[haiku-development] Re: Multi Audio Specification

  • From: Ingo Weinhold <ingo_weinhold@xxxxxx>
  • To: haiku-development@xxxxxxxxxxxxx
  • Date: Sun, 13 Dec 2009 13:48:33 +0100

On 2009-12-13 at 13:14:11 [+0100], Jérôme Duval <korli@xxxxxxxxxxxxxxxx> 
> 2009/12/13 Ingo Weinhold <ingo_weinhold@xxxxxx>:
> > just a quick question: Is there a specification for the multi audio
> > protocol? Besides the header, that is.
> The usual answer: I'm afraid no spec documentation is available,
> reading the sources might help.

That's kind of a problem, since I want to check the sources (the 
MultiAudioNode and hda driver) against the specs.

> A newsletter was written at Be, no real specification though:
> http://www.haiku-os.org/legacy-docs/benewsletter/Issue5-1.html

The article refers to the documents multi_audio.gb and multi_audio.txt as 
the '"complete" documentation'. Does anyone have these files?

> Better ask questions here :)

I'm primarily interested in the exact semantics of the 
B_MULTI_BUFFER_EXCHANGE call. Particularly whether indeed all fields of 
multi_buffer_info structure are output parameters -- the doxygen comment at 
the HDA driver's buffer_exchange() function suggests that 
playback_buffer_cycle isn't, but it still completely ignores it -- and what 
the call is supposed to be waiting for -- the end of the currently played 
buffer or shall it indeed return immediately (with incorrect return 
values), if B_MULTI_BUFFER_EXCHANGE wasn't called for a previous buffer, as 
the HDA driver does.

CU, Ingo

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