I have a question on the design of Phonon:
> As media sources can have multiple audio channels or video channels (e.g. 
> angles for DVDs or TV channels for a TV card) the API needs to provide 
> methods to select the channel.
> On aKademy we decided to add an audio channel selection to AudioPath. But that 
> means, that one media source would need to be able to provide multiple 
> channels:
> 1. Do use cases exist where one would want more than one audio/video channel 
> at the same time?

A possible usage scenario is video or audio processing (not playback). For example there could be some backend/filter for this task:  "Extract all audio channels, and save them to different WAV files on HD."
And if you only talk about playback: it would be cool to see different angles at the same time.

> 2. Is it technically possible? What frameworks can do it (doesn't make much 
> sense if Phonon only theoretically allows this while no framework will ever 
> do this)?

I don't think backends do it at this point of time or in the near future. In my opinion it would be overkill to do this now. So decision should be based on what is easier in terms of implementation. Probably you can design the API, so it can be extended in this direction if neccesary.
About the techincal possibility: Yes, I am sure it is possible. For example it should be no problem to extract multiple audio channels from a DVD at the "same" time.


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