[SDL] threaded audio sync. (for the video heads)

Matt Flax flatmax at Matt.Flax
Thu Sep 1 04:02:43 PDT 2005


I have thought of another way to describe the example I am after ...
for all the video heads out there, think of how you would sync. your 
video frames to the audio clock.

Something like a thread capable library which synchronises callback 
operation on the sound card clock.

In other words, 
* a method to interface to SDL audio using multiple buffers (totalling 
  to a delay of about maximum 40 ms). 
* each buffer requests filling through the user specified callback.

the buffer could be an audio block, a video frame, or perhaps both ?

It must have already been done ... perhaps for video too ???

Any geeks freaked with et ?


On Thu, Sep 01, 2005 at 03:34:29PM +1000, Matt Flax wrote:
> Hello all,
> I would like to use the SDL library for audio signal processing ... more 
> specificly I would like to incorperate WSOLA and SDL to make an audio 
> speed change library.
> OK ... so I am wondering whether anyone knows of any examples which have 
> the following properties :
> a] an init function
> b] a play CALLBACK function which :
> 	loads data from an audio file
> 	signal processes the data
> 	writes the new processed data to the sound device.
> It is important that the play function gets called from an SDL operated 
> thread when need be to read a certain ammount of data for the sound 
> device to play ...
> thanks
> Matt
> -- 
> http://www.flatmax.org
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