[pulseaudio-discuss] alsa pulse bugs

Colin Guthrie gmane at colin.guthr.ie
Mon May 5 03:31:13 PDT 2008

tom at dbservice.com wrote:
>> http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m.html#ga0d9e14a4be65209eb549e48a9f07302
>> Closest it says is: "It's positive and less than buffer size in normal
>> situation".
>> So perhaps this is an invalid assumption at the wine side?
> However this part:
> Delay is distance between current application frame position and sound  
> frame position.
> suggests that it indeed can be zero. Or why would a soundcard have a  
> gap between the read and write positions if it has played everything?

Indeed. I agree. However, for me this is something that should not be in 
high level documentation, that should be an internal thing (i.e. it's a 
detail of the implementation). It's perfectly true of hardware devices 
(no doubt the context when the docs were written) but perhaps this 
should not be true of non-h/w or ioplug based "devices"? Someone who 
vaguely understands the ALSA stuff should have a better insight on this 
to comment :p

>> Is there perhaps a more appropriate API call they can use to do whatever
>> test they are doing?
> What Wine needs to know, is whether a particular sample has already  
> been played or not. It does 'bytes_written - delay_in_bytes' to find  
> out how much of the written data the soundcard has already played. If  
> there is a better test for it, please explain.

I've no idea, I'm just throwing up ideas/suggestions/opinions... there 
is little technical background from my comments, just trying to raise 
some points so people more familiar than I can comment :)

Take care


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