[mythtv] Mythmusic question (to Thor)

Ed Wildgoose lists at wildgooses.com
Sun Nov 28 16:59:43 UTC 2004

Hi, I have been off coding for a little while, but now back and 
investigating converting MythMusic to use the main myth audio output 
layer.  However, I need a few pointers in understanding the global myth 
music architecture please...

Right now I have modified the main myth audio code to include the event 
and visualisation stuff.  I have some rough event firing going on in the 
main audio output look as well.  Mythmusic has been modified so that all 
the decoders call "output()->AddSamples" to pipe their output into the 
audio output layer.  Playbackbox.cpp has also been modified to 
initialise the new audio layer, and the visualise.cpp has some fixup 
stuff in it.

Problem is that I am not getting any audio out yet.  I have some ideas 
on where to look, but it would REALLY help to get a bit of an overview 
on how the major pieces fit together, and how all the events interact.

We seem to have several main pieces:

- Main loop in playbackbox
- Decoder for specific file
- Visualiser
- Audio layer which receives audio and fires events

How are these pieces supposed to all fit together?  In particular which 
events need to fire in order that we can create a decoder, let it fully 
decode a file, get the stuff all sent to the audio output and let the 
visualisations fire?  Oviously I have worked out quite a lot of this 
already, but if you have a few mins to write an "executive summary", 
then I think it would also be useful for others anyway in understanding 
this?  The main issue (for me) is that the extensive use of events makes 
it very tricky to see the flow of code (although I can see how it's 
quite neat).

Thanks for any pointers

Ed W

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