[Portaudio] using paFramesPerBufferUnspecified
rossb-lists at audiomulch.com
Tue Dec 15 01:55:24 EST 2015
On 15/12/2015 5:41 PM, Gilles Barges wrote:
> I’d like to use the paFramesPerBufferUnspecified option to shorten
> In this case, it is said that the number of frames for each callback may
Yes, the value may vary. For example, the value might depend on the fill
level of a native audio buffer at the time of the callback. The callback
will ask to fill all the empty space in the buffer.
> So it seems that I have to wait for the callback to occur in order to
> know how many frames I have to push on output.
> In my architecture I have a dedicated thread (not the CB thread) to
> prepare in advance the next chunk of audio.
It would be unusual for there to be benefit to such a scheme, but I
trust you know what you're doing.
> As soon as the callback occurs, I can start to prepare audio.
Do you mean that as soon as one callback is called, you start to prepare
for the next one?
> But here I don’t know how many frames the next callback will ask !
Neither does PortAudio.
> So, is paFramesPerBufferUnspecified only usable when the audio is
> elaborated directly from inside the callback function ?
You can use it however you want. But you won't know how many samples it
needs until the callback is called.
More information about the Portaudio