Must multimedia players check the message queue and invoke DispatchMessage?

Joerg-Cyril.Hoehle at Joerg-Cyril.Hoehle at
Mon Mar 21 12:50:33 CDT 2011


In Bug #3930
I conjectured that:

1. Since w2k, winmm hijacks the application's thread to play multimedia content.
   Wine does this as well with MCI_WAIT, but it should as well affect
   winmm:playSound, winmm:midi* and winmm:wave*.

2. Consequently, the players must implement a message loop and
   dispatch regular window messages using DispatchMessageA/W
   Currently, Wine does not.  This IMHO has potential for dead locks.
   Music and animations can play for a long time and messages ought to be serviced.

I'm not familiar with windows messages at all.
What do you think about the consequence?

Point 1 explains why tests reveal the current thread as the one
executing all callbacks but one since w2k.

Point 2 should be testable by playing a long piece of video or music
and prequeuing or injecting (how?) some windows events.  How to test
this in a convincing manner?

Would the obligation to service messages disappear if the players ran
in their own thread (like w9x seems to do)?

Thanks for your help,
       Jörg Höhle

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