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Re: VLC needs someone to assist in finishing it's auhal output module
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Re: VLC needs someone to assist in finishing it's auhal output module


  • Subject: Re: VLC needs someone to assist in finishing it's auhal output module
  • From: Steve Checkoway <email@hidden>
  • Date: Tue, 24 May 2005 04:30:24 -0700

On May 19, 2005, at 6:37 AM, Derk-Jan Hartman wrote:

We have tried to develop an auhal output module for the OpenSource VLC media player (http://www.videolan.org/vlc) to tackle the many issues we have with discrete audio on the mac. Unfortunately the OSX developers have no experience in the audio area and we are currently stuck. We need someone to assist us in finishing this so we can put all these issues behind us once and for all.

I only have a tiny bit of experience with CoreAudio. (Just a disclaimer.)


http://developers.videolan.org/cgi-bin/trac.cgi/ticket/12
http://developers.videolan.org/cgi-bin/trac.cgi/browser/trunk/ modules/audio_output/auhal.c?rev=11020


The problems are mostly in the renderer callback. getting the right amount of samples, and doing it at the right time.

Since you mentioned time, I noticed
/* Let's pray for the following operation to be atomic... */
p_sys->clock_diff = - (mtime_t)
AudioConvertHostTimeToNanos( AudioGetCurrentHostTime() ) / 1000;
p_sys->clock_diff += mdate();


in a few places. That seems quite brittle and there is no reason to assmue that it is atomic.

As for the right number of samples, the RenderCallbackAnalog function is passed inNumberFrames so to get the number of samples, you just need to know the number of samples per frame.

If anyone is able to help us fix this before we have to release yet another version with a broken audio output then that would be fantastic.

I agree.

- Steve

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 >VLC needs someone to assist in finishing it's auhal output module (From: Derk-Jan Hartman <email@hidden>)

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